We have already noted that the universe began with something infinitely small, perhaps smaller than an atom, but an atom that was many trillions of degrees hot, that expanded with a speed faster than the speed of light, so that almost at once it had expanded to the size of a The extraordinary rapidity of this expansion ensures that most of the universe will never be observable from earth, as the light from it will be too distant ever to reach us. As the universe expanded, it began to cool. The entities and forces with which physics is familiar began to appear. After about 300,000 years, atoms of hydrogen and, in lesser quantity, helium, began to form. Once clouds of hydrogen and helium appeared, the force of gravity began to sculpt them into forms. A million years or so after the big bang, these forms attained new levels of complexity that gave rise to stars-and to galaxies composed of stars and cosmic dust, taking the form of flat rotating disks with arcs of matter streaming out from very hot centers. Gravity pulled the clouds of hydrogen and helium together, heated them up so that the stars burned with tremendous heat, using the atoms of which they are composed as fuels. It was in the intense heat within stars that all the other elements besides hydrogen and helium were formed: it was the stars that gave rise to chemistry. Very large stars quickly (in cosmic time) burned themselves up and exploded as supernovae, visible to our astronomers, spewing out a variety of chemical elements as they did so. About 4.5 billion years ago, perhaps as a result of a supernova explosion, our sun and solar system emerged, perhaps composed of the debris from the explosion.
David Christian notes that we have not taken seriously enough the meaning of this modern cosmology as it describes the sun and the solar system, including our planet. Copernicus was supposed to have unsettled human self-confidence by pointing out that the earth is not the center of the universe but revolves around the sun. Now it is quite clear that the sun isn’t the center of anything much either. As Christian puts it: “Our sun, it seems, is situated in an undistinguished suburb in [the Milky Way] a second-rank galaxy (the Andromeda Galaxy is the largest in our local group), in a group of galaxies that lies toward the edge of the Virgo Supercluster, which contains many thousands of other galaxies.” 15 How “decentered” can you get?
Our earth was just one of several planets that formed in the solar system revolving around this new star, our sun. The early history of the solar system, and of our planet, consisted of constant collisions of the variety of materials out of which the solar system was being formed. As Christian vividly describes it, “we must imagine the early earth as a mixture of rocky materials, metals, and trapped gases, subjected to constant bombardment by smaller planetesimals and without much of an atmosphere. The early earth would indeed have seemed a hellish place to humans.“16 As the earth increased in size due to the cosmic material that gravity was drawing to it, it heated up so that its interior became molten, with the heavy metallic elements such as iron and nickel forming a core and creating the earth’s characteristic magnetic field, which shielded the earth from the high-energy particles that, had they been able to reach the earth’s surface, might have interrupted the chemical processes that would eventually lead to life. As the metals sank to the core, the gases bubbled toward the earth’s surface, making the earth a “massive volcanic field.” As the earth cooled, the water vapor that had accumulated in the atmosphere “fell in torrential rains lasting millions of years,” thus creating the oceans, where life would first appear.17 There are probably millions of other solar systems just in our own galaxy, but whether any of them are likely to have planets like earth is a matter of dispute.
This is a very brief and inadequate description of the early history of the universe and ultimately of our own planet. Whether Eric Chaisson is justified in speaking of “cosmic evolution” is beyond my competence to decide. He believes that there is a continuity between the increasing levels of complexity involved in the emergence of galaxies, stars, and planetary systems, and the increasing levels of complexity in the evolution of life. Some biologists think that an increase in complexity is only one of the characteristics of biological evolution and not necessarily the most important. In any case it is worth remembering our old friend (or enemy), the second law of thermodynamics. There is a price to be paid for increasing complexity, cosmically or biologically: greater complexity requires greater energy input to sustain it. The stars will eventually all burn themselves up, even a middle-size star like our sun, which will last longer than the huge stars that burned fiercely and blew up as they (relatively) rapidly consumed their own fuel, but the same fate ultimately awaits all the stars, whatever their size.
