Free Cooked: A Natural History of Transformation by Michael Pollan

here’s why cooking may stand a
better-than-average chance of surviving this silly game: Only the control of fire and
consequent invention of cooking can explain the evolution of brains big and
self-conscious enough to construct sentences like “
Homo sapiens
is the
only species that …”
    That at least is the import of “the
cooking hypothesis,” a recent contribution to evolutionary theory that throws a
wonderfully ironic wrench into the scaffold of our self-regard. Cooking, according to
the hypothesis, is not merely a metaphor for the creation of culture, as Lévi-Strauss
proposed; it is its evolutionary prerequisite and biological foundation. Had our
protohuman ancestors not seized control of fire and used it to cook their food, they
would never have evolved into
Homo sapiens
. We think of cooking as a cultural
innovation that lifts us up out of nature, a manifestation of human transcendence. But
the reality is much more interesting: Cooking is by now baked into our biology (as it
were), something that we have no choice but to do, if we are to feed our big,
energy-guzzling brains. For our species, cooking is not a turn away from nature—it
is
our nature, by now as obligatory as nest building is for the birds.
    I first encountered the cooking hypothesis
in a 1999 article in the journal
Current Anthropology
titled “The Raw and
the Stolen: Cooking and the Ecology of Human Origins” by Richard Wrangham, a
Harvard anthropologist and primatologist, and four of his colleagues. Wrangham
subsequently fleshed out the theory in a fascinating 2009 book,
Catching Fire: How
Cooking Made Us Human
. Soon after it came out, we began corresponding by
e-mail, and eventually we had the opportunity to meet, over a lunch (of raw salads) at
the Harvard Faculty Club.
    The hypothesis is an attempt to account for
the dramatic changein primate physiology that occurred in Africa
between 1.9 and 1.8 million years ago, with the emergence of
Homo erectus
, our
evolutionary predecessor. Compared to the apelike habilines from which it evolved,
Homo erectus
had a smaller jaw, smaller teeth, a smaller gut—and a
considerably larger brain. Standing upright and living on the ground,
Homo
erectus
is the first primate to bear a stronger resemblance to humans than
apes.
    Anthropologists have long theorized that the
advent of meat eating could account for the growth in the size of the primate brain,
since the flesh of animals contains more energy than plant matter. But as Wrangham
points out, the alimentary and digestive apparatus of
Homo erectus
is poorly
adapted to a diet of raw meat, and even more poorly adapted to the raw plant foods that
would still have been an important part of its diet, since a primate cannot live on meat
alone. The chewing and digestion of raw food of any kind requires a big gut and big
strong jaws and teeth—all tools that our ancestors had lost right around the time they
acquired their bigger brains.
    The control of fire and discovery of cooking
best explain both these developments, Wrangham contends. Cooking renders food much
easier to chew and digest, obviating the need for a strong jaw or substantial gut.
Digestion is a metabolically expensive operation, consuming in many species as much
energy as locomotion. The body must work especially hard to process raw foodstuffs, in
which the strong muscle fibers and sinews in meat and the tough cellulose in the cell
walls of plants must be broken down before the small intestines can absorb the amino
acids, lipids, and sugars locked up in these foods. Cooking in effect takes much of the
work of digestion outside the body, using the energy of fire in (partial) place of the
energy of our bodies to break down complex carbohydrates and render proteins more
digestible.
    Applying the heat of a fire to food transforms
it in several ways—some of them chemical, others physical—but all with the same result:
making more energy available to the creatures that eat it. Exposure to