Parents didn't stand for children

Carrying your children may well be good for bonding – but, according to new research, it doesn’t explain why we walk upright.

Cute - yes. The reason we walk upright - probably not

Walking upright is one of the key characteristics that separates humans from our primate relatives and many believe that one of the reasons why early humans (hominins) took to two feet was to carry their children more effectively. However new evidence from the University of Manchester has suggested this was not a factor in our bipedal evolution.

By monitoring the oxygen consumption of seven healthy women, they found that the physical energy expense of carrying a child does not favour walking upright indicating that the bipedal evolutionary response was not for child transportation. Although the most popular explanation to why we began walking upright is to free our forelimbs to carry objects.

Dr Jo Watson, who carried out the research at the University of Manchester’s Faculty of Life Sciences, said: “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.”

“Carrying an awkward asymmetric load, such as the infant on one side of the body, is the most energetically expensive way of transporting weight,” said Dr Watson, whose research is published in the Journal of Human Evolution. “Unless infant carrying resulted in significant benefits elsewhere, the high cost of carrying an asymmetrical weight suggests that infant carrying was unlikely to have been the evolutionary driving force behind bipedalism.”

The group hopes this initial research will help build up a picture of how humans evolved onto two legs. The research is part of a larger project, funded by the Natural Environmental Research Council (NERC), which includes the development of computer simulations of animal movements to gain insight into the evolutionary process.

By Leila Sattary