The story I am about to tell, the story of life, is surely more intelligible to human beings than the story I have, in barest outline, just told. After all, we live on the earth and we see life all around us. That it has a long history is not so hard to imagine. That through much of the 4.5 billion years of its history the earth was wildly different from what we know begins to be hard to think about-it takes us close to the borderline of our imagination. But the history of the universe, in the midst of which we still live and out of which our earth came, is intimidating. It seems to intimidate even a Nobel Prize-winning physicist such as Steven Weinberg. Having described some of the competing cosmological models, he writes:
However all these problems may be resolved, and whichever cosmological model proves correct, there is not much comfort in any of this. It is almost irresistible for humans to believe that we have some special relation to the universe, that human life is not just a more-or-less farcical outcome of a chain of accidents reaching back to the first three minutes, but that we were somehow built in from the beginning … It is hard to realize that this [earth] is just a tiny part of an overwhelmingly hostile universe. It is even harder to realize that the present universe has evolved from an unspeakably unfamiliar early condition, and faces a future extinction of endless cold or intolerable heat. The more the universe seems comprehensible, the more it seems pointless.”
Here we see the perils that narrative creates for the narrator. Weinberg’s story creates in him, too, an “almost irresistible” desire for meaning. If, as Mary Midgley writes, “meaning is connection,” then the desire for meaning is perfectly natural, for we are, however hard it is to understand, surely connected to the universe of which we are a part. Our need to find meaning in it is part of our “hunger for meaning,” which is “central to our lives,” as Midgley puts it. “It is the wider motive of which our theoretical curiosity is only a part. It is the impulse of our imaginations to order the world with a view to understanding and contemplating it-something which must be done before theory-building can even begin,” she writes.” Weinberg, by proclaiming that the universe is “overwhelmingly hostile” and in the end “pointless,” wants to sweep any such hunger for meaning aside as something childish. But it could be that it is Weinberg who is being childish, that he is angry because he expected the universe to be nice and have a point, and is disappointed that it doesn’t, almost like finding out that God, in whom he emphatically doesn’t believe, has let him down.20 However, Weinberg can no more evade the search for meaning than the rest of us can. Like Jacques Monod, he has opted for cosmic pessimism as his meaning.
Not quite, though. He does find consolation: “But if there is no solace in the fruits of our research, there is at least some consolation in the research itself … The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce, and gives it some of the grace of In these closing remarks of his book The First Three Minutes (scientists frequently allow themselves rhetorical riffs in their final remarks, which are often most revealing), what Weinberg has really done is to move from science as a cultural system to religion as a cultural system, and affirm the practice of science as his religion; fair enough, if it weren’t quite so condescending to the rest of us who are left at the level of farce. But then religions are often exclusive.”
Although the history of the cosmos is much mo
re intimidating than the history of life, would it not be possible, in the face of the cosmic pessimists, to take a position close to that of Oliver Sacks in relation to biological evolution? After all, our bodies are composed entirely of entities derived from those elementary particles that appeared in the first one-hundredth second after the big bang. We are, quite literally, part of the universe. It is not necessary to think that there was an intelligent designer who had us in mind to be grateful that the universe, after all, did lead to us, and that we can think about the whole of which we are a part. Of course, here I am talking about “worldview,” not science, but I don’t think there is such a thing as a “worldview of science,” because science is not the cultural sphere of worldviews, though it gives rise to many.
Early Life on Earth
Once one begins to understand what the universe is like in which life on earth first appeared, a universe that was already nearly 10 billion years old at the time, it is not so remarkable that we don’t yet fully understand life’s origin. Even the possibility of thinking about this story that led to us is only a little over 150 years old, and it is a story that has been continually filled in almost daily ever since, though the problem of the origin of life is still far from solved. This and other unsolved problems serve to tempt those so inclined to invoke the intervention of a creator or intelligent designer, yet those hypotheses succeed only in increasing by several magnitudes the problems that need explaining.
