Researchers from the University of Cambridge in the UK and the University of Tübingen in Germany set out to investigate how the average body size of humans has changed, and how this could be linked to temperature.

Their findings, published in the journal Nature Communications, are enlightening, to say the least.

To find answers, the team of scientists, led by the two universities, first studied the body and brain size of more than 300 fossils from the “Homo” family – the family to which modern humans belong.

The researchers then related these measurements to the climate each fossil would have experienced while alive.

According to the study, published in early July, temperature was one of the main factors causing human body sizes to change over the last million years.

To summarise, warmer climates led to smaller body sizes, while colder climates caused larger body sizes to evolve.

The researchers also examined the impact of environmental factors on brain size. This time, the correlations were much less clear.

The researchers concluded that climate did appear to play a role in brain size changes, but that this was unlikely to be the predominant factor behind those changes.

For Andrea Manica, a researcher in the University of Cambridge’s Department of Zoology, who led the study: “more diverse diets, and more sophisticated technology were likely the main drivers of changes in brain size.”