MadSci Network: Genetics
Query:

Re: is it genetically possible for a human and a monkey to mate and have succes

Date: Fri Apr 14 17:10:39 2000
Posted By: Mike Conrad, Post-doc/Fellow, Microbiology, UNC
Area of science: Genetics
ID: 954484571.Ge
Message:

If a human and a monkey were to mate would it be possible for there to be 
offspring?

Wow!  What a question!  But it certainly is something that has been wondered 
about before.  No, I don't think it has ever happened.  There have been 
many rumors about that sort of thing happening and there have been 
fraudulent circus demonstrations, like ĎOliverí.  Nothing like that has ever 
turned out to be valid.  Iíll get to the scientific reasons later.

Why?  Because if it had happened, we would have heard about it.  Yes, there 
is something called bestiality.  And yes, with monkeys too, but if human-chimp 
crosses (the chimpanzee is the closest relative to humans) had ever worked, at 
any time down through the ages, we would have heard about it.  And then it would 
have been done again, and there would be all these human-chimp progeny 
somewhere.  But there aren't.  I interpret this lack of evidence as proof that 
it does not happen.  True, this is inductive logic.  A proof from lack of 
evidence is weaker than a positive result, but is further strengthened by the 
following scientific information.

To start with, in the test tube, human sperm don't bind to the receptors on 
a chimp egg.  And even if they did, or you used in vitro fertilization to 
directly inject the sperm into the egg, the chromosomes wouldn't pair up.  
Humans have 46 chromosomes while the other apes have 48 chromosomes.  
Sometime, way back when, on the way to Homo sapiens, the monkey chromosomes 
11 and 12 fused to form what is now human chromosome 2.  There are also 
eight major inversions in human chromosomes when you try to match them up 
with chimp chromosomes.  Chromosome pairing is necessary for fertilization 
and the development of the egg. 

Which brings up the question, after the first chromosome 2 fusion occurred, 
how did it get passed on?  Chromosome events like these often (but not 
always) tend to reduce fertility, although viability may be unchanged (or 
even improved).  These low probability events can be fixed, especially in 
small inter-breeding populations.  But after many changes have occurred 
between the chromosomes, the possibility of interbreeding ceases, and a new 
species has been created.  As a matter of fact, loss of ability to 
interbreed is one of the functional definitions of a species.

Horses and donkeys make mules.  But horses and donkeys are close enough to 
make a viable, although infertile hybrid.  In captivity, lions and tigers 
can make ligers and tiglions (depending upon who is the father), but these 
crosses are also infertile. 
  
True, all sorts of weird cell hybrids have been made in tissue culture.  But 
when nuclei from different species try to pair up and the chromosomes don't 
pair, chromosomes are thrown out, and no individual will be able to develop 
from this.  You may have heard that a human nucleus was recently used to 
replace the nucleus of a cow's egg.  Some cow genes may remain but it's not 
a combination of human and cow chromosomes.  

And people are working on transgenic hybrids between humans and pigs, for 
instance.  This way, organs with human antigens can be grown in pigs.  And 
attempts are being made to produce monkeys, etc, with human genes inserted 
into cells which will allow them be used a subjects for AIDS and other 
disease research.  Many amazing things are coming.  But not direct monkey-
human hybrids.  However, to paraphrase Arthur C. Clarke, "when a scientist 
says something will never happen, heís very probably wrong".   Who knows 
what the future will bring Ė ethical questions aside.  But, up to now, there 
have been no monkey-human hybrids.  Thatís what I think.  Mike Conrad.

Dr Universe gives a similarly negative answer at:  
http://www.columbian.com/kids/druniverse/4-23chimp.html

To read more on the genetic similarities and differences between humans and 
chimps: http://genetics.about.com/library/weekly/aa092598.htm 

Here is a good site discussing the molecular evolution of humans: http://
http://www.dla.utexas.edu/depts/anthro/people/faculty/cbramblett/ant301/fourteen.html

To read about Oliver, see: 
http://www.n2.net/prey/bigfoot/creatures/


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