The impact of a warming planet will no longer be limited to sea-level rises, biodiversity loss, or increased risks of disease. The ongoing climate crisis could lead to humans shrinking in size, a palaeontologist has warned.
The expert said humans might begin to evolve to adapt to rising global temperatures since mammals with smaller frames were better equipped to deal with climate change.
University of Edinburgh Palaeontologist Prof Steve Brusatte said studying how other species had adapted to climate change would allow experts to gain insight into the future of human evolution. He compared the transformation to be similar to that of prehistoric horses, which shrunk as temperatures began to rise around 55 million years ago, during the Paleocene Eocene Thermal Maximum period.
Speaking to The Guardian, Prof Brusatte said there was a great fossil record across that global warming event — the most recent big global warming event in geological records.
It is eerie how similar the two plots are, he said.
In The Rise and Reign of the Mammals, his latest book, Prof Brusatte highlighted that animals in warmers parts of the globe were generally smaller than in colder places. This ecological principle — Bergmann’s rule — has also been observed in humans across the world. Groups of humans living near the poles, such as the Inuit, Sami, and Aleut populations, are heavier on average than humans in lower latitudes.
Prof Brusatte wrote in the book that the reasons were not entirely understood, but were probably, in part, because smaller animals had a higher surface area relative to their volume than plumper animals and could better shed excess heat.
He added that becoming smaller was a common way for mammals to deal with climate change.
While he added the caveat that not every mammal species would get smaller, he said it seemed to be a common survival trick during quick temperature spikes.
Prof Brusatte said it was plausible that humans might get smaller if temperatures spiked quickly.
Previous palaeontological research suggests that prehistoric human species had also shown signs of shrinking at periods when resources were scarce. Prof Brusatte pointed to the Homo floresiensis, dubbed “hobbit-humans” that once inhabited Flores island in Indonesia.
In a recent study, scientists studied human remains over the past million years and discovered that temperatures might have been a key predictor of body size.
In a similar research, scientists studying red deer in Scandinavia and northern Europe believe that warmer winters were contributing to the shrinking of these animals.