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 for humanity.
A monument should be built at this spot in the dim wilderness of Afar country. There should be a tall shrine made of stone to honor the enormous idea that unfolded here 2.6 million years ago. The world’s rulers could be invited to the event. A new international holiday could be added to the global calendar of worthy human events. It could be called Gona Day. But special invitations to that ceremony could only be reserved for the chefs of the planet: the sushi artists of Osaka, the Paris masters of steak, and especially the carvers of beef in Argentina and Texas. I imagine them taking off their hats and raising their knives and cleavers, saluting the location of the oldest stone tools in the world. They would bow to honor the ancestors of the first cooks, the first to take food and cooking seriously.
The Rift Valley of Africa is littered with millions of artifacts from countless centuries ago. Most of these heaps of old tools appear to be linked to one purpose: food preparation. Gona is humankind’s original kitchen. Its ancient chopping and cutting tools have a simple design, called Oldowan. Gona overcame our ancestors’ challenges, like weak bodies and small teeth designed mostly to chew plants. It sliced open the strong animal energy of entire ecosystems. Oldowan tools started a revolution.
Sileshi Semaw, an Ethiopian scientist and researcher, discovered the Gona site. He explains that the first toolmakers began by purposefully knocking off pieces of stone to produce sharp-edged flakes used for cutting up animal carcasses. “The stone tools were mainly used for processing animal carcasses for meat and for breaking bones for marrow,” he says.
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 crafty, squinting early humans at Gona knocked two rocks together to announce their conquest of the world. They probably spooked hyenas and wild dogs away from their kills. These human ancestors ate the work of others.
Ahmed Alema Hessan and I have walked for weeks over discarded Stone Age kitchen tools. It’s the litter of ancient well-fed meat-eaters. Today, people often think of this area of the world as one where there’s not enough food.
We plodded for miles across waterless ravines to Gona. Its silence rang. We collapsed under the spiky shade of an acacia tree, exhausted and ruined by the heat. Yet even there we sizzled in the heat and couldn’t stay long. 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 gave early humans rich sources of food such as animals’ organs and bone marrow. Richer energy inputs may have helped make our big brains. But one researcher, Richard Wrangham of Harvard, thinks the more important breakthrough came with the power of the fireplace and cooking. Not everyone agrees with Wrangham’s view, because solid evidence for controlled fire is fairly recent. Evidence of humans controlling fire is only about 400,000 years old.
Below, Wrangham and I discuss this topic.
Paul Salopek: I walked through the remote Gona site in Ethiopia, which is 2.6 million years old. It is considered to be the oldest stone tool site in existence. There are tools scattered across the desert there like hand axes and picks. They were used mostly to butcher large animals, such as buffalo, which were probably eaten raw. What do we know about the amount of raw meat in our ancient diets? We have a couple 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 our first ancestors regularly used stone tools. That species was called Homo/Australopithecus habilis. Unfortunately, we do not know how much meat they ate, or whether they cooked it. Our digestive system is the part of the body that processes food, such as the stomach and intestines. Homo/Australopithecus habilis’s 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 eating 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. Cooking gave us softer food and allowed our ancestors to have small teeth. They could spend less time chewing, and more time on different, new activities like hunting and toolmaking. Brains use a lot of calories per day. Cooked diets helped brains become bigger. Eating softer food is easier to digest, so 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 healthier for us 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 easier to split. For instance, cooking makes starches gelatin-like and changes proteins. If starch or protein are eaten raw, they are only partly absorbed in the small intestine. The half or more that remains to pass through the large intestine is not very helpful to the body. Second, our bodies use less energy to digest cooked food. This is because cooked food is soft, so our guts can break it down into smaller and smaller bits. Digesting soft food doesn’t require too much muscular action in the stomach, or production of acids and enzymes. We do not know exactly how much cooking increases the energy value of foods. It is probably closer to a 50 percent increase than 10 percent.
Paul: Homo erectus was our first early ancestor to evolve from more apelike lines about 1.9 million years ago. Your theory is that Homo erectus’ bigger brains and smaller teeth are 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 argument?
Richard: My theory relies on a prediction, an educated guess about the future. 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 information might help too, such as evidence of our bodies evolving based on eating cooked food. The cooking theory is based on a biological argument, whereas the challenge comes from a different science field, archaeology.
Paul: We’ve been gathering around hearths for a very long time. People who live in modern suburbs just outside of big cities 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: No matter when fire was first controlled, a fireplace has certainly been a central 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.
