Endurance running has been cited since the 1980’s as a possible explanation for the modern human body plan. Past studies have focused on the running abilities of species such as Homo ergaster and Homo sapiens, with little or no mention of other species or genera. Currently in press in the Journal of Human Evolution is a discussion of Neandertal running capabilities.

The authors observed the length of the calcaneal tuber of the foot, which correlates with how far the Achilles tendon will stretch during movement. For this study measurements were taken of both Homo sapiens and Homo neanderthalensis.  Species with short calcaneal tubers stretch their Achilles tendons to a greater degree, which is then returned in the form of elastic energy. Species with long tubers stretch the Achilles tendon less and therefore have a lower return of elastic energy.

White Line: Calcaneus tuber length. Red Line: Achilles tendon moment. Correlation between the two values. Photo from Raichlen et al.

Simply put, a species with shorter calcaneal tubers will use less energy when running. Anatomically modern humans have been found to have short tubers, while longer ones are found on Neandertal remains. According to the authors, this variation has significant behavioral implications.

Unlike modern humans, the storage of less elastic energy in Neandertals would have made running less efficient. However, Neandertals were not necessarily at a disadvantage in the colder climates they are often said to have inhabited. It is more likely that running over long distances would have been energetically costly to them, without having huge benefits.

Long distance running would prove beneficial in warmer climates where animals are prone to hyperventilate when chased. Modern humans would have benefitted from endurance running because it would have aided in capturing prey. The same model does not necessarily apply in colder climates. A runner could chase an animal all day in low temperatures and never have the animal succumb to heat stress or hyperventilation. It is for this reason argued that the ability to run long distances would not have been as evolutionarily valuable to Homo neanderthalensis.

Discussing endurance running provides fascinating insight into human evolution. While the ability to run long distances can be very revealing about evolutionary history, lack of endurance can be as well.

By Matt Magnani

Raichlen, D.A., Armstrong, H., Lieberman, D.E. (2011). “Calcaneus length determines running economy: Implications for endurance running performance in modern humans and Neandertals.” The Journal of Human Evolution. Article in Press.

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