Why Do Humans Have Such High Running Endurance?

We tend to consider us some helpless creatures. We do have weak muscles and lack fangs when compared to the apes and monkeys. But many ignore one issue: our ability of walking on land surpasses that of any primate: we can sustain a steady 20 km (12 mi) /h over long distances (it is, of course, a genetic ability developed by training, and we won't see this in sedentary people).

This ability enabled early humans to hunt on the African savanna, the way Bushmen still do it. A new research shows that this human ability could be due to the fact that we carry multiple copies of a gene that supplies our cells with energy. It appears that indeed endurance running offered Homo sapiens an evolutionary advantage.

DNA analysis from 10 primate species (chimps, gorillas, baboons, lemurs and other species) revealed that compared with chimps and gorillas, we carry more duplicates of the gene called aquaporin 7 (AQP7), which eases the entrance of water and sugary chemicals into cells. There are five copies of AQP7 in humans, while chimps have just 2, and other primates only one.

"Humans are believed to possess anywhere from 20,000 to 25,000 different genes. But in some cases, we carry multiple copies of the same gene. And the more duplicates of a gene that exist within a cell, the more protein from the gene that gets produced," said James Sikela at the University of Colorado Health Sciences Center in Aurora, Colorado, US.

The effect of an extra copy of a gene varies a lot. Sometimes, it can be harmful: a third extra-copy of the gene encoding the brain protein called alpha-synuclein makes you prone to Parkinson's disease.

The number of the gene copies carried by each species was determined with the help of DNA "micro-array" technology. After screening over 20,000 genes, the team discovered 84 genes for which the humans carry more copies than the other primates. The AQP7 gene captured their attention, as this protein is an important membrane channel, permitting water and a sugary chemical called glycerol, important factors in energy production, to enter the cell.

This enables the muscle cells to accomplish longer bouts of exercise, when the body requires more energy to be mobilized from fat stores. Further analysis of the other duplicate copies of other genes could explain the different human development and physiology compared to other primate species.