The Genetic History Behind The Fastest Runner On Earth

Cheetahs, with their wiry bodies, mega-strong legs, small heads, and incidentally very rough fur that makes
them unlikely targets for poachers, can go from 0 to 70 miles/hour in the span of 4 brief seconds (though that only lasts for about 0.25 miles).  However, they also have a low fertility rate (low sperm count: about 10% of the norm for other cats), a high percentage of birth defects (about 70% of the sperm malformed), and weak immune systems :(

But blood tests brought about a really interesting discovery: this may all be caused by waaaaay too much interbreeding (and we know all how badly that's turned out for some "royal specimens"--see here, here and at the bottom of this post), to the point that it appeared every single cheetah on earth was merely a clone of itself.

It was found that some 12,000 years ago, the cheetah species went through some apocalyptic event (think Ice Age) that wiped out all but a few lucky survivors... the ancestors of our current cheetahs.

Cool fact: females are loners (except when taking care of their cubs) whereas males can travel in packs, and it's the females who pick their own partners!  (Also, if two or more females share the same space, they "may suppress each other's reproductive hormones.")

For you history buffs out there (not completely unrelated):

Class case of inbreeding: King Charles II of Spain who was physically and mentally disabled, and infertile.
Note that in Ancient Egypt, the Pharaohs had to marry their sisters to get a true heir.

And this one's kinda sad, actually, but another good example of the dangers of inbreeding:

Source:
Smithsonian Magazine