In celebration of the ten-year anniversary of Paul Salopek's first steps on his Out of Eden Walk journey, this dispatch is now available for educational use in fifth- and eighth-grade reading levels. The original text is available as the default reading level, as well as on the Out of Eden Walk website.
By Paul Salopek
NEAR GONA, ETHIOPIA (2/8/2013)
Gona is the scene of a long-forgotten leap in human consciousness.
A monument should be erected at this spot in the dim wilderness of Afar country. There should be a tall shrine, made exclusively of stone, to honor the colossal idea that unfolded here 2.6 million years ago. The world’s rulers could be invited to the inauguration. A new international holiday could be added to the crowded global calendar of worthy human events. It could be called Gona Day, perhaps. But celebrity status at any such ceremony could only be reserved for the chefs of the planet: the sushi artists of Osaka, the Paris masters of steak tartare, and especially the carvers of beef in Argentina and Texas. I imagine them removing their hats and raising their knives and cleavers, saluting the location of the oldest stone tools in the world. They would bow to honor their culinary ancestors, the first humans to take food and cookery seriously.
The Rift Valley of Africa is littered with millions of artifacts from the basement of time. The majority of these heaps of old utensils appear to be linked to one purpose: food preparation. Gona, then, is humankind’s original kitchen. Its prehistoric chopping and cutting tools have a simple design, called Oldowan. It overcame our ancestors’ competitive disadvantages, like weak bodies and small teeth designed mostly to chew plants. It sliced open the concentrated, animal energy of entire ecosystems. Oldowan tools started a revolution.
“The first toolmakers began making stone artifacts intentionally by knocking off cobbles [stones] to produce sharp-edged flakes used for cutting up animal carcasses,” says Sileshi Semaw, an Ethiopian scientist at the National Research Center for Human Evolution, in Spain. He discovered the Gona site. “The stone tools were mainly used for processing animal carcasses for meat and for breaking bones for marrow.”
Gona’s blades were probably not used to kill the ancient antelopes whose fossilized bones lay scattered there. The first toolmakers were not brave hunters. The wily, squinting early humans at Gona, who knocked two rocks together to announce their conquest of the world, were likely “power scavengers.” They spooked hyenas and wild dogs to scrounge their kills. They ate the work of others.
Ahmed Alema Hessan and I have walked for weeks over discarded Stone Age cutlery. It’s the litter of ancient well-fed meat-eaters in a landscape often equated, today, with hunger.
We yo-yoed for miles across waterless gullies to Gona. Its silence rang. We toppled, exhausted and devastated by the heat, under the spiky shade of an acacia tree. Yet even there we sizzled and couldn’t linger. There were reports of armed Issa nearby, trying to steal Afar cattle.
“Let’s go, man,” Alema said, kicking my boots.
History is a mirror. The revolution continues.Our movements reflect those of our ancestors.
Did Fire Make Us Human? The Raw Truth about Cooking
Most people who study human origins agree that the invention of stone tools around 2.6 million years ago was a major crossroad in human evolution. Animal butchery allowed early humans to access nutrient-rich sources of food such as internal organs and marrow. Richer energy inputs may have nurtured our big brains. But one researcher, Richard Wrangham of Harvard, thinks the more important breakthrough came with the power of the hearth—cooking. Wrangham’s view is controversial. It is debated because solid archaeological evidence for controlled fire is relatively recent. It is only about 400,000 years old.
Below, Wrangham and I discuss his topic.
Paul Salopek: I walked through the remote Gona site in Ethiopia, which at 2.6 million years old is considered to be the oldest stone tool site in existence. The tools scattered across the desert there—hand axes, picks—were used mostly to butcher large animals, such as buffalo, which were presumably eaten raw. What do we know about the amount of raw meat in our prehistoric diets? We have some pointy teeth for a reason, right?
Richard Wrangham: Cut marks in the meat-bearing parts of fossil bones confirm that a species of early human was eating meat from large animals more than two million years ago. These meat-eaters were most likely ancestors of ours. Some of the first ones to have regularly used stone tools were probably the species Homo/Australopithecus habilis. Unfortunately, we do not know how much meat they ate, or whether they cooked it. Their digestive systems must have been adapted to eating a lot of plants, as they are in chimpanzees and gorillas today. So, it is unlikely that they relied on meat for most of their food. A reasonable guess is that they ate their meat raw when they first started taking it from big game animals, like antelope and hippos. Then, over some tens of thousands of years, they learned that cooking improved it. By the way, canine teeth, the pointy ones, have nothing to do with how primates eat meat. Species with big canines do a lot of fighting with each other. Mostly the ones with big canines are males, such as gorillas and baboons. In some species, like gibbons, females have big canines, too, and they fight hard with other female gibbons.
Paul: You argue that crossing the threshold from raw foods to cooked foods was a key milestone that helped make us fully human. In other words, it made our brains more human. Why?
Richard: Cooked food is different in two very important ways from raw food. It gives us more energy, and it is softer. The increase in energy means that once our ancestors started relying on cooked food, they could live longer. They could have more babies, travel farther, fuel a big brain, and give up having really big guts. The softer food given by cooking allowed our ancestors to have small teeth. They could spend less time chewing, and more time on novel activities like hunting and toolmaking. Brains use a lot of calories per day. Cooked diets helped brains enlarge because, thanks to eating softer food that is easier to digest, humans have small guts. So, some of the energy that had previously been used to power our guts could now be used for brains.
Paul: Why, exactly, are cooked meals more nutritious than raw food?
Richard: First, cooked food gives us more calories per gram of food that we eat. This is because the heat of cooking opens up molecules and makes them more easily split by enzymes. For instance, cooking makes gelatin-like food with starches and alters proteins. If starch or protein are eaten raw, they are only partly digested in the small intestine. The half or more that remains is digested very inefficiently in the large intestine. Second, cooked food costs us less of our body’s energy to digest. This is because cooked food is relatively soft, so our guts can break it down into smaller and smaller bits. Digestion of cooked foods doesn’t require too much muscular action in the stomach, or production of acids and enzymes. We do not know the typical amount by which cooking increases the energy value of foods, but it is probably closer to a 50 percent increase than 10 percent.
Paul: Your theory holds that the bigger brains and smaller teeth of Homo erectus, our first early ancestor to evolve from more apelike lines about 1.9 million years ago, is the result of eating cooked food. But other experts say that the evidence of controlled fire for cooking is a much more recent invention, dating back only about 400,000 years. How do you respond to this critique?
Richard: My theory relies on a prediction. It says that if we look hard enough, we will find evidence of early humans controlling fire by around 1.9 million years ago. Other kinds of data might help too, such as evidence of genetic adaptation, or changes, to cooked food. The cooking theory is based on a biological argument, whereas the challenge comes from archaeology.
Paul: We’ve been gathering around hearths for a very long time. People who live in modern suburbs build fake electric fireplaces in their stylish homes. Why is it so pleasurable to stare into fire embers? Does it tap into some instinct or memory of a full belly to come?
Richard: Regardless of exactly when fire was first controlled, a fireplace has certainly been a critical part of human life for hundreds of thousands of years. It has been a place of safety, satisfaction, meals, and friendship. No wonder that everyone loves it.
