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From: binkley@boulder.Colorado.EDU (Jon Binkley)
Newsgroups: sci.bio
Subject: Re: Human/Chimp Hybrids?
Message-ID: <26700@boulder.Colorado.EDU>
Date: 21 Sep 90 19:59:11 GMT
References: <999@massey.ac.nz> <6284@bgsuvax.UUCP> <26689@boulder.Colorado.EDU>
Sender: news@boulder.Colorado.EDU
Reply-To: binkley@boulder.Colorado.EDU (Jon Binkley)
Organization: University of Colorado, Boulder
Lines: 28

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