Climate Affects Evolution of Human Brain, Body Shape, Says A Recent Study

Evolution is a slow change in the body design of an organism over a long period of time. It helps an organism to survive in its surroundings. Now, according to recent research, scientists have found a connection between environment and evolution. The research was done on 300 human fossils of the Homo genus and was combined with climate models to identify its role in human evolution.

The evolution of humans is a subject of interest for scientists as well as non-scientists. It makes each and everyone curious because this is something mysterious. There are several theories as to how humans evolved and reached the era that they are in at present, but additions to them keep coming in making this particular field of science a matter of interest.

One way of observing evolution is to see the changes in body size and structure over millions of years. And according to a new study, these changes have been affected by climate.

Researchers from Cambridge University and Tübingen University in Germany have published their study in the journal Nature. The study states various hypotheses that indicate the role of environmental, demographic, social, dietary, and technological factors behind human evolution.

The researchers identified temperature as a major predictor of body size variation in Homo Sapiens in the last one million years. They determined what temperature, precipitation, and climate conditions the fossils might have been subjected to during their time when they were alive.

The paper released states, “Throughout the past four million years, human evolution is broadly characterized by a trend of increasing body mass and structure, with an even greater relative increase in brain size, associated with changes in behavior, diet, and demographic expansion.”

Researchers said that body and brain size were two essential biological traits of the adaptive strategy of species. These studies have refined and expanded earlier estimates of variation between body and brain size.

If we look at the last two million years, the estimated body size among most Homo species has increased from an average of 50 to 70 kilograms. To establish the influence of climate, researchers considered long-term, glacial-interglacial climate variations which are a result of changes in the Earth’s orbit around the Sun and greenhouse gases emissions, such as carbon dioxide. They found larger bodyweight in colder environments and a smaller bodyweight in warmer environments. The observations are in line with those seen in animals like bears that live in freezing conditions.

Researchers were also able to successfully establish a link between brain size and climate conditions. The paper said, “We found a relationship with long-term rainfall variability, where brain size was found to decrease with increasing levels of long-term rainfall.”

However, the analyses done by researchers detected no association of temperature with brain size, suggesting that brain size in Homo Sapiens was less influenced by environmental variables than the body size during the time period of the past one million years. Behavioral changes were also observed in response to hunting strategies in more open environments.