Scimex: US and South African scientists compared human bodies with those of our
closest ape relatives, bonobo chimpanzees, to gain insights into our
evolution. They found we're less muscular overall, fatter and have less
skin than bonobos, but it's not all bad - at least we evolved the
ability to sweat profusely, which bonobos can't do.
Human skin, fat, and muscle proportions differ significantly from those
of bonobos, suggesting evolutionary factors that may have shaped the
body structure of Homo sapiens, according to a study.
A lack of
fossilized soft tissues precludes comparison of the musculature, fat
distribution, and skin of human ancestors with modern humans. To
investigate how evolutionary forces may have shaped human body
composition over time, Adrienne L. Zihlman and Debra R. Bolter dissected
13 bonobos—rare members of the Pan genus that represent Homo sapiens’
closest living ape relatives—that had died of natural causes, and
compared soft tissue composition with that of modern humans. Compared
with bonobos, humans have increased body fat, decreased muscle mass, and
decreased skin mass. Further, the authors found that humans display an
evolutionary redistribution of muscle mass to the lower limbs.
Evolutionary factors such as variable calorie intake in new environments
may have led to an increase in body fat percentage. Lengthened lower
limbs with the development of bipedalism may have driven the shift of
muscle mass to the lower limbs, and humans’ ability to sweat may have
led to changes in skin and hair characteristics that may have freed
early Homo species from restricted temperature niches. The
results suggest that various evolutionary pressures likely shaped modern
human body composition, according to the authors.