Dogs in particular
are very inbred because of the huge range of sizes and shapes. You don't get that with other animals. There are many breeds of cats, but they're all about the same size and of similar 'catness'.

Similarly, one white human is pretty much like the next one*, the only distinguishing features being things like hair colour and relatively subtle body shape differences.

But if people from a single small village only breed within their group, after a few generations you'll end up with a very inbred population, with the defects that entails, because the gene pool is so small.

I'm no geneticist, or even biologist, so perhaps Kaol and his ilk will fill us in further, but that's the gist of it.

*humans of other races aren't really much different either, especially compared to a chihuahua and a rottweiler, for example.

Edit for HLT's benefit: I meant that black people are pretty similar to white people, with only minor differences in skeletal structure and (obviously) external coloration. Unlike the case with dogs, which can be entirely different in shape, size, structure and other features beginning with s, or indeed other letters.

Better?
( K2k6 has a proper job these days, Wed 3 Sep 2008, 13:22, Reply)