Chapter 2

Power in the Pleistocene: On Spears, Fires, Furs, Words, and Flutes—And Why Men Are Such Power-Hogs

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Chapter commentary

Richard explains how Power differs from similar books like Sapiens, and why gender inequality is not necessarily inherent to our species.

A system of obedience depends on punishment. Within families or small groups, the mechanism of punishment can be emotional manipulation or physical beatings, but in the politics of large-scale groups, a proactive coalition provides the power. An order given to a subordinate is essentially a threat to use aggression unless the order is obeyed. If the threat depended merely on the fighting power of the leader, it would rarely be convincing. No leader could risk repeated fights. Even an alpha chimpanzee tries to avoid fighting when possible. However, a human leader does not have to fight personally; a coalition of supporters guarantees the value of the leader’s threat, and the likely danger from an aggressive encounter is low for the supporting coalition because their overwhelming power can be brought to bear on the subordinate.

― Richard Wrangham, The Goodness Paradox

Right, as the world goes, is only in question between equals in power, while the strong do what they can and the weak suffer what they must.

― Thucydides

The story of humanity’s development of its awesome and unique array of powers likely began, ironically, with climate change. About 13 million years ago, several centuries of drought ravaged the forests of east Africa. As a result, many tree-dwelling primates were forced to adapt to living in expanding savannahs. The primates that stayed in the shrinking forests were the ancestors of today’s nonhuman great apes—gorillas, chimps, and bonobos. The primates that came down from the trees evolved into several lineages of hominins (i.e., proto-humans). One of those lineages ultimately led to us.

It’s still unclear whether the savannah dwellers developed an upright stance, walking on two legs instead of four (a process that must have taken millions of years), before, during, or after leaving the forest. Nevertheless, living in grasslands rewarded the trait of bipedalism. It was now advantageous to stand tall, so as to peer over high grass to see predators and potential food. Crucially, this increasingly upright posture conferred power in several other ways:

  • Bipedal hominins burned fewer calories as they foraged, compared to knuckle-walking forest primates (walking on two legs isn’t calorically superior to the quadrupedal locomotion of deer or horses, at least over short distances—but our ancestors weren’t directly competing with those kinds of animals; instead, they were competing with other apes).
  • Hominins and their descendants could walk and run long distances at a constant speed. This enabled them to chase down prey such as deer that could sprint much faster, but tired quickly.
  • Hominins’ (and later humans’) ability to walk long distances also helped them to spread out geographically—ultimately hiking, boating, and sledding their way throughout all the Earth’s continents except Antarctica.
  • Crucially, bipedalism freed hominins’ front limbs for tasks other than locomotion.

Meanwhile, life on the savannah required more emphasis on long-distance vision. As their sense of sight increasingly predominated over other senses, proto-humans began to coordinate their eyesight with small, controlled movements of their freed-up hands. Even though the hands of other primates are anatomically similar to those of humans, new neural pathways in hominins helped in the development of the muscle control necessary for grasping, manipulating, and throwing—using what paleoanthropologists appropriately call the “power grip.”

But walking upright imposed costs and required adaptations. Notably, it created the need for a thicker pelvis; and this, in turn, resulted in changes to the process of childbirth. Babies were born smaller, so they required more lengthy parental care before they could fend for themselves. And that period of extended care promoted extended families—which offered more opportunity for social interaction and for the development and transmission of culture.

Increased social contact contributed to one more crucial change in hominins and their descendants: a substantial growth in brain size. Bigger brains co-evolved with walking; with finer, more controlled hand movements; and with increased social interaction. Each of these developments compounded the others. Big brains, for example, also reinforced changes in childbirth, already underway as a result of bipedalism: because of their larger crania, babies had to be born in a less mature state, and were even more dependent on long-term familial care. Meanwhile, more social interaction required more memory and thought—hence bigger brains. Walking, the development of better hand-brain coordination, bigger brains, and increased social interaction, in effect, together constituted a self-reinforcing evolutionary feedback loop. Over nearly seven million years our brains tripled in size, with most of that growth occurring in the past two million years. And, during that same period, humans became some of the most social creatures on the planet.

Crucially, it’s important to remember that these changes were occurring among several pre-human and human species. Even after the appearance of true humans (genus Homo), perhaps three million years ago, several distinct species persisted.

  • The earliest known of the true human species was Homo habilis, which must have emerged nearly three million years ago; all known signs of this species are restricted to Africa.
  • Signs of Homo erectus date from two million years ago; this human species emerged in Africa but then spread to Eurasia. It may have survived in Java as late as 70,000 years ago.
  • Homo denisova, which probably appeared in Africa at least 400,000 years ago, migrated northeast to Siberia, and southeast to Indonesia and New Guinea. Denisovans persisted longest in their southeastern range; genetic evidence suggests they may have interbred with Homo sapiens in New Guinea as recently as 15,000 years ago.
  • Homo neanderthalis, with which we share about 99.8 percent of our genetic code, emerged in Africa at least 400,000 years ago and spread north and northwest to the Middle East and Europe; and later eastward, where Neanderthals probably interbred with Denisovans. Neanderthals had similar-sized brains (perhaps even slightly bigger), on average, to those of sapiens. But the formation of Neanderthal skulls suggests that there may have been differences in how this large brain was organized and used, compared to ours. Neanderthals died out by about 40,000 years ago.
  • There were other human species as well. Homo ergaster, which may have been a variant of Homo erectus or a separate species (experts disagree on this point), lived in southern Africa between 1.9 and 1.4 million years ago. Two species, Homo soloensis and Homo floresiensis, have been identified just in Indonesia, where human fossils seem to have survived particularly well. Homo naledi lived in part of southern Africa 300,000 years ago. Homo heidelbergensis preceded Neanderthals in Europe, and persisted alongside them for a time (it may have been the common ancestor of Homo neanderthalis and Homo sapiens).

All the species mentioned are simply ones whose remains happened to be preserved and were later discovered by modern researchers; there may have been more, evidence of which hasn’t been found. What’s crucial to our story is the clear fact that none of them survived to the present—except one.

Homo sapiens first appeared in Africa roughly 300,000 years ago, then spread out from that continent in at least three waves, the first of which occurred over 250,000 years ago, and another about 100,000 years ago. Sapiens individuals who were part of those early migratory waves interbred with Neanderthals and probably with Homo erectus as well. But these sapiens evidently died out. A later wave of migration began about 70,000 years ago. This time sapiens survived and flourished nearly everywhere it went. All humans outside Africa who are alive today—Asians, Pacific Islanders, Europeans, and Native Americans—descended from that last migratory wave. Meanwhile, in the process of flourishing, sapiens profoundly altered landscapes nearly everywhere it went, wiping out many large mammal and bird species. This was a uniquely powerful kind of primate.

During the last three million years, as these various human species came and went, the environment was in a state of enormous flux. Ice ages lasting tens of thousands of years were interrupted with shorter warming periods during which the ice retreated, opening up space for grasslands and forests. Then the ice would return. Some of these shifts were fairly abrupt, punctuated by sudden, cataclysmic floods and extreme weather events. Neurophysiologist William H. Calvin has theorized that these repeated bouts of climate change acted as an evolutionary pump, forcing humans to adapt repeatedly to dramatically altered circumstances, thereby selecting for larger brain size.1 The notion is hard to prove or disprove, and it raises the question whether there were equivalent evolutionary impacts on other animals. However, it also offers food for thought about our future human response to the climate change that we ourselves are now causing. But—back to our story.

Sidebar 5: Ominous Power from Space: Asteroids, Comets, and Climate Change

In their 1980 book, The Cosmic Winter, astrophysicist Victor Clube and astronomer Bill Napier argued that Earth was bombarded 13,000 years ago by the fragments of a giant comet; this resulted in a cosmic winter that changed the global climate for centuries. Ancient peoples’ later worship of vengeful sky gods, according to the authors, may have been partly a response to periodic rains of fire that persisted, as the orbits of the comet’s remnants occasionally crossed Earth’s path. In the past four decades new findings have lent increasing support to this notion of cosmic catastrophes as contributing drivers of planetary and cultural change.

