The Origin of Life (and Morality) 3.7 Billion Years Ago?

A 3.7-billion-year-old rock from the Isua Greenstone Belt in Greenland showing conical stromatolite-like structures that could be fossil evidence of bacterial activity, and thus the earliest signs of life on Earth.

One of the greatest unresolved mysteries in science is the origin of life.  There is today no generally accepted scientific account of exactly where, when, and how life originated on Earth.  Closely connected with this question is the question of whether life might have appeared elsewhere in the universe beyond the Earth. 

This is a deeply human question because living beings like ourselves want to understand our place in the history of life, and of what that might say to us about the meaning and purpose of life.  Human beings have always heard mythic or religious stories about the origin of all things, including the origin of life and human life.  But now we wonder whether modern science can give us a scientific story of life's origins.  And if we are persuaded by such a scientific story, then we must wonder what this teaches us about how we fit into the history of the universe.

This week, an article for the journal Nature on what is claimed to be the earliest evidence of life has been published online.  Nicholas Wade has written about this for The New York Times.

The oldest fossil evidence of life is stromatolite fossils. A stromatolite (literally, "layered rock") is a solid structure created in shallow marine environments by single-celled microbes called cyanobacteria (blue-green algae).  The photosynthesizing cyanobacteria form colonies and trap sediment with their sticky surface coatings.  The trapped sediment reacts to calcium carbonate in the water to form limestone.  The formation of such microbial mats can be seen today in places like Shark's Bay in Western Australia.

Microbial mats are important for the study of early life on Earth because they are a macroscopic manifestation of microscopic life.  They can be preserved as macroscopic structures in the rock record, which are more easily identified than individual microbial fossils (microfossils).

In northwestern Australia (Pilbaria Craton), the Strelley Pool Chert is a 3.5 million-year-old sedimentary rock formation that seems to show stromatolite fossils.  Until recently, this has been thought to be the earliest fossil evidence for life on Earth (Allwood et al. 2006).  There's a YouTube video on this site.

But now a team led by Allen Nutman of the University of Wollongong in Australia is presenting evidence of stromatolite fossils in rocks from the southwest coast of Greenland that are 3.7 billion years old (Nutman et al. 2016).  If this is correct, this would be the earliest fossil evidence for life.  And yet while cyanobacteria might seem to us to be very simple forms of life, they are actually rather complex, and so they must have been preceded by the evolution of simpler forms of life much earlier than 3.7 billion years ago.

This research is important for astrobiology--the biological study of evidence for life beyond the Earth.  If we were to find rock formations like this on Mars, would this be evidence that life has evolved on Mars?

This research will provoke a lot of scientific debate.  First of all, there will be debate over whether these rock formations were really caused by microbial action, or whether they could have been formed by purely physical or chemical activity, so that this would not be evidence of ancient life. For a decade or more, scientists had assumed that American paleontologist William Schopf had found stromatolite fossils in rocks in Western Australia that were 3.5 billion years old (Schopf 1993).  But then Martin Brasier (a paleobiologist at Oxford University) challenged Schopf's evidence by arguing that the stromatolites presented by Schopf had actually been formed by geological processes, not by bacteria (Brasier et al. 2002).  Later, Brasier presented his own fossil evidence for life that was 3.4 billion years old, but here the fossil patterns were microscopic, with sizes and shapes suggesting a kind of bacteria that lives on sulfur and dies if exposed to oxygen (Wacey et al. 2011).  We can expect, then, that there will be similar criticism of Nutman's evidence.

Another problem for Nutman's research is that if cyanobacteria appeared 3.7 billion years ago, then the simplest forms of life must have evolved during the Hadean period of Earth's history (from 4.5 to 4 billion years ago).  This period is called Hadean because it was a "hellish" time for the Earth, during which the Earth was being bombarded by asteroids.  It's hard to see how life could have emerged and survived in these conditions.

What we see here is one of the fundamental problems of evolutionary science.  We cannot directly observe what happened billions of years ago.  Se we must rely on the indirect evidence of evolutionary history, such as the fossil record.  And that fossil record is limited and hard to interpret.

But at least we can adjudicate the scientific disputes by looking at whatever evidence we have and weighing the arguments over the interpretation of that evidence in the light of the competing scientific theories.

By contrast to this, the critics of evolutionary science--like the proponents of Intelligent Design Theory--do not offer any alternative theories that are testable by evidence.  For example, Jonathan Wells, in his book Icons of Evolution--criticizes evolutionary scientists for not proving the step-by-step evolutionary pathway for the origin of life; and then he asserts that the only alternative is Intelligent Design Theory.  But he does not explain exactly when, where, and how the Intelligent Designer created life.  He does not do this, because his rhetorical strategy is a negative argument from ignorance: he shows that scientists cannot prove the step-by-step evolutionary origins of life, and then he asserts the truth of Intelligent Design by default, without satisfying the standards of proof that he has used against the scientists.

