Thread: Half Humanoid, half Chimpanzoid

Which magazine? I don't know for certain but i would be very suprised if it were possible, they have different numbers of chromosomes, the evolutionary paths diverged quite a long time ago, and if it were possible you would think there would have been some examples.

This answer to a related question seems to suggest that the difference in chromosome number is a barrier:

http://www.madsci.org/posts/archives...0360.Ge.r.html

and a more relevent answer from the same site:

http://www.madsci.org/posts/archives...1655.Ge.r.html

if only this question had been posted about a year ago, while i was in my Physical anthropology of human populations class. one of the books we had to read was What it Means to be 98% Chimpanzee (forgot the author).

during our discussion of the book, someone posed the same question. although the question wasn't discussed at length our prof (who hold a phd in biological ant and a MS in genetics) basically summed it up: "who knows, would you like to try? and if you manage to breed a human and a chimp, what will the morality police say?" and pretty much left it at that.

...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.

http://www.madsci.org/posts/archives...1655.Ge.r.html

...in the test tube, human sperm don't bind to the receptors on
a chimp egg.

http://www.madsci.org/posts/archives...1655.Ge.r.html

Does this receptor obstacle remove all chances of fertilization, or does it just decrease them? Using logics, I believe that the answer to that is "no", and I still believe that there is a very remote chance that a hybrid may have been conceived the natural way, somewhere in history. I don't believe that such a hybrid, having been produced in, let's say the 4th century within a remote community of humans, necessarily would have made itself known of to our days.

So the question is not really whether species do interbreed, but whether they can interbreed under artificial conditions.

http://www.madsci.org/posts/archives...0360.Ge.r.html

Agreed. Let's put the possibilty of a hybrid having been conceived the natural way aside for now, and look at the possibility for occurance under artificial conditions. Here we can discard the receptor obstacle:

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.

http://www.madsci.org/posts/archives...1655.Ge.r.html

Do these different set of chromosome pairs absolutely take away all possibility in interbreeding? I don't think so.

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.

http://www.madsci.org/posts/archives...1655.Ge.r.html

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.

http://www.madsci.org/posts/archives...1655.Ge.r.html

Saying that there are eight major inversions only adds credit to the fact that these inversions do not absolutely prevent pairing, but only decrease the possibility of it.

Besides this fact, there still is a margin of at least one chromosome pair being thrown away, still producing viable offspring. I say this because there are plenty of viable humans with 47 chromosomes with Down's syndrome, while there also are viable humans with 45 chromosomes, known to suffer from Turner's Syndrome.

I think that Dr. Mike Conrad, giving the answer to the question, only really mentions obstacles to succesful breeding between humans and chimpanzees.

Suppose that we made a million or 10^6 laboratory attempts, each time with different sperm and different eggs, I would find reason to believe that maybe one of these could carry viable offspring.

If I now go back to the chance of producing viable offspring under natural conditions, I could make the assumption that when there are no receptors present, it is 10^3 times harder for the sperm to reach the egg and penetrate.

Given these factors, I can multiply them together; (1/10^3)*(1/10^6), and say that the chance in producing viable offspring under natural conditions is 1/10^9.

Let's say that there have been 1000 or 10^3 occurances of breeding during history, then the chance is (1/10^9)/(1/10^3) = 1/10^6 or a chance of one in a million that one of these occurances of breeding actually carried viable offspring.

I'm not saying that viable offspring has ever been born, I'm just saying that the possibility is there. Finding the actual numbers of chance, is just extended research.

I think that the answer given by DrakkenKorin's professor adds credit to this:

although the question wasn't discussed at length our prof (who hold a phd in biological ant and a MS in genetics) basically summed it up: "who knows, would you like to try?

Do you agree with me, or do you have any objections?