eli5 if horses can breed with donkeys and goats can mate with sheep why can’t we make human / ape cross overs?
In: 5
Why does the offspring of a a male donkey and female horse make a different hybrid than the offspring of a female donkey and a male horse?
People mention chromosomal mismatch, and how it works with horses and donkeys and mules, but it is worth thinking about what a chromosome is. A chromosome is like a binder for paper. Most of the time, DNA is unwound in the nucleus of a cell. When a cell divides, the DNA has to be copied, and each new cell has to get one copy. So the DNA is coiled up into structures called chromosomes, and when the cell is split in half, the chromosomes are moved in a controlled way that would be impossible with unspooled strands.
If you have a book that is a thousand pages long, you can put it in ten binders of 100 pages, or five binders of 200 pages, or random sizes, as long as it adds up to 1000. But if you mix together two books, the binder arrangements have to match, or it can’t be copied accurately.
The genes might be similar enough to create a human- ape hybrid, but the chromosome structure just doesn’t match.
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>horses can breed with donkeys
a lot of the time it doesn’t make an offspring, there are even populations of horses and donkeys that cannot interbreed. the mule, is a sterile animal.
>goats can mate with sheep
The offspring of a sheep–goat pairing is generally stillborn. Despite widespread shared pasturing of goats and sheep, hybrids are very rare, indicating the genetic distance between the two species
given the genetic abnormalities that could happen it is morally unethical to even try for human hybrids on the off chance conception was even plausible.
Well first and foremost let’s get the elephant out of the room, the nature of a human/ape hybrid is an ethics and morality nightmare. So much so that it takes the most psychotic of individuals to seriously propose such unions. (Not calling OP psychotic, just the people who have tried to seriously study this in the past).
More scientifically though, humans and great apes are too far removed on the evolutionary ladder. For an ELI5 explanation, our genes do not “match” well enough to combine in a sperm/egg pairing. Any such attempt would most likely fail to even fertilize, and if by a miracle it did fertilize an egg, the embryo would quickly die as the cellular machinery would fail to replicate the genes.
Humans split from our closest living relatives, chimpanzees, about 4 to 6 millions years ago. This means we’ve had 4 to 6 million years of mostly diverging evolution and we’ve built up vastly different genetic structures.
Interestingly though, modern humans, i.e. homo-sapiens, did breed with other species, most notably Homo neanderthalensis, AKA Neanderthals. In fact most humans alive today have a fair bit of Neanderthal DNA. There were also other species that we bred with to lesser extents. However, modern humans were significantly faster to adapt, mostly due to our intelligence, and thusly we out competed these other human species and either drove them to extinction or forced them to merge into our populations, or both.
In theory this can happen, but in the case of goats/sheep and horses/donkey that breeding was done by humans for a specific purpose. Wolfotes and Ligers are pretty uncommon in the wild.
Humans and bonobos are about as different chromosomally as members of the equidae family that we know can reproduce and create sterile offspring. The issue is that it isn’t solely about the chromosome similarity, it is about how those chromosomes produce traits that can be compatible. Even though the chromosomal differences between equine species, and between homo and pan genus are about the same, the differences they produce in body plan and hormones *is* significantly different. If we had another species in the homo genus (like a neanderthal) we *could* hybridize with them. In fact, we did.
Technically there is evidence that we have redheads because we were breeding with Neanderthals…
we did, that’s what people are! now reread some of those old texts and consider the possibility some tribes were different hominid groups.
Honestly, the most eli5 answer is that biology is weird, and interspecies mating is a weird exception to how biology normally works.
It’s rare, but some species that are very closely related can mate, and usually the offspring is sterile (e.g. Donkeys and horses will produce a mule, but the mule is sterile and cannot reproduce), and even more rarely, closely related species can produce fertile offspring (e.g. Wolfes and coyotes can produce coywolves that are fertile and can have their own offspring with wolves, coyotes, or other coywolf hybrids).
The definition of species is that a species should only be able to mate with other members of that species, but biology is weird and sometimes they are exceptions.
In humans, we have previously had interspecies mating of fertile offspring between homo sapiens and Neanderthals (though some scientists think we are actually two subspecies and not 2 separate species). But we diverged from other apes too long ago and are too different from them to mate.
We already merged with our nearest relatives 50.000-60.000 years ago. (neanderthals and denisovians) which is why we have a number of genes from them. 4-6% denisovian I think, 30% neanderthal.
Apes are much more distant relatives.
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