Before we start thinking of miraculous interventions, however, what this relatively recent knowledge should do to us is to make us realize both what a gigantic cosmic history we are a part of and what very small and limited creatures we are in the face of it. Richard Dawkins, who is, when he is not bashing religion, a gifted science writer, has pointed out that we see the world through a narrow slit in the electromagnetic spectrum that is otherwise entirely dark to us and that reaches from radio waves at the long end to gamma rays at the short end. Other species have slightly different capacities: for example, some insects can see ultraviolet waves that we cannot see, and so live in an “ultraviolet garden” to which we are blind. But this is only one indication of our profound limitations:
The metaphor of the narrow window of light, broadening out into a spectacularly wide spectrum, serves us in other areas of science. We live near the centre of a cavernous museum of magnitudes viewing the world with sense organs and nervous systems that are equipped to perceive and understand only a small middle range of sizes, moving at the middle range of speeds. We are at home with objects ranging in size from a few kilometres (the view from a mountaintop) to about a tenth of a millimetre (the point of a pin). Outside this range even our imagination is handicapped, and we need the help of instruments and mathematics-which, fortunately, we can learn to deploy. The range of sizes, distances or speeds with which our imaginations are comfortable is a tiny band, set in the midst of a gigantic range of the possible, from the scale of quantum strangeness at the smaller end to the scale of Einsteinian cosmology at the
Dawkins quotes Haldane, a great mid-twentieth-century evolutionary biologist, as saying, “Now my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose … I suspect that there are more things in heaven and earth than are dreamed of, or can be dreamed of, in any philosophy.“24 If Haldane is right that we live in a very strange universe, then we should not be surprised that very strange things happen, without needing to imagine external interference.
One of the stranger things about our universe is that we are present in it. One way of thinking about it, to stay at the planetary level, is called the anthropic principle, which starts from a simple, though in the larger scheme of things quite startling, fact that “we exist here on earth.“25 There are a great many things about our earth that make our existence possible, such as the presence of liquid water, essential to life, but if earth had had an orbit closer to the sun, that water would be boiling, or if farther, frozen. Further, the earth’s orbit had to be close to circular rather than strongly elliptical or in some seasons our climate would have been too hot for life and in other seasons too cold. And, as Dawkins points out (contra Monod and Weinberg), if we live on a “friendly” planet, one that can support life, we also live in a “friendly” cosmos: “Physicists have calculated that, if the laws and constants of physics had been even slightly different, the universe would have devel oped in such a way that life would have been impossible.“26 But even with a cosmos and a planet that were in some deep sense “friendly” to life, the emergence of life itself is also extraordinarily strange. To quote Dawkins again, “The origin of life only had to happen once. We can therefore allow it to have been an extremely improbable event, many orders of magnitude more improbable than most people realize.“27
It is true that the warm sea of 3.5 billion years ago was a kind of “chemical soup” with many of the molecules that could form parts of unicellular organisms already present. There are a number of theories about what had to happen before self-replicating organisms emerged, and many of them are plausible. So far laboratory experiments to recreate the conditions in which primal life originated have not succeeded in creating life, which is hardly surprising, given that we do not know exactly what that chemical soup was composed of or what exactly the conditions were on earth at the time. There are two main ways in which the problem of the origin of life is framed. One has to do with statistical probabilities, which I have already mentioned. Our sense of probabilities is based on a lifetime of less than a century, and it is in that framework that we necessarily and usefully think about probability. But if life appeared on earth spontaneously around a half billion years after our planet was formed, that gives an entirely different range of probabilities, so that something that would happen extremely rarely might still happen. That way of approaching the problem makes it a matter of a sheer chance encounter of just the right variables to produce life.
