With many monkeys, climbing is as easy as walking

Scientists have long thought that walking is easier than climbing, and this explains why we humans evolved on the ground. But recent research reveals that this is not true.

Round-tailed lemur in Madagascar.(Photo: lostworldarts)

The team found that, at least for some small primates like squirrel monkeys and lemurs, climbing is not more difficult and energy-consuming than walking.

And it also explains the difficult evolutionary question that why about 65 million years ago, the youngest ancestors of humans, humanoid monkeys and monkeys climbed trees and never went to the ground.

In a study published recently in Science, the science group at Duke University in North Carolina and the University of South Alabama in Mobile said they tried to understand some small primates, climbing trees by hand and The limbs are more energy-efficient than walking.

Tested on 5 species: slender loris in Sri Lanka, slow lions in Indochina, round-tailed lemurs and mongoose lemurs in Madagascar and squirrel monkeys of Bolivia.

Daniel Schmitt, a team leader, said scientists had previously believed that gravity always made walking less energy-intensive than climbing.

And the team designed a "climbing machine", to measure the amount of effort animals take when climbing, through the amount of oxygen consumed in the room.

The team found that for animals that weigh less than half a kilogram, there is no difference between walking and climbing. Moreover, in small primate groups that weigh more than half a kilogram, climbing does not cost significantly more energy.

And the same scenario certainly happened with the earliest ancestors of humankind - often the size of a large mouse. They do not have to spend more energy to climb trees, than when walking on the ground.