sbishop@desire.wright.edu (09/26/90)
In article <26700@boulder.Colorado.EDU>, binkley@boulder.Colorado.EDU (Jon Binkley) writes: > In article <26689@boulder.Colorado.EDU> I wrote: > >>Ah, but horses and donkeys have different numbers of chromosomes as well. >>This makes their hybrids sterile, but they are viable. I don't remember >>the numbers and I'll try to find out. They are off by one pair, I believe, >>similarly to humans/apes. Of course this proves nothing; but differing >>chromosome numbers is not sufficient to prevent interspecies crosses. > > Found a reference-- _An Atlas of Mammalian Chromesomes_, > compiled by T.C. Hsu and Kurt Benirschke, Springer-Verlag, 1967. > > Donkey's have 62 (31 pairs), horses have 64 (32 pairs). Presumably > two horse chromosomes are similar to one large donkey chromosome; > the atlas shows their keryotypes, but I'm no cytologist. > > Obviously, there is sufficient homology for the chromosomes to > line up properly at mitosis. Meiosis and gamete formation are > screwed up though, so mules and jennies are sterile (usually). > >>I'd bet 5 cents that a chimp/human hybrid would be viable, making humans >>and chimps, by definition, the same genus. I also hope I'm never proven >>right. > > As I said, I'm no cytologist, but the keryotypes of horses and donkeys > look less similiar to me than the keryotypes of humans and chimps, also > shown in the atlas. I raise my bet to 10 cents! > > -jon Could some of the biologists out on the net comment on this? I found it of great interest. If you can explain why chimp/man would not be inter-fertile then please do so. And in layman's terms, please. If keryotypes are simular what would need to be dissimular to prevent conception? I also am willing to consider immunological responses on the part of the host mother.
binkley@boulder.Colorado.EDU (Jon Binkley) (09/28/90)
Since in article <1297.270090e2@desire.wright.edu>, sbishop@desire.wright.edu took the time to repost my chromosome number articles, I'll take the time to correct them. I wrote: >> Obviously, there is sufficient homology for the chromosomes to >> line up properly at mitosis. Meiosis and gamete formation are >> screwed up though, so mules and jennies are sterile (usually). It was pointed out to me in e-mail by Jeff Haemer that chromosomes don't line up in mitosis, so homology is not important (at least as far as chromosome segregation is concerned). sbishop@desire.wright.edu writes: >Could some of the biologists out on the net comment on this? I found it of >great interest. If you can explain why chimp/man would not be inter-fertile >then please do so. And in layman's terms, please. If keryotypes are simular >what would need to be dissimular to prevent conception? I also am willing to >consider immunological responses on the part of the host mother. I would like to comment that I don't consider immunological responses a barrier to interspecies crosses. The mother's immune system is no more likely to attack the developing hybrid than it would a child of her own species. Someone mentioned the response to Rh+; remember, this response rarely occurs in the first Rh+ pregnancy of an Rh- mother. This is because the mother's and child's blood do not come into direct contact until birth. At this time, the mother develops anti-Rh antibodies, and subsequent Rh+ pregnancies are affected. Since there are now several people named Jon responding to this line, I'd like to restate that while I think chimp/human hybridization is possible, I believe that under no circumstances should it be done. Certain people have equated this with being anti-technology in general. I'm not; in fact I work in a lab that does the type of things that make Luddites like Rifkin cringe. Nor am I generally opposed to animals being used for experiments. However, since I obviously believe chimps to be members of my own genus, I feel they should be left alone from human experimentation. Yes, kids, even for AIDS research. -Jon Binkley