Simple model explains why different four-legged animals adopt similar gaits

Date: November 21, 2019

Source: PLOS

Most mammals walk at slow speeds and run or trot at intermediate speeds because these movement strategies are energetically optimal, according to a study published in PLOS Computational Biology by Delyle Polet and John Bertram of the University of Calgary in Alberta, Canada.

When unconstrained at a given speed, members of a quadrupedal species will generally select a common gait, which is seldom unique to that species alone. With few exceptions, mammals choose a walk at slow speeds, a running trot at intermediate speeds, and a gallop at high speeds. The consistency of gait choice is remarkable, given how many alternatives exist. In the new study, Polet and Bertram explore why quadrupedal mammals move in such consistent ways, when so many options are available. They tackled this problem by determining energetically optimal gaits using a simple computational model of a four-legged animal.

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DNA shows that horse's 'funny walk originated in York'

By Matt McGrath Environment correspondent

8 August 2016

The speedy, almost comical horse step known as an ambling gait originated in England in the middle of the Ninth Century, scientists say.

The gait, which makes horses comfortable to ride on long journeys, is an inherited trait that springs from a single genetic mutation.

According to this new analysis, it first appeared in horses in York about AD850.

Vikings took these horses to Iceland, and the trait spread globally.

Smooth ride

Horses have three essential speeds:

walk

trot

gallop

However, a four-beat rhythm, where the horse moves both legs on the same side at the same time has long been a prized feature of some breeds.

Called an ambling gait, the step produces a much smoother ride, particularly over longer distances or rough terrain.

It is as comfortable as a walk but the horse goes as fast as a trot.

In 2012, researchers examined Icelandic horses, and discovered that a single mutation in a gene involved in the movement of limbs was responsible for this ambling ability.

In this new study, scientists extended their search for the origins of this variation of the DMRT3 gene by examining genetic material from 90 horses, some dating back before 3500BC.

The earliest examples they found were in samples from York dating between AD850 and AD900, when the area was being raided and temporarily settled by Vikings.

"The first occurrence of this mutation was in two samples from medieval England from the York Archaeological Collection," said one of the authors, Dr Arne Ludwig, from the Leibniz Institute for Zoo and Wildlife Research.

"It is unlikely that it was present before, especially not in high frequency, because this is a big advantage, this specific movement of the horses."

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Horse gaits controlled by genetic mutation spread by humans

Date: February 4, 2014

Source: Wiley

Summary: From the Faroe Pony to the Spanish Mustang, fewer animals have played such a central role in human history as the horse. New research reveals that a horse's gait, an attribute central to its importance to humans, is influenced by a genetic mutation, spread by humans across the world.

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