Not asking if it* should* be done, just asking if it *could *be done given the current state of the art in biological science?
At this point, it is somewhat simple to create an animal-human chimera, an animal that expresses some human gene, say a goat that expresses antithrombin in its milk: http://www.nytimes.com/2009/02/07/business/07goatdrug.html?_r=0
Is that what you meant? Hell no, you want your monkey-man, because … kool!!1!!
But why would we do that. The goat created above provides us the a useful medicine, doesn’t even need to be killed for it, just milked.
This is like why we don’t have flying cars. We telecommute instead. Saying “But, but … George Jetson …” hasn’t convinced the FAA that people need to fly cars. And no one’s gonna make a monkey man, “jus’ cause.”
Not my field of expertise by a long shot, but I think it’s more a matter of simple genetics than anything science can do about it.
Humans and apes have different numbers of chromosomes. In humans, two of our ape ancestor chromosomes fused to become a single chromosome. Having the chromosomes not quite line up like that isn’t necessarily a barrier to breeding, though. Horses and donkeys have a different number of chromosomes, and they can breed, though the offspring is usually infertile as the mismatched chromosomes lead to incompletely formed reproductive systems.
A “humanzee” would probably be similarly possible, and likely would be similarly sterile.
There have been a few claims over the years about human-chimp hybrids, though none of them have withstood scientific scrutiny. One of the more famous is Oliver, who was thought to be a hybrid. He had a flatter face than a normal chimpanzee and tended to walk upright. However, closer examination proved that Oliver was just a weird chimp.
ETA: Wikipedia’s Humanzee article:
Obviously, chimps and humans cannot produce viable hybrids via sex. The genetics of hybrid incompatibility is a complex subject, see here for a good account, somewhat technical:
Chimps & humans are closely related, so it’s likely that only a few loci are responsible for our hybrid incompatibility, although so far as I know we have no idea what these loci might be - ethical experiments to untangle this would be hard to conceive, it’s difficult enough in Drosophila. A notable genomic difference is that human chromosome 2 is a fusion of two ancestral chromosomes, all other Hominidae including chimps have 24 pairs.
Exactly what a “man-chimp hybrid” means is somewhat subjective. There’s very little difference between the human versions of many genes and the chimp versions. So a human genome with (say) the chimp version of just a few random genes would likely be viable and just like any other human. If you want to go “half and half”, then the simplest way to do this would be to use entire chromosomes, taking half from one species and half from the other, and then to proceed along the lines of cloning technology, inserting the composite genome into an enucleated egg cell of one species or other, and implanting into a host mother from that species. I would’t quite say that we have this technology, but I think if there were an incentive to do such a thing, it would not take too long to figure it out.
Which combinations of chromosomes would be viable would be unpredictable, since we don’t know what loci are responsible for incompatibility. The majority of zygotes would probably just die at an early stage. But since the genomes are pretty similar, my guess is that if we just took random assortments of chromosomes, there might be a few combinations that would produce viable offspring. The viable ones would probably just be quite similar to the host mother species. Something viable that looks halfway between a chimp and a human is implausible.
Big 10 Football…?
Why is that obvious? Humans and chimps are only separated by about 5 million years. That puts them at about the same level of relatedness as wolves, jackals and coyotes, all of which are perfectly interfertile. I can’t think of any other species that are separated by such a short period that aren’t capable of reproducing via sex. Most species that are separated by twice as long remain interfertile to some degree. It would be quite surprising to me if the same wasn’t true of humans and chimps.
Domestic horses and Przwalski horses have different chromosome numbers, and are perfectly interfertile, producing fertile young. They are in fact a good analogy to the situation with humans and chimps. In both sets of species, one chromosome has fused to produce reduced chromosome count in one lineage.
Heh. I’ve had an idea for a SciFi story along these lines. Suppose there’s a future where where pro sports teams (maybe NOT Football) have limits on how many gene manipulated players they can have or what changes are acceptable…
I agree, I was wrong to say “obviously”.
The molecular genetic evidence shows that genetic material has not been exchanged between chimp and human populations for several million years, despite coexistence in the same locations. This means that fertile hybrids are extremely unlikely, but it certainly does not rule out infertile hybrids.
In any event, no hybrids are known. How likely is it that hybrids via ordinary mating are possible, but that nobody has ever tried & succeeded?
There is some anecdotal evidence that captive chimps will try to mate with human females, but would that ever happen in the wild? Would a wild chimp try to have intercourse with a human female? Seems unlikely, what’s the benefit? Would a human male try to have intercourse with a female chimp? This seems probable, actually. But what have the opportunities been? In the wild you would think a human approaching a female chimp on estrus would be torn limb from limb, or at the least wouldn’t know the cues/wouldn’t be strong enough to make it happen. In captivity I can start to see where a researcher might be in a position (heh) to make it happen. Has it? Who knows.
Put it another way, domestic horses/donkeys/Przewalski’s horses, and wolves/coyotes/dogs are, I suggest, much more compatible in size, strength, behavior, and opportunity than humans and chimps.
Thinking back on the experiment where the scientists reactivated long dormant genes in birds by blocking certain proteins during embryonic development and allowing them to form bones instead of beak, basically reverting back to earlier ancestral forms, I think a more likely scenario instead of creating some new hybrid, would be to bring back some atavistic nightmare genetic throwback humanoid by looking in our own genetic code, then after realizing the dangers of tampering with nature we would have to kill it dead again.
