Mankind

by Pamela D. Toler

  Homo erectus, like his fellow hominids, could raise a sharpened stick and bring down a small animal. But he was the first to go the next step and cook raw meat over an open flame. With the domestication of fire, Homo erectus changed everything for the Homo sapiens who came after, making the intentional use of fire the first Goldilocks moment in human evolution.

  FIRE

  Mastery of fire was the first step toward civilization, and it could only happen on Earth. Fire requires three elements: fuel, heat, and oxygen. It’s the oxygen that’s the tricky part. Oxygen is the third most abundant element in the sun after hydrogen and helium. It is the most abundant element not only in the rocks, meteorites, and asteroids that litter space, but also in the terrestrial planets. But most of that wonderful oxygen isn’t available in a form that either human lungs or hungry flames can use. Gaseous oxygen is one of the first by-products of life, produced by the blue-green bacteria that covered the earth’s oceans three billions years ago as they photosynthesized sunlight and carbon dioxide into food. From the viewpoint of those early bacteria, oxygen was toxic pollution, pure and simple. Over time, life developed in such a way that some creatures produced oxygen and others consumed it, creating an atmosphere with a stable oxygen level of 21 percent. (Mars comes in second among the terrestrial planets, at 9 percent.) That abundant supply of oxygen makes fire possible.

  Today, sealed in our twenty-first-century man-made environments, it is hard to fathom the competition for survival that occupied our early human ancestors from sunup to sundown. It is even more difficult to imagine living without the benefit of millennia of human know-how, and without language, history, science—or fire.

  BASED ON ANCIENT MYTHS and primitive art we can speculate that the earliest hominids learned the fine points of hunting by watching and imitating the actions of the nonhuman hunters with whom they shared the Great Rift Valley, and later, Eurasia and the Americas. Unlike the animal-teachers with whom they often competed for the same prey—rabbits, small cats, and warthogs—early humans had no sharp teeth or claws. To compete with other predators, our ancient relatives employed stone-tipped spears fashioned with their more dexterous limbs and fingers, and applied their superior problem-solving skills to outthink their prey and work in cooperation with other human hunters. With these assets in place, the prehistoric hunt was finally on.

  HUNT TO SURVIVE

  TWO STRONG YOUNG MEN IN THEIR TWENTIES RUN with muscular legs through the brush, holding spears. One man signals to the other. Both stop and crouch down, using binocular vision to scan the horizon for signs of motion in the grass. The first man has seen something, and indicates it to the other, his brother. There ahead, an antelope is grazing.

  A hundred feet behind, a woman stands, holding her spear, watching her men conduct the hunt. By her side, holding her free hand, is her toddler son. The mother leans down and puts her mouth next to the child’s ear, urging the boy to keep quiet, and watch. He is learning his own future and the survival of his species. Concerned only with the present, mother and son watch as the men chase the warthog, their actions urgent and swift as they slip stealthily through the bush, out of the woman’s sight.

  The hunters sprint ahead, and again they stop. Crouching, the first man reaches into the dirt at his feet and pours some out of his hand to check the wind direction. They are upwind from their prey. They turn and reverse direction, stalking, low, and far enough away to remain out of the animal’s sight and hearing range. The man in the lead stops and raises a hand, his other hand gripping his spear firmly. Suddenly the antelope bolts. Instantly the men are on their feet and running, chasing and encircling the animal. The first man releases his spear, landing it in the antelope’s flank. The hunt ends in blood and victory.

  Hours later, against a darkening sky, the two men are reunited with the woman and child. The group sits around a fire, with a skinned hog flank suspended above the fire pit, pierced by a stick. Juices drip from the carcass, causing flames to spike and tickle the meat as it turns shades of brown and charcoal black. While the family waits, there is time to savor the hunt, and to enjoy a rare opportunity to socialize and rest.

  Once the meat is cooked and pulled from the flames, the men use their teeth and hands to strip it from the bone, chewing each piece thoroughly. The woman shreds hers into smaller bits, placing them one at a time in her child’s open mouth.

