In the 1990s, Wrangham began to develop his Cooking Hypothesis, which he more fully elucidated in , published in 2009. Wrangham marshaled numerous lines of evidence to support his hypothesis, which was widely pilloried by his colleagues. Wrangham conceded that the archeological record was scarce for the early control of fire, but he countered that evidence for early fires would rarely survive. Most caves last a quarter million years or so; they are made from soft stone, and the geological dynamics that create caves also destroy them. Also, early humans, just like gorillas and chimpanzees today, and even early hunter-gatherers, would have been constantly on the move, never sleeping in the same place twice. If the first fires were made in the African woodlands and grasslands, the evidence would not survive for long, just as the remnants of today’s hunter-gatherer fires on the African savanna quickly disappear. The gist of Wrangham’s Cooking Hypothesis is this:
Wrangham’s hypothesis is more robust and subtle than this essay can do justice to, but I will survey some of the findings, implications, and controversy. Raw food has various nutritional properties that are superior to cooked food, such as vitamins, but because cooked food provides more digestible calories for humans than raw food, it represented an evolutionary advantage. Meat, starches, and seeds are far more digestible when cooked, and are much easier to chew. Today, chimps in will not eat raw seeds of trees, but when a fire passes through the savanna, they search the ground below the trees and eat their cooked seeds.
Two major events happened soon after appeared, and their sequence seems to support the Cooking Hypotheses. The first of which was the migration of from Africa ; they spread to and by 1.8 mya (perhaps 1.6 mya in the case of Java), and . It was the , and may have become the first multi-continental member of the human line, and certainly the first widespread one. Favorable climates and a lower Himalaya range and Tibetan Plateau may have encouraged that migration. Unlike Miocene apes that began to migrate from Africa 16.5 mya, there was no unbroken forest to sustain journey to East Asia. Those migrants would have to sleep on the ground for much of the journey and were not adapted for sleeping in trees, . From today’s viewpoint, it may seem that they were adventurers, but as will also become obvious with the spread of , in one individual’s lifetime, there was probably only modest movement, expanding into the next uninhabited valley or two. Such an expansion happened one valley at a time, one generation at a time, to make it across a continent in a few thousand years for those that could adapt to changing biomes. Migrating at the same latitude would not have presented great climatic issues. As those migrations happened during the ice age, they were along southern Eurasia. There is no evidence yet that ever made it to Australia, probably because of the ocean crossing required for passage.
The derision was loud from Wrangham’s colleagues…until evidence of was found at in South Africa by using new tools and techniques. The chortling is subsiding somewhat and scientists are now looking for the faint evidence, and long-disputed evidence of 1.5-1.7 mya controlled fires is being reconsidered, although his hypothesis is still widely considered as being only "mildly compelling" at best. New tools may push back the control of fire to a time that matches Wrangham’s audacious hypothesis. Wrangham cited the Expensive-Tissue Hypothesis as partially supporting the Cooking Hypothesis, but , the energy to power the human brain may not have solely derived from cooked food’s energy benefits. Wrangham has cited numerous lines of evidence, one of which is a that has to find honeybee hives and smoke them out; the humans get the honey and the honeyguide gets the larvae and wax. According to recent molecular evidence, the evolutionary split of the honeyguide from its ancestors happened up to three mya, which supports the early-control-of-fire hypothesis. There is great controversy regarding these subjects, from recent findings that to scientists making arguments that to the social impacts of campfires. This section of this essay will probably be one of the first to be revised in future versions, as new evidence is adduced and new hypotheses are proposed.
Did the control of fire to , ? Or did merely use it to begin dominating the world? Was cooking the seminal event in the appearance of humans? Those questions may not be definitively answered in my lifetime, and led to the somewhat uncertain title of this chapter. Highly transformative developments coincided with the appearance and dispersal of , which was a radical break from all that came before – biologically, technically, and culturally – and strongly implies great cognitive enhancements. I believe that the control of fire and cooking would leave deep cultural and biological impacts on the human journey, and because barely changed during its nearly two-million year tenure on Earth, both in biology and in Acheulean artifacts, I favor Wrangham’s hypothesis, at least until the Next Big Finding. Just as Einstein said that and that his theories would one day become obsolete, but that their best parts would survive in the new theories, I suspect that significant aspects of Wrangham’s hypothesis will live on in successor hypotheses, and other scientists have been following Wrangham’s lead.
Were the dramatic changes in a result of cooked food, or was Turkana Boy as his species became hunters instead of hunted, and the stone tools softened up the meat and plant foods so that he did not need to chew as much? Wrangham co-authored a that began with . It concluded that food processing, cooking in particular, accounted for the effect. Cooked food versus raw food and the number of neurons that can be supported in a brain has been . The primary reason why Wrangham’s hypothesis was initially dismissed was that archeological evidence for fires that long ago is almost nonexistent. When was published, the earliest evidence with wide acceptance only supported fires , where Israel is today, which is more than a million years after Wrangham’s estimated timeframe. Wrangham did what all bold scientists do: he made falsifiable predictions. If it turned out that no evidence of early fires was ever found, his hypothesis could begin looking shaky.
"A basic hypothesis of natural medicine states that the introduction into the human body of molecules and energies, to which it is not accustomed, is much more likely to cause harm than good. Microwaved food contains both molecules and energies not present in food cooked in the way humans have been cooking food since the discovery of fire. Microwave energy from the sun and other stars is direct current based. Artificially produced microwaves, including those in ovens, are produced from alternating current and force a billion or more polarity reversals per second in every food molecule they hit. Production of unnatural molecules is inevitable. Naturally occurring amino acids have been observed to undergo isomeric changes (changes in shape morphing) as well as transformation into toxic forms, under the impact of microwaves produced in ovens.
Wrangham made the ability to sleep on the ground a key part of his Cooking Hypothesis. was not only adapted for ground living, , which would have reflected eating soft and easy-to-digest food. Along with organ meats, cooked food is the leading candidate for soft foods. If habilines mastered fire, they would have almost immediately used it for cooking.