Abundant evidence shows that Earth underwent rapid cooling 12,800 years ago. Average temperatures dropped as much as 14 degrees Fahrenheit in just a couple of years in some parts of the Northern Hemisphere, and ice cores from Greenland show that this cool period lasted about 1,400 years. Climate historians call this the Younger Dryas period. It marked the beginning of a decline in ice-age megafauna, such as mammoth and mastodon, eventually culminating in the extinction of more than 35 genera of animals across North America.

For decades, most geologists tied the Younger Dryas to the failure of glacial ice dams holding back huge lakes in central North America. The sudden influx of freshwater into the North Atlantic would have shut down ocean circulation and cooled the temperate regions of the Northern Hemisphere.

However, a competing hypothesis holds that an extraterrestrial impact contributed to this chain of events by igniting massive wildfires that blocked sunlight with their smoke. Ocean, lake, soil, and ice samples from around the world show large peaks in particles associated with burning in the layers associated with the start of the Younger Dryas. So much soot was released so quickly that scientists estimate that as much as ten percent of the world’s forests and grasslands may have burned. The Younger Dryas boundary layer is also rich in impact-related materials such as silica-rich tiny magnetic spheres, nanodiamonds, melt-glass, nickel, osmium, iridium, and platinum.

How much power can an asteroid or comet impact deliver? It’s estimated that the Tunguska detonation of 1908, in which a comet fragment exploded over Siberia, released 20-30 megatons of energy, while the Chicxulub impact in Central America that likely killed off the dinosaurs 60 million years ago is estimated to have had the explosive power of 100 trillion tons of TNT, or over a billion Hiroshima bombs. The detonation of the object that triggered the Younger Dryas would have had a power somewhere between those two values.

Figure 2.1 Global temperatures during the Pleistocene and Holocene.
Credit: Adapted from an illustration by Glen Fergus, CC BY-SA 3.0, via Wikimedia Commons.

All human species walked upright. All used their opposable thumbs to make and use tools. Why did the last great migration of Homo sapiens out of Africa succeed, when earlier ones didn’t? It would appear that sapiens had acquired some crucial power advantage in the meantime that enabled it to outcompete all other human species, either deliberately or inadvertently driving them to extinction.

The prime candidates for this hypothetical new source of power, according to most paleoanthropologists, are the fabrication and use of more sophisticated tools, control of fire, and language-based social skills.2 Spoiler alert: the question of how and why other human species died out is still open and the evidence is inconclusive. Nevertheless, it’s worth exploring these three advantages one by one, as they profoundly shaped who we are today. Whether or not they enabled sapiens to outcompete other sorts of humans, these were unquestionably the sources of power that ultimately led our kind to dominate the rest of the biosphere.

Sidebar 6: A Watery Theory of Human Origins

Initially proposed by marine biologist Alister Hardy in 1960, and developed by Elaine Morgan in her books The Aquatic Ape Hypothesis (1982) and The Scars of Evolution (1990), the aquatic ape theory is a heterodox alternative to the widely accepted notion that humans evolved mostly in the African savannah. The theory argues instead that early Homo sapiens became adapted to swimming and diving in freshwater lakes, and that various unusual human anatomical features resulted from adaptation to watery surroundings.

Geological evidence shows that deep freshwater lakes appeared and disappeared all along the East Africa Rift Valley between 2.6 million and 1 million years ago—a key period in human evolutionary history. The Valley was a highly variable environment that forced our primate ancestors to accommodate themselves to alternating aquatic ecosystems and relatively dry ecosystems, and that also forced them to migrate.

Plentiful remains of Homo sapiens, about 200,000 years old, have been found in the Rift Valley and along the African coast. These coastal humans gathered, opened, and cooked shellfish, and made spears—possibly for fishing. By 90,000 years ago, modern humans had begun making tools that were unambiguously designed for fishing. They lived in caves in at least a dozen sites along the coast. And they were the last hominins to leave Africa, around 60,000 years ago.

Proponents of the aquatic ape theory suggest that humans’ upright posture developed for wading in shallow water and swimming, not seeing over tall grass; that early stone tools were used more often to break open shellfish than to kill and butcher land animals; and that we lost our body hair and replaced it with fat for positive buoyancy and warmth in the water—as did seals and manatees. They point out that we are the only primates that can float, and that we are the only primates born with a breath-holding instinct. The crab-eating macaque is the only other primate that spends much time in the water and that can hold its breath for any length of time (about 30 seconds), and it lives in coastal mangrove swamps. Compared to our closest primate relatives, the chimps and bonobos, humans are far more attracted to water and are much better swimmers and divers.

The human speech apparatus allows the nasal cavity to be either connected or disconnected from the other supralaryngeal air passages. It’s not clear how or why this feature evolved; however, one benefit from this arrangement is that it prevents water entering the nasal cavity from reaching the lungs. This anatomical feature allows us to control our breathing more than other primates and allows us to make a wider variety of sounds, while also enabling us to swim and dive. Thus, according to the aquatic ape theory, our watery early environment may have played a key role in the human development of speech and language.

The aquatic ape theory is discounted by most anthropologists, who offer alternative explanations for the development of several key human anatomical features. Nevertheless, this neglected theory may hold clues to the origins of at least some uniquely human adaptations and powers.

Hands and Stone

Tools leverage power. A stone axe, for example, can focus the force of a swinging arm onto a tiny area, delivering a blow that can break open a hard nut or bone, or crush the skull of an animal. Something similar can be said for most of the vast range of other tools that have followed upon the simplest and earliest ones used by our ancestors, from the wheel to the smartphone: they offer means of transferring energy in ways that increase useful power.

While chimpanzees use sticks and simple stone tools, they don’t do much to alter their stones, which they employ mostly just for breaking open nuts. The earliest proto-humans, when they first appeared roughly three million years ago, did a little more than that: they began to reshape the stones they used. Mainly this consisted of striking one stone against another to knock off a flake, thereby creating a cutting edge. But this was a crucial difference: making and altering tools was what set genus Homo on the path toward ever-growing infatuation with and reliance on technology. Still, as archaeologists survey strata from the past three million years, they find surviving stone tools that remained relatively plain and simple for a very long time—until just the past few tens of thousands of years.

There is evidence that early humans also made tools out of wood, leaves, reeds, skin, bone, sinew, and other animal and plant materials. However, most of that evidence is indirect: these kinds of tools were highly perishable (unlike stone tools, which by their nature are more apt to survive). Some of them, such as boats made from tree trunks or hides and poles, and sleds made of poles and split wood—the earliest transportation tools—would be essential in the process of human dispersal around the world. Stone tools were used in manufacturing nearly all of these ephemeral technologies.

Many early tools were weapons—axes, knives, and projectiles that expanded humans’ power over other animals and other humans. Weapons were a leveling force in human social relations: without them, the individual with greater size and physical strength typically prevailed in any contest. With weapons as part of the equation, strategy took on greater importance. A smaller but cleverer individual could realistically hope to overcome a bigger opponent. Through the millennia, weapons would become pivotal tools, with technological advances contributing to the beginnings of warfare, the formation of early states, and the rise of empires (these social developments would, of course, come much later; we’ll discuss them in the next chapter).

Innovations in designing and crafting stone tools probably occurred redundantly as well as repeatedly: individuals in more than one place would come up with a new way of making or using a tool, then forget it, then think of it again as the need arose. Gradually and fitfully, tools became more specialized and sophisticated.

Homo habilis mastered the simplest human tool set, which consisted of flaked stones with suitable characteristics. These stones, intended to have a cutting edge, were probably mostly used to butcher and skin animals. With tools like these, Homo habilis had the power to thrive in environments previously inhospitable to primates; that’s because it had access to new food sources and could make clothing (more on that below).

