The Accidental Species: Misunderstandings of Human Evolution (21 page)

My aim in the rest of the book, therefore, will be to show that our view of these attributes as uniquely or specially human is an illusion, created by our view that evolution is linear and progressive—as John Zachary Young put it, “culminating in Man.”

I have a suspicion that the distinction between humanity and the rest of creation is a relatively recent phenomenon. Folk wisdom and popular mythology—as opposed to state-sanctioned or official religion—have always respected nonhuman creatures, and even inanimate objects, as individually powerful with distinctive attributes that might be the envy of humans. Animals in folklore and nursery tales are able to converse with one another, and even humans, using human language. Such animals are intelligent, with motivations as complex as those of any human.

In her book
The Animal Connection
, paleontologist Pat Shipman contends that one of the things that make us human is a deep connection with animals. When human beings were first able to paint pictures, they painted pictures of animals. Everyone is familiar with the remarkable cave paintings—even if as reproductions—from caves such as Lascaux in France and Altamira in Spain, as well as from a host of other sites. But it had never occurred to me, until I read Shipman’s book, to wonder why the pictures are almost exclusively of animals. There are no portraits of human beings—certainly nothing to rival the naturalistic accuracy of the animal paintings. People appear as handprints, cartoonish stick figures, or grotesque “Venus” figurines. Neither are there pictures of plants, landscapes (plains, mountains, volcanoes), or weather (sunshine, clouds, rainfall, lightning), which one would have thought would have figured large in the lives of the artists. I suspect that the painters did not see themselves as we are inclined to do—as somehow separate from the animal world—but very much a part of it. Animals were to be hunted, to be sure, but also to be venerated.

Importantly, people were accustomed to seeing the world from the animals’ point of view. This can be seen in very early depictions of people dressed as animals. “Therianthropes”—sculptures of people with the heads of animals—are among the earliest known human artworks.
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This tendency goes right down to the present day. When I was a stu
dent I used to play piano accordion with a band that accompanied a side (troupe) of Morris dancers. For those who don’t know, Morris dancing is a type of folk dance typical of southern England. Modern metropolitan types tend to dismiss the sight of grown men (Morris sides are traditionally all-male) dancing around with ribbons and bells attached to their ankles as twee, even effeminate. The reality is rather different. Morris men, thundering around a pub car park, are formidable, primeval, perhaps rather frightening.

One of the dances performed by my Morris side was called “Shooting the Badger.” One of the dancers wore a badger mask, for all the world like an Ice Age therianthrope. The other dancers carried short staves and circled round, beating the staves together in rhythm, until—at a signal—they all pointed their staves inward at the badger and said “Bang!,” at which point the badger fell down “dead.” It was the task of the lead dancer—the “squire”—to accost an attractive young woman from the audience to “revive” the badger—after which the badger got up and the dance continued. I do not know this for sure (I have never investigated it), but this dance looks very much as if it harks back to fertility rituals from the earliest days of modern humanity in Europe, as represented in early cave art, in which animals are objects of awe and reverence rather than subservience.

Until recently, and even today in some societies, animals carry a social or even a legal status equivalent to that of humans, so much so that they can even be tried in a court of law.
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During the Napoleonic Wars, a French ship was wrecked off the northeast coast of England, and the only crew member that made it alive to the nearby port of Hartlepool was a pet monkey. The citizens of Hartlepool—never having seen a Frenchman before and not wishing to take any chances—put the monkey on trial as if it were a French serviceman and sentenced it to death by hanging. To this day, citizens of Hartlepool are sometimes known as “monkey hangers”—an epithet that Hartlepudlians wear with pride.
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In terms of the folk wisdom of the age, the citizens of Hartlepool were acting entirely logically—provided that one’s worldview was more accommodating of the notion that human beings and animals were of equivalent status. It could well be that the distinction between humans and animals, something we very much take for granted as having pertained since time immemorial, is in fact a more recent, post-Enlightenment fancy.

7
:
The Way We Walk

It happened a long time ago, but the experience was so traumatic that I remember it as if it were yesterday—the moment when the outraged, elderly professor pinned me against a wall and harangued me for having rejected his paper on why human beings got up on their hind legs and walked. Human beings became bipeds, yelled the prof, to free the hands so that mothers could cuddle infants close to their chests. How could I have had the temerity, screamed the empurpled sage, to have rejected a paper that made so much sense?

One of the problems with human evolution, as opposed to, say, rocket science, is that everybody feels that their opinion has value irrespective of their prior knowledge (the outraged academic in the encounter above was a scientist, but not a biologist, still less an evolutionary biologist). It’s obvious to see why—we are all human beings, and we are all bipeds, so we think we know all about it, intuitively. What we think about bipedality “stands to reason.” Now, I’d be the last to disparage anyone who wanted to express an opinion, however cockeyed, but it is sometimes the case that the most perplexing problems are those that seem the simplest at first sight.

It is always a wonder to me that there is still much to be discovered about something so screamingly obvious as the way we humans walk. However, much about human walking remains to be understood. Why, for example, do we walk the way we do? Why, when moving faster than a certain speed, do we start to run? Why do we walk upright at all, when other animals get by perfectly well on all fours? These and other such questions are still being debated by scientists. I remember publishing a research paper showing that there was a perfectly feasible gait, somewhere between walking and running, which people never used.
¹
I enjoyed demonstrating the gait to my colleagues, as if it were something out of the famous Monty Python sketch about the Ministry of Silly
Walks. We might not know the arcane secrets of the universe, but we are all perfectly familiar with walking and running, so how could there be a third, distinct gait, available all the time for our use, and we somehow missed it?

