Free The Accidental Species: Misunderstandings of Human Evolution by Henry Gee Page B

evolved many millions of years before birds took to the air, among dinosaurs that patently would not have been able to fly. It is even possible that some dinosaurs, having evolved feathers, lost them again. This kind of backward-reasoning, in which adaptations are seen as having a purpose in some great transcendental game that lasts for millions of years, is also widely seen in schemes of human evolution that suppose, for example, that humans stood on two legs in order to free up the hands for making tools, to nurse babies, and so on.
    This style of reasoning, in which evolution is assumed to have a purpose or a goal, is naturally accompanied by an assumption of progress, very much in the pre-Darwinian style. The assumption of progression is not only a misrepresentation of evolution, but ignores most of what is actually going on.
    When we strip away the assumption that evolution is progressive, we find a different picture, both richer and stranger. Most of what seems to be going on in evolution is not the acquisition of new, improved ways of living, but their wholesale loss. This is quite at variance with the picture of evolution most people have, of a march of greater complexity and improvement—a picture that, as I hope is becoming clear, is sometimes misinformed. The concept of loss is explored in the next chapter.

3 :
Losing It
    Evolution by natural selection, then, is not a noble or divine force that carries organisms on tracks of inevitable and inexorable improvement from the past to the future. Once we’ve roasted that old canard and served it up with orange sauce, we can begin to demolish as spurious the case for human exceptionalism.
    But there’s a catch—such progressive and inexorable improvement seems to have been precisely what has happened. Over the eons, living things really do seem to have become more complicated. Simple creatures consisting of single cells, such as bacteria, evolved into complicated creatures consisting of trillions of cells, such as human beings. If “improvement” can be equated with “complexity,” then there seems to have been a general trend, throughout the history of life, for complexity to increase.
    It is said that it takes just one ugly fact to destroy a beautiful hypothesis—so how fares my contention that natural selection is a consequence of several circumstances acting together only in the here and now, without having any end in view?
    There are (at least) three answers to this. The first was very well put by Stephen Jay Gould in his book
Full House
. Yes, complexity has increased—but how could it not? If the earliest life was simple and microscopic, the only way was up. That aside, complexity seems to have been the concern of the rather small subset of creatures that includes ourselves. Even today, most creatures are simple and single-celled, and almost all of these are bacteria. Bacteria swarm on (and in, and around) every surface in uncounted profusion. Anyone who has eaten reheated cooked rice and come down with poisoning by
Bacillus cereus
might be astonished to know that the symptoms of poisoning are apparent only if there are more than 100,000 bacterial cells per gram of food. 1 This means that you can still swallow hordes of germs—cities, dynasties, empires of them—without even noticing, and suffer no ill effects whatsoever. Unbeknownst to our everyday selves, our skins crawl with bacteria, and bacteria in billions infest our guts. 2 Were every living creature counted as an equal, the total sum of nonbacterial living creation would be utterly insignificant. Complex organisms, rather than representing a general trend toward improvement, seem to have been a somewhat esoteric diversion.
    Second, it all depends on what you mean by “complexity.” How can such a thing be measured, and can it really be equated with “improvement” in any simple way? The simplicity of bacteria is more apparent than real. Bacterial cells might look simple—they are usually