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In the 1920s Joseph Stalin sent researchers to Africa as part of a secret program to create
a hybrid race of 'man-apes'.
Meant to be physically superior soldiers, these man-apes would have been a formidable
force that featured (hopefully) the intelligence of a man with the strength and speed of a
gorilla or chimpanzee.
Yet ultimately despite dozens of attempts to impregnate women with chimpanzee sperm,
and apes with human sperm, the program ended in completely failure with not a single viable
pregnancy.
Hello and welcome to today's episode of The Infographics Show- today we're taking a look
at why humans can't breed with other animals.
Reproductive isolation is the evolutionary mechanisms, behaviors, and physiological processes
by which a species is unable to mate outside of its own species, and is critical for speciation-
or the process by which populations become distinct species.
Scientists have identified a host of factors that make it impossible for us to interbreed
with animals and separated them into two groups: pre and post-zygotic reproductive isolating
mechanisms.
Pre-zygotic reproductive isolating mechanisms are all the things that make it physically
impossible to attempt to breed in the first place.
Geographic isolation is one of these mechanisms- after too long apart one species has physically
changed so much that it simply does not find another species sexually attractive and there
is no inclination for either to attempt to mate.
Other mechanisms include physical attributes such as incompatible genitalia, psychological
factors such as a prey/predator relationship, and sperm motility- one species' sperm for
example may not be capable of navigating the reproductive tract of another.
Post-zygotic reproductive isolating mechanisms are those factors that make it impossible
for a hybrid fetus to grow into a reproductive adult- so even if two animals of completely
different species managed to mate, they could still produce no viable offspring.
The further apart two animals are genetically, the less likely they are to be able to successfully
mate, and for humans specifically we've simply been too far removed from our ape cousins
for our genetics to match up anymore.
With humans diverging from apes as late as 7 million years ago, there's simply not enough
common ground anymore for viable offspring.
While there are several factors and scientists still don't fully understand all of them,
the biggest factor is simply DNA- human and animal DNA simply doesn't match up to produce
anything useful.
As our body's 'operating system', DNA tells every cell in our body what to become and
how to become it- one cell might become muscle tissue while another becomes a red blood cell.
Basically, DNA is our own internal instruction manual, and things have to line up very, very
precisely in order for DNA to do its job properly.
When we attempt to mix human and animal DNA however, the instructions simply don't match.
Imagine you have one set of instructions for building a boat, and another for building
a skyscraper- mixing them up together results in one document that makes no sense and is
no good for building either a boat or a skyscraper... and least of all a floating skyscraper!
Yet recent evidence in our DNA shows that humans have interbred with other species such
as Neanderthals, who make up a few percentage points of everyone's DNA- including your own!
So why Neanderthals and not Stalin's gorillas and chimpanzees?
Well, first we have those pre-zygotic reproductive isolating mechanisms which in this case are
not working as they would.
Humans and Neanderthals looked very physically similar, so some attraction was inevitable.
We also shared a very similar psychology, both lived in family groups and had the same
customs and traditions such as burial of the dead- we were close enough culturally to consider
each other viable mates.
Our physical bodies also aligned properly, being a near mirror copy of each other.
Upon successful mating, those post-zygotic reproductive isolating mechanisms also failed
to come into effect- our reproductive tracts were nearly identical so human sperm could
easily navigate the reproductive system of a neanderthal female and vice-versa.
Our DNA was also so closely similar that the instructions 'made sense', and resulted in
viable offspring.
Nine months later- a happy and healthy human/neanderthal hybrid would be born, but with humans flourishing
while Neanderthals were slowly going extinct it would be humanity who rose to prominence,
with just a splash of our late cousins in each and every one of us.
Had Stalin's plans succeeded he may indeed have created an unstoppable army of human/ape
hybrids, so ultimately let's all be thankful for DNA keeping us human.
Stalin may not have been able to make a race of ape-man super soldiers, but if he had had
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But what if humans and animals could mate, what kind of people would exist in the world
today?
What animal attributes would you love to have?
Let us know in the comments!
Also, be sure to check out our other video called Illegal Things That YOU Do Every Day!
Thanks for watching, and, as always, don’t forget to like, share, and subscribe.
See you next time