  EARLY HUMANS PROBABLY LEARNED to use naturally occurring fire before they learned how to create a spark with a flint stone, tending the embers to create their own fires. But fire under those conditions was a force of nature, both boon and bane. Things changed when Homo erectus learned to use flint stones to start their own fires. With fire at their call, if not completely under their control, humans could do more than cook their food, and share it around a hearth as a family or tribe. They could keep animals away at night, including the cave bears and giant wild cats that had previously made life in a cave exciting, if not impossible. They could bake clay to make a waterpot, an image of a fertility goddess, or bricks to build a shelter or even a temple. Fire was the tool that made other tools possible, from the first copper blade to the propulsion tanks for a communications satellite. Fire didn’t just shape tools; it may also have contributed to the evolutionary movement from Homo erectus to Homo sapiens sapiens.

  Cooking meat doesn’t just make an animal taste better; it breaks down proteins, making the meat easier to chew and digest. With fire, humans no longer needed massive jaws to chew their raw food. Smaller jaws left room for a larger brain, taking hominids one step closer to modern humans.

  OUT OF AFRICA

  AFTER ABOUT ONE HUNDRED thousand years, bands of Homo erectus, now armed with fire to keep them warm and probably driven by increased population and competition for resources, began to travel farther from the warmth of the Great Rift Valley in search of food, eventually crossing the land bridge where Africa joins Asia. By about 400,000 BCE, small tribes of Homo erectus lived throughout Eurasia, reaching as far east as China.

  When they arrived, they found they weren’t the only hominids on the planet.

  Hominids in Africa and Eurasia took different evolutionary paths in the half million years after Homo erectus left Africa. When bands of Homo sapiens reached the Near East, they found that Europe and the Middle East were already populated by another bipedal, big-brained species, Homo neander-thalensis, popularly known as “Neanderthal man.”

  Today, the word Neanderthal is often used as shorthand for an uncivilized or unintelligent brute. Cartoons show Neanderthals as hulks whose knuckles scrape the ground. It’s true that Neanderthals were stockily built, with heavy bones and signs of powerful muscle attachments that suggest they were extraordinarily strong by modern standards. Their faces looked more like those of Homo erectus than of modern humans, with a protruding jaw, a receding forehead, a weak chin, and a large nose. Nonetheless, Neanderthals walked upright, and their brains were larger than ours.

  Comparing evidence from archaeological sites in Africa and Europe suggests that Homo sapiens and Neanderthal man were at a comparable cultural level when they met. They made similar stone tools. They hunted small, easy-to-kill animals. Though they created no art that we know of, you could argue that Neanderthals were one step closer to civilization than our ancestors, since they were the first hominids to bury their dead in a way that suggests ritual behavior.

  Neanderthal man and Homo sapiens were close neighbors in the Middle East and Europe for about seventy thousand years; then the Neanderthals seem to disappear from the fossil record. For many years, the standard theory about their disappearance was that Neanderthal man was slowly pushed out of his habitats and into extinction by Homo sapiens, who was assumed to have been better adapted for the fight for survival. The latest science provides a more complex picture.

  Beginning around 70,000 BCE—for Neanderthals and Homo sapiens alike–survival meant confronting a time of subfreezing temperatures and massive glaciers known as the Great Ice Age. It was
not the first time ice had covered Earth. It might not be the last.

  MODERN NEANDERTHALS

  Until recently, scholars have assumed that interaction between the two species of human stopped short of mating, or, as one author puts it, hybridizing. DNA sequencing has destroyed that theory.

  About ten years ago, scientists at the University of Montreal identified a set of DNA variations in the human x chromosome that didn’t seem to fit. These variations formed a haplotype, meaning they are normally inherited together. The Montreal researchers were not able to identify the origin of the haplotype. It remained unexplained until 2010, when researchers from Harvard and MIT sequenced more than 60 percent of the Neanderthal genome, using more than one billion DNA fragments taken from Neanderthal bones. Researchers then compared the Neanderthal genome with both the unusual haplotype and the DNA of living humans from around the world. The haplotype matches a sequence of the Neanderthal genome. It also makes up between 1 and 4 percent of the DNA of modern humans who are not from sub-Saharan Africa or Australia. Evidently the rumors of Neanderthal man’s extinction are exaggerated. He lives on in us.

