Evolutionary backing found in analysis of mammalian vertebrae

Date:  May 13, 2019

Source:  New York University

Differences in numbers of vertebrae are most extreme in mammals which do not rely on running and leaping, such as those adapted to suspensory locomotion like apes and sloths, a team of anthropologists has concluded in a study appearing in the journal Nature Ecology & Evolution.

Previous research had posited that running speed specifically determines variation in vertebral numbers -- a conclusion not supported by the new work.

"The classic body plan of many mammals is built on a mobile back and this body plan is conserved regardless of running speed," explains New York University anthropologist Scott Williams, the paper's senior author. "More specifically, we find that a particular type of locomotor behavior -- suspensory locomotion, which involves hanging below tree branches, rather than speed -- is associated with increases in variation in numbers of vertebrae across mammals."

The work centers on an effort to better understand why certain aspects of mammals remain consistent over time -- a phenomenon known as evolutionary stasis.

Despite the diversity evolution has yielded, there remain consistencies across a wide range of distantly related organisms. Of particular note is the number neck (cervical) and back (thoracic and lumbar) vertebrae of mammals.

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