8 Forces Driving More
Nor can they compete with a lion’s sharp claws and nighttime vision.
Unlike microscopic organisms, which have survived for . billion
years, humans do not have a long genetic record. In fact, our species is
quite recent, only coming on the scene some 00,000 years ago.
So with nonstop environmental pressures, how have humans man-
aged to survive? Three behaviors forever remapped the way humans
interacted with the environment and other species. The resulting bene-
fits were immense, but so also were the vulnerabilities.
Starting the ball rolling was fire.^ Fire changed everything. As it
killed pathogens and cooked food, it unlocked nutrition bound up in
the cellulose of plants, as well as the tissues and bones of animals. Ill-
ness and death diminished. The amount (and likely the kind) of nutri-
ents the human body could absorb shot up 0 – 9 percent,paving the
way for brain size to increase and the number of neurons to rise dramati-
c a l l y.^ Enormous advances in cognitive reasoning followed, along with
greater ability to regulate complex bodily functions. Today’s humans
have a smaller, more efficient digestive system,^ and a brain almost seven
times larger than mammals of similar mass.^ At just percent of body
weight, the brain uses a quarter of the energy consumed from food.
As fire killed pathogens and improved nutrition, it also made our
ancestors’ lives easier. Fire kept people warm, scared away predators
at night, allowed hunters to flush out and corner potential game, and
even made chewing and digestion less of an effort by softening up
meat and plants alike. While cooking changed humans physiologically,
harnessing the energy of fire changed societies, eventually creating
modern economies powered by burning fossil fuels.
Fire also set the stage for the second behavior that separates humans
from other animals: language. As people coordinated hunts of larger
animals, attracted mates, lived in communities, and avoided preda-
tors and marauders, complex communication became indispensable
for survival. Development of precise forms of language and expression
accelerated discovery and became the foundation for science and
technology.
Language, in turn, set up the third behavior: collective memory.
Thanks to memory, experiences were no longer forgotten when people