  Born in fire, the earth is gradually cooling off. For roughly two million years, glaciers have expanded and contracted more than twenty times, at intervals of roughly a hundred thousand years. Brief periods of interglacial warming lasting about ten thousand years are followed by long periods of cold. (“Brief” is relative. The entire recorded history of mankind has occurred during the most recent warm spell.)

  At the height of the Great Ice Age, around 20,000 BCE, glaciers covered one-third of the planet, including all of Greenland and much of Europe, northern Asia, and the Americas. As water froze, sea levels dropped hundreds of feet, exposing land bridges in the shallow waters of the Bering Strait, the English Channel, and the South China Sea. The temperature dropped to roughly minus 60 degrees Celsius (minus 74 degrees Fahrenheit). Glacial expansion seems to be caused by a combination of tiny changes in three different ways the earth moves: the tilt of the earth on its axis, the earth’s orbit around the sun, and the wobble of the earth on its axis (picture what happens when a top slows down).

  Each of these movement patterns operates on a different cycle; each affects the relationship between the earth’s poles and the heat of the sun in a different way. The wobble, in particular, is erratic, affected by earthquakes, tidal waves, typhoons, and, ironically, the melting ice at the end of an ice age. Over time, the patterns interweave, pulling together and apart, sometimes increasing their effects, sometimes canceling them out.

  Humans had evolved in the warmth of Africa’s Great Rift Valley in an interglacial period. They had grown accustomed to the harsher climate of the Middle East and Europe in the thirty thousand years since they moved out of Africa. But with the advent of the Ice Age, survival required much greater resourcefulness. It was a make-or-break moment in time.

  HOW COLD IS AN

  ICE AGE?

  Can’t imagine what 60 below feels like? The average temperature in Fairbanks, Alaska, in January is minus 23 degrees Celsius (or minus 9 degrees Fahrenheit). For our Ice Age ancestors, 23 below would have been a heat wave.

  SOME OTHER COLD SPOTS

  SOUTH POLE

  Average winter temperature: -58°C

  THE TOP OF MOUNT EVEREST

  Average January temperature,

  before wind chill: -18°C

  Average January temperature,

  with wind chill: -100°C

  THE COLDEST TEMPERATURE RECORDED ON EARTH?

  Vostok Station, Antarctica, July 21, 1983 -89°C

  Outside the space shuttle, facing deep space -156°C

  Cryonic freezer

  -195.85°C

  STICKS AND STONES AND ANTELOPE BONES

  In the years before the Ice Age, humans supplemented their diet of foraged vegetation by hunting animals that were easy to kill and not particularly dangerous. With the arrival of the glaciers, foraging provided less food, and humans looked with hungry eyes at the herds of large herbivores that roamed the tundra. It was the age of what paleontologists call megafauna: aurouchs, Irish elk, cave bears, woolly mammoths and rhinoceroses, and forest elephants. Humans learned to work as a group to hunt animals that were too big for one man to hunt alone: a woolly mammoth could easily weigh six tons. Individual animals were isolated and driven off cliffs or into ravines.

  Hunting megafauna required more than just working as a group. Early Stone Age knives and spears required hunters to get close to their prey. In the Ice Age, hunters developed new weapons that allowed them to attack their prey from a distance. The first and most important of these improvements was the atlatl—a wood or bone rod with a hook at one end that fit into a socket at the base of a spear. The hunter held the end of the atlatl in his palm and threw the spear with his arm and wrist. The atlatl effectively increased the length of the spear thrower’s arm, adding both range and impact: the principle is similar to that of a catapult. From the hunter’s point of view, it was as revolutionary as gunpowder.

