Tuesday, June 27, 2017

2640. The Energy Expansions of Evolution



By Olivia P. Judson, Nature, April 28, 2017

Abstract

The history of the life–Earth system can be divided into five ‘energetic’ epochs, each featuring the evolution of life forms that can exploit a new source of energy. These sources are: geochemical energy, sunlight, oxygen, flesh and fire. The first two were present at the start, but oxygen, flesh and fire are all consequences of evolutionary events. Since no category of energy source has disappeared, this has, over time, resulted in an expanding realm of the sources of energy available to living organisms and a concomitant increase in the diversity and complexity of ecosystems. These energy expansions have also mediated the transformation of key aspects of the planetary environment, which have in turn mediated the future course of evolutionary change. Using energy as a lens thus illuminates patterns in the entwined histories of life and Earth, and may also provide a framework for considering the potential trajectories of life–planet systems elsewhere.

Free energy is a universal requirement for life. It drives mechanical motion and chemical reactions—which in biology can change a cell or an organism1,2. Over the course of Earth history, the harnessing of free energy by organisms has had a dramatic impact on the planetary environment3, 4, 5, 6, 7. Yet the variety of free-energy sources available to living organisms has expanded over time. These expansions are consequences of events in the evolution of life, and they have mediated the transformation of the planet from an anoxic world that could support only microbial life, to one that boasts the rich geology and diversity of life present today. Here, I review these energy expansions, discuss how they map onto the biological and geological development of Earth, and consider what this could mean for the trajectories of life–planet systems elsewhere.


In the beginning

From the time Earth formed, around 4.56 billion years ago (Ga), two sources of energy were potentially available to living organisms: geochemical energy and sunlight. Sunlight is a consequence of the planet's position in the Solar System, whereas geochemical energy is an intrinsic property of the Earth. Geochemical energy arises when water reacts with basalts and other rocks8, 9, 10. These water–rock reactions—which continue today11—generate reduced compounds such as hydrogen, hydrogen sulfide, and methane8, 9, 10. Oxidation of these compounds releases energy, which organisms can capture and store in the form of chemical bonds. Although sources of geochemical energy can be at or near Earth's surface, they need not be: many are deep within the planet, out of reach of sunlight.
Assuming that life did not parachute in, fully formed, from elsewhere, a number of authors12, 13, 14, 15 have argued that the transition from non-life to life took place in the context of geochemical energy, with the ability to harness sunlight evolving later (Fig. 1). Consistent with this, both phylogenetic16 and biochemical13,17 evidence suggest that the earliest life forms were chemoautotrophs, perhaps living by reacting hydrogen with carbon dioxide and giving off acetate, methane and water13,16. Mounting evidence18, 19, 20, 21, 22 suggests that the transition from non-life to life may have taken place before 3.7 Ga—a time from which few rocks remain23.


Figure 1: Key events during the energy expansions of evolution.
Figure 1
(i) Life emerges; epoch of geochemistry begins. (ii) Anoxygenic photosynthesis: start of energy epoch 2, sunlight. (iii) Emergence of cyanobacteria. (iv) Great Oxidation Event: energy epoch 3, oxygen. (v) Probable eukaryotic fossils appear. (vi) Fossils of red algae appear. (vii) Start of energy epoch 4, flesh. (viii) Vascular plants colonize land; fire appears on Earth. Finally, the burning logs indicate the start of energy epoch 5, fire. The dates of (i)–(iii) are highly uncertain. For (i) I have taken the earliest date for which there is evidence consistent with life20. For (ii) I have taken the earliest date for which there is evidence consistent with photosynthesis18,19,21. For (iii), I have marked the date currently supported by fossil evidence for the presence of cyanobacteria (see main text, ‘Cyanobacteria and the oxygenation of the air’). Tick marks represent intervals of 25 million years. Figure drawn by F. Zsolnai.
Full size image

Energy epoch one: geochemical energy

Analysis of biochemical pathways suggests that, under favourable environmental conditions, early autotrophs could readily have adopted a heterotrophic lifestyle, feeding on the contents of dead cells24. At this time in Earth history, oxygen was at trace levels25, so the first ecosystems would have been anaerobic.
Early ecosystems may have quickly diversified to take the form of a microbial mat, where the waste products of one group of life forms feed the metabolism of another26,27. Such an arrangement generates layered communities of organisms, each layer having a different metabolic speciality28,29. In anaerobic ecosystems of this type, mobile predation is essentially nonexistent: growth rates are so low that hunting and consuming other organisms doesn't yield enough energy30. Viruses, however, are likely to have been an important force from early in the history of life31. They act as agents of death—and by lysing cells, they would have provided additional sources of organic carbon to heterotrophs. Viruses also transport genes from one host to another, and thus may have enabled the spread of evolutionary innovations. Many of the coevolutionary selection pressures of the modern biosphere would have been minimal (for example, predation and the opportunity to live inside other organisms) or absent (for example, sexual selection).
The niches available would have been those near sources of geochemical energy, suggesting a patchy, local distribution of life. Consistent with this, geochemical models32, 33, 34 suggest that the productivity of the biosphere before it was powered by the sun would have been at least a thousand times less than it is today, and may have been one million times less.
Owing to the scarcity of rocks from Earth's remote past, the impact of early life on the planetary environment is also hard to assess. Life inevitably creates a suite of changes in its environment (Box 1), and the establishment of life would have initiated biogeochemical cycling, but owing to the low productivity of the biosphere, the initial effects are likely to have been small32, 33, 34.


Energy epoch two: sunlight

At some point early in the history of the Earth—perhaps by 3.7 Ga18,19,21(Fig. 1)—organisms evolved to harness the energy in sunlight to drive chemical reactions. Today, several groups of bacteria engage in photosynthesis, using a variety of different pathways35. One pathway, oxygenic photosynthesis, gives off oxygen as a by-product; the others, all forms of anoxygenic photosynthesis, do not. Genetic35, fossil36, and biochemical37 evidence all suggest that of the two, anoxygenic photosynthesis evolved first.
Because sunlight is abundant across the planet's surface, the ability to use it made far more of the planet available to life. Consistent with this, models of the early Earth suggest that the advent of anoxygenic photosynthesis greatly increased the productivity of early ecosystems32,33. At the same time, microbial ecosystems were able to become more diverse. Forms of photoheterotrophy38 may also have begun to evolve. This lifestyle does not involve fixing carbon—organisms still require a source of organic carbon—but does involve transducing sunshine into ATP, which reduces energy needs from other sources.
During this epoch, the impact of life on the planetary environment expanded too. Structures such as stromatolites39 and banded iron formations19 began to appear, and methane may have started to build up in the atmosphere40. Indeed, the climate of the early Earth appears to have been temperate41 despite the fact that, back then, the sun had only about 70% of its current brightness42. Methane, along with ethane, which can be produced from methane by photochemical reactions in the atmosphere43, are greenhouse gases: thus, methane production on the part of living organisms may have helped to keep the early Earth from freezing25,43.
But the crucial event of this period—the one that would go on to have by far the most biological and geological impact—was the evolution of oxygenic photosynthesis, an innovation that appeared in just one phylum, the cyanobacteria.
Cyanobacteria and the oxygenation of the air. In the absence of a biotic source of oxygen, trace quantities of the gas can be generated abiotically: water molecules can be split by sunlight44 or radioactive decay45. However, these abiotic processes are much less efficient than their biotic equivalent34,44. Had cyanobacteria, or something like them, never evolved, oxygen would never have built up in the atmosphere of the Earth.
But build up it did. Between 2.45 and 2.32 Ga (ref. 46), significant quantities of oxygen began to accumulate in the air, an episode known as the Great Oxidation Event. Before the Great Oxidation, atmospheric oxygen levels were less than 10−5 of the present atmospheric level of ∼21%. By ∼2 Ga, they had risen to perhaps 0.1–1% of the present atmospheric level25. Although the subsequent history of oxygen is complex and many details are uncertain47,48, Earth's atmosphere has contained an appreciable level of the gas ever since. (Full oxygenation of the oceans, however, would not happen until around 1.8 billion years after the Great Oxidation47.)
Of all the events in the early history of the Earth, the Great Oxidation is the least controversial. It marks a line across the history of the planet, with a suite of geological markers showing a shift in the prevailing chemistry44,49. In contrast, there is enormous uncertainty about when cyanobacteria first evolved, with estimates spanning a period of one billion years35,47. However, genetic50, fossil51, and geochemical47,52evidence all suggest that cyanobacteria evolved at least 300 million years before the Great Oxidation Event.
But if cyanobacteria evolved hundreds of millions of years before the Great Oxidation, why did oxygen take so long to accumulate? This question has been studied extensively, and various hypotheses have been put forward (for a review see refs 25,53). In essence, though, it's a matter of planetary chemistry. Both the atmosphere and ocean of the early Earth were full of molecules such as hydrogen, methane and ferrous iron that oxygen reacts with; oxygen may thus have been removed as fast as it was produced25,54. Until sources of oxygen began to exceed the sinks, the gas would have been unable to accumulate25.
Even before the Great Oxidation, the emergence of cyanobacteria would have increased both the productivity and complexity of microbial ecosystems. As well as a variety of heterotrophs, modern microbial mats and stromatolites often contain photosynthetic organisms of several different types55. Moreover, in evolving to extract electrons from the hydrogen in water, rather than from substances such as ferrous iron or hydrogen sulfide, cyanobacteria would have been far less constrained in the habitats they could occupy. Cyanobacteria may even have been among the first organisms to colonize land surfaces56, increasing the weathering of rocks, and thus the flow of nutrients into the oceans57. But these impacts are dwarfed by those that resulted from the accumulation of oxygen in the air.
Oxygen and the planetary environment. The Great Oxidation Event had a dramatic impact on the planetary environment. First, the transition to an oxygen-rich atmosphere took place in tandem with the establishment of the ozone layer54,58,59, thus changing the physical context in which organisms, especially those on land, evolve. Second, the diversity of minerals at the Earth's surface began to increase60, eventually more than doubling61.
Third, the appearance of atmospheric oxygen created a variety of new abiotic niches. As well as the anoxic and micro-oxic niches that had existed from the outset, the oxygenation of the atmosphere created an abundance of oxygen-rich niches, too. Today, aerobic prokaryotes show an enhanced ability to tolerate extremes of salinity and pH compared to their anaerobic counterparts62, suggesting that the availability of oxygen might also have allowed for the colonization of other, previously inaccessible, abiotic niches. At the same time, the availability of oxygen would have increased the availabilities of oxidants such as nitrate and sulfate—and thus would also have increased the productivity of chemotrophic life forms.
Fourth, the Great Oxidation seems to have coincided with a series of extreme ice ages63. The reasons for this are unresolved63, but some authors25,64,65 have suggested it could have been due to a decline in the flux of biogenic methane reaching the atmosphere, and a corresponding decline in the contribution of methane and its byproducts to keeping the climate warm.
But the most significant environmental impact of the Great Oxidation was a change in the prevailing chemistry, and the ready availability of oxygen gas as a source of energy for living organisms.

