According to a research report published in the journal Nature Communications, the size of the human body has fluctuated considerably over the last million years due to climate change.
A team of researchers led by the University of Cambridge, the United Kingdom and the University of Tübingen in Germany has collected measurements of brain and body size from more than 300 fossils of the Homo genus or family, to which modern humans – homo sapiens – belong.
The team has used this data and combined it with a reconstruction of the earth’s regional climate from the last million years to calculate what climate each fossil would have experienced when it was a living human.
Larger bodies tolerate cold better
The researchers’ findings were that climate – especially temperatures – has been the most important driver for changes in body size over the last million years. Research shows that the harsher and colder the climate, the larger the bodies, while the warmer climate was associated with smaller bodies.
Larger bodies can protect individuals from cold temperatures. The larger you are, the smaller the surface area compared to your volume. This saves heat more efficiently, says Andrea Manica, professor of evolutionary ecology at the University of Cambridge to CNN.
This is something you see in many animal species, she says. The new thing is that we now know that climate change was a major cause of the changes in body size in the last million years, the professor adds.
Not as sure about the brain
The researchers also investigated whether climate could have affected brain size. There, however, they are not as safe.
The research team found that climate has played a role in brain size, but there were also many variations in brain size that could not be explained by climate change.
Among other things, they found no connection between brain size and temperature. Instead, they found a connection between large brains and stable environments, where there has been good access to resources.
Andrea Manica at the University of Cambridge says that among the oldest fossils from the gay family, they found larger brains in those who lived in open habitats. This is probably because they had to hunt very large mammals.
This, he believes, shows that other factors such as cognitive challenges, increasingly complex social lives, more varied diets and more sophisticated technology were the main drivers of changes in brain size.
Will probably not happen now
Manica believes it is unlikely that the climate changes we are experiencing today will have any dramatic impact on our bodies yet.
– The changes we describe have happened over tens of thousands of years, so a few years of climate change will do little with our bodies and brains.
– .
