New perspectives on the 'running walks' of a domestic equid, the horse (Equus caballus)
@beartracker @paradoxornithidae @botswanabugs @matthewinabinett
Please see the Wikipedia site on the ambling gait in the horse (https://en.wikipedia.org/wiki/Ambling_gait).
This thoroughly covers certain gaits of which this species (Equus caballus) is capable. These gaits (https://en.wikipedia.org/wiki/Gait), being important for equestrians, have been carefully studied.
Despite the detail in this account, much remains unexplained/confusing.
This is partly because the term ‘amble’ is ambiguous. I use it to describe a walking gait, whereas Wikipedia uses it to describe a running gait.
What is not pointed out in Wikipedia is that these nuances of gait are ‘running walks’. I.e. the horse has been selectively bred to locomote in a way unknown among wild equids, probably including its own (extinct) ancestor (https://en.wikipedia.org/wiki/Wild_horse).
Please note that
- a run is defined as any gait in which, in each footfall-cycle, all four hooves are above the ground simultaneously - albeit only by a few millimeters and only for a split-second, and
- the trot (https://www.shutterstock.com/image-photo/portrait-welsh-pony-horse-stallion-trotting-1710897232 and https://www.shutterstock.com/image-photo/portrait-welsh-pony-horse-stallion-trotting-1710897247) is the standard slow-running gait in quadrupeds.
The footfall sequences described in Wikipedia are characteristic of walking. However, they have been speeded up into running gaits.
What few realise, and what is not made particularly clear in the otherwise thorough account in question, is as follows:
- A major emphasis in selective breeding of the horse has been to bring out an ability – which its wild ancestor may or may not have possessed – to perform walking gaits at a running speed. This has been mainly in aid of comfort for the human rider.
- In a way, one could almost define the horse as a form of equid in which locomotion has been artificially modified in order to include running walks unexpected in wild ungulates of this body size (although achieved in extremis by elephants).
One could read several books on the horse without realising this perspective.
If one overlooks the semantic ambiguities, basic points are that
- many quadrupedal mammals walk with a four-beat gait, which is in some cases closer to a diagonal gait and in some cases closer to a parallel gait; and
- giraffes are on the parallel side, and bushbucks are on the diagonal side; however, all these four-beat gaits are walking gaits, because there is no moment in the whole sequence of footfalls in which all four hooves are off the ground, for even a split-second.
What the relevant account in Wikipedia describes is a certain phenomenon in which these various walking gaits are speeded up to running gaits, without a change in the footfall sequence.
This phenomenon is unique to the horse among ungulates.
Camels (Camelus spp.) run with pacing gait, which might be mistaken for a speeded-up form of the walking gait that I call an amble (https://www.youtube.com/watch?v=NPLQLUqB-fo). However, this is not true, because
- the pacing run of camels achieves perfect synchrony between fore- and hindlimbs on a given side (left or right), whereas
- no walking gait, in any animal, achieves this degree of same-sided synchrony.
Also relevant are elephants, in which the fastest gait is a speeded-up walk, except in extreme circumstances.
In wild equids, as the animal speeds up, it switches gaits completely. It abandons the walk, and gears up to the trot. This is true also in many quadrupeds, e.g. canids, felids, mustelids, gazelles, eland, waterbuck, deer, etc.
The trouble is that the trot is a jarring and jolting gait to ride, from an equestrian point of view. When the wild horse, E. ferus, began to be domesticated, artificial selection tended to bring out an ability to ‘run like an elephant’, for the purposes of comfort for the rider.
It is because the trot happens to be a jolting gait for a rider that the horse has been shaped into something unique among ungulates: a species capable of various versions of a ‘running walk’.
The horse is the only living ungulate that is capable of a walking run, in the sense that it can shift into a running mode while retaining the footfall-sequences (various versions of a four-beat gait) typical of quadrupeds in general.