Energy epoch three: oxygen

Oxygen is a rich source of energy: the use of oxygen as an electron acceptor releases more energy per electron transfer than that of any other element except for chlorine and fluorine66. (Neither chlorine nor fluorine is cosmically abundant, however, and both are so reactive as to be an unlikely foundation for any kind of biology66.) The diversification of the biosphere that would ultimately take place was, to a large extent, enabled by the growing abundance of oxygen.
The emergence of the ability of living organisms to use oxygen as an energy source is shrouded in at least as much mystery as the emergence of cyanobacteria. At issue is whether early life forms could have evolved to use trace oxygen or hydrogen peroxide produced through abiotic processes67—and thus whether aerobic respiration originated before the advent of cyanobacteria, or whether it evolved in conjunction with them. Whatever the case, long before the Great Oxidation Event, aerobic organisms, if they existed, could have prospered in oxygen-rich oases generated by cyanobacteria68,69.
As well as being a source of energy, oxygen is both a biological problem and an opportunity. Problem: the presence of oxygen inactivates some enzymes, and oxygen derivatives such as hydrogen peroxide and the superoxide ion are reactive compounds that damage both DNA and proteins70,71. To survive in the presence of oxygen, organisms need a superstructure of protective enzymes. Opportunity: the availability of oxygen permits the construction of new molecules, such as collagen72.
During this epoch, two momentous events took place: the emergence of eukaryotes and the emergence of the lineage that would eventually produce land plants. Both events represent fusions between two previously independent lineages, an archaeon and an alphaproteobacterium in the case of eukaryotes73,74, and a eukaryote and a cyanobacterium in the case of the plant lineage75; the alphaproteobacterium evolved to become the mitochondrion, the cyanobacterium, the chloroplast. Both events thus also represent important shifts in the capacity for organisms to transduce energy. Fossils of red algae show that both events had taken place by ∼1.2 Ga (ref. 76), and microfossils that are probably eukaryotic in origin date to 1.8 Ga (ref. 77).
In extant eukaryotes, organelles of mitochondrial origin take several different, but related, forms78. Notably, only one—the ‘standard’ mitochondrion found, for example, in humans—requires oxygen. Three others are involved in forms of anaerobic metabolism; of these, two produce hydrogen. These observations fit with the hypothesis, advanced by Martin and colleagues74,79, that the ancestral eukaryote resulted from a prior symbiotic association between a hydrogen-dependent archaeon and a metabolically flexible alphaproteobacterium that, in the absence of oxygen, lived anaerobically producing hydrogen, and in the presence of oxygen, lived aerobically. If this hypothesis is correct, the ancestral eukaryote could have been a facultative anaerobe, able to live in both oxic and anoxic environments. Such a scenario not only accounts for the different types of mitochondria seen in extant eukaryotes78, but also for the fact that, today, species with mitochondria that produce ATP through anaerobic pathways are sprinkled across the eukaryotic tree while exhibiting a similar underlying biochemistry78,80.
Eukaryotes differ from prokaryotes in many respects, from meiosis and syngamy to the presence of a cell nucleus, as well as a suite of other features. In addition, complex multicellularity and large size has evolved only in eukaryotes—which Lane and Martin81 have attributed to an enhanced capacity to generate energy owing to the possession of mitochondria (Box 2). From the point of view of the biosphere, the emergence and diversification of eukaryotes provided a new set of niches for prokaryotes to occupy—which in turn allowed eukaryotes to occupy a far wider variety of niches. Today, most, perhaps all, eukaryotes have symbiotic dependencies on consortia of prokaryotes—microbiomes—that give them access to a greater variety of energy sources and metabolic capabilities82.



For the purposes of this Perspective, however, one feature of eukaryotes is particularly important. This is the ability to engage in phagocytosis—the engulfment of particles and, sometimes, other life forms. The wholesale engulfment of other beings appears to be a eukaryotic invention83, and it whets the appetite for:

Energy epoch four: flesh

Around 575 million years ago (Ma), during the Ediacaran Period, a new form of life began to become abundant: animals84. And with animals would soon come a powerful new force of nature: the acquisition of energy through the active hunting and eating of other life forms, especially, other animals. This would produce a radical shift that, within a mere 40 million years, transformed the Earth. Before this epoch, ecosystems were microbial. The advent of widespread flesh-eating launched the Phanerozoic, triggering an enormous increase in organism size85, a new tempo of macroevolutionary change86,87, new kinds of ecosystems86, 87, 88, and an increased impact of life on the fabric of the planet87.
As in the case of oxygen, however, flesh-eating has a prehistory. Predation by single-celled eukaryotes may have caused the evolution of the first armoured algae, around 770 Ma89, 90, 91, as well as a major increase in eukaryotic diversity92. Moreover, animals represent one of several transitions to complex multicellular life93—transitions that Stanley86 suggested might, in part, have resulted from single-celled eukaryotes engulfing and consuming each other. Indeed, molecular clocks show that the first animals also evolved around this time94,95(Box 3), leading Knoll and Lahr92 to propose that tiny animals might have helped drive the diversification of eukaryotic protists.



Today, animals influence diversity at all levels of an ecosystem, with grazers such as slugs96 or zooplankton97 maintaining the diversity of plants or phytoplankton, and carnivores such as wolves98 maintaining the diversity of plants through their predation on herbivores. This kind of ecology—complex food webs with many types of eaters—was absent from Earth until around 550 Ma, when the first animals that eat animals evolved. Their appearance seems to have triggered the rapid diversification of animal life sometimes referred to as the Cambrian Explosion.
In addition to their effects on the structure of ecosystems, the flourishing of flesh-eating animals heralded a step-change in both biomass and biodiversity87. In the oceans today, for example, Butterfield87 has estimated that animals may comprise as much as 80% of the biomass in the pelagic zone. Furthermore, with the evolution of animals, new coevolutionary selection pressures—in particular, arms races between the eaters and the eaten—appeared, accelerating the pace of macroevolution99. At the same time, animal guts and external surfaces provided new niches for other life forms, both symbiotic and hostile.
On the geological side, the flourishing of animals had at least four major impacts. First, the evolution of predation rapidly led to the evolution of armour—shells, scales, spikes and carapaces built from materials such as calcite and silica100. Although, as noted above, the first protective coverings (on algae) date back to around 770 Ma (ref. 90), it's not until the evolution of flesh-eating animals that shells and other forms of protection became widespread. This development would eventually result in vast deposits of materials such as radiolarite101, limestone102, coquina103 and chalk104 and would also produce changes in ocean chemistry, as organisms removed dissolved materials such as silica and calcium and used it for themselves105,106.
Second, animals produce faeces, which have important effects on the way that nutrients are distributed around the globe. For example, in the ocean, zooplankton faecal pellets sink more rapidly than individual algal or bacterial cells, and thus transport organic matter from the surface to the seabed107. Today, the faeces of sperm whales bring iron from the deep sea to the ocean surface108; the faeces of birds like cormorants transport nutrients from the ocean onto land, sometimes in fantastic quantities109.
A third geological impact of animals is caused by their ability to burrow. Simple, horizontal burrows appear in the fossil record around 555 Ma (ref. 110); by the early Cambrian, the abundance, size, depth and complexity of burrows had increased considerably110. Widespread burrowing creates a mixing of sediments known as bioturbation. As Darwin111 observed with respect to earthworms, burrowing is analogous to ploughing: it redistributes nutrients as well as sifting, irrigating, and aerating sediments and soils.
Finally, from bioturbation, faeces, and the evolution of armour, a fourth major impact of flesh-eating life forms emerges: a reorganization of Earth's biogeochemical cycles105,112, 113, 114.

Energy epoch five: fire

Of all the planets and moons in the Solar System, Earth is the only one to have fire. This is because, to have fire, all of three conditions must be met. (1) Fire needs a source of ignition—such as lightning strikes. Throughout Earth history, these have been abundant; today, there are more than 1.4 billion lightning strikes per year (ref. 115), of which an appreciable number ignite wildfires116. Lightning occurs on other planets117, but none of these meets the other two conditions. (2) Fire needs oxygen. Assuming current atmospheric pressure, Earth's air must contain at least 16% of the gas118,119. For most of Earth's history, oxygen levels have been lower than this threshold. (3) Fire needs fuel. So it is not until the evolution of vascular plants on land, around 420 Ma, that all three conditions were met120.
From the start, fire has had both geological and biological impacts. Fire regimes drive the evolution of plant traits121; fires affect soils and air quality; and although, each year, a significant amount of biomass goes up in smoke, fire can promote biodiversity122. Fire may even have driven the initial spread of flowering plants123—an event that led to radiations of many other groups, including ants124, bees125 and mammals126. Furthermore, fire contributes new material to the Earth—charcoal, ash and soot—and may also act as a control on planetary oxygen levels127. But as an energy source, per se? That's a more recent development, and has come in two phases.
The first phase began with the evolution of a fire creature. This creature—a member of the genus Homo128—began to control the use of fire, deliberately setting fires alight and using fire for cooking. Exactly when cooking began remains controversial, with possible dates ranging from 1.5 Ma to 0.4 Ma (ref. 129). The important point, though, is that cooking is a kind of predigestion: cooked food, be it meat130, vegetable130 or lipid131, delivers more energy than the same food eaten raw. In using fire to cook food, hominins thus developed a way to extract more energy from their diets, and to eat a wider variety of food.
The second phase of fire as an energy source is even more recent—but the onset is nonetheless difficult to pinpoint. Does it start with the use of fire to manufacture labour-saving tools? With the smelting of iron, something otherwise energetically impossible? With the burning of fossil fuels such as coal to generate heat and light? With the invention of the internal combustion engine? Or with the discovery of the Haber–Bosch process for fixing nitrogen—which, in 1925, Alfred Lotka132described as the start of “a new cosmic epoch”? Perhaps these last three are the most important contenders, as together, they have transformed the planet7. In particular, the human input of energy to manufacture and deliver an otherwise limiting nutrient has produced far higher crop yields, enormously larger human populations, and gigantic populations of human-associated animals such as pigs, cows, horses and chickens133. Erisman and colleagues134 estimate that between 1908 and 2008, industrially produced nitrogen fertilizer supported an additional four billion people and that by 2008, nitrogen fertilizers were responsible for feeding 48% of the human population. Meanwhile, Pimm and colleagues135 judge that extinction rates are now 1,000 times greater than the typical background rate. In sum, in this epoch of fire, total biomass has remained high, but biodiversity has begun to fall.
The geological impacts of the age of fire are also poised to be dramatic, with rising levels of carbon dioxide and other greenhouse gases in the air, rising sea levels, increasing levels of nitrogen and plastic pollution, a remaking of the landscape with mines, tunnels, dams and cities, the introduction of new chemical compounds, and massive shifts in several biogeochemical cycles. However, the full geological effects of this epoch are, as yet, unknown.

