OK, this really has to do with primatology, which is still a branch of biological anthropology. I was wondering if chimps, gorillas, orangutans, the three non-human apes (some would include bonobos as a fourth), are interfertile or not? To be interfertile, members of a population must have the same genes (having different alleles for any gene is not a problem), the same number of genes, usually the same number of chromosomes, correct?
There are seven living species of Great Apes in four genera: Pan troglodytes (the "true" chimpanzee), Pan paniscus (the bonobo), Pongo pygmaeus (the Borneo orangutan), Pongo abelii (the Sumatra orangutan), Gorilla gorilla (the western gorilla), Gorilla beringei (the eastern gorilla), and Homo sapiens (the modern human). In general, two species within the same genus are interfertile, although their courtship rituals may be so different that fertilization can only be accomplished by AI. (In fact, back in my day, before DNA analysis, the definition of "genus" we were taught in high school biology was "a group of interfertile species.") One would then suppose that the two species of chimpanzees, or of orangutans, or of gorillas, could probably hybridize. Certainly the odds are on at least two of the three.Please Register or Log in to view the hidden image! However, I'm surprised to find no information on the subject in a quick search. This probably has something to do with the fact that until rather recently there was thought to be only one species of each, and zoos routinely put them together haphazardly. There may be some hybrids out there and they just haven't been identified yet. The Great Apes comprise the family Hominidae. There is also the family of Lesser Apes, the Hylobatidae, or gibbons. This is a more prolific family with something like twenty species spread among four genera. Hybridization among gibbon species is well documented. The two families of Great Apes and Lesser Apes together comprise the superfamily of apes, Hominoidea, one of several intermediate taxonomic groups within the order Primata. Interbreeding occurs between a number of related pairs of primate species, especially in captivity or domestication, but occasionally in nature. With the way the definition of "genus" has changed in the last fifty years, resulting in the taxonomic reclassification of many species, there is now documented interbreeding between genera, and this occurs (at least) among baboons. I have never seen the word "anthropology" used for the study of any animals except humans, including our ancestral species within genus Homo. Where did you pick up that usage? It was coined from those two Greek roots in order to specifically mean "the study of man."
Certainly none of the three are infertile, otherwise there would be none of them at all. If you are asking, however, whether chimps could mate with orangutans and produce viable offspring, I'm not certain. IIRC, most apes have 48 chromosomes, while humans have 46; so that pairing is out right away. http://www.indiana.edu/~ensiweb/lessons/chr.bk1.html
The study of non-human primates is very much the domain of anthropology and primate evolution courses that deal mostly with non-human primates are often mandatory for anthropology majors. There was also a news item last year or two ago that suggested that early hominids or even ancient humans once mated with a chimp ancestor -but I forget the context or the hows and whys this was suggested. I'll have to dig & see if I can find this again.
There are lots of rumors of such hybrids (and even hybrids of humans with other Great Ape species), but as far as I can see none of these are documented and thus fall into the category of urban legends, or perhaps more specifically "urban zoo legends." He wrote "interfertile," not "infertile." The family Hominidae and the term "hominid" includes all Great Ape species, not just humans. Since the clade of humans, genus Homo, and the clade of chimpanzees, genus Pan, together comprise a higher-order clade, there may well have been a point near the separation of the two when their DNA was still close enough that they could have interbred. But perhaps their offspring were not fertile (like horses and donkeys), so they became neither a bridge between the two bloodlines preventing the separation, nor progenitors of a third bloodline. As River points out: eventually our DNA diverged to the extent that crossbreeding was no longer possible. I'm sure this is the typical course of clade separations.
Difference in the number of chromosomes is not in itself sufficient to prevent interfertility, especially since the human chromosome 2 is two ape chromosomes stuck together. Down Syndrome and several other diseases result from having more than 46 chromosomes, yet they do not prevent interfertility between people. If chimps, gorillas, and orangutans are indeed interfertile, it might make a strong argument for the existence of human (and ape) "races".
"Interfertile" just means that mating can result in the birth of viable offspring. Right? The offspring themselves have to be fertile, or at least interfertile with a purebred individual, before they have any impact on the evolution of either species. That's why I mentioned the horse and donkey. In domestication they routinely mate and give birth to healthy hybrid offspring, but the number of those mules who are capable of reproducing and producing another generation is statistically negligible. Pet breeders are always trying to come up with exotic hybrids because there's a steady and lucrative market for them. "Mule" has been generalized into a code word for infertile first-generation hybrids that cannot be bred into a second generation, and it happens routinely.
Yeah, yeah... I was posting on the sly from work and not trying to get into a book length description. Fingers were typing while the brain was doing work stuff.... Please Register or Log in to view the hidden image! Anyway, I was thinking hominin not hominid, hominidae or even Homonoidea. It was more typo than sloppy thinking. Hominin, of course, is generally used to refer to the sub-family of humans, archaic humans and human ancestors since divergence from the ape lineage (although I won't quibble over whether or not humans are apes, etc. -these are all constructs of human understanding and labels that suit our own needs to begin with). The paper I was referring to appeared in Nature in 2006 and here's an excerpt: The entire thing can be found online if you have access to Nature or, perhaps, its made available in limited capacity on their sites as they so often do. Patterson, Nick; et al (2006). Genetic evidence for complex speciation of humans and chimpanzees. Nature, 441, pp. 1103-1108.
I only just noticed that it is At World's End who is asking questions about mules. Clever. Was that deliberate, At World's End? Does it represent the foundation of your purpose here on sciforums?
To pick out one point: Hybridization is more common now because of the impact of man on the environments of other species. In the past, each of two related species had adapted ideally to its environment, and a hybrid of the two would not be as well-adapted to those environments as either of them. The constructions of man have made the sudden appearance of new environments more common and frequent, which may no longer be perfectly suited to either ancestral species. For example, stands of hybrid plants are a common sight along roadways, where the drainage, etc., is different from the conditions their ancestors adapted to. There used to be a vast forest along the Mississippi River, and the rose-breasted grosbeak had adapted to the environment of the ancient geology to the east, whereas the black-headed grosbeak was better suited to the more rugged land mass in the west. Man came along and replaced the forest with farms, teeming with fruit and other delectables that attracted both species. They began interbreeding and today hybrid grosbeaks have spread out widely, into the lands now populated by man with his alien flora. They show up at the totally artificial environment of our feeding stations two thousand miles away in California. Macaws are curious, gregarious, highly intelligent birds who are sometimes adventurous enough to experiment with inter-species dating where their ranges overlap in the wild. In domestication, the species boundaries break down and there is now a spectrum of hybrid macaws in a rainbow of colors.
