Last Ape Standing: The Seven-Million-Year Story of How and Why We Survived (22 page)

Gibraltar, surrounded by water and so far south, would have remained temperate even in the face of the descending glaciers, up to a point. By twenty-four thousand years ago, as the ice age tightened its frigid grip, even Gibraltar grew arid, the marshlands died off, and the game with it. Each day would have become a little harder, and finally, impossible.

Someone had to be the last Neanderthal, an individual like you and me. He, or she, didn’t know it, but whittled down and alone, that person’s end was more than a single death. It was the passing of an entire species shaped and hammered in evolution’s crucible for hundreds of thousands of years. What were those last hours like?

I would like to think they were spent sitting on a Gibraltar precipice, high above the shallow Mediterranean, looking west as the sun descended into the Spanish mountains. Maybe in those last moments the pale light faded on the Neanderthal’s sloped and beetled brow while that strange and fiery orange ball slipped mysteriously away, and with it the last Neanderthal mind, with its last, unique Neanderthal thoughts. After two hundred thousand years, a time that mangles and boggles our ken, extinction had at last come.

But why the Neanderthal and not us? To say it was because we were smarter somehow, or better communicators, or more social, strategic, or creative begs the deeper question, what happened that we developed those gifts and not them? What made the difference? As usual, the answer isn’t simple, but it’s fascinating, and once again it is linked to our childhood.

When teeth are formed, they are built one layer of enamel at a time, each deposited on top of the other. This leaves a pattern, if you inspect them closely enough, that resembles the growth rings of a tree; the more enamel that is laid down, the wider the spaces, or perikymata, become.

You wouldn’t think that ancient teeth could possibly have much to say about human evolution, but, as it turns out they speak volumes and provide a terrifically convenient way to measure how quickly different primates, including our human relatives, grew up. Even if a scientist has nothing more than a single, ancient molar or bicuspid to work with—which, in paleoanthropology, is often the case—it’s remarkable how illuminating a tooth can be. By inspecting the speed with which the perikymata of even very different primates were laid down, it is possible to compare how “old” they were, relative to one another, when they reached adulthood, or puberty, or even when they were likely weaned, all depending on when the tooth stopped growing. In this way a tooth can act as a rock–solid biological clock set against other biological life events that can help shed some much–needed light on whether our ancestors matured more quickly, or less quickly, than we did.

You and I, we already know, take eighteen to twenty years to reach physical adulthood, whereas chimpanzees and gorillas reach adulthood by age eleven or twelve, in nearly half the time. The main reason for this is our extended childhood. The point is, our rates of growth over our lifetime are different from those of other primates. We cut our first permanent molars around age six, but chimps lose their baby teeth around the age of three and a half. The earliest humans, such as
afarensis
, developed at the same rate as chimpanzees, and so did their teeth. But later, with the arrival of
Homo habilis
and
Homo erectus
, childhood lasted longer and growth slowed. A
Homo erectus
child cut her first molar between ages four and four and a half.

All of these findings pooled together from studying the teeth of precursors from around the world readjusted the age of the most famous youngster in all of anthropology, the Nariokotome (or Turkana) Boy (see
chapter 2
, “The Invention of Childhood”). Originally scientists pegged his time of death at age twelve, but now the consensus is that he was closer to eight even though he was already an impressive five feet three inches tall. He was hitting his adolescent growth spurt (the one that drives parents crazy when they are trying keep their kids in reasonably fitted clothes) even though by our lights he should still have been a little boy. (He was, therefore, about halfway between us and chimpanzees in his growth rate.) All of this tells us that earlier in our evolution our ancestors grew up faster, which means their childhoods were shorter, which further means that they had less time to learn before they began to get set in their adult ways.

You would think that by the time Neanderthals had arrived on the scene that the speedier growth rates of Nariokotome Boy would have evolved out of us and caught up to rates similar to ours today. After all, we and Neanderthals evolved from the same common stock and came into existence at about the same time. We were roughly the same physical size and so were our brains.

For some time it looked exactly this way, then in 2001 Alan Walker, one of the team who had originally discovered Nariokotome Boy, found that Neanderthals didn’t attain modern growth rates like
Homo sapiens
until about 120,000 years ago, 80,000 years after they first arrived. Or so he thought. But soon this conclusion was proven wrong when a Harvard researcher named Tanya Smith and her colleagues, after the careful inspection of many teeth, concluded that not only did Neanderthals not lengthen their lives or their childhoods as much or as early as Walker had thought, they had actually shortened them, reversing a trend at least seven million years in the making! Smith says Neanderthals reached full maturity by age fifteen, three to five years earlier than us and not terribly different from the pace that Nariokotome Boy was on, nearly a million and a half years earlier. On the other hand, human fossils unearthed in Morocco indicate that we
Homo sapiens
reached current growth rates as early as 160,000 years ago.

What, however, would cause a childhood–lengthening trend that had been in the works for so long to reverse itself in Neanderthals? The same force that causes all evolutionary trends to turn and twist—the need to survive.

Neanderthals, you might recall, had a rough time of it fighting cold climates and hunting enormous animals at close quarters, among other challenges. Their population, even when the climate grew warmer, never took off, which meant that from the first moment they emerged, they were, essentially, an endangered species. It’s true they were enormously strong and as tough a creature as ever walked the planet, yet they didn’t live long. Because they were so quickly snuffed out, and because they congregated in small groups, evolution apparently began to favor Neanderthal children who grew up faster, could bear children sooner, and reached adult size and strength as rapidly as possible to replace the older members of the troop who passed on so quickly.

