The Accidental Species: Misunderstandings of Human Evolution (4 page)

I have chosen to highlight the case of
Homo floresiensis
as it’s the best example I can think of, from my own experience, of a new discovery that challenges our expectations, our restricted notions of evolution based on human exceptionalism, and with it an idea of progressive improvement.

The tale of the Hobbit is the book in microcosm. It shows that new discoveries often challenge deeply held notions of how we think evolution really ought to have happened, such that we humans are the culmination of some cosmic striving for order and perfection. It also shows us that stories we tell based on fossils are often easily bruised by the sheer scale of our ignorance. Fossilization is rare—so rare that there could well have been an entire episode of human evolution, a pre-
Homo
exodus from Africa, that has left no trace in the geological record other than the Hobbit.

If there is one lesson that science holds for us, it is this—that our special estate, based either on a progressive scheme of evolution leading to its inevitable human culmination, or on a narrative reading of
prehistory, is never justified. It was Charles Darwin himself who put it best. Right at the end of
The Origin of Species
, he presented the idea of the “tangled bank,” his vision of evolution in action: “It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us.” From this, it’s evident that Darwin saw evolution not as progressive or improving, but as an activity that happens in the continuous present, as creatures interact with one another, moment by moment. From this it is clear that evolution has no plan. It has neither memory nor foresight. No vestige of cosmic strivings from some remote beginning; no prospect of revelatory culmination in some transcendent end.

Rather than being at the pinnacle of creation, human beings are just one species on the tangled bank of Darwin’s imagination. Human beings are special in many ways—of course we are—but so is each and every other species, from the insects flitting above the bank to the birds perching on the branches to the worms struggling through the damp earth beneath.

The idea of progress is, however, deeply pervasive. Our culture is drenched in it: our politics, our economics, and our science, including (and perhaps especially) evolution. It is always assumed that things advance unerringly upward as if motivated by some inherent force. Progress is unstoppable. What’s more, we are told that we need it, that we are reliant on it, and that the stagnation or reversal of progress is a Bad Thing.

Progress is destiny. The only way is up.

To be sure, if you look back from the viewpoint of the present day to any period in the past, progress seems natural and inevitable. But such a perspective is limited, because it denies that any other course might have been possible, and edits out any promising side branches that went nowhere.

An important concept to take away from this discussion is that of
loss
. Stories of progress are written by history’s victors—or at least its survivors. Such tales tend to talk of increasing complexity and sophistication, and ignore the perhaps different perspectives of creatures that have become extinct.

The concept of loss is vital to a proper understanding of evolution. This is especially so for human evolution, a subject that is often deficient in perspective: understandably so, because we, the story tellers, are only human. The history of life told by other organisms might have different priorities. Giraffe scientists would no doubt write of evolutionary progress in terms of lengthening necks, rather than larger brains or toolmaking skill. So much for human superiority. If that’s not ignominy enough, bacterial scientists would no doubt ignore humans completely except as convenient habitats, the passive scenery against which the bacterial drama is cast. Now, ask yourself—which of these stories is any more valid than any other, at least as a narrative?

The late Stephen Jay Gould punctured the idea of inevitable progression in his book
Wonderful Life
, by introducing the concept of “contingency.” That is, creatures need to be more than fitted to their lives and lifestyles by evolution: they also need a generous dollop of luck. Once luck has been stirred in, the whole idea of progress driven by some innate striving, or superiority, or destiny, becomes nonsense.

Gould started
Wonderful Life
by showing how our idea of human evolution as a matter of inevitable progress is so deeply ingrained in our culture that admen use it as a way to sell products. Admen use the metaphor of human evolution so frequently that it’s become a cliché. You’ll no doubt have seen a progression of apelike beings, walking from left to right, each one following the next, each more upright and humanlike than the last.
Figure 1
is my own modest contribution to the canon.

Figure 1

Admen complete this familiar parade with the latest computer or washing machine. The subtext is that the consumer product we’re being urged to buy is the result of successive improvements in a kind of mechanical evolution, each better than the one before. Some commercials even exploit popular notions of evolution explicitly. The TV commercial that presents evolution as a device to produce a creature sufficiently evolved to appreciate Guinness beer was especially memorable.
My favorite variation on this theme concerns a car. “It’s Evolved” purrs the voice-over.
²⁴

The idea of human evolution as a tale of inevitable progress is, however, a travesty, and has nothing much to do with Darwin. The bastardized view of evolution that’s become so much a part of the general consciousness—so much so that it’s so much low-hanging fruit for admen—owes much to Ernst Haeckel, Darwin’s number one fan in Germany.