Implications

Different schemata for considering the history of life allow different types of insights. For example, de Duve136 identified a series of (mostly) biochemical events that happened just once, and discussed to what extent they would be likely to happen again were the tape of life to be replayed. Knoll and Bambach137 put forward six ‘megatrajectories’ in the history of life, where each megatrajectory corresponds to the ecological diversification of a new type of life form (prokaryotes, unicellular eukaryotes, land plants, etc), thus linking evolutionary change with ecological complexity. And famously, Maynard Smith and Szathmáry138,139 proposed a framework based on transitions between different replicating units (genes, chromosomes, individuals, and so on); this has been profoundly helpful in generating a deeper understanding of the levels at which natural selection operates140.
In recent work, Lenton and colleagues7 developed a schema for thinking about ‘revolutions’ in the history of life and Earth. As in the Perspective presented here, their focus is energy. But rather than considering expansions in the types of energy underpinning the biosphere, the authors examined a series of changes in free energy inputs and how these have altered global material cycles. On the basis of their analyses, they conclude that human sustainability will not only require a shift from fossil fuel to solar power, but also a far more active effort to recycle materials such as metals.
Here, I have taken a more bottom-up approach. In considering expansions in the types of energy underpinning the biosphere, I have sought to describe the step-wise construction of a life–planet system. Using energy expansions as the lens reveals a fundamental, recursive interplay between events in the evolution of life and the development of the planetary environment. From this viewpoint, a number of insights emerge.
First, increasing the types of energy sources available to life has led to a far more complex biosphere. Although only geochemical energy and sunlight can power the de novo transformation of inorganic carbon into living tissue, the complexity of the current biosphere rests on multiple levels of energy use. Cyanobacteria, for instance, often require the presence of non-light-using consort organisms in order to grow well141, 142, 143. Conversely, owing to the metabolic capacities of their prokaryotic symbionts and endosymbionts, eukaryotes are able to live in a far wider range of environments than they could otherwise access82. The step-wise diversification of the biosphere has, in turn, led to an expansion of possible niches, from more complex microbial mats to old shells and abandoned burrows. At the same time, the capacity of life to impact the planetary environment—and thereby the environment in which future life will evolve—has expanded dramatically with each epoch.
Because the construction of the biosphere has depended on these energy expansions, the vanishing of an energy source, even temporarily, could cause a corresponding contraction in the biosphere. In the context of the Phanerozoic, some authors have attributed large-scale patterns of both biospheric expansion and contraction to corresponding fluctuations in oxygen availability, with expanding ocean anoxia corresponding to mass extinction events (end-Permian144,145; end Triassic146). Likewise, Krin147 has suggested that one factor in the mass extinction at the end of the Cretaceous may have been dust ejected by the Chicxulub asteroid impact, which may have blocked out the sun long enough to cause a global collapse in photosynthesis. Quantifying this pattern further would be an interesting line for future research.
A related avenue for future research would be an examination of macroevolutionary trends of energy use. For example, Vermeij148 argued that the Phanerozoic has been characterized by the repeated replacement of low-energy life forms by those able to harness larger amounts of energy. Among the trends he identified were endotherms tending to replace ectotherms, and angiosperms tending to replace gymnosperms. (The lower-energy form does not always become extinct; sometimes its range is just restricted to a low-energy environment.) Investigating this trend for earlier epochs—or even applying it to human societies149—might be enlightening.
A second insight that emerges from this Perspective is that the two clear inflection points in the history of Earth—the Great Oxidation Event and the emergence of mobile animals—also coincide with expansions in the kinds of energy sources available to, and consumed by, living beings. The Great Oxidation shifted the prevailing chemistry of the atmosphere and upper ocean and made oxygen gas abundant. The emergence of life forms that eat one another transformed the nature of ecosystems, and introduced a powerful new set of evolutionary interactions, thus accelerating the pace of macroevolutionary change. From this point of view, the familiar observation that Earthly life is powered by the sun takes on a more nuanced aspect: the modern biosphere is powered not merely by sunshine but by the oxygen that results from using sunshine in a particular way.
This Perspective further suggests that, through the harnessing of fire as a source of energy, Earth has now arrived at a new inflection point. Considering life–Earth history through the lens of energy expansions supports the view that the Anthropocene is a genuinely novel phase of the planet's geological and biological development—a conclusion independently reached by Lenton and colleagues7. The technology of fire may also, perhaps, mark an inflection point for the Solar System and beyond. Spacecraft from Earth may, intentionally or not, take Earthly life to other celestial objects (though whether any Earthly life forms can thrive elsewhere remains unknown).
As this is the only life–planet system we currently know of, it is impossible to know how representative it is of life–planet systems in general. But if the development of other life–planet systems requires a similar series of energy expansions, the framework presented here suggests a way to anticipate the paths that such systems might take. For instance, if a planet has only geochemical energy—perhaps because it is far from its star, or because it is a nomad150,151 and has no star at all—any life present may have “a limited future in terms of the heights it could achieve”152. Or suppose a planet is unable to accumulate oxygen. This could happen if living organisms never evolve a way of splitting water to produce the gas in the first place6,153; but even if they do, the planet itself may have characteristics that prevent oxygen from ever building up6,66. Without oxygen, the geological, ecological and evolutionary potential of a life–planet system is likely to be constrained, even if life forms analogous to eukaryotes in their energy-harnessing power (Box 2) were to evolve. Conversely, some planets might be able to accumulate new forms of energy, and life forms able to take advantage of them, much faster than Earth has66.
In short, this Perspective of energy expansions suggests that the likely development of a life–planet system will depend on the interplay between the planet's cosmic situation, its intrinsic properties, and the paths that evolving life can potentially take. The example of this life–planet system suggests that the development of a flourishing, complex biosphere depends on a virtuous circle between evolving life forms and transformations of their planetary home.

