[extropy-chat] Re: Human Evolution

[kevinfreels at hotmail.com]

A horse has 66 and a donkey has 64 (I found one reference that said 62).

Also, here's a couple of things I found at
http://members.aol.com/jshartwell/hybrid-mammals.html

The Asian and African elephants look similar, but are not only different
species, they are different genera I.e. each belongs to a different genus,
making them even more distantly related). Crossbreeds between different
genera is regarded as impossible. In 1978, an Asian elephant cow gave birth
to a hybrid calf sired by an African elephant bull. Though the pair had
mated several times, pregnancy was believed to be impossible. The hybrid
male calf, had an African elephant's cheek, ears (large with pointed lobes)
and legs (longer and slimmer), but the toenail numbers, (5 front, 4 hind)
and the single trunk finger were like Asians although the wrinkled trunk was
like an African. The forehead was sloping with one dome and two smaller
domes behind it. The body was African in type, but had an Asian-type centre
hump and an African-type rear hump. Sadly the calf died of infection 12 days
later.

In the primates, many Gibbons are hard to visually identify and are
identified by their song. This has led to hybrids in zoos where the Gibbons
were mis-identified. For example, some collections could not distinguish
between Javan Gibbons, Lar Gibbons or Hoolocks and their supposedly pure
breeding pairs were mixed pairs or hybrids from previous mixed pairs. The
offspring were sent to other Gibbon breeders and led to further
hybridization in captive Gibbons. Hybrids also occur in wild Gibbons where
the ranges overlap. Gibbon/Siamang hybrids have occurred in captivity - a
female Siamang produced hybrid "Siabon" offspring on 2 occasions when housed
with a male Gibbon; one hybrid survived, the other didn't. Anubis Baboons
and Hamadryas Baboons have hybridized in the wild where their ranges meet.
Different Macaque species can interbreed. In addition, the Rheboon is a
captive-bred Rhesus Macaque/Hamadryas Baboon hybrid with a baboon-like body
shape and Macaque-like tail.


----- Original Message -----
From: "Robert Bradbury" <bradbury at blarg.net>
To: <extropy-chat at lists.extropy.org>
Sent: Wednesday, November 19, 2003 5:24 AM
Subject: [extropy-chat] Re: Human Evolution


> aperick, commenting on kevin's comments wrote:
>
> > I want to know all the facts re primate hybrids.
> > How many chromosomes does each have?
>
> I thought there was a slight difference but I checked in Google.
> Chimps and Gorillas have 48 chromosomes vs. 46 in humans.
>
> > And what about other hybrid species, is the same number of
> > chromosomes required for a live birth?
>
> You might manage a live birth with and abnormal number or
> mis-formed chromosomes.  Down's syndrome (trisomy 21)
> comes to mind.  There are others (humans can apparently
> survive with trisomy 21, 18, 13 and 8).  But the consequences
> may be quite significant.  [Google: trisomy syndromes].
>
> We do not know enough to reliably predict in any way the
> results of an untried cross breed.  But for cases where there
> is an extensive amount of work (e.g. plants) there may be
> enough knowledge to make an educated guess as to whether
> it will work.
>
> It remains (to my knowledge) a mystery in biology the
> specific requirements that allow the development of new
> species.  This may involve simple chromosome rearrangements
> or in the more difficult cases an increase or reduction in the
> number of chromosomes.  Increases or reductions probably
> make reproduction much more difficult and so those lines
> in most cases die out.
>
> The technology for chromosome mapping is now relatively robust.
> So we can look at human chromosome segments and know what
> mouse chromosome segments they match up against.  So even
> though humans and mice are separated by many tens of millions
> of years of evolution we can look at the genomes and know
> that in the process of evolution "this went here and that went there".
>
> Probably sometime later in this decade or early in the next decade
> someone will try to backtrack this information and assemble
> the proto-genome for mammals.  After that attempts at the
> assembly of the proto-genome for older higher level organisms
> (reptiles, fish, etc.) will probably be attempted.  There is a
> lot of room for graduate students making a mark for themselves
> in attempting such reconstructions.
>
> So -- I would not be surprised at all if we could eventually
> recreate the Neanderthals, the Mammoths and eventually
> the Dinosaurs.  We might even be able to recover what
> was lost after the Cambrian Explosion.
>
> Robert
>
>
>
>
>
>
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