Species, Subspecies, and Race (Especially Species)
Give orange me, give eat orange, me eat orange, give me eat orange, give me you. —Nim the chimpanzee, using sign language
The issue to be discussed in this post is one that has mildly exasperated me ever since I first began studying taxonomy as a biology student many years ago. Rather than becoming less troubling (or ridiculous) over time as science has progressed, it has become more so, until political correctness has stepped in and turned it into an utter farce. Science, in some ways, is actually retrogressing.
It is written that Carolus Linnaeus (1707-78), the founder of modern biological taxonomy, realized that humans and chimpanzees ought to belong to the same taxonomic genus, presumably Homo; however, he also realized that if he classified humans and apes so closely together he would very probably be excommunicated from the Church, which in those days amounted to social suicide. (Some Christians have insisted that we shouldn’t be in the same taxonomic kingdom, i.e., that we shouldn’t even be classified as animals, but as a form of organic life completely unique.) So, Linnaeus bowed to 18th century political correctness and placed chimpanzees in the genus Pan, and humans in the genus Homo. Not only are we in different genera, we are in different families—the chimpanzees in Pongidae along with gorillas and orangutangs, and we in Hominidae, even though chimps are more closely related to us genetically than they are to gorillas or orangutangs. It is practically proverbial that we and chimpanzees share more than 98% of the same DNA; actually, if only active genes are considered it’s more like 99%. Carl Sagan wrote in one of his books that we could probably interbreed and produce sterile mule offspring, like horses and donkeys can. But, although in the 21st century Christianity no longer rules over science, and although we ought to know better than to keep things as they are, we remain classified as members of a different family from our closest living relatives, and they from theirs.
This sort of sloppy science has bugged me since I was a student; but now it’s even worse. The Neanderthals used to be classified as a subspecies of “modern” humans, Homo sapiens neandertalensis; but lately anthropological fashion has declared them a distinct species, Homo neandertalensis. (Both classifications have existed practically from the beginning, although when I was in school the subspecies interpretation was more “correct,” and now it’s the other way round.) Thus scientists who consider only members of H. sapiens to be fully “human” are constrained to consider Neanderthals to be, essentially, non-human. And this despite the fact that we now know that early Homo sapiens and Neanderthals interbred and produced fertile offspring—we Eurasians have, on average, around 3% Neanderthal ancestry. So, are we 3% inhuman also? How can two beings interbreed and produce fertile offspring and not be of the same species? (Botanists can point out that it happens with plants all the time, but we’re not talking about plants. We’re very different from plants.)
This leads us to the question of what it is that determines a species, which is a taxonomic controversy known as “the species problem.” How do we know if two organisms are of the same, or different, species? The New Oxford American Dictionary has this as a definition of the problematic term: “a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.” But this definition is not comprehensive; for example primitive organisms that reproduce asexually, like bacteria and amoebas, would not be accounted for. Nevertheless, the most common interpretation of “species” is along the lines above: the “Biological Species Concept,” or BSC, is widely accepted and is defined as a group of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. So, why the hell aren’t Neanderthals the same species as us! We’re 3% Neanderthal for crying out loud! It seems pretty obvious to me that if two organisms, a girl one and a boy one, are capable of reproducing together and producing viable, fertile offspring, then they are both members of the same species, even if amoebas don’t do that. Seems pretty straightforward.
This does result, however, in some counterintuitive consequences. For instance, not only dogs, wolves and coyotes would belong to the same species, as they can all interbreed and produce viable offspring, but even lions and tigers, who also interbreed in captivity to produce fertile ligers and tigons, would belong to the same species. At most they would have to be considered subspecies, or different races of the same species. Well, so be it. Going with this interpretation, we and Neanderthals would also qualify as separate subspecies or races, not separate species.
Lately the field of taxonomy has been fairly taken over by the new technology of DNA sequencing. Rather than basing species, subspecies, etc. on physical traits, many biologists compare genetic sequences between two groups of organisms. In popular literature one may come across the use of percentage similarity, as I mentioned above between us and chimps; although in scientific journals other measures are used to determine “genetic distance.” One of the most common, and presumably useful, is the “fixation index,” or FST, which estimates mutual reproductive isolation, genetic differentiation, and the variance in allele frequencies between individuals or entire populations. It’s calculated like this:
I’m not even going to tell you what P stands for. If you can understand this, with or without P, you are a pathetic geek with no social life, and I pity you.
At this point, as was inevitable, we venture into the realm of wanton political incorrectness. Recently in my researches and wanderings through the cybersphere I came across the information that the genetic distance between the two species of chimpanzee, Pan troglodytes and Pan paniscus, measured by FST, is approximately 0.10; the genetic distance between the two gorilla species, Gorilla gorilla and Gorilla beringei, using the same standard, is around 0.04; while the distance between a black West African human being and a Japanese human being has been measured at 0.23, more than twice the difference between the two species of chimp and almost six times the difference between the gorillas! (One source I’ve seen has the distance between West African Bantus and Anglo-Saxons calculated at 0.23 also; whereas the table from which I extracted the African/Japanese statistic has the difference between West African and English people at 0.15.) The apes are considered to be different species, yet nowadays it is claimed that humans, despite significantly greater genetic distance, do not belong even to separate races. Furthermore, I may as well throw in that the measured FST between Neanderthals and modern Eurasians is around 0.08.
Thus, if we are to be rigorously consistent, either there is only one species of gorilla, and one species of chimp, or there are two or more species of modern human. And before you start calling me a Nazi in loud shrill tones, remember my own expressed opinion that if two organisms can interbreed and produce viable offspring, and Bantus and Anglo-Saxons certainly can, then they should be considered members of the same species. I’m simply pointing out the ridiculous and foolish subjectivity of anthropocentric science, which will be pointed out all the more in the next post, after reading which, maybe then you can call me a Nazi.
|Gorilla gorilla and Gorilla beringei, probably two “races” of gorilla|