Researchers led by the University of Cambridge and the University of Tübingen in the United Kingdom and Germany, respectively who gathered measurements of body and brain size.
Around the globe, the researchers from both the universities have gathered over 300 fossils of ancient humans. And, have found that the average body size has fluctuated significantly over the last million years with larger bodies evolving in colder regions.
The researchers’ team used this data to combine with a reconstruction of the Earth's regional climates and calculated the climate that had been experienced by each fossil when it was a living human.
Researchers also found that climate change particularly temperature has been the main reason of all changes in body size for the last million years.
The researchers found that colder and harsher climates linked to larger bodies while the warmer climates were linked to smaller bodies. Researchers also studied at the impact of environmental changes on brain size.
Homo sapiens emerged around 3 million years ago in Africa. And, the Homo genus which includes Neanderthals and other related species such as Homo habilis and Homo erectus has existed for much longer.
Researchers said that earlier species such as Homo habilis and Homo sapiens are 50 per cent heavier and our brains were three times larger. While the reasons behind such changes are still debated today.
The researchers’ team also found that climate change does have a role in brain size but there were so many variation in brain size which can't be explained by environmental changes.
Dr. Manuel Will at the University of Tübingen who is the first author of the study said, “We found that different factors determine brain size and body size, they’re not under the same evolutionary pressures." Dr. Will further added that the environment has a much greater influence on our body size than our brain size.
Dr. Will added more, “There is an indirect environmental influence on brain size in more stable and open areas as the amount of nutrients gained from the environment had to be sufficient to allow for the maintenance and growth of our large and particularly energy demanding brains.”
This research also said that not only environmental factors but not non-environmental factors were more important for driving larger brains than climate.
Prime candidates are being the added cognitive challenges of increasingly complex social lives, more diverse diets and more sophisticated technology.