Climate Change May Have Affected the Body and Indirectly the Brain Size of Prehistoric Humans, Study Found

Anthropologists studying human evolution said that their recent study shows how climate had directly affected the human body size but not much on the brain size. The London Free Press reported that the findings contradict some previous studies.

Jay Stock, an anthropologist at Western University, teamed up with another anthropologist named Manuel Will at the University of Tübingen, Germany, to investigate the body and brain size of 300 Homo genus fossils found from different parts of the world.

The two teamed up with ecological and climate experts from the University of Cambridge to match each of the fossils at the specific climate it lived from millions of years ago.

Impact of Climate on the Body and Brain Size

The study, titled "Different environmental variables predict body and brain size evolution in Homo," published in the journal Nature Communications, shows the impact of climate on the Homo species, but not the Homo sapiens that emerged 30,000 years

The team found that colder climates led to larger body sizes, while hotter temperatures lead to smaller bodies. However, they found a weak connection between climate and brain size.

Professor Andrea Manica of the Department of Zoology of the University of Cambridge said that climate has been the main driver of changes in body size for millions of years and that it is observable in modern humans. Those who live in areas with hotter climates tend to be smaller than those in colder areas.

Moreover, Science Daily reported that Homo species living in ecologically more stable areas and habitats with less vegetation, such as open steppes and grasslands, tend to have a larger brain size. They combined their findings with archaeological data and found that humans in these areas engaging in the complex activity of hunting large animals as food might have triggered the evolution of larger brains.

The team concluded that different factors determine brain size and body size but did not happen in similar evolutionary pressures like previous scientists thought. But they agree that the environment plays a greater influence on both brain and body size.

They emphasized an indirect environmental influence on the brain size of those prehistoric humans living in more stable and open areas. Nutrients must be sufficient to support and maintain the growth of the large and energy-demanding human brains.

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Brains Could Shrink in the Next Few Thousand Years

Aside from the climate and environment, researchers also noted some non-environmental factors that could affect brain size. According to News Medical Life Sciences, brain size appears to be shrinking since the beginning of the Holocene era, around 11,650 years ago.

The shrinking of the brain is largely associated with the advancement and dependence on technology. The more people outsource complex tasks to computers, the more likely the brains shrink and even more so in the next few thousand years.

But further research is needed, especially on Homo species fossils, to understand other factors that might have contributed to human evolution. Studying this will give valuable insight into the underlying pressures of the morphological changes that happen to humans.