Scientists investigating the reasons why early humans – the so-called hominins – began walking upright say it’s unlikely that the need to carry children was a factor, as has previously been suggested.

Carrying babies that could no longer use their feet to cling to their parents in the way that young apes can has long been thought to be at least one explanation as to why humans became bipedal.

But University of Manchester researchers investigating the energy involved in carrying a child say the physical expense to the mother does not support the idea that walking upright was an evolutionary response to child transportation.

“Scientists have long hypothesised as to the reasons why hominins became bipedal in a relatively short space of time but the truth is we still don’t know for sure.

“Our study focused on the amount of energy required to carry 10kg loads, including a mannequin child. Importantly, the distribution of the weight varied in each instance.”