Roughly at the same time as the appearance of Homo erectus came tools that were more thoroughly worked. Stone tools were more carefully shaped, and their edges were retouched with softer hammers of wood or bone to produce knives and axes that were finely chipped all over. Such tools could be used to slice, something previous tools couldn’t effectively do.

Still another characteristic tool set was associated with Homo neanderthalis and early Homo sapiens; it included smaller, carefully worked flakes that would have required more hand strength and flexibility for their manufacture and manipulation.

A much more diversified and refined tool set is found in sapiens sites dating between 50,000 and 10,000 years ago. The people who made these tools seem to have relied increasingly on finely worked stone blades for hunting, and there is clear evidence that the blades were mounted on shafts, using string or sinew and glue, to reduce breakage and improve leverage. There is also evidence that rocks with particularly desirable properties (such as obsidian, which can be flaked to an extremely sharp cutting edge) were sometimes sourced from hundreds of miles away, implying the existence of trading networks.

Early archaeologists ventured some faulty guesses about stone tools—how they were made, how they were used, and what they were used for. Researchers (some of whom were credentialed archaeologists, some of whom were amateurs) took a big step forward in their understanding when they started to make and use stone tools themselves. Today, primitive technology classes are offered in many places around the world; in a two-day or week-long workshop, you can learn the very basics of how to flake and haft stone tools, among other useful skills. As a result of what they’ve learned this way, scientists now appreciate much better the care and skill required to craft and use stone implements—especially ones made after about 50,000 years ago.

The manufacture of these sophisticated tools required skills developed during hundreds or thousands of hours of practice on the part of the manufacturer, as well as the ability to pass those skills on to others, no doubt using language (which we’ll discuss shortly). These tools took a variety of forms—from hoes to hammers, bowls to baskets, and needles to knives—and included an increasing variety of projectile weapons (spears and spear throwers, bows and arrows, and slings).

Could it be that these sophisticated tools gave an edge—perhaps quite literally in some cases—to sapiens over other human species? That was long the assumption of many theorists. But it’s unclear whether this was really the case, or whether improved tools were merely part of a more complicated story. Neanderthals, after all, made and used tools, in some cases ones almost indistinguishable from those crafted by sapiens during roughly the same period.

Setting aside once again the problem of what enabled sapiens to survive when other human species didn’t, let’s return to the more basic question of how tools expanded humans’ power over the rest of nature. At the time of their earliest tool kits, humans were probably scavengers. Like today’s great apes (all of which are endangered), early humans were also prey to big predators. They were capable of killing only small animals for food and probably led a precarious existence.

With spears for killing at a distance, and knives for butchering, all that changed. Humans became formidable hunters. And away went the wooly mammoth, the short-faced bear, the hornless rhino, the giant wombat, the giant ground sloth, the moa, the giant wallaby, the marsupial tapir, the giant platypus, the giant echidna, and many other species of megafauna. Moreover, big predators—including lions, tigers, and bears—now had to fear armed humans as much as humans feared them.

But long before many of these developments, we sapiens had set in motion other elements in the feedback process that propelled our primate lineage to the pinnacle of power. Let’s turn to what was almost certainly the next element in line, in terms of chronology: controlled combustion.

The Fire Ape

As we saw in Chapter 1, a few bird species in Australia have been observed deliberately spreading fires in order to flush out prey. Our distant ancestors adopted a similar behavior and developed it further by learning to make and manage fire. This gave them significant power in three ways.

First, when fire was used for cooking, it enabled early proto-humans and humans to increase the amount of energy their bodies could derive from food. As anthropologist Richard Wrangham argues in his book Catching Fire: How Cooking Made Us Human, cooking “gelatinizes starch, denatures protein, and softens everything.” As a result, “cooking substantially increases the amount of energy we obtain from our food.”3

The benefits of cooking aren’t obvious to everyone. Many people extol the advantages of raw food over cooked—including the preservation of essential enzymes in the food itself and the promotion of stronger teeth and jaws in those who eat it (there is good evidence that eating softer foods has led to narrower jaws, malocclusion, and impacted wisdom teeth, among other maladies). However, Wrangham points out that, whatever the costs, cooking nevertheless makes it much easier for us to digest a range of foods. Evolutionary success is mostly concerned with energy, so, “if cooking causes a loss of vitamins or creates a few long-term toxic compounds, the effect is relatively unimportant compared to the impact of more calories.”4 Cooking, in other words, gives us more nutritional power—and the advantages conveyed by accessing more power, in this case as in so many, overwhelm other concerns.

Second, campfires offered our ancestors warmth and light in the night. They also kept predatory animals away while humans slept—not a small advantage if one happens to have big cats or other fearsome predators as neighbors. Some have argued that campfires helped spur the development of language and religion; after all, what do we ourselves do when we sit around a campfire at night? We tell stories to entertain one other. Maybe ancient humans did the same.

Third, fire enabled early humans to alter woody landscapes to make them more productive for human purposes. This turned out to be a world-changing sort of power. Over a few tens of thousands of years, humans had vast impacts on landscapes on every inhabited continent.

There is no starker example than that of Australia. Humans arrived on this fairly isolated continent roughly 50,000 years ago. As they advanced, they set fire to thickets and dense forests in order to force game into the open, and to clear space for grassland ecosystems that were more amenable to human habitation. Before 45,000 years ago, Australia’s forests consisted of trees that are now rare; eucalyptus trees (which are fire-resistant, contrary to popular myth) and grasslands took their place. Australia would never be the same.

Other ecosystems were similarly transformed. When Europeans arrived in the Americas, they observed and described landscapes that likewise had been profoundly altered, and were being deliberately managed by the resident humans—again, largely with fire.

How humans started taming fire is a question that will probably never be answered with direct evidence, but it’s pretty easy to infer the process. Research has shown that hunter-gatherers who live in lightning-prone environments tend more commonly to use fire; this supports the widespread speculation that the first uses of fire by humans consisted simply of removing burning limbs from lightning-caused fires, then using those blazing logs to start controlled fires elsewhere. Learning to make fire with friction (using flint or sticks) was a big advance, but it might have occurred more than once among various human groups. (Again, it’s instructive to take a class on primitive technology in order to learn first-hand the various ways of starting a fire from scratch, how much work it is, and how much skill it takes.)

Exactly when humans started taming fire is another question that can’t easily be answered with direct evidence. At a site in the northern Jordan River Valley, dating from almost 800,000 years ago, there are clear signs of people who “had a profound knowledge of fire-making,” according to the archaeologist who uncovered the site, Nira Alperson-Afil.5 But Wrangham invokes two lines of indirect evidence to argue that the first controlled use of fire occurred earlier still.

The first line of evidence: The study of Homo erectus skeletons suggests that this human species was able to climb only poorly. Therefore, erectus must have slept on the ground—but how could it do this without fire to keep predators away?

The second: Among humans we can observe today, softer foods make for narrower faces and smaller teeth than was the case with their ancestors. Therefore, the adoption of cooking should have left similar signs in ancient skeletons. Wrangham argues that skeletal evidence suggests the adoption of cooking most likely corresponded with the emergence of homo erectus, 1.8 to 1.9 million years ago. If he’s right, we have been using fire a long time indeed.

Once the use of fire took off, there were multiple side effects, not the least of which was an increase in the size of the human brain as a result of increased food energy from cooking. Brains require a lot of energy: for humans today, the brain uses about 20 percent of resting metabolic energy, though it accounts for only 2.3 percent of body weight. This proportional difference is greater in humans than in any other mammal. In Catching Fire, Wrangham examines the whole process by which brains grew, starting five to seven million years ago when the proto-human lineage diverged from lineages of the other great apes. The first spurts of brain growth can be attributed to eating different foods (roots instead of leaves). But later and more dramatic phases of brain enlargement seem tied to cooking. Further, in Wrangham’s words, cooking “surely continued to affect brain evolution long after it was invented, because cooking methods improved.”6

Cooking also made us more social: we brought much of our food back to the campfire to be cooked, rather than simply eating it where we found it. In addition, keeping a fire going required somebody to stay home to look after it. Thus “home” became a place of greater social importance. Further, humans likely developed more sharing behaviors as a result of cooking.