As I have indicated in a previous post, there is another side to this debate over stromatolite fossils that has to do with the evolution of morality.  Microbial mats form because hanging together allows these microorganisms to stick to the rocks in shallow sea water without being washed away by the tides.  By hanging together, these microorganisms are cooperating with one another for their mutual benefit.  And while we might not see this as morality in the strict sense, we might see it as at least incipient moral behavior.  The morality of human social cooperation could be seen as the culmination of a long history of life in which living beings have evolved to cooperate for their mutual benefit.  Something like this is suggested in Aristotle's biological works.


REFERENCES

Allwood, A. C., M. R. Walter, B. S. Kamber, C. P. Marshall, and I. W. Burch. 2006. "Stromatolite Reef from the Early Archaean Era of Australia." Nature 441: 714-718.

Brasier, M. D., et al. 2002. "Questioning the Evidence for Earth's Oldest Fossils." Nature 416: 76-81.

Nutman, A. P., V. C. Bennett, C. R. L. Friend, M. J. Van Kranendonk, and A. R. Chivas. 2016. "Rapid Emergence of Life Shown by Discovery of 3,700-Million-Year-Old Microbial Structures." Nature http://dx.doi.org/10.1038/nature19355.

Schopf, J. W. 1993. "Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life." Science 260: 640-46.

Wacey, D., et al. 2011. "Microfossils of Sulphur-Metabolizing Cells in 3.4-Billion-Year-Old Rocks of Western Australia." Nature Geoscience 4: 698-702.

Wells, Jonathan. 2000. Icons of Evolution: Science or Myth? Washington, DC: Regnery Publishing.

The Big History of Morality: The Pursuit of Happiness from Stromatolite Cooperation to the Global Morality of Sustainability

Lower Proterozoic Stromatolite Fossil from Bolivia

Stromatolites at Shark Bay, Western Australia

"Big history" is the term coined by David Christian for the history of everything in the universe from the Big Bang to the present, and including plausible speculations about the future of the universe.

Modern academic history has traditionally identified the beginning of history with the invention of writing about 6,000 years ago, because this began the written records that historians have needed to reconstruct history.  Consequently, such history has been the history of literate peoples, and everything prior to the invention of writing has been considered "prehistory."

David Christian and other proponents of big history--such as William McNeil, Fred Spier, Dan Smail, Cynthia Brown, and Craig Benjamin--have argued that this is an unreasonably narrow view of history that ignores the fact that modern evolutionary science can reconstruct the entire history of the universe through empirical evidence (such as fossil evidence on Earth and astronomical data from beyond the Earth) that does not depend on written records.  Moreover, there is a great intellectual benefit in big history in that it provides a grand interdisciplinary integration of the natural sciences, the social sciences, and the humanities, which looks like what I have called "Darwinian liberal education."

Throughout history, human beings have constructed universal histories of the universe through religiously based creation stories (like that in the Bible or in Plato's Timaeus), which depend on religious beliefs in supernatural activity that cannot be confirmed with empirical evidence.  But now modern science can construct a secular universal history based on inferences from empirical evidence.  As suggested by some scientists like Eric Chaisson, some of the proponents of big history argue that the general theme of this universal history is the evolution of complexity made possible by the flow of energy through matter.

The first big history, in ancient Rome, was Lucretius's On the Nature of Things, a history of the universe based on an Epicurean science of evolutionary atomistic materialism.  Although Lucretius professed to believe that gods existed, they exercised no creative power over the universe, and they were indifferent to human affairs.  Later, in the first half of the 19th century, Alexander von Humboldt's Cosmos: A Sketch of a Physical Description of the Universe and Robert Chambers's Vestiges of the Natural History of Creation provided modern scientific accounts of the natural evolution of the universe from the beginning to the present.  Humboldt never mentioned God or divine activity.  Chambers invoked God as the First Cause of nature, but his natural history of the universe did not require miraculous acts outside of the laws of nature.  Big history continues this tradition of writing, but proponents of big history can claim that the scientific knowledge accumulated over the past two centuries allows them to base their history on the best empirical science.

The religiously based universal histories provided a moral teaching as grounded in a divine cosmic order:  in learning how they were created by God and how they were commanded to obey His laws, human beings recognized a moral law for their lives derived from divine law.  By contrast, the scientifically based universal history as reconstructed by big historians does not seem to provide any moral teaching, because modern science must be value-free in explaining what is the case, but without explaining what we ought to do.  Thus, it seems that morality must be a matter of personal choice for each individual without any guidance from big history.

But what happens when many people in the modern world no longer find creation stories and religiously based morality credible, or when globalization brings ever more people into contact with others who do not share their religious world views?  So, for example, how do we resolve the conflicts that arise when radical Islamists declare holy war against the infidels, because they believe that they are fighting the Last Battle that will bring the end of history?

Among the proponents of big history, Fred Spier has begun to argue that big history must include the big history of morality, and that this might support a scientifically grounded view of morality.  Spier's writing on this include a few passages in his Big History and the Future of Humanity (2015a), his unpublished paper on "Morality in Big History" (2015b), and a published article on "Pursuing the Pursuit of Happiness: Delving into the Secret Minds of the American Founding Fathers" (Social Evolution & History, vol. 12, no. 2, September 2013, pp. 156-182). 

