The average body size of humans has fluctuated significantly over the last million years and is strongly linked to temperature.
The average body size of humans has fluctuated significantly over the last million years and is strongly linked to temperature. Colder, harsher climates drove the evolution of larger body sizes, while warmer climates led to smaller bodies. Brain size also changed dramatically but did not evolve in tandem with body size.
An interdisciplinary team of researchers, led by the Universities of Cambridge and Tübingen, has gathered measurements of body and brain size for over 300 fossils from the genus Homo found across the globe. By combining this data with a reconstruction of the world’s regional climates over the last million years, they have pinpointed the specific climate experienced by each fossil when it was a living human.
The study reveals that the average body size of humans has fluctuated significantly over the last million years, with larger bodies evolving in colder regions. Larger size is thought to act as a buffer against colder temperatures: less heat is lost from a body when its mass is large relative to its surface area. The results are published today in the journal Nature Communications.
Our species, Homo sapiens, emerged around 300,000 years ago in Africa. The genus Homo has existed for much longer, and includes the Neanderthals and other extinct, related species such as Homo habilis and Homo erectus.
Read more at University of Cambridge
Image: Skulls: - Left: Amud 1, Neanderthal, 55.000 years ago, ~1750 cm³ - Middle: Cro Magnon, Homo sapiens, 32.000 years ago, ~1570 cm³ - Right: Atapuerca 5, Middle Pleistocene Homo, 430.000 years ago, ~1100 cm³ Femora: - Top: Middle Pleistocene Homo, Trinil, 540.000 years ago, ~50 kg - Bottom: Neanderthal, La Ferrassie 1, 44.000 years ago, ~90 kg (Credit: Manuel Will)