Today we regard open fire as an inefficient and unsustainable way of heating and cooking. But that’s partly because we likely haven’t thought very hard about how our ancestors actually used it. Our ancestors didn’t just use their campfire for these two obvious purposes. They also used it for illumination, food preservation, water heating, clothes drying, signaling, and protection from predators and insects, among other things.7 When you add all those services together, an open fire begins to look like a cheap and ingenious solution to innumerable problems.

Altogether, fire helped fuel the evolutionary self-reinforcing feedback process that also led to tool making, big brains, and greatly increased social interaction. Fire gave us power. But was it fire that led sapiens to dominate other human species? It appears not. As we’ve already seen, Homo erectus probably used fire. And there is clear, direct evidence that Neanderthals not only used fires, but knew how to start them.8

Nevertheless, if stone tools made us a more powerful animal in relation to other animals, fire made us powerful in relation to whole environments. Crucially, burning stuff made us unique in another important way. It enabled us to derive useful energy from our environment via a source other than food. Gradually we would learn to use fire for ever more projects: to transform materials, to smelt and work metals, and (much later) to run engines. Moreover, as a result of our discovery and use of fuels other than firewood, fire would eventually open the way for technological marvels that have recently changed the world in truly remarkable and ominous ways, as we will see in Chapter 4.


In Chapter 1, I called tools “detachable organs.” The idea goes back at least to William Catton, who, in his marvelous book Overshoot: The Ecological Basis of Revolutionary Change, described technologies as prosthetics.9 We modern humans can, at least metaphorically, strap a Boeing to our waists and fly across a continent with prosthetic wings. In a similar light, clothing can be thought of as prosthetic fur—a detachable layer of insulation that enables us to live in environments that would otherwise be forbidding.

Humans evolved as furless apes. Why we lost our fur is a matter of speculation; it could have been so that we could cool more efficiently during and after a long-distance run. This explanation is supported by the fact that we also evolved dense sweat glands; we are by far the sweatiest of all primates. But after exiting Africa, humans encountered Ice Age conditions. For creatures with no fur, clothing meant the difference between life and death. With time, suitably insulated humans could take over increasingly remote ecosystems. In doing so, they expanded their range, their numbers, and their power.

The first clothes were probably animal skins, but using skins this way requires that they be scraped and dried, and in some cases tanned—processes that entail tools and skill. Later developments included the ability to cut hides to a desired size (this depended on finely sharpened slicing tools), and the ability to sew (which requires needles). We don’t know when people made their first shoes or hats, but these could again have been fashioned from fur or other materials. Some early clothing was no doubt made from leaves or grass draped, wrapped, or tied around the body or feet.

During the many thousands of years in which they refined their clothing, people gradually figured out which pelts were warmer, easier to work, and more comfortable. The wolverine, for example, has particularly thick fur, which makes its pelt even today a top choice among the Inuit.

The earliest use of clothing cannot be dated by direct evidence, since furs and fibers don’t fossilize well. As a workaround, genetic researchers have been able to sequence the DNA of parasites that are well adapted to living in human clothing, and that mutated to their current form in order to thrive up close to humans.10 Ralf Kittler, Manfred Kayser, and Mark Stoneking, anthropologists at the Max Planck Institute for Evolutionary Anthropology, were able to trace the crucial mutation in human body lice to around 170,000 years ago. However, a second group of researchers, using similar genetic methods, arrived at a much earlier date of around 540,000 years ago.11

Assuming the more recent date, was something happening then to encourage people to adopt clothing? Around this time, several human species were radiating out from Africa into new territories. Meanwhile, the Northern Hemisphere was in the early phase of a glacial period that would last roughly 50,000 years. Time to bundle up.

Sewing needles found in the Denisova Cave in Siberia have been dated to at least 50,000 years ago, while the earliest dyed flax fibers, dated to 36,000 years ago, were found in a cave in the modern-day nation of Georgia. By 25,000 years ago we see carved images offering us pictures of what then-current clothing must have looked like. The “Venus of Lespugue” figurine, found in southern France, appears to wear a cloth or twisted fiber skirt. Other figurines from western Europe sport woven hats, belts, and cloth body straps worn just below shoulder level. Thus, during the period from 50,000 to 25,000 years ago, as tools were becoming more refined and specialized, clothing was becoming more sophisticated as well.

What started as a way to stay warm became part of our quest for beauty, as we will discuss in more depth later in this chapter. Humans may have been using body painting before they adopted clothing, and, starting quite early on, some of the features of the human body likely evolved to look the way they do today partly in response to sexual selection pressures. After the invention of clothing, items of decoration quickly appeared, including shell necklaces, beads, and dyes. Thus, almost from the very beginning, clothes were an aesthetic statement. Clothing would later become a badge of social status, a consumer product, and a sign of conformity or non-conformity.

Clothing made us more powerful, but—like tools and fire—it wasn’t the special sauce that led sapiens to outcompete other human species. After all, Neanderthals wore clothes, and it’s likely that Homo erectus did too. It was probably something else that made sapiens a lethal threat to other human species. Could it have been language?

From Grunts to Sentences

Language is power. But it’s a kind of power that differs from the measurable force exerted by a hammer or axe. Language gives us social power—the ability to influence the behavior of other people. And language can thereby magnify all the other powers available to us.

Language is also a tool, though a different kind of tool from a basket or knife. The latter entail the use of our hands, whereas the speaking of words involves our brains, mouths, throats, and lungs. As it happens, the parts of the brain used in speech—Broca’s area and Wernicke’s area—are very close to those that are activated when we manipulate tools with our hands. That’s probably why we often use our hands to gesture while we speak. Think of language as a “soft” technology. If stone tools were our first technological hardware, words and grammar were our initial software.

But language is a very special tool, as we’re about to see.

Figure 2.2 Key language, motor, and auditory areas of the brain.
Credit: Adapted from an illustration by staff in “Medical gallery of Blausen Medical 2014.”

All animals communicate, and plants do as well. Some people speak of the “language” of plants or birds, and there is nothing wrong with using the word this way. But here I will employ the word language to refer only to the unique verbal communication used by humans, with its abstract symbolism and rules of grammar. Human language is clearly different from the communicative habits of other species. I don’t believe that humans are intrinsically superior to other animals because of language (a judgment our kind all too quickly makes, in my view). However, if we hope to understand the enormous power that language gives us, we must start by appreciating what sets it apart.

Language consists of a set of essentially arbitrary sounds or vocalizations (or gestures or marks), used as symbols, that can be combined and recombined in endless ways, but always according to a consistent set of rules. Those rules enable us to string together sounds that, in the proper order, signify thoughts; further, we can string verbal thoughts together, and insert thoughts within thoughts; and we can express thoughts about imaginary things, and about other places and times. Those sounded thoughts can be framed as questions or speculations, as well as statements or commands, including deliberately misleading ones. Using language, it’s possible to say not just, “Hey, everybody, I just laid an egg!”, as the chicken in the backyard coop outside my office window has just announced, but, “The wholesale price of eggs has been rising in recent weeks, posing a financial obstacle to the profitability of the mayonnaise industry.” Just about every word in the latter sentence conveys a thought that would be inexpressible by any non-human animal, using its native communicative abilities. And this was just a single sentence I made up on the spot, to make a point. Language enables us to convey far more expansive, detailed, and abstract thoughts than that weird little sentence does.

The origin of language is a real problem for theorists, since language seems only to work once the basics of grammar are in place. But how did grammar arise? It’s difficult to imagine a step-by-step process by which all the interlocking parts of language could have come into being.