This would have two immense and not terribly favorable long–term effects. First, it meant Neanderthal children spent less time playing,
learning, and developing socially and creatively in early life. The effect—less personal adaptability and creativity. They had less time to develop unique personalities and talents. Second, it meant fewer mentors who could pass valuable knowledge along to younger members of the clan. Neanderthals became so focused on their short–term need to survive that they were unable to develop the more complex skills that saved us
Homo sapiens
over the long haul.

From an evolutionary point of view, however, what other route could they have taken? Neanderthal mothers could not suddenly begin to have litters of offspring like a cat or a pig to compensate for their kind’s high mortality rate, and given their sparse numbers and tiny tribes, they simply didn’t have the “bench strength” that a larger population supplies. They were caught in an evolutionary catch–22, and accelerating their childhoods was the best Darwinian solution at hand. For two hundred thousand years, it worked. And then it didn’t.

We
Homo sapiens
were luckier. Though we had swung precariously close to extinction ourselves fifty thousand years earlier, the climatic forces behind our demise struck quickly, then reversed. Despite our near–death experience, there wasn’t enough time for a genetic solution à la the Neanderthals, so when the climate recovered, so did we, in a hurry. DNA analysis shows we rapidly fanned out into Europe and Asia, and all points beyond. The main reason we could was because we had already maximized the lengths of our childhoods, which now poised these strange, slender savanna apes with their youthful looks, big brains, and enormous personal diversity to change the world in profound and startling ways.

Which brings us to the next part of our story.

I cannot imagine, even in our most primitive time, the emergence of talented painters to make cave paintings without there having been, near at hand, equally creative people making song. It is, like speech, a dominant aspect of human biology
.

—Lewis Thomas,
Lives of a Cell

You may not find it particularly attractive to perforate your upper lip and then slip a large metal and bamboo ring called a pelele into it to force your lip two inches beyond your nose, but women in the Makololo tribe of south–central Africa did it in the nineteenth century, and the men loved it, even when a smile sent the ringed lip flipping up to cover the eyes of the woman who wore it.

In 1860, when a British explorer asked the Makololo chief, “Why do women wear these things?” the chief, in stunned disbelief, answered, “For beauty! They are the only beautiful things women have; men have beards, women have none. What kind of a person would she be without pelele? She would not be a woman at all with a mouth like a man, but no beard.”
¹

It is difficult to underestimate the power of the visual cues that drive human behavior, including those devoted to the arts of seduction. “Savages at the present day deck themselves with plumes, necklaces, armlets, ear–rings, etc. They paint themselves in the most diversified manner,” Charles Darwin wrote in 1860. He devoted an entire chapter in
The Descent of Man
to exhaustively detailing the wild and alien ways people all over the world embellished themselves to attract and impress the opposite sex. The natives of Malaysia painted their teeth black because it was shameful to have white teeth “like those of a dog.”
Some Arabs believed that no beauty could be perfect until the cheeks or temples “have been gashed.” The Botocudos of Brazil placed a four–inch disk of wood in their lower lip, and the women of Tibet elongated their necks by placing metal ringlets one on top of the other until their heads almost appeared to hover magically above their shoulders.

Most of the time, Darwin observed, women’s adornments focused on enhancing their beauty. Men concentrated on making themselves physically attractive, too, but mostly they favored adornments designed to strike terror into their enemies during battle because a fierce warrior is often attractive to the opposite sex. So they embellished themselves with paint of all kinds, or, like the Maori of New Zealand with remarkably detailed facial tattoos. The women of some African tribes found a star stamped on a man’s forehead and chin absolutely irresistible.

Darwin’s anecdotes aren’t the only testament to how important we consider our appearance to be. Human beings focus on appearance all the time, everywhere. In 2011 the cosmetics industry induced men and women worldwide to separate their wallets from $12.5 billion. And in 2010, Americans, without help from anyone else in the world, spent $50 billion on jewelry.
²

Darwin enumerated example after enthralling example of this aspect of human behavior because he was trying to make
the
central point of
The Descent of Man
—species work to guarantee their survival in two ways. First, by outflanking disease, parasites, predators, foul weather, and all the other countless dangers of their environment. And second, by having sex. Only by finding willing mates with whom to get on with the business of bringing new offspring into the world, he pointed out, can any species hope to survive. This process he called “sexual selection.” The two strategies are intimately bound. Survival serves no purpose without sex, and sex, of course, is impossible without survival. Naturally, the first step to being sexually selected is getting the attention of the opposite sex in the first place. You can’t mate if you can’t manage to be irresistible. To go unnoticed is to go unloved, and unrequited love in nature is a sure path to extinction, at least for you and the DNA you personally have to offer the gene pool.

This makes fewer goals in life more important—from an evolutionary point of view—than successfully landing at least one sexual partner. This has caused the forces of natural selection, given their collective knack for conjuring strange genetic fabrications in the interest of survival, to cook up some extravagant ways to advertise just how alluring the members of various species can be to one another. Peacock feathers are surely the most celebrated, but there are also the colossal antlers of the (now extinct) Irish elk, the elaborate songs that the red–eyed vireo sings to charm females, the thick manes of lions, and the vibrantly colored bottoms and faces of male mandrills. Even the bright colors and fragrances of flowers are a kind of sexual allurement because they attract bees that then “impregnate” other flowers by proxy.