As anyone who has watched a cruising toddler will attest, simply the act of standing up on two feet requires a great degree of control, and scientists still have a great deal to learn about how this is achieved—and this is with modern human subjects who can be watched and their activities measured. And even after all this, robots that can walk with anything like the natural grace of a human have yet to be built. How much harder it is to learn about how bipedality evolved, still less why.
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The very fact of bipedality remains a taxing problem for those versed in fields as diverse as evolutionary biology, mechanical engineering, and robotics. It’s not the easy problem that people so often imagine.

The common or garden explanations put forward by armchair theorists tend to avoid the problems that engage serious scientists—problems of energetics, and posture, and balance, and anatomy, and neuromuscular control, in other words anything that might require some actual scientific training and a facility with at least the basics of mechanics—and cut to the chase of why the ancestors of humans became bipedal. These explanations are invariably teleological. That is, they are driven by some inherent purpose or striving, in the manner of Lamarck—or, indeed, of the popular model of evolution as “progressive,” which I have demonstrated as erroneous. For example, humans got up
so that they could
free their hands in order to make tools or grasp low-hanging fruit;
³
or
in order to
cuddle babies close to their chest; or
in order to
see longer distances; or
in order to
live better in open country rather than in forests, as our ape cousins still do.

All such arguments are easily demolished. For example, many animals make tools, irrespective of whether they have hands; nonhuman animals of all sorts have no problem cosseting their young close to their chests; many animals are tall, or can make themselves so, without being bipeds; many large primates such as baboons live in open country and do so on all fours without extravagant distress. So why should bipedality be in any way remarkable, a qualitative advance over what other animals can achieve? Why not stay on four legs and evolve longer legs? Or longer necks? Why not evolve jumping or hopping?

Another idea is that bipedality evolved
in order to
make it easier for
people to keep cool in hot climates.
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A biped presents a much smaller cross section to the sun—just the top of the head rather than the whole body. The rest of the body, not pointing sunward, is thus free to radiate away any excess heat. This idea makes sense, in part, because it seeks to explain a suite of other features of humans that don’t immediately seem connected with bipedality. These include our hairlessness relative to other primates, and the presence of large numbers of sweat glands in our skin. Taken together, you can see how a creature with exposed skin and plenty of sweat glands could have stood up in a breeze to cool off—an advantage in the hot, dry climates of Africa in which the human lineage is thought to have evolved.

This all seems fine, except that there are lots of other animals that live in hot climates that are both quadrupedal and very furry. And the idea also doesn’t explain another feature of human heads, namely male-pattern baldness. Why should males become bald, exposing their scalps to the direct glare of the sun, while females generally retain their heads of hair?

The problem is that you can come up with any number of other ideas that “explain” any suite of features you choose, all of which have much to recommend them, and none of which can be shown to have any more scientific validity than any other. Just come up with a scenario, and then cherry-pick the features of modern humans you need to make the theory work, and ignore any others.

An example of this kind of approach is the “aquatic ape” theory, promoted for many years by Elaine Morgan.
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Morgan selects a range of features of modern human physiology and behavior to suggest that there was once a period in human evolution during which humans were aquatic—that is, lived in and around water, and became adapted to an aquatic environment in a way that our close ape cousins did not. This idea is perhaps the most developed of all the various ideas I have described as teleological, and the subject of several books that have gained a degree of respectable support.

The anatomy of humans is certainly peculiar in many ways relative to that of apes such as chimpanzees and gorillas. Humans are much fattier than apes and are much less hairy. In contrast to almost all other primates, humans are capable swimmers, and newborn babies appear to have an inborn capacity for swimming. In these respects humans are less like apes than, say, seals and other aquatic mammals, which are relatively fatty and hairless, compared with their purely terrestrial
cousins. Humans, in contrast with apes, have historically eaten a lot of seafood, a diet that offers minerals and fatty acids essential for development, especially for the brain and nervous system, but otherwise hard to come by unless humans once spent a great deal of time in and around water.

There is a lot more to the “aquatic ape” idea than that, of course, but from this brief description you can, I expect, already identify some flaws. The first is that it’s always a problem identifying features that humans have now and inferring that they must have had some adaptive value in the past. It’s entirely true that humans seem to have an unusual fondness for seafood—but we still do, and it remains an important part of our diet. But we humans also consume an extraordinary range of foodstuffs compared with other animals, including substances that are noxious or even bad for us, such as capsaicin (the substance that makes chili peppers hot), alcohol, tobacco, and dangerous drugs. What of body fat and hairlessness? If they were once selectively advantageous for water-loving humans, why are we still relatively fatty and less hairy than other apes? Presumably other factors have come into play that might have nothing in particular to do with an aquatic stage in our history.

Second, it’s notoriously hard to infer habits from anatomical structure. If a busload of Martian anatomists came across the skeleton of a goat, the one who said that goats would be good at climbing trees would be laughed off the planet. With their long, spindly legs and complete lack of grasping hands or feet or tail, you’d think that goats could climb trees as handily as giraffes can ride unicycles. However, it so happens that goats are surprisingly good at climbing trees.
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And you’d never guess from her fur that my golden retriever, Heidi, is a capable and strong swimmer, regularly braving pounding North Sea surf to retrieve a stick or ball. Heidi is very far from hairless—indeed, she can brave the cold and wet of the sea because she has more fur, rather than less, an extra layer of underfur that keeps the cold and wet away from her skin.

The relative hairlessness of humans is complicated, however, by sex. It’s easy to say that being relatively fatty and less hairy might be a sign of aquatic ancestry, but this doesn’t explain why human females are very much fattier and less hairy than human males. In addition, men become more hirsute as they mature (excepting male-pattern baldness, as I mentioned above). Sex differences in fat content and hairlessness
are intriguing and demand explanation. Their presence might even shed light on why we humans are bipeds.