Early theorists reasonably assumed that human speech evolved from primate communication, and therefore studied monkeys and apes for clues as to how the process might have occurred. The difficulty here is that there’s little discernible gradual increase in complexity of communication among primates as you get genetically closer to humans. Vervet monkeys are as avid communicators as chimps. And, to further confound the situation, it turns out that non-human primates are far from being the best communicators among all animals. Birds generally do much better in this regard. Vervets have about ten “words,” but my backyard chickens have roughly 25 unique vocalizations with which they say everything from the near-daily call that roughly translates to, “I just laid an egg!” to one that means, “Watch out for that hawk!” And the starling’s extraordinary communicative abilities are just coming into focus.

In his book The Language Instinct, evolutionary psychologist Steven Pinker calls the ability to learn and use language an instinct, similar in this regard to spiders’ web-weaving or beavers’ dam-building behavior. It wasn’t just an intensification of what other primates were already doing, and it’s not something that each infant has to develop from scratch. It was a whole new package of behaviors that, once acquired, became largely innate.

But that doesn’t tell us how language evolved. In order to develop language, people would have had to be spending a great deal of time in one another’s company, presumably cooperating to ever higher degrees. Such high levels of cooperation are hard to evolve. As biologist Edward O. Wilson has noted, there are only 19 kinds of animals in all of nature that have evolved to be even nearly as cooperative as humans are. What got the ball rolling? Language certainly made us more cooperative—but we already would have had to be highly cooperative to invent language. Therefore, in order to explain the origin of language, we also have to explain how and why people were becoming more cooperative.

Earlier in this chapter we saw how walking upright led to the birthing of babies that needed longer periods of care before they matured. This probably led to greater sociality among early humans, but it almost certainly wasn’t the only cause of our cooperativeness, perhaps not even the main one. Anthropologist Richard Wrangham, in Catching Fire, suggests that campfires also made us more social and therefore more prone to start talking to one another. But in a more recent book, The Goodness Paradox, Wrangham digs deeper, arguing that the beginnings of speech were tied to human “self-domestication” (domestication also figures strongly in Chapter 3 of this book).12 What does he mean by that?

Domesticated animals have been deliberately and selectively altered by humans, most of them in prehistoric times. The process probably often started with choosing the least aggressive individuals from a group of captive wild animals, and allowing them to mate and have offspring. From those, again the least aggressive and most docile were selected. After 30 to 50 generations of this, the wild animal would have become permanently tame; the fierce wolf became a friendly dog. But domestication has unintended consequences. Across species, artificially reduced aggression seems consistently to correlate with a set of other characteristics: floppy ears, white spots of fur, less gender dimorphism (males and females are closer in size), a smaller or flatter face, an over-bite or under-bite in the jaws, and a smaller brain. The reasons for this well-studied “domestication syndrome” have to do with the multiple roles of genes: the DNA sequences that control emotional reactivity also code for proteins involved in other, seemingly unrelated traits.

Wrangham’s point is that humans show many of the signs of domestication, with one partial exception: throughout its evolution the human brain was growing, not shrinking—until it reached a peak size about 15,000 to 10,000 years ago; since then it has indeed, on average, shrunk a bit. Otherwise, we fit the description quite well: compared to our closest primate cousins, we are less aggressive, we have flatter and smaller faces, and we exhibit less gender dimorphism (since we’re furless, we don’t have white patches).13 The domestication syndrome appears to be related to another syndrome called juvenilization, whereby adults of a domesticated species tend to show physical characteristics and behaviors of the juveniles of related wild species. A human face in profile, for example, looks more like a juvenile chimp’s profile than that of an adult chimp.

But if humans are a domesticated species—an observation that was familiar to Darwin, though he ultimately rejected it for lack of a good explanation—then who domesticated us? Unless you happen to believe in prehistoric visits by space aliens, the only realistic candidate is ourselves.

Self-domestication could have happened this way—though this is only a hypothesis, and we may never know the real story. Suppose primordial groups of humans systematically began killing the most troublesomely aggressive males among them (indeed, capital punishment of extremely troublesome people is a practice observed among all hunter-gatherer groups that have been studied). Highly aggressive men might therefore have less opportunity to mate and leave offspring. Over time, people would have become more docile, thus better able to live together in larger groups and cooperate.

One thing would have been especially useful in the primordial capital punishment of overly aggressive males: the ability to gossip and plan. That means language. Thus, language may have co-evolved with human self-domestication.

Whatever its contributing causes, this gradual shift toward increased docility and cooperation likely brought with it the rest of the domestication syndrome. And, as people became less aggressive and spent more social time together, there was at least the opportunity for language to develop, or to develop much further. With a changing climate, with new environments to explore via migration, and with more time spent making and using tools, there would have been plenty to talk about.

Here’s another hypothesis. In a much-discussed 2018 paper, authors Oren Kolodny, a biologist at Stanford University, and Shimon Edelman, a professor of psychology at Cornell University, claimed that the development of sophisticated tools drove language acquisition.14 Making a stone tool requires a specific sequence of processes, and teaching others how to make the same tools depends on communicating that same sequence. Kolodny and Edelman argue that ancient humans began inadvertently to couple the neural networks required for complex, hierarchical, sequence-dependent tool production with the cognitive processes in their brains’ communicative apparatus. Thus, word order and sentence structure began to play key roles in the production of meaning. Gradually, the rudimentary language that had developed in the context of toolmaking and teaching broke free from these immediate contexts, enabling new cognitive pathways to be used for a wide array of other purposes. The result was our modern wide-ranging faculty for language.

There are still huge explanatory gaps in getting from primate grunts to human sentences, but theories about self-domestication and increased time and space for cooperation and tool making provide a good start toward bridging some of those gaps.

When language originated is, again, a thorny dilemma for theorists. There’s no direct evidence, since human vocal utterances disappear into the air far more quickly than ancient clothing and wooden tools biodegrade. Anthropologist John Shea, in Stone Tools in Human Evolution, argues that the ways later human tool manufacture and use differ from early hominin tool use are similar to the ways that animal communication differs from human speech.15 And, as we have already noted, the parts of the brain used in speech and tool use are connected. For Shea, dramatic changes that occurred in tools roughly 50,000 years ago suggest that this was the time language appeared.

Many scientists believe that the appearance of cave art around 40,000 years ago (which I’ll say more about below) indicates that the people who produced it must have been able to think symbolically, and therefore to speak. If so, this would establish the very latest date at which language could have emerged.

But the process may have gotten started much earlier. Richard Wrangham argues that language began to take form as early as 300,000 years ago, since it was implicit in most of the evolutionary and cultural changes that have occurred in sapiens since its appearance. Kolodny and Edelman imply the process of language development could have gotten started even earlier, perhaps when tools began to become more sophisticated, roughly 1.5 million years ago. Did language start 40,000 years ago or 1,500,000? That’s a huge range.16

Altogether, there is startling lack of agreement among experts. It’s conceivable that some integrated aspects of language appeared quite early, then other important chunks fell into place later. The process may have been complex, with more than one contributing cause. Much of the story of language’s origin is still guesswork.

What language did for us is less controversial. Language served our survival by enabling us to cooperate in domestic tasks and in searching out and harvesting wild foods. It empowered people to associate in larger, more cooperative groups, thus making them more formidable against big animals and other human groups. And it enabled our ancestors to make more effective tools (all of our subsequent development of technology, from wheels to typewriters to nuclear-tipped guided missiles, has occurred via the ever-greater magnification of our tool-making ability through our use of words).

Was the extinction of non-sapiens human species a result of our development of language? Neanderthals may have had some ability to speak, but such ability, if it existed, was probably more limited than that of sapiens. Neanderthal tools didn’t quickly become more refined and diversified 50,000 years ago; they continued to look like ones made tens of thousands of years previously. And no cave paintings can be clearly attributed to Neanderthals. Therefore, language and increased cooperative behavior are probably the best candidates, among those we’ve surveyed, for the key factor that enabled sapiens to out-compete other species of humans.