Although Spier and I disagree on some points, I am interested in his reasoning,  because it sounds a lot like what I have long argued for--a biological ethics rooted in human nature as shaped by evolutionary history.

In considering how morality could be derived from nature, Spier has looked to Paul-Henri Thiry Baron d'Holbach (1723-1789), who was a French atheist philosopher of German descent, who led a famous salon in Paris where many of the leaders of the Enlightenment met for discussions.  In his book Systeme de la nature (1770), he argued that an atheistic morality could be rooted in the natural pursuit of happiness, because people could recognize that living a virtuous life in cooperation with others was necessary for one's happiness.  Spier thinks there is some evidence that Thomas Jefferson's appeal to the "pursuit of happiness" as a natural right in the Declaration of Independence shows the influence of d'Holbach's writing.

If we define moral rules as the rules for the successful cooperation necessary for the pursuit of happiness, Spier argues, then we can see the big history of morality as beginning with the first forms of social cooperation among living beings.  The evolution of cooperation for improving survival and reproduction might have emerged more than 3.5 billion years ago, when single-celled microorganisms gained some advantage in the struggle for survival by hanging together.

The oldest fossil evidence of life is stromatolite fossils.  A stromatolite (literally, ‘layered rock’) is a solid structure created by single-celled microbes called cyanobacteria (blue-green algae). The photosynthesizing cyanobacteria form colonies and trap sediment with their sticky surface coatings. The trapped sediment reacts to calcium carbonate in the water to form limestone. 

Microbial mats can still be seen today in places like Shark's Bay in Western Australia.  Hanging together allows these microorganisms to stick to the rocks in shallow sea water without being washed away by the tides.  By hanging together, these microorganisms are cooperating with one another for their mutual benefit.  And while we might not see this as morality in the strict sense, Spier observes, we might see this as at least "incipient moral behavior" (2015b, 20).

Cooperation requires communication, so that organisms can coordinate their behavior.  Microorganisms, plants, and animals use chemical signals to do this.  Animals with brains and nervous systems can create mental images of their physical and social environments through which they can form social rules of cooperation.  Through language, human beings can create and communicate complex cultural rules of cooperation.  Like other social animals, human beings cannot survive and reproduce successfully without learning the rules of cooperation and competition developed within their social groups.  Ultimately, their motivation to do this is their desire for happiness.

Spier surmises that there must be some form of chemical reward for cooperation that supports feelings of happiness.  He notes that some scientists have reported that a neurotransmitter called hypocretin increases when people are happy and decreases when they are sad.  He wonders whether this chemical signal could be a biological reward for doing the right thing, and if it is very old, this could be the ancient biochemical mechanism for the pursuit of happiness, which might have appeared first among microorganisms (2015b, 21-22).

Spier's reference to the neuropeptide hypocretin is remarkable to me, because the other common name for this neuropeptide is orexin.  This word was coined in 1998 from the Greek word orexis, a Greek noun for "desire" or "appetite" that was coined by Aristotle from the Greek verb orego, which means "to reach out."  Desire, Aristotle thought, was the mind's "reaching out" for something in the world.  For Aristotle, in The Movement of Animals, desire is the general term for all kinds of longing or striving, including physical appetites, social emotions, and intellectual yearnings.  I have used the word "desire" in the same way as a general term for all kinds of psychic impulse or inclination.  With that sense in mind, I have defended a natural morality of informed desire: the good is the desirable, and reason judges how best to satisfy the desires in the most harmonious way over a whole life.  There are at least 20 desires of evolved human nature, and so we can judge our moral standards for how well they satisfy those desires.

Spier points in this direction when he refers to "standards of desired, or at least acceptable, behavior", "desirable standards of conduct," and moral standards judged as "the most desirable" (2015b, 8, 20, 29).

In their voluntary activity, animals move to satisfy their desires in the light of their information about opportunities and threats in their particular circumstances.  Like other animals, human beings move to satisfy their desires in the light of their information about the world  They have a natural range of desires that they share as members of the human species and that distinguish them from other animals.  The human pattern of desires includes appetitive desires such as hunger and sexual lust, social desires such as anger, love, and honor, and intellectual desires such as curiosity and wonder.

Human beings have uniquely human capacities for language and deliberation that allow them to gather and assess information about the past, the present, and the projected future, so that they can consciously formulate long-term plans of action based on their conceptions of happiness (a whole life well-lived).  Big history is part of this, because a scientific history of everything from the beginning of the universe could help human beings to plan for the future in the pursuit of happiness.

So, for example, Spier thinks big history can help us to see that the future happiness of humanity depends upon an environmentalist morality of sustainable development for the Earth.  If preserving the human species and human civilization depends upon the availability of matter and energy to support the complex order of human life, and if human beings are now nearing the exhaustion of the nonrenewable resources of matter and energy necessary for human life, then the most critical moral question today is whether human beings on planet Earth can learn to cooperate in reaching environmental sustainability based on renewable energy sources.

I am not persuaded, however, that Spier's environmentalist pessimism is plausible.  And I will explain why in a future post.