Another approach argues that sheer fortuitous accident as an explanation for the origin of life is difficult to imagine even at the most cosmic level of chance probabilities. This alternative approach turns to the phenomenon of emergence, in which apparently chaotic phenomena show the possibility of self-organization, again under just the right circumstances, yet more probable circumstances than sheer chance alone. There are a number of people who have pursued the idea of emergence in somewhat different ways. At the moment the jury is still out on how to explain the origin of life, but both theoretical and experimental work proceeds apace, so we will surely know more before long. In any case the emergence of radical novelty is a recurring theme in evolution, and we will return to it as we go along.28
The oldest surviving form of life on earth, though probably preceded by simpler forms, is the unicellular organisms called prokaryotes, whose DNA floats freely within the cell, with ribosomes that assemble proteins using instructions from the DNA. Prokaryotes multiply by cell division. For over a billion years these were the only organisms there were until, quite suddenly, 2.5 billion years ago, eukaryotes appeared, still unicellular though considerably larger than prokaryotes, and with a nucleus for the DNA and a number of other kinds of complexity, including new ways of multiplying. Both prokaryotes and eukaryotes often had tails that allowed movement. The division between prokaryotes and eukaryotes is the basic division of all life forms, for it is from the eukaryotes that multicellular organisms formed, and all multicellular organisms are composed of combinations of eukaryotes, and in an important sense are eukaryotes, having marginally and relatively recently branched off from the much more numerous unicellular prokaryotes.
But let us go back to the prokaryotes, often called bacteria, unicellular microorganisms that have been the most successful forms of life so far. They have made an incalculable contribution to other forms of life; not only have they created an atmosphere rich in oxygen through photosynthesis, but they are vital in recycling nutrients, with many steps in nutrient cycles depending on them, in the fixation of nit
rogen from the atmosphere, and in putrefaction. Being mainly microscopic, they exist within animals and plants as well as independently, and, though some of them can cause disease, they also play significant positive roles, as in aiding human digestion. The fact that some of them cause disease has given bacteria a bad name, and has indeed led to the development, in multicellular organisms like ourselves, of immune systems to counteract them, though something like an arms race develops as both bacteria and immune systems evolve to fight each other. We know that antibiotic medicines that help our bodies fight some bacteria are also involved in such an arms race. Important as all this is, it should not distract us from trying to understand the remarkable phenomenon of bacteria.
We like to think of ourselves, of human beings, as the most successful of all biological species, of our age as “the age of man,” or, at least, “the age of mammals,” whereas in fact we live, as all life for 4 billion years has lived, in “the age of bacteria,” as Stephen Jay Gould has put it. Bacteria are “the organisms that were in the beginning, are now, and probably ever shall be (until the sun runs out of fuel) the dominant creatures on earth by any standard evolutionary criterion of biochemical diversity, range of habitats, resistance to extinction, and perhaps, even in biomass.” Gould then goes on to say, “The tree of life is, effectively, a bacterial bush. Two of the three domains [bacteria and archaea] belong to prokaryotes alone, while the three kingdoms of multicellular eukaryotes (plants, animals, and fungi) appear as three twigs of the terminus of the third domain.“29
So we learn that not only is our sun a minor star in a not very interesting galaxy nowhere near the center of anything, but that our species, of which we are so justly proud, is far from the center of the biological universe, though a considerable danger to the survival of much of that universe-bacteria, however, being relatively safe from our depredations. Gould has long argued that the primary trend of biological evolution is toward diversity, variety, rather than toward greater complexity, which is only a marginal and minor development taking life as a whole.30 Indeed, there has also been massive evolution toward decreased complexity, as among the vast number of parasite species that normally are less complex than their ancestors after they have offloaded functions onto their hosts. Gould often turns Darwin’s image of the tree of life into the bush of life, as a bush shows less directionality in its widely branching stems. I am ready to agree with Gould in giving us another shock to our natural anthropocentrism, but I don’t believe, and neither does Gould, that our sheer existence and our complexity are not worthy of the most careful study. However far out in right field (Gould was a great fan of baseball) we as a species might be, we are the only species that we are and we must surely try to understand ourselves. But, as I noted in the Preface, a vote of thanks to the bacteria is surely in order: “The Age of Bacteria transformed the earth from a cratered moonlike terrain of volcanic glassy rocks into the fertile planet in which we make our home.“31 And lest we underestimate these tiny organisms, invisible to the naked eye, we must remember what extraordinary capacities they have.
Religion in Human Evolution: From the Paleolithic to the Axial Age Page 10