Whatever the original motives for the development of language, it’s safe to say it has had consequences that were far more sweeping than early humans could have conceived. Language has proven to be such a powerful and versatile ability that we have used it for activities that were unimaginable to early humans—from writing books about human evolution to tweeting insults about political rivals. And, in the process, language has reshaped the human mind. Thinking with words has led to a deepened split between the functions of the left and right hemispheres of the human brain (in most people, the left brain is more verbal), and between the conscious mind (containing all that can be verbalized) and the unconscious (what can’t).

The ability to ask questions must have led to the posing of questions that no one could factually answer (What happens to us when we die? Why are we here? How did the world come to be?), but to which imaginative answers could be supplied. Hence came religion (as we will discuss more in Chapter 3)—just one byproduct of language, but one that has played an incalculable role in cultural evolution and the history of ideas.

Despite its extraordinary nature and consequences, we take language for granted. How could we do otherwise? We inhabit a mental world of language-mediated thoughts that shape our consciousness as much as, and often far more than, our awareness of our immediate surroundings. When we see someone crossing a street staring at their smartphone but ignoring oncoming traffic, that’s a testament to the power of language. Most of us spend virtually our entire waking time talking, listening, reading, or thinking in words; categorizing, commenting, instructing, complaining, criticizing, praising, describing, or explaining. It’s difficult for us to imagine consciousness without words, because we are so habituated to using words for thinking.

Biological evolution is slow, and so is the evolution of behavior that’s purely gene-coded, such as the complex mating calls and behavioral displays of some birds. Cultural evolution, which occurs primarily via language and technology, can be very fast by comparison.17 Watch a movie from the 1930s—less than a century ago. If dogs, cats, or chickens appear in it, you will note that they engage in dog, cat, or chicken behavior that is identical to the behavior of present-day dogs, cats, and chickens. But the people in the film are using different figures of speech than we use today, as well as different means of travel and different modes of communication; they’re wearing different clothes, and (for the most part) listening to different music. Yet just one human lifespan of time separates us from the somewhat alien cultural world we glimpse in those old movies. Language and tools have enabled humans to dramatically increase the pace and scope of cultural evolution. And that has greatly accelerated our attainment of power.

Gender Power

One of the central problems this book proposes to address is how some humans became so much more powerful than others. It is therefore crucial that we explore perhaps the oldest power imbalance within our species—that between women and men.

I must emphasize that all of the human behavioral and anatomical gender differences discussed below, and elsewhere in this book, are based on statistical averages. In every society and culture, and presumably stretching back into prehistory, the human family has included individuals who expressed extremely polarized gender qualities, as well as individuals who expressed characteristics of both genders—anatomically, behaviorally, and psychologically. This is a fascinating area of discussion on its own, but this is not the place for it. This briefest of disclaimers is merely intended to prevent the misconception that gender differences are always expressed in the same ways or to the same degrees.18 That said, we can proceed.

Human gender relations are often described as a “battle of the sexes.” It’s a peculiar battle, though, to which the two sides bring different kinds of power. Males more often use displays of dominance (via signs of physical strength, wealth, or social influence) to impress potential mates, and more often resort to violence or intimidation in order to control women’s behavior and reproduction. Men are also more aggressive with one another. Indeed, among primates, males are responsible for nearly all violence (in some evolutionarily distant species, such as hyenas, females are more dominant and violent; but this is not the case for any monkeys or apes—with the partial exception of bonobos, which we will discuss shortly). The historical and intercultural evidence is overwhelming and inescapable: while men aren’t always brutes, they all too often are. Women more often use attraction, nurturing, and persuasion to achieve their power. In anthropological literature, women’s power is often described as informal or non-hierarchical. Especially in pre-industrial societies, women exerted considerable, if not primary, control over domestic affairs, and most of society was domestically-oriented.19

In different cultures, and at different times, the balance of power between the genders has shifted. As we’re about to see, evidence suggests that in human evolution female sexual selection via mate choice appears to have contributed substantially to the development of certain uniquely human physical and behavioral characteristics. On the other hand, as we will see in Chapter 3, in early agricultural and animal-herding societies men became more controlling, especially in the public sphere: they regarded women as property, and often exerted sexual violence with impunity. Still more recently, in much of the world during the 20th century, women gained political and economic equality to a degree probably unprecedented since the origin of agrarian societies, and possibly since the dawn of the species.

But let’s back up for a moment and look at the subject of gender power through an evolutionary lens. Yes, men are often brutes. But, among primates, human males aren’t always the worst offenders. For perspective, it’s helpful to compare our species with our closest primate cousins, chimpanzees and bonobos, with which we share about 96 percent of our genetic material. At first glance the bonobo, which used to be called the “pygmy chimp,” does look like a smallish chimp, but it’s actually a separate species (among other differences: bonobos have a flatter, more open face and a higher forehead than chimpanzees—that is, they show signs of the domestication/juvenilization syndrome). Chimps have been known to Europeans since at least the 17th century. However, the bonobo wasn’t discovered by scientists until 1929 and its behavior wasn’t studied by university researchers until the 1970s.

Chimps have a strict male dominance hierarchy, and more-dominant males generally engage in more aggression. Even if they aren’t at the top of the hierarchy, aggressive males tend to sire more offspring. However, alpha males at the top of the hierarchy aren’t bullies; their social role includes stopping fights and distributing food. Adult male chimpanzees travel with other males, grooming one another frequently. They have to stick together to fight off males of neighboring communities, as chimp “wars” are vicious and lethal. The dominant male of the group will typically mate with all the females, but every male in the troop is dominant in relation to every female. Males often charge at females, and may rip out their hair and slap, kick, or beat them. Dominant males sometimes kill the babies of their rivals; therefore, female chimps mate with many males in the troop in order to create uncertainty about the paternity of their offspring. When they are at their most fertile, however, females seek to mate with the males they prefer, presumably so as to increase their chances of producing fit offspring.20

Bonobos occupy the other end of the spectrum in terms of primate gender power. Bonobo society is both female-centered and female-dominated. If a male bonobo tries to harass a female, the other females band together to chase him off. Bonobos use sex to reduce tension and aggression. They engage in sex more often than any other primate, and in nearly every partner combination (though less often with close family members). Bonobo rates of reproduction in the wild are about the same as those of chimps, so most of this frequent sex is not aimed at reproduction. Females are almost continuously sexually attractive and active. All of this sexual activity is quick, casual, and relaxed, and appears to be an expected part of social life.21

Sidebar 7: Male Violence

In the modern world, where statistics can be gathered with some precision, it is clear that the great majority of human-on-human violence is attributable to men.

In the United States, during the years in which data have been available, men have been held responsible for roughly 90 percent of homicides. In addition, according to 2011 FBI data, males constituted 98.9 percent of those arrested for forcible rape, 87.9 percent of those arrested for robbery, 85 percent of those arrested for burglary, 79.7 percent of those arrested for offenses against family and children, and 77.8 percent of those arrested for aggravated assault.22

In addition, war—the deadliest and most socially valorized form of violence—has traditionally been a male pursuit. There have been exceptions: for example, during World War II, the Soviet Union sent many women into combat, and roughly eight percent of troops were female. In the United States in 2014, approximately 14 percent of active duty Army personnel were female, as well as 23 percent of the Army Reserve and 16 percent of the Army National Guard. While there are and have long been women warriors, as anthropologist Richard Wrangham notes, “…They are women serving in a men’s army, fighting men’s wars.”23

Two broad explanations have been proposed to explain men’s greater tendency toward violence: genetics and socialization. The evidence for a genetic basis for men’s greater proclivity for violence starts with men’s greater height and strength, on average. Most surveys show women to be about 50 to 60 percent as strong as men in the upper body, and 60 to 70 percent as strong in the lower body. Over the course of human evolution, this sexual dimorphism probably contributed to men specializing in violent activities.

The argument for socialization as the source of men’s scrappiness stresses the roles of education, child rearing, and social expectations in encouraging more violent behavior in boys and men than in girls and women.