Additional information

How to cite this article: Judson, O. P. The energy expansions of evolution. Nat. Ecol. Evol. 1, 0138 (2017).
Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  1. 1.
    ,  &  Energy conservation in chemotrophic anaerobic bacteria. Bacteriol. Rev. 41, 100–180 (1977).
  2. 2.
     &  Energetics of overall metabolic reactions of thermophilic and hyperthermophilic Archaea and Bacteria. FEMS Microbiol. Rev. 25, 175–243 (2001).
  3. 3.
     La Biosphère (Félix Alcan, 1929).
  4. 4.
     Atmospheric and hydrospheric evolution on the primitive earth. Science 160, 729–736 (1968).
  5. 5.
     General Energetics: Energy in the Biosphere and Civilization (John Wiley and Sons, 1991).
  6. 6.
     &  Revolutions that Made the Earth (Oxford Univ. Press, 2011).
  7. 7.
    ,  &  Revolutions in energy input and material cycling in Earth history and human history. Earth Syst. Dynam. 7, 353–370 (2016).
  8. 8.
    , ,  &  Catabolic and anabolic energy for chemolithoautotrophs in deep-sea hydrothermal systems hosted in different rock types. Geochim. Cosmochim. Acta 75, 5736–5748 (2011).
  9. 9.
    , , ,  &  Hydrogen generation from low-temperature water–rock reactions. Nat. Geosci. 6, 478–484 (2013).
  10. 10.
     &  Serpentinites, hydrogen, and life. Elements 9, 129–134 (2013).
  11. 11.
    , ,  & Pathways for abiotic organic synthesis at submarine hydrothermal fields. Proc. Natl Acad. Sci. USA 112, 7668–7672 (2015).
  12. 12.
    ,  &  Serpentinization as a source of energy at the origin of life. Geobiology 8, 355–371 (2010).
  13. 13.
    ,  &  How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays 32, 271–280 (2010).
  14. 14.
    , , ,  &  The role of energy in the emergence of biology from chemistry. Orig. Life Evol. Biosph. 42, 459–468 (2012).
  15. 15.
     et al. Early bioenergetic evolution. Phil. Trans. R. Soc. Lond. B 368, 20130088 (2013).
  16. 16.
     et al. The physiology and habitat of the last universal common ancestor. Nat. Microbiol. 1, 16116 (2016).
  17. 17.
     &  The stepwise evolution of early life driven by energy conservation. Mol. Biol. Evol. 23, 1286–1292 (2006).
  18. 18.
     13C-depleted carbon microparticles in >3700-Ma sea-floor sedimentary rocks from west Greenland. Science 283, 674–676 (1999).
  19. 19.
     et al. Atmospheric hydrogen peroxide and Eoarchean iron formations. Geobiology 13, 1–14 (2015).
  20. 20.
    , ,  &  Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon. Proc. Natl Acad. Sci. USA 112, 14518–14521 (2015).
  21. 21.
    , , ,  &  Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures. Nature 537, 535–538 (2016).
  22. 22.
     et al. Evidence for early life in Earth's oldest hydrothermal vent precipitates. Nature 543, 60–64 (2017).
  23. 23.
     Mineral environments on the earliest Earth. Elements 6, 25–30 (2010).
  24. 24.
    ,  &  On the origin of heterotrophy. Trends Microbiol. 24, 12–25 (2016).
  25. 25.
     in Treatise on Geochemistry 2nd edn (eds Holland, H.& Turekian, K.) 6, 177–195 (Elsevier, 2014).
  26. 26.
     &  Archaean metabolic evolution of microbial mats. Proc. R. Soc. Lond. B 266, 2375–2382 (1999).
  27. 27.
    , ,  & Physiological differentiation within a single-species biofilm fueled by serpentinization. mBio 2, e00127–11 (2011).
  28. 28.
     Energetics of syntrophic cooperation in methanogenic degradation. Microbiol. Mol. Biol. Rev. 61, 262–280 (1997).
  29. 29.
     &  Life: past, present and future. Phil. Trans. R. Soc. Lond. B 354, 1923–1939 (1999).
  30. 30.
     &  Ecology and Evolution in Anoxic Worlds(Oxford Univ. Press, 1995).
  31. 31.
     &  The origin of viruses. Res. Microbiol.160, 466–472 (2009).
  32. 32.
    ,  &  A coupled atmosphere–ecosystem model of the early Archean Earth. Geobiology 3, 53–76 (2005).
  33. 33.
    ,  &  Early anaerobic metabolisms. Phil. Trans. R. Soc. Lond. B 361, 1819–1836 (2006).
  34. 34.
     &  Niches of the pre-photosynthetic biosphere and geologic preservation of Earth's earliest ecology. Geobiology 5, 101–117 (2007).
  35. 35.
    ,  &  Evolution of oxygenic photosynthesis. Annu. Rev. Earth Planet. Sci. 44, 647–683 (2016).
  36. 36.
     &  Hydrogen-based carbon fixation in the earliest known photosynthetic organisms. Geology 34, 37–40 (2006).
  37. 37.
     &  Evolution of photosynthesis. Annu. Rev. Plant Biol. 62, 515–548 (2011).
  38. 38.
     Photoheterotrophy in marine prokaryotes. J. Plankton Res. 31, 933–938 (2009).
  39. 39.
    ,  &  A likely role for anoxygenic photosynthetic microbes in the formation of ancient stromatolites. Geobiology 5, 119–126 (2007).
  40. 40.
    , , ,  & Evidence from fluid inclusions for microbial methanogenesis in the early Archaean era. Nature 440, 516–519 (2006).
  41. 41.
     &  Processes on the young Earth and the habitats of early Life. Annu. Rev. Earth Planet. Sci. 40, 521–549 (2012).
  42. 42.
     &  Earth and Mars: evolution of atmospheres and surface temperatures. Science 177, 52–56 (1972).
  43. 43.
    , ,  &  A revised, hazy methane greenhouse for the Archean Earth. Astrobiology 8, 1127–1137 (2008).
  44. 44.
     &  How Earth's atmosphere evolved to an oxic state: a status report. Earth Planet. Sci. Lett. 237, 1–20 (2005).
  45. 45.
     Radiolysis of water: a look at its origin and occurrence in the nature. Radiat. Phys. Chem. 72, 181–186 (2005).
  46. 46.
     et al. Dating the rise of atmospheric oxygen. Nature427, 117–120 (2004).
  47. 47.
    ,  &  The rise of oxygen in Earth's early ocean and atmosphere. Nature 506, 307–315 (2014).
  48. 48.
    ,  &  The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans. Environ. Microbiol. 18, 325–340 (2016).
  49. 49.
     The problem of the Precambrian atmosphere. S. Afr. J. Sci. 24, 155–172 (1927).
  50. 50.
    , ,  &  The evolutionary diversification of cyanobacteria: molecular–phylogenetic and paleontological perspectives. Proc. Natl Acad. Sci. USA 103, 5442–5447 (2006).
  51. 51.
    , ,  &  Morphological record of oxygenic photosynthesis in conical stromatolites. Proc. Natl Acad. Sci. USA 106, 10939–10943 (2009).
  52. 52.
    ,  &  Geological constraints on the origin of oxygenic photosynthesis. Photosynth. Res. 107, 11–36 (2011).
  53. 53.
     What caused the rise of atmospheric O2? Chem. Geol.362, 13–25 (2013).
  54. 54.
    ,  &  Bistability of atmospheric oxygen and the Great Oxidation. Nature 443, 683–686 (2006).
  55. 55.
    , ,  &  Composition and structure of microbial communities from stromatolites of Hamelin Pool in Shark Bay, Western Australia. Appl. Environ. Microbiol. 71, 4822–4832 (2005).
  56. 56.
    ,  &  Geochemical evidence for terrestrial ecosystems 2.6 billion years ago. Nature 408, 574–578 (2000).
  57. 57.
    ,  &  Contributions to late Archaean sulphur cycling by life on land. Nat. Geosci. 5, 722–725 (2012).
  58. 58.
     &  Evolution of a habitable planet. Annu. Rev. Astron. Astrophys. 41, 429–463 (2003).
  59. 59.
    ,  &  Biogeochemical modelling of the rise in atmospheric oxygen. Geobiology 4, 239–269 (2006).
  60. 60.
     &  The Great Oxidation Event and mineral diversification. Elements 6, 31–36 (2010).
  61. 61.
     et al. Mineral evolution. Am. Mineral. 93, 1693–1720 (2008).
  62. 62.
     et al. Aerobically respiring prokaryotic strains exhibit a broader temperature-pH-salinity space for cell division than anaerobically respiring and fermentative strains. J. R. Soc. Interface 12, 20150658 (2015).
  63. 63.
     et al. in Reading the Archive of Earth's Oxygenation(eds Melezhik, V. A. et al.) 1059–1109 (Springer, 2013).
  64. 64.
    ,  &  The loss of mass-independent fractionation in sulfur due to a Palaeoproterozoic collapse of atmospheric methane. Geobiology 4, 271–283 (2006).
  65. 65.
     &  The effect of widespread early aerobic marine ecosystems on methane cycling and the Great Oxidation. Earth Planet. Sci. Lett. 434, 42–51 (2016).
  66. 66.
    , ,  &  Why O2 is required by complex life on habitable planets and the concept of planetary “oxygenation time”. Astrobiology 5, 415–438 (2005).
  67. 67.
    ,  &  Availability of O2 and H2O2on pre-photosynthetic Earth. Astrobiology 11, 293–302 (2011).
  68. 68.
    ,  &  Quantifying the areal extent and dissolved oxygen concentrations of Archean oxygen oases. Chem. Geol. 362, 35–43 (2013).
  69. 69.
     &  Biogeochemical transformations in the history of the ocean. Annu. Rev. Mar. Sci. 9, 31–58 (2017).
  70. 70.
    ,  &  Reactive oxygen intermediates in biochemistry. Annu. Rev. Biochem. 55, 137–166 (1986).
  71. 71.
     The molecular mechanisms and physiological consequences of oxidative stress: lessons from a model bacterium. Nat. Rev. Microbiol. 11, 443–454 (2013).
  72. 72.
     Oxygen-collagen priority and the early metazoan fossil record. Proc. Natl Acad. Sci. USA 65, 781–788 (1970).
  73. 73.
    , ,  &  An archaeal origin of eukaryotes supports only two primary domains of life. Nature 504, 231–236 (2013).
  74. 74.
    ,  &  Endosymbiotic theories for eukaryote origin. Phil. Trans. R. Soc. Lond. B 370, 20140330 (2015).
  75. 75.
     The number, speed, and impact of plastid endosymbioses in eukaryotic evolution. Annu. Rev. Plant Biol. 64, 583–607 (2013).
  76. 76.
     Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes. Paleobiology 26, 386–404 (2000).
  77. 77.
     Paleobiological perspectives on early eukaryotic evolution. Cold Spring Harb. Perspect. Biol. 6, a016121 (2014).
  78. 78.
     et al. Biochemistry and evolution of anaerobic energy metabolism in eukaryotes. Microbiol. Mol. Biol. Rev. 76, 444–495 (2012).
  79. 79.
     &  The hydrogen hypothesis for the first eukaryote. Nature 392, 37–41 (1998).
  80. 80.
     &  The rise of oxygen and complex life. J. Eukaryot. Microbiol. 59, 111–113 (2012).
  81. 81.
     &  The energetics of genome complexity. Nature 467, 929–934 (2010).
  82. 82.
     Symbiosis as a general principle in eukaryotic evolution. Cold Spring Harb. Perspect. Biol. 6, a016113 (2014).
  83. 83.
    , ,  &  The origins of phagocytosis and eukaryogenesis. Biol. Direct 4, 9 (2009).
  84. 84.
     The Ediacara biota: Neoproterozoic origin of animals and their ecosystems. Annu. Rev. Earth Planet. Sci. 33, 421–442 (2005).
  85. 85.
     et al. Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity. Proc. Natl Acad. Sci. USA 106, 24–27 (2009).
  86. 86.
     An ecological theory for the sudden origin of multicellular life in the late Precambrian. Proc. Natl Acad. Sci. USA70, 1486–1489 (1973).
  87. 87.
     Macroevolution and macroecology through deep time. Palaeontology 50, 41–55 (2007).
  88. 88.
     Origins and early evolution of predation. Paleontol. Soc. Papers 8, 289–318 (2002).
  89. 89.
