The Exercise Paradox

Scientific American, February 2017
The Exercisesad0217Pont3p.indd 26
February 2017, ScientificAmerican.com 27
IN BRIEF
Conventional wisdom holds that physically active peo-
ple burn more calories than less active people do.
But studies show
that traditional hunter-gatherers,
who lead physically hard lives, burn the same number of
calories as people with access to modern conveniences.
The discovery that
human energy expenditure is tightly
constrained raises questions about how our large brain
and other energetically demanding traits evolved.
Comparisons with energy expenditure
in great apes
suggest that the human metabolic engine has evolved to
get more work done to support our costly features.
The Exercise

Studies of how the human engine
burns calories help to explain why
physical activity does little to control
weight - and how our species acquired
some of its most distinctive traits
EVOLUTION
By Herman Pontzer
Illustration by Bomboland
sad0217Pont3p.indd 2712/14/16 4:00 PM
28 Scientifi c American, February 2017
Mwasad led our party—Dave Raichlen from the University
of Arizona, a 12-year-old Hadza boy named Neje and me—out of
camp just after daybreak. Dave and I were of little use in this
endeavor. Mwasad had invited us along as a friendly gesture
and for the extra help to carry the butchered animal back to
camp should our search e? ort succeed. As anthropologists who
study human ecology and evolution, we jumped at the opportu-
nity to tag along—Hadza men"s tracking abilities are legendary.
It certainly beat the prospect of a long day in camp spent fi d-
dling with research equipment.