There are no known societies in which the violence of females exceeds that of men. However, the levels of overall violence in societies diverges significantly. For example, homicide rates in recent years have ranged from 0.27 per 100,000 of population in the nation of Oman, to 43.85 per 100,000 in Jamaica (the US rate is 4.96 per 100,000 per year).24 This wide variation offers hope that, even if males are genetically more prone to violence than women, human violence overall can be reduced very substantially. Over the long term, humans could conceivably evolve to become more bonobo-like, with reduced sexual dimorphism and male violence.

Gender relations among humans have some chimp-like and some bonobo-like qualities, but have also evolved their own unique patterns. Let’s look at some of these patterns as possible evidence for how power relations between the sexes might have shifted in prehistory.

Along with bipedalism and bigger brains, discussed earlier, modern humans differ from all other great apes, and presumably our early pre-human ancestors as well, in terms of some gender-specific physical characteristics:

  • Adult women have large breasts compared to other primates, and their breast tissue is permanent (in other primates, breast tissue develops only during lactation).
  • Human females have concealed ovulation: even women themselves may not know when they are fertile, and men have no clue whatever (among other primates, estrus is conspicuously signaled by swollen or brightly colored tissue around the genitals).
  • Compared to the females of other primate species, women have narrow waists, wide hips, and fatty hips and buttocks.
  • Men have the largest penis of any primate, and lack the baculum, or penis bone (all other male primates except the spider monkey have one of these).
  • As we’ve already mentioned, there is less sexual dimorphism among humans than among other primate species.
  • While humans lack fur, both genders grow pubic hair at puberty, and have scalp hair that grows continually; men begin to grow facial hair at puberty that, like scalp hair, can reach extreme length.

In addition to these physical characteristics, humans have gender-related behaviors that distinguish them from other primates:

  • Human males and females are sexually picky (in other primate species, males will mate with any available female, and, among both chimps and bonobos, females mate with all available males).
  • Human males and females form pair bonds to a far greater extent than chimps or bonobos.
  • As pointed out earlier, men make a significant reproductive investment, which they share with women, via care for their infants and children (among both chimps and bonobos, women have all the child-care responsibilities).

Also, as we’ve already noted, human males (unlike male chimps) don’t routinely kill the offspring of sexual rivals. Male infanticide among humans does indeed occur during wars, but it’s not routine. Over all, human males are less aggressive than male chimps.

Now, how did we get this way? There are only a few possibilities. The one that comes first to mind is, of course, natural selection—adapting to the environment in order to promote survival and the ability to leave behind more offspring. But there is also sexual selection, involving patterns of mate choice, which can, over time, produce changes to the gene pool that may not result in increased survival fitness. In addition, there is group selection, in which it is competition not between individuals but groups that is decisive (we haven’t explicitly discussed group selection so far, but will do so in more detail in the next chapter). All three of these are processes of biological evolution. Then there is cultural evolution via language, customs, and cultural artifacts, including all forms of technology. Finally, we know that some characteristics are not themselves adaptive, but arise as a result of being genetically tied to adaptive changes (we see this with the domestication syndrome and the related juvenilization syndrome, and with the cascade of changes to human anatomy and behavior that flowed from walking upright).

Ascribing specific uniquely human characteristics to one or another of these pathways is a theoretical problem that calls for conjecture, and scientists differ in their opinions, sometimes strenuously. Some of these questions may never be settled. However, I am persuaded by Richard Prum’s argument, in his thought-provoking book The Evolution of Beauty, that reduced sexual dimorphism, the large male penis, and reduced male infanticide all suggest evolution by mate choice (i.e., sexual selection) on the part of women. Others of these characteristics (the tendency of women to be large-breasted and small-waisted, compared to other primates) suggest sexual selection by men. Male reproductive investment and pair bonding no doubt flow from our adoption of upright posture and the resulting birth of less-mature and more-dependent infants; however, female sexual selection may have accentuated these behavioral trends. In Prum’s view, humans’ sexual pickiness is also a product of aesthetic evolution (i.e., sexual selection), perhaps on the part of both genders. The evolutionary cause of concealed ovulation in women is widely disputed; Prum and others link it to female sexual selection aimed at reducing male infanticide (because of concealed ovulation, it’s harder for males to tie a particular act of copulation to a resulting pregnancy; thus there’s more uncertainty with regard to paternity). Some of our unique characteristics (like men’s facial hair) seem pretty arbitrary and may end up being difficult to explain by any of these routes.

The physical evidence is hazy and open to different interpretations. The best window we have into primordial gender relations is probably via hunter-gatherer societies that survived into the 20th century, when anthropologists and ethnographers could visit and study them. Social relations in such societies are universally described as egalitarian. Rarely could anyone compel anyone else to do something against her or his will, and almost everyone had at least some say in decisions affecting them. Modesty and generosity were expected and commonly shown, at least partly because vain, pushy, or greedy people (typically men) were usually dealt with harshly by the rest of the males in the group through banishment or capital punishment.

Gender roles among hunter-gatherers have long been stereotyped in the popular imagination: men hunted, while women gathered wild plant foods and did the cooking. But, in reality, life prior to the agricultural revolution was more complicated. In some societies, women shared in hunting at least the smaller prey, and men did some of the gathering and cooking. Since meat often made up only a relatively small portion of total caloric intake, women were substantial providers, and were respected as such. Baskets served group survival, in their way, as much as spears did. Men had their secret societies in which they engaged in sacred rituals related to imaginative and supernatural powers, but, at least in some societies, so did women. Child care was mostly women’s responsibility, but, once boys were old enough, their fathers and other male relatives would spend considerable time with them, teaching them practical skills and cultural traditions. The ability of women to contribute to group decision making varied greatly from one group to another, and in many societies men’s voices predominated. Still, at least in some groups, unusually skilled and sociable women gained high social status. In short, while the hunter-gatherer way of life was hardly a feminist ideal, from women’s point of view it typically offered substantially greater freedoms and opportunities than the agrarian and animal-herding lifestyles that would appear later.

It’s interesting also to inquire briefly about same-sex sexual relations in such societies. Many hunter-gatherer societies, such as the Aché, who inhabit a region in Paraguay, have special categories for individuals who defy binary gender description (this was true of many native North American societies as well). The Aché maintain a category called panegi for transgendered androphilic males; panegi look, act, and talk like females and engage in female work and social activities. In other societies, such as the Aka of central Africa, same-sex sexual behavior appears to have been rare, even if tolerated.25 But such examples give us relatively little insight into same-sex sexual behavior in human evolution. Richard Prum hypothesizes different pathways for the development of female same-sex preference as opposed to male same-sex preference, with female same-sex preferences arising from protective female social networks. Male same-sex preference could have resulted from female sexual selection, because it contributed to “male supportive and protective nonsexual relationships with females.” But these are really just informed speculations. What we do know is that later societies, including many animal-herding groups and early agrarian states, banned and punished same-sex sexual behavior, often with death, as a few countries still do. The advance of women’s power in the modern world has been accompanied by dramatically increased acceptance of variety in sexual expression and gender identity.

Throughout human evolution, women appear to have found ways to assert freedom and agency through mate choice, through provision of the bulk of necessary nutrition for the community, through domestic work, through participation and leadership in cultural activities, through child-rearing, and by cooperating with one other to overcome male intimidation or violence. Environmental or cultural circumstances have sometimes enabled men to (re)assert chimp-like patriarchal dominance. Shifts in gender power have continued right up to the present day, and will likely persist as long as our species does. Richard Wrangham and Dale Peterson, both experts on wild primates, concluded in their book Demonic Males: Apes and the Origin of Human Violence that, if we wish society to become more peaceful, we should find more ways to emulate bonobos’ female-centeredness and work to increase women’s power.

