The next generations could shrink because of a phenomenon that has already started.
In recent years, the French have grown. According to the investigation Obepi-Roche 2020, in eight years (2012-2020), men have gained 1.2cm with an average height of 176.6cm and for women, they measure 163.9cm on average with 1.3 centimeters more in less than ten years . However, this trend could be reversed in the future, according to Steve Brusatte, a paleontologist at the University of Edinburgh.
Humans could, in the future, shrink and it would not be due to a genetic issue. This phenomenon would be caused by an adaptation to its environment and in particular to rising temperatures. He compares this situation to that of mammals that live in warmer regions: they are smaller than those that live in cold places. “The reasons are not fully understood, but it is likely, in part, that smaller animals have greater surface area relative to their volume than larger animals and can therefore better expel excess heat,” writes the specialist in The Rise and Reign of the Mammals published at the house of Mariner Books in 2022.
This principle is known as Bergmann’s rule, from the 19th century German biologiste century Carl Bergmann. He explains that animals with the smallest ratio between surface area and body volume then have less heat loss and thus adapt better to the cold.
Thus, humans could shrink to adapt to rising temperatures with the effect of global warming. In an interview with The Guardian, Steve Brusatte qualifies by specifying that it is a “common survival tip”, but not systematic for all species of mammals. However, it raises the question: “If temperatures rise very quickly, could humans become dwarfs, could humans become smaller? And I think that’s certainly plausible,” he said.
The paleontologist is not the only one to pose this theory. In another studyresearchers who studied human remains from the last million years have suggested that temperature may be a major contributor to variation in body size. However, this hypothesis remains to be confirmed and if this happens, we would have to wait a long time. Correlations between size and temperatures may also be due to the difference in resource availability during high heat.