John Hawks reviews a new paleoanthropology book by Richard Wrangham called ““Catching Fire: How Cooking Made Us Human.” He worries that Wrangham’s umbrella thesis (a thesis based on a one-cause argument) may not be enough.
Wrangham’s hypothesis falls into a long tradition in paleoanthropology — the “umbrella hypothesis”, a term coined by John Langdon (1997). In Wrangham’s version, cooking was the fundamental change from which most of the other changes in early Homo can be derived. Other well-known umbrella hypotheses include the “expensive tissue” hypothesis, the aquatic ape hypothesis, and the “killer ape” hypothesis.
An umbrella hypothesis isn’t necessarily false just because it relies on a single cause. Hey, maybe cooking really did cause all that other stuff. Many well-respected scientific theories started out as umbrella hypotheses, like continental drift, or the K-T impact hypothesis.
But an umbrella hypothesis can be difficult to test because its supporters may draw in many facts that are explained equally well by other causes, or worse may be irrelevant. Take for example the argument that a fire provides an attractive location for social interactions. That is certainly true in many recent human hunter-gatherers. But food-sharing hominids may have had home bases attractive for social interactions without fire. And ethnographic hunter-gatherers really do leave groups because of social conflicts. They are much freer to move than male chimpanzees are, and this freedom to move has nothing obvious to do with cooking.