The Power of Art

Humans began making art and music early in their evolutionary journey. Cave paintings and bone flutes started appearing roughly 40,000 years ago—about the same time as language and stone tools likely took a leap forward. Paleolithic paintings of animals and humans are exquisite and expressive. Ancient flutes, made from mammoth and vulture bones, produce tones with the same tonal relationships (whole tones, half tones) as the tones produced by modern musical instruments like the piano or guitar. We also see evidence of body art and decoration around that time. Moreover, as soon as we had language, we probably started using it playfully and creatively to make songs, poems, sagas—and jokes. Little of this had to do with survival needs. Music, art, and wordplay implied a power not of domination, but of shared celebration and transcendence.

It’s common to speak of the power of a work of art—a painting, a musical performance, a dance, a play, or a piece of literature. But what kind of power is this? It’s a different kind than those we have addressed so far, and to ignore it would be to overlook an essential aspect not just of humanity, but of nature itself. The evolution of life via the maximum power principle seems straightforward: those organisms that are able to harness and exert more power leave behind more offspring and displace other organisms. Viewed this way, life appears grimly competitive. Yet, when we look at the result of billions of years of evolution, it’s amazingly beautiful.

As we saw in Chapter 1, animals and plants devote enormous effort toward creating beauty as part of reproduction. And, as we have just seen, aesthetic preferences have, via sexual selection, also likely sculpted the human body and altered our instinctive behavior. With sexual selection, evolution was no longer tied just to fitness.

Once beauty assumes a priority, it often becomes an end in itself. Though it may begin with courtship displays, beauty can take on a significance of its own. Birds appear often to sing for pure pleasure, even when there’s no need to attract a mate. With humans, as cultural evolution accelerated, our quest for beauty also became largely detached from sexual selection. Aesthetic appreciation and the production of beauty co-evolved ever more quickly to become overwhelming obsessions.

Sidebar 8: Human Aesthetic Decadence

Investment in display behavior to attract mates can proceed to such extremes that it leads to “aesthetic decadence,” contributing to a species’ decline and even extinction, as we saw in Chapter 1. The question must arise as to whether at least some of humanity’s exuberant aesthetic production is “decadent” in the evolutionary sense, in that it reduces our species’ survival prospects. Unfortunately, the notion of aesthetic decadence is weighted with prejudice and with some rather awful history: Hitler thought virtually all modern art was decadent and ordered many important paintings and sculptures destroyed; during the 1930s and early ’40s, artists like Ernst, Mondrian, and Duchamp fled their homelands to avoid harassment or worse—as did composers such as Hindemith and Schoenberg. Though Stalin’s politics were diametrically opposed to Hitler’s, the Soviets likewise regarded modernist composers as decadent, periodically making life hellish for Shostakovich and Schnittke. One person’s decadence is another’s masterpiece.

However, in my opinion the contemporary world does provide persuasive evidence of aesthetic decadence. What I have in mind is music and art produced specifically for commercial purposes. Advertising art can be clever and entertaining: that helps it sell products. But, as we’ll see in Chapter 4, advertising is one of the pillars (along with cheap energy and consumer credit) of consumerism, and consumerism is in turn the engine of economic growth. As the economy grows, it chews up and digests ever-greater swathes of the natural world, leaving depletion, pollution, and habitat destruction in its wake. Our survival is very much in peril as a result.

In a capitalist society, commerce influences nearly all art and music, though to greatly varying degrees. Professional hip-hop artists and singer-songwriters struggle to find a unique “voice” that will appeal to agents, concert bookers, and fans willing to buy tickets or downloads. This constant striving for uniqueness is specific to the modern commercial milieu: in pre-capitalist or pre-industrial societies, multi-generational tradition guided aesthetic preference to a much greater degree. One could say that capitalism produces greater artistic variation, thereby speeding up aesthetic evolution. But if the species is rapidly evolving toward decadence and possible extinction, then its proliferation of increasingly varied forms of art and music is destined to be short-lived, however ingenious and enjoyable those forms may be.

The result, today, is that we live in an aesthetic human world. Nearly every surface in a modern city is designed. Cars, houses, office buildings, and tools of all kinds—from motorcycles to fountain pens—have become canvases for the creative process. And we are immersed in entertainment of every imaginable variety—from background music to novels to television dramas. The typical modern human “consumes” art almost from the moment they wake up till the moment they fall asleep at night.

The obsessiveness with which we pursue artistic production and appreciation can be illustrated by one activity to which (for better or worse) I have devoted tens of thousands of hours: playing the violin. Try watching and hearing violinist Hilary Hahn perform Paganini’s 24th Caprice on YouTube. A dozen or more notes may fly by each second, each perfectly in tune, and each perfect also in articulation and tone color. Hahn’s two hands are engaged in entirely different tasks that must somehow be exactly synchronized. And the point of the exercise isn’t just to make no mistakes while doing several nearly impossible things simultaneously, but to confidently create beautiful and moving music. With all due respect to brain surgery, I can say with some assurance that no activity by a human or any other animal requires as much digital precision as top-level fiddling does. And it’s not just the violinist’s fingers that are involved, but the wrists, arms, and back muscles—and, first and foremost, the brain. Finger exercises (which every serious violinist spends endless hours on, to the weary aggravation of all within hearing distance) are useless without a trained “ear”—which really means a highly trained brain—that can recognize tiny variations in pitch and rhythm, and make nearly instantaneous corrections on the fly.

This digression underscores a point I’ve already made: that the dexterity of the human hand cannot be explained solely by anatomical factors. The evolution of violin playing, and of tool use in general, took place on many levels—anatomical, mental, social, and aesthetic—more or less simultaneously.

However, my example primarily illustrates many humans’ utter devotion to aesthetics, to a degree that is difficult to justify in terms of either natural selection or sexual selection. Yes, many young men buy a Stratocaster and take guitar lessons in order to impress the girls. But I find it difficult to imagine that such a motive would compel a five-year-old child to begin practicing a supremely difficult musical instrument several hours a day and to continue doing so all through adulthood. Nor is pursuit of fame or financial reward an adequate explanation. Are violinists more fit than other humans? Do they leave more offspring? Do they tend to earn higher salaries? Do they attract more desirable sexual partners? My past experience as a volunteer board member of a local musicians’ union, of which most members were professional symphony orchestra players, leads me to doubt that any of these is reliably the case (though learning a musical instrument does seem to give children an advantage in math and reading). Why should people devote so much more effort to developing the skill of violin playing than any of a hundred other skills that are much less demanding and that might have a better chance of leading to wealth or social prominence?

The sports lover will recognize a similar obsession. Devotees of soccer, surfing, and sumo exhibit a similar level of compulsion, and the subjective experience of an outstanding performance in any sport can be described as aesthetic. Commitment to athletics can perhaps more readily be explained in terms of competition, selection, and fitness (and the financial rewards for professional-level performance are sometimes astronomical), but the pursuit of excellence in sports and the arts is, in both cases, quasi-spiritual.

Evolution gave us power over the natural world. But in doing so it gave us abilities that could be used for things that had little or nothing to do with power in the conventional evolutionary sense—i.e., the ability to get food or find a mate. The power to communicate aesthetic pleasure and thereby to feel profound affinity with other people, including individuals of other species (as we do when we enjoy the beauty of birdsong or thrill to the sight of a pod of dolphins “dancing” in perfect synchrony through the waves, to cite just two possible examples), propel human culture forward in ways that are hard to measure, but that are impossible to ignore. These are powers that, as we’ll see later in this book, provide hope for our future.

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With tools and fire, we humans gained unprecedented power to control our environments. We reshaped landscapes. We drove other animals to extinction. And with language and social coordination, our species of humanity may have wiped out competing human species. Still, within the one surviving human species—Homo sapiens—power relations probably remained fairly simple, if the study of surviving hunter-gatherer peoples is a reliable guide. No single individual could dominate everyone else without provoking a coordinated backlash, and no group of sapiens could systematically exploit another group for long. However, starting about 11,000 years ago, at the dawn of the Holocene epoch, that changed. The result was history.