Climate affects human body evolution, says new study

Several previous studies had
proven that human evolution pattern involves an increase in the size of the
brain and the body. This is why our species, Homo sapiens, which is part of the
Homo genus-group that emerged about 300,000 years ago, have brains three times
larger than our counterparts who lived a million years ago. While the factors
causing this change in size has always been a matter of debate, a new study has
determined the role of climate changes in this evolution process.

A
study led by Cambridge University and Tübingen University researchers has shed
light on the contribution of climate changes in human evolution. The study
revealed that temperature has a strong link with human body evolution over the
years.

“The
colder it gets, the bigger the humans are, If you’re bigger, you have a bigger
body – you are producing more heat but losing relatively less because your
surface is not expanding at the same rate,” said Dr Manuel Will, a
Tübingen University researcher and joint first author on the study.

Those
who study science might understand a rule that backs up the claim, Bergmann’s
rule. This relationship between climate and body mass is consistent with this
rule. The rule says that the larger bodyweight is found in colder environments
while a smaller bodyweight is observed in warmer environments. This is also
observed in animal species such as bears – polar bears living in the Arctic,
for example, weigh a lot more than brown bears living in comparatively warmer
climates.

The
study also takes other climatic factors like precipitation and pressure into
consideration. 

As
far as the link between the brain and climate is concerned, the research found
that environmental factors have substantially less influence on the brain size
than they do on body size.

“This
phenomenon shows that body and brain size are under different selective
pressures. This study really manages to detangle the fact that both [brain and
body size] is increasing, but increasing for very different reasons,” said
Prof Andrea Manica, another researcher on the study.

However,
the study results showed no association of brain size with temperature.
Instead, the researchers found that more stable climates with bigger brains.
This effect links to the dietary needs of humans living in environments of
variable climatic stability. The study was published in Nature Communications.