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Is a human-chimp chimera possible?
I have spent at least thirty minutes of my life thinking or talking about this question. (Is that more or less than you would have expected?) I see at least the beginnings of an answer from Olivia Judson, who writes an excellent blog-like entity for TimesSelect. The bottom line is as follows...
In species where females are promiscuous, there is a big conflict of interest between males and females over the amount of resources each child should get. The father of one child probably won’t be the father of the next (or even of others in the same litter), so his genes — which he passes on to the child — should evolve to try to get more resources for his offspring. Genes that come from the mother, meanwhile, evolve to suppress this effect, so that all her offspring aren’t fighting each other for resources. In species where females are monogamous, in contrast, male and female interests are more or less the same, since the same male is likely to sire many litters with the same female.
In humans, mice and other mammals of our sort, the activities of the placenta are — ready for this? — largely controlled by the father’s genes. Now consider what happens when certain close species try to mate. Female deer mice are much more promiscuous than female oldfield mice, so a male deer mouse’s genes are predicted to fight for resources much more than a male oldfield mouse’s genes would. Consistent with this, when a male deer mouse mates with a female oldfield mouse, both placenta and fetus become huge, and the mother often dies. Any fetus that manages to be born is one third bigger than babies from either species usually are. When the oldfield mouse is the father, on the other hand, the pregnancy is much less risky for the mother — but the baby is a runt.
...female chimpanzees are much, much more promiscuous than human females. So, assuming you could get fertilization, here’s my prediction: if the chimpanzee were the father, the pregnancy would be extremely dangerous for the mother. Probably, few pregnancies could be carried to term. Any children that did result would be huge. In contrast, if the human were the father, the children would be small, and both mother and child would be more likely to survive.
Posted by Tyler Cowen on June 19, 2006 at 03:30 AM in Science | Permalink
Comments
I would have expected more, but only when also thinking about other species chimeras.
Did you read the Nature article about interbreding of human and chimp ancestors when you thought about that? -> Here's a nice article about it: http://www.livescience.com/animalworld/060517_hybrid_ancestors.html
There were also thoughts of injecting human stem cells in mouse brains. I Hope they don't end up like Pinky and the Brain ;)
Is it moral to do that? And what are the legal rights of those humans/animals/chimeras? Is there already someone thinking about this?
This may be a little bit offtopic, but I think about that often, especially when I think about genetic modification of human babies. I believe there will be a huge black market, especially in countries like China where parents have only one chance and don't want to trust nature. Just modify it a little bit for their needs: son, no inherited disease, more intelligent, good looks (I think thats very hard to do genetically) Monetary this would be wiser to do before birth when you weight it against the costs of medicine, schooling, tutoring etc.
Posted by: Steffen Roecker at Jun 19, 2006 10:42:56 AM
Genetic modification is still a ways off, but you can achieve all of the things you mention via preimplantation selection. Fertilize a hundred eggs, sequence the blastocysts, implant the one with the genetic profile that looks best to you. There are still some wrinkles to work out; the cost of sequencing is still kind of high for this (but falling rapidly), the genes for the various attributes you want not fully known (but a torrent of information is flowing). And there seem to be some not-well-understood negative outcomes associated with in-vitro fertilization and implantation. Nonetheless I expect this type of selection to be big business in ten years, and China as you note would seem to be fertile ground for it to take off.
Posted by: bbartlog at Jun 19, 2006 1:22:41 PM
Oh, and why would it be black market? It's not like the Chinese are Catholic - this sort of thing would probably be perfectly legal there.
Posted by: bbartlog at Jun 19, 2006 1:24:55 PM
The mMhref="http://en.wikipedia.org/wiki/Liger">ligers and tigrons pack more narrative pucnch.
This paternal genes-gaming-the-placenta affect also occurs with the big cats, so ligers ( a male lion / female tiger cross) can grow to enourmous sizes exceeding 500 kg, while Tigons (a male tiger / female lioncross) are typcially the size of their parents.
Posted by: Tylerh at Jun 19, 2006 2:41:53 PM
Sorry about the munged link. That first line should be:
Mice are cute but ligers and tigrons pack more narrative punch.
Posted by: tylerh at Jun 19, 2006 2:44:32 PM
It has already happened - my daughter dated him for awhile.
Posted by: save_the_rustbelt at Jun 19, 2006 3:07:11 PM
Humans have 23 pairs of chromosomes. Chimps have 24. It is unlikely that straight cross-fertilization would produce viable offspring.
Splicing human genes into chimp chromosomes on the other hand ...
Posted by: Tex at Jun 19, 2006 5:11:20 PM
I get dibs on the term "man-panzee".
Posted by: Tex at Jun 19, 2006 5:13:48 PM
Horses and donkeys have different numbers of chromosomes too, but they can produce offspring... I believe that there are other crosses between species with different numbers of chromosomes as well. So that's not an insuperable objection.
Posted by: bbartlog at Jun 19, 2006 5:22:28 PM
I'd love to see the informed consent form for an experiment to test this hypothesis!
Posted by: anon at Jun 20, 2006 2:21:46 AM
Is this a possible explanation for our President?
Posted by: K Huna at Jun 20, 2006 1:48:47 PM
the logic is right. here is my interview with david haig, the theorist who has developed imprinting & kinship theorists to their greatest extent. also, for those interested in the topic, further posts on the topic. the phenomenon that judson alludes to has been found in closely related species of mice with alternative "lifestyles." also, a minor note, females tend to have "repression" genes whch do try to "fight" the impact of paternally inherited loci.
Posted by: razib at Jun 20, 2006 5:33:25 PM
K Huna,
You wrote:
"Is this a possible explanation for our President?"
NO, but a Manatee cross may account for Teddy K.
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Posted by: levan at Sep 8, 2006 6:11:02 AM
If it could be proven humans and chimps produce viable offspring then chimps would be
reclassified as human (according to the scientific definition of species) and would no longer be used
for medical research. If I had a womb I would volunteer.
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Posted by: 南京北春 at Aug 21, 2007 3:22:29 AM
What makes you think humans aren't used today for medical experiments? There are many examples in the past (some,like with sexually aquired diseases, in the USA), and I'm sure it happens in places like China.
Posted by: wolfbane at Jan 1, 2008 6:34:59 PM
If a human-chimp hybrid could be produced it would nonetheless destroy the distinction between human and non-human forever. This could only be of benefit to the treatment of the great apes, whales, dolphins and other non-human sentient species.
I believe the ethical problems outweigh the scientific ones.
goat-sheep chimeras have been produced by mixing the early embryos of a sheep and a goat in a test-tube and implanting the resulting hibrid embryo in a sheep and bringing it to term. Goats and sheep cannot cross naturally-their genetic distance is slightly greater than that between a human and a chimp.
One argument against such an experiment is that it would produce the equivalent of a mentally retarded child. Another way of looking at the same scenario though is of raising the intelligence potential of the chimp genome rather than lowering that of the human.
Somebody somewhere will one day mix human and chimp dna using some technique or other and bring the resulting offspring to term-if it has not been done already.
We can only hope the results wll be made public so that non-human sentient beings can be seen as having rights too.
Posted by: Steve at Jan 20, 2008 5:43:46 AM
Humans are perfect in every way we do not need to cross breed our species with that of animals, if it was meant to be it would have already happened naturally. I accuse you mad theorist bunch as being the same perverts that frequent the bestiality sites. Patrick how dare you offer your womb for these evil experiments, if you had one you monster as a woman you would not even consider it. Shame on you people.
Posted by: Alicia at Jul 21, 2008 12:22:55 PM
