Let us talk briefly about hyenas. PBS Eons have recently released yet another one of their YouTube videos, this time about the hyena evolution, but somehow I do not think that they have done those animals justice. Therefore, let us talk.
For a start, people tend to get an incorrect idea
about the modern hyenas because of the reasons listed below.
To begin, we must put all of the four modern and
existing hyena species into a row, from the biggest to the smallest: we got the
spotted, the striped, the brown and the aardwolf. Though we have not
professional biologists, but if we look at this quartet, we get to see that the
spotted hyena stands out from the rest of its’ kin. Why and how?
First, because it is spotted, while the other hyena species have stripes. Seriously, the striped hyena is named after its’
coloration pattern, while the aardwolf looks like a miniature version of the
striped hyena, and the brown hyena may be mostly brown, but it still has some stripes, albeit mostly on its’
legs; still, they’re stripes, not spots.
Second, the spotted hyena has a differently shaped
jaws and muzzle from the other three species: it is shorter and broader than in
the other three species. This is more than justified: the structure of the
spotted hyena’s jaws and skull, as well as its’ postcranial skeleton is what
gives it strength and power to crush bones and to get through flesh so easily;
the spotted hyena is the stereotypical bone crusher, put otherwise.
The other hyenas, conversely, well… The aardwolf has
become an obligate insectivore instead: it feeds only on insects, mostly social
insects such as ants and termites; it has lost most of its’ teeth, though its’
canines are still large and formidable for its’ size – the aardwolf uses them
for defence.
…Yes, this is a reference to the Thylacosmilus, the
marsupial sabretooth. Initially it was thought to be a marsupial counterpart to
the better-known sabretooth cats such as Smilodon, but now it is known that
Thylacosmilus led a very different life-style, which just do not know which
one. Maybe it was an atypical insectivore such as the modern aardwolf…or the
bat-eared fox – more about that below.
Anyways, the striped and the brown hyenas are more
formidable than the aardwolf is, but they still fall short to their spotted
cousin – and they look much more canine, or maybe lupine, than the spotted
hyena does, (whose appearance is pretty unique in the mammal kingdom). The same
can be also said for the aardwolf, who is called a ‘wolf’ for that reason: it
does look like a wild dog of some sorts on the surface. More succinctly, while the
spotted hyena does not look anything
like a wild dog, the other three species do.
In behavior, however, the situation appears to be
reversed: the spotted hyena is a pack hunter, just as the wild dog species are,
while the other three hyena species are not. Fair enough, but how do they live?
In family groups – small in the case of the aardwolf,
larger in the case of the striped and the brown hyena, but whereas the spotted
hyena is loud and brash and in your face, the other hyena species are shyer and
more retiring and aren’t encountered by humans very often. (Especially the
aardwolf, for the obvious reason). Consequently, while most people know of the
spotted hyena, (especially thanks to Disney’s Lion King Movie from the 1990s
and beyond); the other three species of hyena tend to be more overlooked,
especially by the non-scientific crowd. What next?
…The hyenas are accused of having lost to the dogs in
the evolutionary race. There’s some justification there, as only the striped
hyena occurs outside of Africa; the brown hyena in particular is restricted to
the countries in the African south, and is a rather shy animal when compared to
its’ spotted cousin, but…
However, what an evolutionary win is? From a human point of view, (and we don’t have anyone else’s, ‘cause
we’re still the only sentient species on planet Earth, regardless of what the
Yetis and co. think), this means that your species continues to thrive, if not
outright flourish, on the face of the planet, and here the hyenas…well, make do
– they might not be as widespread as the wolves are, but…
However, if we look at the wild dogs, which have
supposedly beaten the hyenas, then we see a picture that is not too different
from the hyenas. The pack-forming canines are not all that numerous: we got the
wolf, (whose main success is in the north, where there are few other large
carnivores, save for bears, and the bears are more omnivorous instead). There
is the African wild dog that is not found outside of Africa, the dhole, which
lives mostly in Southeast Asia, and the Australian dingo, which is found only
in Australia, and whose taxonomic status is still debated – is it a wild dog or
merely a ‘feral’ one? The rest of the wild canids, including the jackals of the
Old World, the coyote of the Americas, and the singing dog of Papua New Guinea
tend to live in much smaller family groups – just as the non-spotted hyenas do.
So, what does prevent the hyenas from leaving Africa and succeeding elsewhere?
…Because they have already succeeded in Africa, that
is why. The non-human mammals, as well as the other animals, tend to lack
ambition, especially in human terms; whereas humans often cannot be sated until
they have it all, the other mammals can get along with each other under the
sun; yes, the prehistoric hyenas have existed outside of Africa and now they’re
gone, but so’s their world; the prehistoric wild dogs might’ve displaced them
at one point, but now they’re also largely gone; all that’s left are the
people, (and the domestic dogs, but they’re something else), and they’re the
ones keeping the hyenas, well, subdued, and the same goes for the wild dogs.
The bat-eared fox, incidentally, is the canine
counterpart to the aardwolf: it is bigger than fennec, (made famous by the
Zootopia movie), but not unlike the aardwolf it lacks most specialized
adaptations of a ‘professional’ insectivore, save for teeth and extra-large
ears. It lives… alongside the aardwolf, actually, but it does not outcompete
the hyena, cough. Therefore, I feel safe to say that the concepts of the canine
success and hyena failure are coined human terms and thus should be treated
with a grain of doubt when applied to the actual animals.
End