     &  Testate amoebae in the Neoproterozoic Era: evidence from vase-shaped microfossils in the Chuar Group, Grand Canyon. Paleobiology 26, 360–385 (2000).
  90. 90.
     The rise of predators. Geology 39, 607–608 (2011).
  91. 91.
     &  Scale microfossils from the mid-Neoproterozoic Fifteenmile Group, Yukon Territory. J. Paleontol.86, 775–800 (2012).
  92. 92.
     &  in Multicellularity: Origins and Evolution (eds Niklas, K. J. & Neumann, S. D.) 3–16 (MIT Press, 2016).
  93. 93.
     The origins of multicellularity and the early history of the genetic toolkit for animal development. Annu. Rev. Genet. 42, 235–251 (2008).
  94. 94.
     et al. The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334, 1091–1097 (2011).
  95. 95.
    , ,  &  Estimating the timing of early eukaryotic diversification with multigene molecular clocks. Proc. Natl Acad. Sci. USA 108, 13624–13629 (2011).
  96. 96.
    , , ,  & The effect of slug grazing on vegetation development and plant species diversity in an experimental grassland. Funct. Ecol. 19, 291–298 (2005).
  97. 97.
     The paradox of the plankton. Am. Nat. 95, 137–145 (1961).
  98. 98.
     &  Trophic cascades in Yellowstone: the first 15 years after wolf reintroduction. Biol. Conserv. 145, 205–213 (2012).
  99. 99.
     Animals and the invention of the Phanerozoic Earth system. Trends Ecol. Evol. 26, 81–87 (2011).
  100. 100.
     The origin of skeletons. Palaios 4, 585–589 (1989).
  101. 101.
     Mesozoic radiolarites–accumulation as a function of sea surface fertility on Tethyan margins and in ocean basins. Sedimentology 60, 292–318 (2013).
  102. 102.
     Towards an unbiased estimate of fluctuations in reef abundance and volume during the Phanerozoic. Biogeosciences 3, 15–27 (2006).
  103. 103.
     &  Patterns in bioclastic accumulation through the Phanerozoic: Changes in input or in destruction? Geology 22, 1139–1143 (1994).
  104. 104.
     Influence of seawater chemistry on biomineralization throughout Phanerozoic time: Paleontological and experimental evidence. Palaeogeogr. Palaeoclimatol. Palaeoecol. 232, 214–236 (2006).
  105. 105.
    ,  &  Secular change in chert distribution: a reflection of evolving biological participation in the silica cycle. Palaios 4, 519–532 (1989).
  106. 106.
     &  in Coccolithophores: From Molecular Processes to Global Impact (eds Thierstein, H. R. & Young, J. R.) 99–125 (Springer, 2004).
  107. 107.
     &  Role of large particles in the transport of elements and organic compounds through the oceanic water column. Prog. Oceanog. 16, 147–194 (1986).
  108. 108.
     et al. Iron defecation by sperm whales stimulates carbon export in the Southern Ocean. Proc. R. Soc. Lond. B 277, 3527–3531 (2010).
  109. 109.
     The biogeochemistry of vertebrate excretion. Bull. Am. Mus. Nat. Hist. 96, 1–554 (1950).
  110. 110.
     &  When life got smart: the evolution of behavioral complexity through the Ediacaran and early Cambrian of NW Canada. J. Paleontol. 88, 309–330 (2014).
  111. 111.
     The Formation of Vegetable Mould, Through the Action of Worms, with Observations on Their Habits (John Murray, 1881).
  112. 112.
     &  Animal evolution, bioturbation, and the sulfate concentration of the oceans. Proc. Natl Acad. Sci. USA106, 8123–8127 (2009).
  113. 113.
     et al. Stabilization of the coupled oxygen and phosphorus cycles by the evolution of bioturbation. Nat. Geosci. 7, 671–676 (2014).
  114. 114.
    , ,  & Terminal Proterozoic reorganization of biogeochemical cycles. Nature 376, 53–56 (1995).
  115. 115.
     et al. Global frequency and distribution of lightning as observed from space by the Optical Transient Detector. J. Geophys. Res. 108, 4005 (2003).
  116. 116.
    ,  &  Lightning and lightning fire, central cordillera, Canada. Int. J. Wildland Fire 11, 41–51 (2002).
  117. 117.
     New results on planetary lightning. Adv. Space Res. 50, 293–310 (2012).
  118. 118.
     &  Limits for combustion in low O2redefine paleoatmospheric predictions for the Mesozoic. Science321, 1197–1200 (2008).
  119. 119.
    , , ,  &  Baseline intrinsic flammability of Earth's ecosystems estimated from paleoatmospheric oxygen over the past 350 million years. Proc. Natl Acad. Sci. USA 107, 22448–22453 (2010).
  120. 120.
    ,  &  Charcoal in the Silurian as evidence for the earliest wildfire. Geology 32, 381–383 (2004).
  121. 121.
    , , ,  &  Fire as an evolutionary pressure shaping plant traits. Trends Plant Sci. 16, 406–411 (2011).
  122. 122.
    ,  &  The global distribution of ecosystems in a world without fire. New Phytol.165, 525–538 (2005).
  123. 123.
     &  Fire and the spread of flowering plants in the Cretaceous. New Phytol. 188, 1137–1150 (2010).
  124. 124.
    , , ,  & Phylogeny of the ants: diversification in the age of angiosperms. Science 312, 101–104 (2006).
  125. 125.
     &  Bees diversified in the age of eudicots. Proc. R. Soc. Lond. B 280, 20122686 (2012).
  126. 126.
     et al. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs. Nature 483, 457–460 (2013).
  127. 127.
     in Fire Phenomena and the Earth System: An Interdisciplinary Guide to Fire Science (ed. Belcher, C. M.) 289–308 (John Wiley and Sons, 2013).
  128. 128.
    , , ,  &  The raw and the stolen: cooking and the ecology of human origins. Curr. Anthropol. 40, 567–594 (1999).
  129. 129.
     &  Earliest fire in Africa: towards the convergence of archaeological evidence and the cooking hypothesis. Azania 48, 5–30 (2013).
  130. 130.
    ,  &  Energetic consequences of thermal and nonthermal food processing. Proc. Natl Acad. Sci. USA 108, 19199–19203 (2011).
  131. 131.
    ,  &  Cooking increases net energy gain from a lipid-rich food. Am. J. Phys. Anthropol. 156, 11–18 (2015).
  132. 132.
     Elements of Physical Biology (Williams and Wilkins, 1925).
  133. 133.
     Enriching the Earth (MIT Press, 2001).
  134. 134.
    , , ,  &  How a century of ammonia synthesis changed the world. Nat. Geosci. 1, 636–639 (2008).
  135. 135.
     et al. The biodiversity of species and their rates of extinction, distribution, and protection. Science 344, 1246752 (2014).
  136. 136.
     Singularities (Cambridge Univ. Press, 2005).
  137. 137.
     &  Directionality in the history of life: diffusion from the left wall or repeated scaling of the right?Paleobiology 26, 1–14 (2000).
  138. 138.
     &  The Major Transitions in Evolution (WH Freeman, 1995).
  139. 139.
     Toward major evolutionary transitions theory 2.0. Proc. Natl Acad. Sci. USA 112, 10104–10111 (2015).
  140. 140.
     &  (eds) The Major Transitions in Evolution Revisited (MIT Press, 2011).
  141. 141.
    , , ,  & Facilitation of robust growth of Prochlorococcus colonies and dilute liquid cultures by ‘helper’ heterotrophic bacteria. Appl. Environ. Microbiol. 74, 4530–4534 (2008).
  142. 142.
     Interaction between cyanobacteria and aerobic heterotrophic bacteria in the degradation of hydrocarbons. Int. Biodeter. Biodegr. 64, 58–64 (2010).
  143. 143.
    , , ,  &  Morphological and physiological changes in Microcystis aeruginosa as a result of interactions with heterotrophic bacteria. Freshwater Biol. 56, 1065–1080 (2011).
  144. 144.
     &  How to kill (almost) all life: the end-Permian extinction event. Trends Ecol. Evol. 18, 358–365 (2003).
  145. 145.
     et al. Anoxia/high temperature double whammy during the Permian–Triassic marine crisis and its aftermath. Sci. Rep. 4, 4132 (2014).
  146. 146.
     et al. Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction. Geology 43, 307–310 (2015).
  147. 147.
     The Chicxulub impact event and its environmental consequences at the Cretaceous–Tertiary boundary. Palaeogeogr. Palaeoclimatol. Palaeoecol. 255, 4–21 (2007).
  148. 148.
     Inequality and the directionality of history. Am. Nat.153, 243–253 (1999).
  149. 149.
     Energy in Nature and Society: General Energetics of Complex Systems (MIT Press, 2008).
  150. 150.
     Life-sustaining planets in interstellar space?Nature 400, 32 (1999).
  151. 151.
    , ,  & Nomads of the Galaxy. Mon. Not. R. Astron. Soc. 423, 1856–1865 (2012).
  152. 152.
    ,  &  Hydrogen-driven subsurface lithoautotrophic microbial ecosystems (SLiMEs): do they exist and why should we care? Trends Microbiol. 13, 405–410 (2005).
  153. 153.
     Implications of an anthropic model of evolution for emergence of complex life and intelligence. Astrobiology 8, 175–185 (2008).
  154. 154.
     &  Catalytic proficiency: the unusual case of OMP decarboxylase. Annu. Rev. Biochem. 71, 847–885 (2002).
  155. 155.
    , , ,  &  Role of microbes in the smectite-to-illite reaction. Science 303, 830–832 (2004).
  156. 156.
    ,  &  Carbon isotope discrimination and photosynthesis. Annu. Rev. Plant Physiol. Plant Mol. Biol. 40, 503–537 (1989).
  157. 157.
     Carbon isotopes as biogeochemical recorders of life over 3.8 Ga of Earth history: evolution of a concept. Precambrian Res. 106, 117–134 (2001).
  158. 158.
     The function of genomes in bioenergetic organelles. Phil. Trans. R. Soc. Lond. B 358, 19–38 (2003).
  159. 159.
     et al. The genome of Naegleria gruberiilluminates early eukaryotic versatility. Cell 140, 631–642 (2010).
  160. 160.
     &  Metabolic efficiency and amino acid composition in the proteomes of Escherichia coli and Bacillus subtilis. Proc. Natl Acad. Sci. USA 99, 3695–3700 (2002).
  161. 161.
     Cost-minimization of amino acid usage. J. Mol. Evol.56, 151–161 (2003).
  162. 162.
     Selection on synthesis cost affects interprotein amino acid usage in all three domains of life. J. Mol. Evol. 64, 558–571 (2007).
  163. 163.
     &  Selection costs of amino acid substitutions in ColE1 and ColIa gene clusters harbored by Escherichia coli. Mol. Biol. Evol. 15, 774–776 (1998).
  164. 164.
     &  Oxygen and animal evolution: did a rise of atmospheric oxygen trigger the origin of animals?BioEssays 36, 1145–1155 (2014).
  165. 165.
    , , ,  & Of early animals, anaerobic mitochondria, and a modern sponge. BioEssays 36, 924–932 (2014).
  166. 166.
     et al. Oxygen, ecology, and the Cambrian radiation of animals. Proc. Natl Acad. Sci. USA 110, 13446–13451 (2013).
  167. 167.
     Oxygen as a prerequisite to the origin of the Metazoa. Nature 183, 1170–1172 (1959).
  168. 168.
     &  Early animal evolution: emerging views from comparative biology and geology. Science 284, 2129–2137 (1999).
  169. 169.
     et al. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals. Nat. Commun.6, 7142 (2015).
  170. 170.
    , , ,  &  Earth's oxygen cycle and the evolution of animal life. Proc. Natl Acad. Sci. USA 113, 8933–8938 (2016).
  171. 171.
    , , ,  &  Co-evolution of eukaryotes and ocean oxygenation in the Neoproterozoic era. Nat. Geosci. 7, 257–265 (2014).
Download references