It’s not that clear cut. While human and chimp populations initially diverged about 100mya, there were multiple backcrossings until about 5mya at the latest. Because of that it’s impossible to really say what *is *human genetic material and what is chimp genetic material.
All we really know is that the genetic evidence shows a degree of divergence of some genetic material between modern humanity and modern chimpanzees. But both populations have undergone very recent extreme genetic bottlenecks, so that is fairly meaningless.
Our species do not co-exist to any extent. Humans occasionally enter forests but can’t actually live there. Chimps occasionally enter savannas, but savannah chimps are all but extinct. The actual degree of overlap is tiny.
Very, very likely.
Humans hunt chimps much as wolves hunt jackals. So despite the fact that wolves and jackals are perfectly interfertile, actual matings are very, very rare and only occur when wolves are hunted to the point where the bitches can not find a male wolf to mate with. The same is likely true with chimps and humans. Even if we had perfect interfertility we would be unlikely to ever interact to find out.
Any mating attempts would have to involve a wild caught chimpanzee. But chimps are big aggressive animals. While people probably adopted orphan chimps, they would be killed once they became large and aggressive enough to pose a danger. Someone having close contact with an adult chimp would be historically rare, to say the least.
But even for captive chimps, it would involve restraining a female chimp, which would be incredibly risky in its own right, or else a woman deciding to have sex with a captive male chimp that might well rip her head off.
Neither scenario is likely to have ever occurred. Humans have sex with *domesticated *animals, which chimps are not. I have *never *heard of an account of a human having sex with a wild animal of any type. So it is clearly a rare event. Added to that, chimps were very rarely taken and kept alive prior to the 19th century, which makes the likelihood even rarer. The fact that they are strong, aggressive and unpredictable animals makes the likelihood that it has ever been tried miniscule.
If you can find any evidence that such a mating has occurred even once in history I would like to see it.
No, the MRCA (common ancestor) of humans and chimps lived around 5mya. There is no sense in which human and chimp populations “initially diverged” prior to that date, because humans and chimps did not exist then, and there were no distinct human and chimp ancestors prior to that date, only common ancestors.
Comparative genomic analysis to analyze population histories and speciation follows the Neutral Theory, by which to a good approximation most mutations are fixed in a population by random genetic drift. The usual procedure is to align non-coding regions of different species and look at single-nucleotide differences. The human and chimp genomes have accumulated different single-nucleotide mutations, i.e. they have drifted apart, because no genetic material has been exchanged between the populations. The rate of accumulation of these mutations is roughly constant, so they provide a molecular clock. In other words, the degree of single-nucleotide divergence between the human and chimp genomes shows us when the populations diverged and stopped exchanging genetic material. Subject to calibration of the molecular clock, this is the principal evidence for the ~5mya divergence. (Population bottlenecks are irrelevant, since they reduce diversity within a population, and we are concerned with divergence of fixed mutations between populations.)
There is similar single-nucleotide divergence across the entire genome, showing that no genetic material whatsoever has been exchanged between human and chimp populations for at least several million years.
For completeness: the divergence on the X chromosome is significantly lower. On this basis, a controversial paper by David Reich’s lab in 2006 suggested a significant hybridization event some time after the primary speciation event - but still several million years ago.
David Reich paper
I accept your arguments here as sound. I’m not sure I’d go so far as concluding that it’s “very, very likely” however, any more than my “obviously” to the contrary was justified. It’s a tough hurdle to claim that humans and chimps have never attempted to procreate in fairly recent history. Still, it may be that viable hybrid zygotes are relatively uncommon, i.e. the miscarriage rate would be high, so perhaps many interspecific matings would be required to produce one viable hybrid.
I’m kinda surprised, and a little concerned, that “God Schmod” hasn’t shown up in this thread. Is Simpsons citing a thing of the past?
This comes up every year or so. There are a bunch of threads on this subject if you just search.
I’ll just start by saying that I don’t know of two large mammal species that are as closely related as humans and chimps are that are known to be unable to produce hybrids. And many, many species that are more distantly related and that can.
Obligatory link to Known Mammalian Hybrids
And today I learned that a domestic canary/goldfinch hybrid singing bird is called a mule.
You should see them carry 100 lb loads up a mountain!
Do you have a cite for inter-mammal generic distances? I think your claim is correct, but it would be interesting to look at data.
I was able to find
In Table 8.2 of Human Paleobiology by Robert B. Eckhardt (available at Google Books) I see 0.244 as the “Genetic Distance (D)” between Homo sapiens and Pan troglodytes; D = 0.197 between H. sapiens and P. paniscus; and D = 0.121 between Panthera leo and P. tigris.
Wikipedia has a page on Felid hybrids. The only alleged cross between felid species with MRCA much more distant than that of Chimp-Human is the Pumapard which isn’t even mentioned on the Felid hybrid page (though it is linked to).
The Chimp-Human MRCA is ~5.5 million years ago; the Gorilla-Human MRCA is ~7.2 million years ago. Maybe the interbreeding goal should be set higher. :rolleyes:
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BTW, different chromosome counts may not define species distinction. The riverine and swamp water buffalos have respectively 50 and 48 chromosomes even though both are classed as species Bubalus bubalis.