Early hominins' walk was as energetic as modern humans: Study

London: A study has shown that the walk of hominins in the Pleistocene era, which lasted from about 2,588,000 to 11,700 years ago, was no less efficient energetically than that of present-day humans.

Traditionally, it was thought that the leaner skeletons of modern humans reflected biomechanical advantages which made locomotion a more efficient activity.

The slimmer pelvis of our species entails greater difficulty for childbirth, but it reduces the force that the abductor muscles of the hip have to exert to maintain the stability of the pelvis while walking.

"However, that doesn't imply that the hominins with wider pelvises expend more energy walking. In fact, the results obtained show that wider pelvises, at the height of the iliac crest, allow the energy cost of locomotion to be significantly lower," said lead author Marco Vidal Cordasco, from the National Research Center on Human Evolution, also known as CENIEH in Spain.

For the study, published in the American Journal of Physical Anthropology, the team analysed the influence of body proportions on the cost of locomotion by means of an experimental energetic study with 46 subjects of both sexes.

The researchers used the relationship between the width of the hip, the length of the femur and the body mass to model the energy cost of locomotion in extinct hominins.

Since two million years ago, with the appearance of the species Homo ergaster, the body mass and the brain size of the hominins have risen considerably. 

These changes have entailed an important readjustment at the metabolic level, with greater demand for energy to maintain these larger organs.

"However, our results show that the greater efficiency of locomotion was not a mechanism to compensate for this increase in size," Cordasco said. 

"That is, the changes observed in the width of the pelvis and the length of the lower limbs did not reduce the cost of walking sufficiently to offset the rise in energy cost caused by the increased body mass," he added.