Acknowledgements

Many thanks to G. Carr, T. Carvalho, D. C. Catling, D. Haydon, T. Goldberg, P. Jarne, A. H. Knoll, E. Kroll, N. Judson, N. Lane, T. Lenormand, G. Lichfield, B. C. T. Mason, O. Morton, J. Rolff, J. Swire, and especially A. Courtiol for helpful discussions and for comments on an earlier draft of the manuscript. Many thanks to W. F. Martin and T. M. Lenton for insightful reviews that improved the manuscript. Figure 1was drawn by graphic designer F. Zsolnai, many thanks.


Figure 1: Key events during the energy expansions of evolution.
Figure 1
(i) Life emerges; epoch of geochemistry begins. (ii) Anoxygenic photosynthesis: start of energy epoch 2, sunlight. (iii) Emergence of cyanobacteria. (iv) Great Oxidation Event: energy epoch 3, oxygen. (v) Probable eukaryotic fossils appear. (vi) Fossils of red algae appear. (vii) Start of energy epoch 4, flesh. (viii) Vascular plants colonize land; fire appears on Earth. Finally, the burning logs indicate the start of energy epoch 5, fire. The dates of (i)–(iii) are highly uncertain. For (i) I have taken the earliest date for which there is evidence consistent with life20. For (ii) I have taken the earliest date for which there is evidence consistent with photosynthesis18,19,21. For (iii), I have marked the date currently supported by fossil evidence for the presence of cyanobacteria (see main text, ‘Cyanobacteria and the oxygenation of the air’). Tick marks represent intervals of 25 million years. Figure drawn by F. Zsolnai.
Full size image
Posted by at No comments:
Labels: , , ,

2639. Who Can Stop the Climate Crisis?

By Kamran Nayeri, June 27, 2017


The transition to a post-carbon society is largely political
In the “100%-Renewables: A Few Remarks about the Jacobson/Clack Controversy” (June 27, 2017) François-Xavier Chevallerau, Founder-Director of the Biophysical Economics Policy Center based in Brussels, has made an insightful contribution to the debate about the technical feasibility of transition to a post-carbon society powered by “clean” renewables by the mid-21 century.  (For Jacobson et. al. papers see here; for Clack et.al paper see here)  Mr. Chevallerau argues the scientific/technical debate is missing the point. The transition to a post-carbon society is mostly political, not technical.  Thus, he writes:
“This debate is or should be, first a foremost, a political debate, and the outcome of the transition will depend, first and foremost, on how we will manage to design, implement, and sustain new economic, social and political balances of power, within and between countries. This, much more than the accuracy of technical roadmaps that we may be able to design today, will determine whether, how and how successfully we will be able to transition to renewables.”
Mr. Chevallerau’s observation is a critical one that I hope will receive recognition among broader layers of the climate justice and ecology movements.  But he leaves the crucial question of who would “design, implement, and sustain new economic, social and political balances of power, within and between countries” hanging. Would that be the world capitalist elite? Or the billions of citizens of the world who by-and-large are excluded from such policy discussions? 

The climate justice and ecology movements lag
Last September in a review essay focusing on action programs to stop and reverse the climate crisis, I welcomed Bill McKibben’s policy essay "A Wold at War" in the New Republic that embraced the Jacobson et.al. plan for transition to a post-carbon society but criticized it for reducing the climate crisis to a technical matter (Nayeri September 3, 2016).  

In my view, the climate crisis is one aspect, a crucial one to be sure, of the planetary crisis, which includes another existential threat, the Sixth Extinction.  The planetary crisis itself is the manifestation of the Anthropocene (Age of Man), a new geological epoch in which human productive/destructive powers have grown so much that they are undermining the life-support systems of the planet. The monstrous growth of productive/destructive forces themselves is the result of the dynamics of the anthropocentric industrial capitalist civilization, itself the latest in a series of civilizations organized to exploit nature and labor for the ruling elite. Some of these civilizations collapsed due to ecological crises.  Clearly, we cannot honestly believe that the planetary crisis, including the climate crisis, can be overcome without transcending the anthropocentric industrial capitalist civilization. 

Would the Democratic Party do it? 
In the same essay, I noted what I considered as progress especially by the authors of The Leap Manifesto: A Call for a Canada Based on Caring for the Earth and One Another but also even by Edward O. Wilson who proposed to set aside at least half of the planet for wildness reserves as a way to stop and reverse the Sixth Extinction, and by The Climate Mobilization’s Victory Plan because it did not limit itself to restoring “a safe and stable climate” by calling for action to reverse the “ecological overshoot” and ending the Sixth Extinction.  The Victory Plan included a laudable transformation of the energy, food, transportation and other systems. They called for a World War II-style governmental mobilization to implement such changes. 

The fundamental problem with these proposals is the “crucial question” posed by Mr. Chevallerau. Who is going to change the world? The world capitalist elite who benefit from the status quo or the billions of working people who must be transformed in consciousness as part of the process to transcend the anthropocentric capitalist civilization? 

During the 2016 presidential election, we learned what McKibben and the 350.org  and The Climate Mobilization opted for. They turned from climate justice coalitions into campaign offices to get the vote out for Hillary Clinton who openly endorsed fracking and was the favorite candidate of the capitalist class (None of the Fortune 100 contributed to the Trump's campaign).  When Clinton did not win the presidency, the climate justice movement experienced a setback because the larger forces in it based their strategy and tactic on the Democratic Party being in power.  Ezra Silk, a leader of The Climate Mobilization, wrote in an email that they are going to revisit their strategy.  That is because their strategy was to elect public officials who would be climate policy friendly.  Of course, anyone interested in political history would know that the labor movement, the women's movement, the balck movement, and the enviromentalist movement, all followed this policy for decades and are all in crisis today.  The "strategy" is a failure. 

The sudden decision by the 350.org and The Climate Mobilization to support Hillary Clinton betrayed another problem.  They turned a climate justice coalition, this is what they say they are, into a vote-gathering machine for the Democratic Party, one the two pillars of power of the American and world capitalist elite, without any discussion among their membership.  In this, they betrayed the trust of those who worked with them.  In 350.org affiliate in Sonoma County, California, several members were left with no choice but to withdraw, including those who supported Jill Stein, the Green Party candidate, and myself who supported none of the nationally known candidates.  Clearly, these organizations cannot be leaders of a transformational movement to end the planetary crisis. 

The problem is even deeper. Edward O. Wilson’s proposal to stop the Sixth Extinction overtly relies on the magic of the competitive market economy which he says is the socially constructed parallel of the evolutionary biology. (Nayeri 2017) 

Organizing from below
To be sure, there are reforms that can and should be fought for win under capitalism.  But even fighting for such reforms should be carried out in ways that increase the self-reliance and self-confidence of the working people as it they who must transform Our Way of Life to become compatible with a just and ecologically sound society. 

Suppose the People’s Climate March some 200,000 people in Washington D.C. on April 29 educated each and everyone about the root-causes for climate change and about our own action program forged in a broad and democratic discussion in the movement to stop and reverse it.  Furthermore, suppose that everyone who came to the march would commit to educate, organize and mobilize a family member, friend, neighbor, coworker, fellow student, etc.,  as part of the climate justice movement.  Assume this process is repeated every six month—each person in our movement would recruit a new person over the course of the next six month.  Watch how the number of climate justice activists grow over time.

  • April 2017 200,000 participants in the People’s Climate March
  • October 2017  400,000 climate justice activists or active supporters
  • April 2018  800,000 climate justice activists or active supporters
  • October 1,600,000 climate justice activists or active supporters
  • April 2019 3,200,000 climate justice activists or active supporters
  • October 2019  6,400,000 climate justice activists or active supporters
  • April 2020 12,800,000 climate justice activists or active supporters
  • October 2020 25,600,000 climate justice activists or active supporters

Would this not be a formidable force in the streets demanding affirmative change according to our own action program, not one cooked up by the capitalist elite, their politicians, technocrats, and bureaucrats? More importantly, would it not also be a transformation in the making in-and-of itself.  Clearly, such activists would live according to what we preach.  A new world would be unfolding as part of our climate justice and ecological movements' daily activities.  

The problem is not that this is not possible.  History tells us this is how radical social change ever happens.  The problem is that too many of us are too tied up in the political and ideological hegemony of the anthropocentric industrial capitalist civilization that can envisage a strategy of mass education, organization, and mobilization truly independent of the capitalist overlords and to break with institutional arrangements that we have grown to feel comfortable with even though they undermine us and eventually us as a species. 

But the planetary crisis is an existential crisis.  There are no saviors from within the system. I invite the reader to offer her/his own view of how to proceed.  

Acknowledgment: Thanks to Bill Henderson for sharing Chevallerau's commentary.  Of course, he bears no responsibility for my views expressed here. 

References:
Chevallerau, François-Xavier. “100% Renewables—A Few Remarks about the Jacobson/Clack Controversy.” The Biophysical Economics Policy Center, June 26, 2017. 
Nayeri, Kamran. “Strategy and Tactics for the Climate Justice Movement: A Critique of 350.org ‘Break Free from Fossil Fuels’ Campaign.” Our Place in the World: A Journal of Ecosocialism, March 31, 2016.
————————. “How to Stop the Sixth Extinction: A Critical Assessment of E. O. Wilson’s Half-Earth.” Our Place in the World: A Journal of Ecosocialism. May 14, 2017.
Posted by at No comments:
Labels: , , , , ,

Monday, June 26, 2017

2638. Philosophy vs. Science: A Dialogue

By  and 

Julian Baggini No one who has understood even a fraction of what science has told us about the universe can fail to be in awe of both the cosmos and of science. When physics is compared with the humanities and social sciences, it is easy for the scientists to feel smug and the rest of us to feel somewhat envious. Philosophers, in particular, can suffer from lab-coat envy. If only our achievements were so clear and indisputable! How wonderful it would be to be free from the duty of constantly justifying the value of your discipline.

However – and I'm sure you could see a "but" coming – I do wonder whether science hasn't suffered from a little mission creep of late. Not content with having achieved so much, some scientists want to take over the domain of other disciplines.

I don't feel proprietorial about the problems of philosophy. History has taught us that many philosophical issues can grow up, leave home and live elsewhere. Science was once natural philosophy and psychology sat alongside metaphysics. But there are some issues of human existence that just aren't scientific. I cannot see how mere facts could ever settle the issue of what is morally right or wrong, for example.

Some of the things you have said and written suggest that you share some of the science's imperialist ambitions. So tell me, how far do you think science can and should offer answers to the questions that are still considered the domain of philosophy?

Lawrence Krauss Thanks for the kind words about science and your generous attitude. As for your "but" and your sense of my imperialist ambitions, I don't see it as imperialism at all. It's merely distinguishing between questions that are answerable and those that aren't. To first approximation, all the answerable ones end up moving into the domain of empirical knowledge, aka science.

Getting to your question of morality, for example, science provides the basis for moral decisions, which are sensible only if they are based on reason, which is itself based on empirical evidence. Without some knowledge of the consequences of actions, which must be based on empirical evidence, then I think "reason" alone is impotent. If I don't know what my actions will produce, then I cannot make a sensible decision about whether they are moral or not. Ultimately, I think our understanding of neurobiology and evolutionary biology and psychology will reduce our understanding of morality to some well-defined biological constructs.

The chief philosophical questions that do grow up are those that leave home. This is particularly relevant in physics and cosmology. Vague philosophical debates about cause and effect, and something and nothing, for example – which I have had to deal with since my new book appeared – are very good examples of this. One can debate until one is blue in the face what the meaning of "non-existence" is, but while that may be an interesting philosophical question, it is really quite impotent, I would argue. It doesn't give any insight into how things actually might arise and evolve, which is really what interests me.

JB I've got more sympathy with your position than you might expect. I agree that many traditional questions of metaphysics are now best approached by scientists and you do a brilliant job of arguing that "why is there something rather than nothing?" is one of them. But we are missing something if we say, as you do, that the "chief philosophical questions that do grow up are those that leave home". I think you say this because you endorse a principle that the key distinction is between empirical questions that are answerable and non-empirical ones that aren't.

