Human ancestors and Neanderthals living in colder places generally had larger bodies.
The research offers conclusive evidence that human body size and climate are historically connected.
The authors of the new study also found that the rapid increase in human brain size over the last million years was not strongly correlated with climate.
The new findings are “reasonably convincing,” says Mark Collard, who studies human evolution at Simon Fraser University in Canada and who was not involved in the study.
However, he suspects that the new analysis may overstate the relationship between temperature and body size because of uncertainties in both the fossil record and climate data, he says .
It’s also possible that more complex social structures and group communication are linked to brain growth in human ancestors .