Elephants walk as their fastest gait. The usual interpretation is that they would risk shattering their limb bones if they tried to trot.
Rhinoceroses and the hippopotamus (Hippopotamus amphibius) manage to trot at great body mass, presumably because they have different body conformation from elephants. The square-lipped rhino (Ceratotherium simum) trots proficiently (https://www.nickdalephotography.com/blog/rhino-facts and https://wildlifereferencephotos.com/media.details.php?mediaID=80101 and https://es.123rf.com/photo_70097430_white-rhinoceros-running-in-hlane-royal-national-park-swaziland.html), despite being almost elephantine in body mass.
However, the horse has evolved a rapid walk (a walking gait pursued at a running speed) for reasons other than body mass: to allow its human rider a smooth ride.
Reading about the gaits of the horse, one is bewildered by all the detail (much of which is hard to visualise and even hard to track with the naked eye) and all the terms such as ‘amble’, ‘tolt’, pace, trot, four-beat gait, etc. (https://www.youtube.com/watch?v=B6H4sUpmWzU and https://www.youtube.com/watch?v=RV9P0w8vZi8 and https://www.youtube.com/watch?v=4PMj_kiL5GY and https://www.youtube.com/watch?v=-7rWeWymJDw and https://m.facebook.com/watch/?v=2100704143329663&_rdr).
And one never hears of any comparison with other ungulates.
Thus, what may not emerge in the account in Wikipedia are the most basic facts of this topic, namely that
- a major aspect of the domestication of the horse has been to give it the ability to perform ‘running walks’, in which the smoothness of the various versions of walking gaits (whether just qualifying as diagonal or just qualifying as parallel gaits) are combined with the speed of running gaits; and
- this versatile capacity is extremely unusual - indeed possibly unique - among ungulates.
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Further thoughts on gaitedness in the domestic horse, w.r.t. use of feral horse by indigenous Americans in the pampas of Argentina (https://en.wikipedia.org/wiki/Pampas):
It is worth reading the introduction and last part of the discussion in http://www.ucm.es/data/cont/docs/345-2014-10-07-gait_keeper_mutation.pdf . Doing so prompted the following thoughts, for me:
The form of the horse taken by the Spanish to Argentina about 1500 was a gaited breed, i.e. it was capable of the ‘running walk’.
What this means is that, when the Mapuche ‘Indians’ (https://en.wikipedia.org/wiki/Mapuche) adopted an equestrian way of life in the 1600’s as a way of exploiting the feral horse now abundant in the Pampas, they were dealing with an animal capable of the running walk.
I suspect that these indigenous Americans were able to befriend and ride the feral horse merely be ‘speaking to it nicely’ and then riding bareback, without saddle, reins, or stirrups.
The fact of ‘gaitedness’ seems to strengthen this argument.
It is one thing to manage to ride a trotting horse despite the jolting on the horse’s bare back. It is another to be able to ride smoothly on an ‘ambling’ horse using a walking gait at running speed – something virtually ‘made on heaven’ from the bareback rider’s point of view.
The point is that my hypothetical scenario is made more likely by the following: the Mapuche were blessed with not just any old feral horse, but a breed capable of a ‘running walk’, and therefore well-suited to being ridden bareback.
https://www.alamy.com/greater-one-horned-asian-rhino-eating-at-the-wilds-in-cumberland-ohio-powerful-rhinoceros-with-single-horn-trotting-around-cage-in-captivity-endange-image272806648.html?imageid=F3AB1CC2-8A05-40F8-8C6D-6FC8A6C7BD0D&p=861799&pn=1&searchId=4ad6399a190a00e8f72349262da5432b&searchtype=0
In the spotted hyena (Crocuta crocuta, https://www.inaturalist.org/taxa/41886-Crocuta-crocuta), walking gaits shift marginally around the distinction between a semi cross-walk and an amble - depending on whether the animal is carrying a burden in its jaws.
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