My contention is that the chief philosophical questions are those that grow up without leaving home, important questions that remain unanswered when all the facts are in. Moral questions are the prime example. No factual discovery could ever settle a question of right or wrong. But that does not mean that moral questions are empty questions or pseudo-questions. We can think better about them and can even have more informed debates by learning new facts. What we conclude about animal ethics, for example, has changed as we have learned more about non-human cognition.

What is disparagingly called scientism insists that, if a question isn't amenable to scientific solution, it is not a serious question at all. I would reply that it is an ineliminable feature of human life that we are confronted with many issues that are not scientifically tractable, but we can grapple with them, understand them as best we can and we can do this with some rigour and seriousness of mind.

It sounds to me as though you might not accept this and endorse the scientistic point of view. Is that right?

LK In fact, I've got more sympathy with your position than you might expect. I do think philosophical discussions can inform decision-making in many important ways, by allowing reflections on facts, but that ultimately the only source of facts is via empirical exploration. And I agree with you that there are many features of human life for which decisions are required on issues that are not scientifically tractable. Human affairs and human beings are far too messy for reason alone, and even empirical evidence, to guide us at all stages. I have said I think Lewis Carroll was correct when suggesting, via Alice, the need to believe several impossible things before breakfast. We all do it every day in order to get out of bed – perhaps that we like our jobs, or our spouses, or ourselves for that matter.

Where I might disagree is the extent to which this remains time-invariant. What is not scientifically tractable today may be so tomorrow. We don't know where the insights will come from, but that is what makes the voyage of discovery so interesting. And I do think factual discoveries can resolve even moral questions.

Take homosexuality, for example. Iron age scriptures might argue that homosexuality is "wrong", but scientific discoveries about the frequency of the homosexual behavior in a variety of species tell us that it is completely natural in a rather fixed fraction of populations and that it has no apparent negative evolutionary impacts. This surely tells us that it is biologically based, not harmful and not innately "wrong". In fact, I think you actually accede to this point about the impact of science when you argue that our research into non-human cognition has altered our view of ethics.

I admit I am pleased to have read that you agree that "why is there something rather than nothing?" is a question best addressed by scientists. But, in this regard, as I have argued that "why" questions are really "how" questions, would you also agree that all "why" questions have no meaning, as they presume "purpose" that may not exist?

JB It would certainly be foolish to rule out in advance the possibility that what now appears to be a non-factual question might one day be answered by science. But it's also important to be properly sceptical about how far we anticipate science being able to go. If not, then we might be too quick to turn over important philosophical issues to scientists prematurely.

Your example of homosexuality is a case in point. I agree that the main reasons for thinking it is wrong are linked with outmoded ways of thought. But the way you put it, it is because science shows us that homosexual behavior "is completely natural", "has no apparent negative evolutionary impacts", is "biologically based" and "not harmful" that we can conclude it is "not innately 'wrong'". But this mixes up ethical and scientific forms of justification. Homosexuality is morally acceptable, but not for scientific reasons. Right and wrong are not simply matters of evolutionary impacts and what is natural. There have been claims, for example, that rape is both natural and has evolutionary advantages. But the people who made those claims were also at great pains to stress this did not make them right – efforts that critics sadly ignored. Similar claims have been made for infidelity. What science tells us about the naturalness of certain sexual behaviors informs ethical reflection, but does not determine its conclusions. We need to be clear on this. It's one thing to accept that one day these issues might be better addressed by scientists than philosophers, quite another to hand them over prematurely.

LK Once again, there are only subtle disagreements. We have an intellect and can, therefore, override various other biological tendencies in the name of social harmony. However, I think that science can either modify or determine our moral convictions. The fact that infidelity, for example, is a fact of biology must, for any thinking person, modify any "absolute" condemnation of it. Moreover, that many moral convictions vary from society to society means that they are learned and, therefore, the province of psychology. Others are more universal and are, therefore, hard-wired – a matter of neurobiology. A retreat to moral judgment too often assumes some sort of illusionary belief in free will which I think is naive.
I want to change the subject. I admit I am pleased that you agree that "why is there something rather than nothing" is a question best addressed by scientists. But I claim more generally that the only meaningful "why" questions are really "how" questions. Do you agree?

Let me give an example to put things in context. Astronomer Johannes Kepler claimed in 1595 to answer an important "why" question: why are there six planets? The answer, he believed, lay in the five Platonic solids whose faces can be composed of regular polygons – triangles, squares, etc – and which could be circumscribed by spheres whose size would increase as the number of faces increased. If these spheres then separated the orbits of the planets, he conjectured, perhaps their relative distances from the sun and their number could be understood as revealing, in a deep sense, the mind of God.

"Why" was then meaningful because its answer revealed a purpose to the universe. Now, we understand the question is meaningless. We not only know there are not six planets, but moreover that our solar system is not unique, nor necessarily typical. The important question then becomes: "How does our solar system have the number of planets distributed as it does?" The answer to this question might shed light on the likelihood of finding life elsewhere in the universe, for example. Not only has "why" become "how" but "why" no longer has any useful meaning, given that it presumes purpose for which there is no evidence.

JB I don't know whether it's a virtue or a vice, but in philosophy, there is nothing "only" about subtle disagreements! But given we've got as close as we're probably going to on ethics, let's turn to the difference between "how" and "why" questions.

Again, I agree with a lot here. I am unpersuaded, for example, by the argument that there is never any conflict between religion and science because the latter deals with "how" questions and the former "why" ones. The two cannot be so easily disentangled. If a Christian argues that God explains why there was a big bang, then that inevitably says something about God's role in how the universe came into being, too. But I would not go so far as to say that all "why" questions can only be properly understood as "how" ones. The clearest example here is of human action, for which adequate explanations can rarely do without "why" questions. We do things for reasons.

Some very hard-nosed philosophers and scientists describe this as a convenient fiction, an illusion. They claim the real explanation for human action lies at the level of "how", specifically, how brains receive information, process it and then produce action.

But if we want to know why someone made a sacrifice for a person close to them, a purely neurological answer would not be a complete one. The full truth would require saying that there was a "why" at work, too: love. Love is indeed at root the product of the firings of neurons and release of hormones. How the biochemical and psychological points of view fit together is clearly puzzling, and, as your aside on free will suggests, our naive assumptions about human freedom are almost certainly false. But we have no reason to think that one-day science will make it unnecessary for us to ask "why" questions about human action to which things such as love will be the answer. Or is that romantic tosh? Is there no reason why you're bothering to have this conversation, that you are doing it simply because your brain works the way it does?

LK Well, I am certainly enjoying the conversation, which is apparently "why" I am doing it. However, I know that my enjoyment derives from hard-wired processes that make it enjoyable for humans to tangle linguistically and philosophically. I guess I would have to turn your question around and ask why (if you will excuse the "why" question!) you think that things such as love will never be reducible to the firing of neurons and biochemical reactions? For that not to be the case, there would have to be something beyond the purely "physical" that governs our consciousness. I guess I see nothing that suggests this is the case. Certainly, we already understand many aspects of sacrifice in terms of evolutionary biology. Sacrifice is, in many cases, good for the survival of a group or kin. It makes evolutionary sense for some people, in this case, to act altruistically, if propagation of genes is driving action in a basic sense. It is not a large leap of the imagination to expect that we will one day be able to break down those social actions, studied on a macro scale, to biological reactions at a micro scale.

In a purely practical sense, this may be computationally too difficult to do in the near future, and maybe it will always be so, but everything I know about the universe makes me timid to use the word always. What isn't ruled out by the laws of physics is, in some sense, inevitable. So, right now, I cannot imagine that I could computationally determine the motion of all the particles in the room in which I am breathing air so that I have to take average quantities and do statistics in order to compute physical behavior. But, one day, who knows?

JB Who knows? Indeed. Which is why philosophy needs to accept it may one day be made redundant. But science also has to accept there may be limits to its reach.

I don't think there is more stuff in the universe than the stuff of physical science. But I am sceptical that human behavior could ever be explained by physics or biology alone. Although we are literally made of the same stuff as stars, that stuff has organised itself so complexly that things such as consciousness have emerged that cannot be fully understood only by examining the bedrock of bosons and fermions. At least, I think they can't. I'm happy for physicists to have a go. But, until they succeed, I think they should refrain from making any claims that the only real questions are scientific questions and the rest is noise. If that were true, wouldn't this conversation just be noise too?


LK We can end in essential agreement then. I suspect many people think many of my conversations are just noise, but, in any case, we won't really know the answer to whether science can yield a complete picture of reality, good at all levels, unless we try. You and I agree fundamentally that physical reality is all there is, but we merely have different levels of optimism about how effectively and how completely we can understand it via the methods of science. I continue to be surprised by the progress that is possible by continuing to ask questions of nature and let her answer through experiment. Stars are easier to understand than people, I expect, but that is what makes the enterprise so exciting. The mysteries are what make life worth living and I would be sad if the day comes when we can no longer find answerable questions that have yet to be answered, and puzzles that can be solved. What surprises me is how we have become victims of our own success, at least in certain areas. When it comes to the universe as a whole, we may be frighteningly close to the limits of empirical inquiry as a guide to understanding. After that, we will have to rely on good ideas alone, and that is always much harder and less reliable.