Haeckel took Darwinian natural selection and bolted on to it older ideas of progress popular among nineteenth-century German thinkers. Take a series of forms, each one more advanced than the last—according to whatever criterion you desire, be it larger brains, longer necks, more prominent plumage, whatever—and simply draw arrows between them, representing some innate striving toward cosmic perfection.

And that’s evolution—or, at least, evolution as most people think of it—a kind of cartoon, infused more by our prejudices, desires, and innate self-regard than any actual evidence.
Figure 2
is my version—my parade of likely characters, linked by arrows, pointing in the direction of progress.

Figure 2

The arrows represent natural selection, or evolution, as essentially and inherently an agency of inevitable progression, with—perhaps—the aim of producing, in its final form, the perfection that is Man (with a capital
M
).

Yes, to be sure, I’m having a lot of fun at everyone’s expense, but how can this cartoon be in any way wrong as a picture of human ancestry, at least in a general sense?

No sensible, informed person would doubt that we all had ancestors, and the further back you look in time, the more apelike they’d have looked, right?

This cartoon picture of human evolution doesn’t really represent our actual ancestors, but metaphors, right?

Well, yes, up to a point. That we all had ancestors is true—emphatically so. That our ancestors would have been more apelike the further back in time we look is also highly likely, given that our closest living relative in the animal kingdom is the chimpanzee, and it remains reasonable to suggest that the chimpanzee has evolved less far from our common ancestral state than we have.
²⁵

But if the figures in this parade are metaphors, what do these metaphors represent? The figures, surely, represent idealized evolutionary stages, between ancient ape and modern human, rather than specific individuals or even species. That’s fair enough.

But my argument is less with the figures themselves than the arrows between them, arrows that seem to represent inevitability and progress, of evolution leading, inexorably, through one lineage and one lineage alone, to its culmination, the latest model human (or washing machine or car), more refined, more sophisticated, and crucially, more perfect than the one before.

Another problem pointed out by Darwin in the
Origin
was what he called the “imperfection” of the fossil record. The record of life preserved as fossils is immediate evidence for evolution having happened. It is, however, rarely good enough for us to be able to trace the evolution of one particular species from another with any confidence. It is important to remember that fossils, on their own, are remnants of creatures toiling on some tangled bank of the past. They do not, of themselves, represent coherent statements about evolutionary history—still less, evolutionary progress. If a fossil is a statement, it is not a sentence, such as

because fossils are not buried with their pedigrees, nor prognostications on the future of their progeny, if any. No, fossils are not statements. Nor are they phrases, or words, but exclamations, from which we, the finders, are invited to make what we can.

Piecing together the tale of evolution from fragmentary fossils is a hard business. Because fossils are so rare, and because an unknowably large proportion of the history of any lineage will have been erased, what fossil hunters can never do with confidence is look at a fossil and assert that it is the actual ancestor of any creature now living (or of any
other fossil). To be sure, the fossil might be such an ancestor—because, after all, we do have ancestors—but the chances of this in any particular case are unknowable, and in any case vanishingly small. There is, happily, a way out of this apparently blind alley, and that is the fact of evolution.

Evolution is demonstrated by the existence of fossils and the community of all life. By this, I mean that the chemistry that animates you is virtually identical to that which animates every other living creature. Because of this, there is very good reason to suspect that all life shares a single common ancestor.
²⁶
This is more than a supposition—the notion of a single common ancestry has been tested, formally and rigorously, and has been found to support the pattern of extant life far better than any model positing independent origins.
²⁷
It follows, therefore, that any fossil we find will be a cousin, in some degree, of any other creature, living or extinct, discovered or undiscovered—even if we can never show that anyone was anyone else’s ancestor.

In short, this approach to reconstructing the story of evolution as a matter of degrees of relationship, which can be inferred and tested, is far superior as a scientific approach to evolution than suppositions about of ancestors, descendants, and “missing links”—which can be inferred but never falsified. My task here, though, is to show how the sparseness of the fossil record is sufficient to mislead us, were we bent on thinking of evolution as an onward march of progress and improvement.