  The atlatl gave the Ice Age hunter’s arm extra power; new techniques and materials for creating blades gave it a sharper point. Blade flakes—long, thin flakes cut off a central core of flint or obsidian—allowed Ice Age weapon makers to maximize their production of points, producing 300 to 1,200 percent more cutting edge from the same amount of stone. The blades were mankind’s first interchangeable parts, used to make knives, hide scrapers, spear points, and drills. At the same time, bone and antler, more durable than wood and more flexible than stone, allowed the creation of new tools with more complicated shapes: fish hooks; long, thin knives; sewing needles; clothing fasteners; and harpoon barbs.

  replicas of artifacts found in Gough’s Cave, first explored in 1890

  Stone Age sharpened bone fragments found during excavations at the Blombos cave site in South Africa.

  SURVIVING THE ICE AGE

  AN ICE AGE FAMILY FINDS SHELTER IN A SHALLOW cave in Southern France around eighteen thousand years ago. Mile-thick glaciers covered northern Asia, Europe and America, locking up so much water that the sea level was more than three hundred feet lower than it is today. With average temperatures similar to those at the modern South Pole, and little buffer against the elements, these humans lived a precarious existence.

  These Ice age humans make spears from antlers and sticks, tipped with blades chipped from stones. Theirs is a life and death contest for survival with other beasts, requiring ingenuity and dexterity. Foraging no longer provides enough food to sustain them. Instead they must hunt the herds of large mammals: dangerous work for many men.

  Today, they are after smaller game. At midday, when the outside temperature is warmest, the family leaves the protection of the cave to check on a trap set the day before. They are clothed in the furs and hides of different animals, sewn together with needles fashioned from small animal bones. Each type of animal skin offers a different level of insulation from the elements—making fur an unnecessary adaptation for mankind.

  The group walks silently over snow-crusted ground until they reach patches of exposed dirt and wet ground where ice has melted. They walk in single file, always watchful for danger that may lurk ahead from a larger predator, or the appearance of opportunity in the form of a carcass left behind. Along the way the woman forages: today she is lucky enough to find berries and gathers them into her basket. At the trap, they rejoice to see that they’ve successfully snared a rabbit. They bring the animal back to their camp at the mouth of the cave, where they skin it and place the raw flesh over a fire.

  While the rabbit cooks, a particularly bold wolf approaches the young boy who has finished his skinning chore and is now wandering outside the cave. The boy’s mother rises, shouts, and throws something at the wolf—a bone. The wolf runs to the place where it landed, crouches down and chews. The boy returns to the fire with his mother, leaving the half-tamed animal to enjoy its share of the day’s bounty. This wolf and these humans have been in each other�
�s midst for years now, evolving from competitors to friends.

  The family has managed to survive another day.

  WHAT WAS DOMESTICATED WHEN

  CAT ca. 9000 BCE Mesopotamia

  SHEEP ca. 9000 BCE Western Asia

  GOATS ca. 8000 BCE Western Asia

  PIGS ca. 7000 BCE Western Asia

  CATTLE ca. 7000 BCE Eastern Sahara

  HORSES ca. 6000 BCE Central Asia

  CHICKENS ca. 6000 BCE China

  LLAMA ca. 5400 BCE The Andes

  CAMEL ca. 3600 BCE Southern Russia and the Arabian Peninsula

  REINDEER ca. 1000 BCE Siberia

  EVERY DOG ALIVE TODAY IS descended from Eurasian wolves. Dogs were the first animal that humans domesticated, possibly up to thirty thousand years ago. There’s a difference between taming and domesticating an animal. Individual wild animals can be tamed to live, and even work, with humans. Domestication implies that over time an animal changes into a form that is biologically and behaviorally different from its wild ancestors, a form that is presumably more useful to humans. At various times, white deer, elephants, and cheetahs have been tamed by humans, but they have never been domesticated.

  The relationship between man and dog may have begun when earlier canines followed nomadic humans as scavengers. The relationship continued because wolves are “preadapted” for domestication, thanks to their well-defined pack hierarchies, high degree of sociality, and pack hunting behaviors. At first, dogs served humans as sentinels, hunting companions, and a food source when times were tough. (Some dogs were bred specifically as food animals in ancient China, Aztec Mexico, and Polynesia.) As humans domesticated other species, dogs learned to herd animals they had previously hunted.