Julian Baggini is a British philosopher and Lawrence M. Krauss is a Canadian-American theoretical physicist. 
Posted by at No comments:
Labels: ,

Friday, June 23, 2017

2637. A Case for Community-led Sustainable Energy Programs

By Wolfgang Hoeschele, Shareable, June 23, 2017 

The energy infrastructure that we inherited from the 20th century is one dominated by fossil fuels and uranium, mined in relatively few localities in the world. The distribution and refining of these fuels is tightly held by a few large corporations. Electricity generation typically occurs in plants that hold local or regional monopolies, with vast profit potential. While gasoline is burned in millions of vehicles, the distribution system remains within the control of a few corporations, which often have regional or national oligopoly or monopoly control. The environmental impacts of the energy industry are staggering. It is high time for a change.
On the positive side, the need for change to a 21st-century energy system based on renewable sources of energy is widely recognized, the necessary technologies exist (and are often cheaper than conventional forms of energy provision), and considerable progress has been made. We can build locally-based renewable energy infrastructures. Renewable energy from the sun, wind, water, organic waste, and geothermal heat can be found everywhere on the planet. Hence, every city and town can make use of available renewable energy sources that offer economic opportunity and enhance resilience in the face of global economic crises and environmental change. On a regional level, localities can exchange energy in order to even out seasonal or daily imbalances in supply and demand.
A locally based vision of renewable energy generation could eliminate global- or national-level domination of the energy infrastructure by a few large players, and thus the concentration of profits in the hands of a very few. It could also reduce our greenhouse gas emissions to very low levels, comparable to the emissions before the industrial revolution. But the local orientation alone would not ensure that the benefits would be shared among all sectors of the local population, and therefore it would not guarantee widespread and active support. This is where sharing solutions come in. Shared energy infrastructure means that people together own and operate both the distributed energy generation facilities and the infrastructure to deliver that energy from where it is generated to where it is used.
In a sharing vision of a local renewable energy system, many households will generate their own renewable energy (as in solar photovoltaic or solar thermal systems on their rooftops), but many more, for whom this is not an option, will share in the ownership and operation of off-site renewable energy generation infrastructure such as wind turbines. The distribution systems by which energy is delivered to households will belong to cooperatives, municipalities, or trusts that are accountable to their customers and therefore do not take advantage of the potential of supply monopolies to generate economic rents (unearned income, extraordinary profits). The energy infrastructure is built by companies controlled by their employees, ensuring equitable sharing of the economic benefits. The construction and maintenance of this entire infrastructure is financed in such a way that it benefits the producers and consumers (and often prosumers — people who both produce and consume what they produce), rather than simply providing growth opportunities for the finance "industry." Consumers use their buying power to ensure that they obtain renewable energy that is produced under fair conditions.
All the elements of this locally-based, sharing vision of a renewable energy infrastructure already exist. Some have even been brought to considerable scale, as for example in Denmark, where a large proportion of the wind energy generation is accomplished by local wind cooperatives. The challenge is to bring all these elements together into mutually supportive networks, and to establish such networks essentially everywhere.
In many countries, much of the grid is owned by municipal authorities, which is an excellent solution as long as democratic accountability of these authorities is ensured. Unfortunately, there has been a trend in recent years to privatize electric distribution grids, on the basis of the argument that private control is automatically more "efficient." However, this argument is only valid if there is true market competition, which is not the case in most energy distribution systems.
In this context, the best way to ensure that a business serves its customers is for the customers to take over the business. There are different models to do this: in rural areas — as in much of the U.S. — rural electric cooperatives have long played a large role in running the local grids. In large urban areas, however, this model has not been as successful. At the urban scale, municipal ownership or trusts are more prevalent.
Finally, it is important that the workers installing all this equipment get a good deal — and this works best if they themselves own their own companies and make the important decisions. The challenge now is to bring all these elements together and help them to grow, in order to build an energy infrastructure that allows all of us to live well while ensuring good living conditions for all the other species on this planet.
Posted by at No comments:
Labels: , ,

Thursday, June 22, 2017

2636. Film Review: John Coltrane Lite

By Marty Goodman, Socialist Action, June 22, 2017

“Chasing Trane,” a documentary film by John Scheinfeld.
“Trane is now a scope of feeling. A more fixed traveler, whose wildest onslaughts are gorgeous artifacts not even deaf people should miss.” — Amiri Baraka, poet, jazz critic, and activist
In July 1967, I heard on a late night jazz radio show in Miami that visionary jazz saxophonist John Coltrane had died at the age of 40 of liver cancer. Doom and gloom was the mood, although the host tried his best to assure us that jazz would live on—somehow. Now, 50 years later, a new Coltrane biopic film, “Chasing Trane,” is out. Written and directed by documentarian John Scheinfeld, it is the first film made in cooperation with the Coltrane family.
“Chasing Trane” is jazz retrofitted for the mainstream—that is, mostly white, middle-class jazz fans. But it is an inadequate and misleading introduction for jazz beginners. It is an anti-jazz avant-garde work that simultaneously lionizes an avant-garde icon. There isn’t one complete performance in the entire film, so people cannot judge Coltrane’s adventurous music for themselves. A “Coltrane lite” film was apparently what director Sheinfeld hoped for. Mission accomplished.
Coltrane was a jazz revolutionary, the avant-garde’s leading persona in an era of civil rights and emerging Black nationalism.
To its credit, “Chasing Trane” tells the story of the musician’s early life in Jim Crow North Carolina. As a boy, John was immersed in Black church music; two grandfathers were preachers. As African American Professor Cornell West explained in the film, ”Black music was a Black response to being terrorized and traumatized … that’s Black music, a response to a catastrophe.”
Coltrane was never overtly political, although he did attend a Malcolm X speech on the recommendation of his first wife Naima, a Muslim. But Coltrane was deeply affected by the Black struggle, Dr. King, and, as the film highlights, the 1963 racist bombing of a Black church in Birmingham, Ala., that killed four African American girls. Coltrane dedicated his mournful piece, “Alabama” to the victims, it is said, set to the cadence of an MLK speech.
In those times, Coltrane and the overwhelmingly African American jazz avant-garde were challenging conventional Western music’s structure, melody, and harmony. In particular, the avant-garde became famous for discordant, unconventional honks and angry screams. The music was sometimes overtly political, sometimes spiritual, often a mixture of both or simply neither. What was always clear was that society must change!
The mostly white jazz old-guard pushed back. In 1962, prominent jazz critic Leonard Feather, writing in Downbeat, the leading jazz magazine, called the avant-garde “anti-jazz,” a shot aimed mostly at Coltrane. Even jazz musicians got up and walked out on Coltrane, as did European audiences in hearing the work of early 20th-century modernist classical composers.
Coltrane’s evolution
After the passing of several family members, John took up music. After high school, he joined his family in Philadelphia, where he enlisted in the Navy in 1945 and joined a Navy jazz band. By ’45 he had caught live jazz god Charlie “Bird” Parker, the center of the be-bop revolution. Parker, and his gifted sidemen, trumpeter Dizzy Gillespie and pianist Bud Powell, played a new, fast-paced jazz tempo that was distinctly urban and reflective of postwar Black life. Said Coltrane, “the first time I heard Bird play, it hit me right between the eyes.” John was screaming.
June 2017 Coltrane sailor
John Coltrane in the U.S. Navy, 1945, when he made his first jazz recordings.
After playing with lesser bands as a would-be Charlie Parker, Coltrane got to play occasionally with his idol Parker in the late ’40s. From 1949-51, Coltrane began traveling with Dizzy Gillespie and then in 1955, with trumpet superstar Miles Davis.
During the 1950s, Coltrane struggled with heroin addiction, as did many jazz musicians. Drugs were glorified by Charlie Parker as a door to creativity. By 1951 Coltrane was booted out of Dizzy Gillespie’s band, and also from Miles Davis’ classic quartet in 1957 (Miles had his own bouts with heroin), and from the band of pioneer bop composer/pianist Thelonious Monk.
Charlie Parker’s drug-ravaged body succumbed in 1955, but Coltrane cold turkeyed on his own. Coltrane was back with Miles in 1958 in time for the all-time classic Miles album, “Kind of Blue” (1959).
But with Miles, Coltrane was feeling a creative impasse. At the risk of oversimplification, Miles represented “cool jazz” to whites, a less threatening alternative to bop and the drug culture of Parker. Trane felt confined artistically and left Miles. In 1958, jazz critic Ira Gitler coined the term “sheets of sound” to describe the unique, evolving Coltrane style as he worked with Miles.
July 2017 Coltrane Blue Train 1957
Recording “Blue Train” in Hackensack, N.J., 1957.
In the early 1960s, radical stylists appeared around Coltrane and within the broad avant-garde. The “radicals” (my favorites) included alto sax man Ornette Coleman—on a different path than Coltrane but an anti-establishment hero, particularly after his pivotal “Free Jazz” album (1960). Collaborators with Coltrane were the short-lived experimenter, saxophonist Eric Dolphy; the angry, political tenor sax man, Archie Shepp; the fearless Pharoah Sanders; bombshell innovator Albert Ayler; and pianist Cecil Taylor, whose volcanic style first took shape in the 1950s.
Several of these ground-breaking artists are still alive today—Sanders, Shepp, Coltrane bassist Reggie Workman, and Cecil Taylor. Archie Shepp’s classic first album “Four for Trane” showed Coltrane standing next to him on the cover. Yet Shepp and the others do not speak a word in the film.
A few weeks after the film was released in April, I spoke with David Murray, thought to be the best of the 1970s post-Trane tenors, rooted in Coltrane and the avant-garde. Murray dedicated an album to Coltrane tunes.
Murray was playing at the world famous Village Vanguard with his provocatively named unit “Class Struggle.” I snatched an opportune moment as Murray walked past, sax in hand: “David, quick question. Did they call you for the Coltrane movie?” He answered, “Nope, they went straight to [Wynton] Marsalis!” I shot back, “Why am I not surprised!”
To jazz radicals, trumpeter Marsalis is musical neo-conservatism incarnate, but he appears several times in the movie. Marsalis came into prominence during the Reagan era and is the longtime artistic director of “Jazz at Lincoln Center” in New York. Marsalis has been sharply criticized for his systematic exclusion of today’s talented free-jazz musicians. Marsalis has said, “post-1965 avant-garde playing is outside of jazz,” calling some avant-gardists ‘“charlatans.” That apparently sits well with Lincoln Center’s wealthy funders and cultural Czars.
Also in the film was jazz fan and ex-president Bill Clinton, who represented what Coltrane despised—war, racism, corruption and lies. Clinton, an untalented saxophone player, contributed little other than star power. What is this guy doing here, I asked myself?
Somewhat more palatable was Cornel West, the African American writer and supporter of liberal democrats. But West got with the underlying motif, dissing the avant-garde. West portrayed Coltrane’s late works as indecipherable and ultimately dismissible. “I still don’t understand it,” said West. Okay, but what are you doing in this movie?
Let the music speak for itself!
For those new to Coltrane, his creative highs include: “Giant Steps” (1960), Coltrane playing his own compositions; “My Favorite Things” (1961), a cover of the sappy Broadway tune, radically transformed into a searching, almost eastern sound; “A Love Supreme” (1964), a non-sectarian musical prayer for peace and tolerance that is Coltrane’s most revered album; the daring free-jazz “Ascension” (1965); and “Live at the Village Vanguard Again!” (1966), which includes a soul-stripping solo by Sanders.
In his book, “Black Nationalism and the Revolution in Music” (1970), Frank Kofsky quotes Archie Shepp’s brief but apt description of the music capitalist, “You own the music and we make it.” Kofsky added, “Part of the ownership Shepp refers to includes ownership of the means of mental production,” that is, club owners, the record producers and, of course, jazz filmmakers.
The genius of Coltrane will outlive the cultural mediocrity of late capitalism. Coltrane lives!

Posted by at No comments:
Labels: , ,
Subscribe to: Posts (Atom)