Why we can run so far

Some American Indians would hunt deer by running them down. Deer can run faster in short spurts but if you keep chasing them they will eventually collapse in exhaustion, while humans can keep running much longer. This ability of humans to endure long runs is not present in other primate cousins and emerged over 2 million years ago when we separated our life style of living in the trees like apes to walking upright on the open Savannah. The genetic specifics of this ability are unclear but one clue recently reported is the inactivation of a gene on chromosome 6 called CMAH that was inactivated in humans at the time they diverged from apes. The CMAH gene makes a protein that serves in cell receptors. This mutation possibly took hold and became fixed and universal because of a certain strain of malaria that killed all the people who didn’t have it.

A recent report (1,2) shows that mice with their CMAH gene inactivated as in humans can run a lot longer. Mice with this mutation voluntarily ran 30% longer in their treadmills and at a 12% faster pace. Further experiments showed that there was better oxygen delivery and utilization in their muscles.

There were lots of other interesting differences detected and there is more to learn about this phenomenon but these authors concluded that, “For the time being, given the timing of the mutation and the potential relevance of its fixation to the emergence of the genus Homo, it is reasonable to speculate that this mutation may have been essential for running faster and further. Thus, the emergence of an endurance phenotype critical to our ancestral lineage: an increased range for resource exploration and the ability to chase down prey over long distances.”

Sometimes not having a gene is better than having it but it doesn’t matter anymore because we have cars now.

1. Goldman JG. Going the distance. A genetic tweak may have helped give humans their running ability. Scientific American; January 2019:17.

2. Okerblom J et al. Human-like Cmah inactivation in mice increases running endurance and decreases muscle fatigability: implications for human evolution. Proceedings of the Royal Society B. 2018 12 September;285:1886. https://doi.org/10.1098/rspb.2018.1656