Comparing the evolution of people to that of the first horses, whose body size became smaller as temperatures rose, around 55 million years ago, Professor Steve Brusatte, a paleontologist at the University of Edinburgh, suggested that the climate crisis and rising temperatures might reduce the size of humans. Indeed, according to him, small mammals adapt better to rising temperatures.
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Bergmann’s rule
The professor indeed notes that animals in the warmer regions of the world are often smaller than those in colder regions, an ecological principle well known as Bergmann’s rule. A principle that explains that external temperature and the ratio of body surface area to weight in warm-blooded animals are correlated. Thus, birds and mammals in cold regions are larger than individuals of the same species in warm regions. “The reasons are not fully understood, but it is probably, in part, because small animals have a higher surface area to volume ratio than plumper animals and can therefore conduct excess heat better”explains Steve Brusatte in The Guardian.
Thus becoming smaller would be a common way for mammals to cope with climate change. “This is not to say that all species of mammals would become smaller, but it seems to be a common survival trick of mammals when temperatures rise quite rapidly. Which begs the question: if temperatures rise very rapidly, humans might -they become dwarfs, might humans become smaller? And I think that’s certainly plausible.”
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Resource availability
However, not all experts agree that increasing temperature causes mammals to shrink. For some scientists, “mammalian body temperature and size can often be related to the availability of food and resources”explains in The Guardian Professor Adrian Lister, of the Natural History Museum from London. But according to him, “We’re not really controlled by natural selection. If that were to happen, tall people would have to die before they might reproduce because of global warming. That’s not happening in today’s world. .We wear clothes, we have heating, we have air conditioning if it’s too hot”.
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