A physicist looks at biology’s problem of “speciation” in humans
|August 25, 2018||Posted by News under Human evolution, Intelligent Design, speciation|
Consider this item on the recent find of the remains of a girl from 90,000 years ago:
The discovery of the first-known offspring of parents from two different hominin species took scientists by surprise. While evidence has been pointing to interbreeding among the ancestor species of modern humans, the direct link is being hailed as a significant finding.Kevin Kelleher, “A Neanderthal Mom and a Denisovan Dad: 90,000-Year-Old Bone Fragment Reveals Startling Human Hybrid” at Fortune
“Species” “hybrid” “interbreeding”? What kind of talk is this about humans getting together? Yet it is everywhere.
A reader wrote to ask,
I’m not an expert on how ancient human species were defined, but I would assume that the authors aren’t using the biological species concept (the ability to mate and produce viable offspring that can reproduce) to define species. My question is, could we then call midget humans and very tall humans two different species?
I (O’Leary for News) replied,
Here is my theory: In Darwinism, somebody has got to be the subhuman. Otherwise, there is no beginning to human history. Hence the dehumanizing terminology.
Fortunately, physicist Rob Sheldon offered some more comprehensive thoughts on the geneeral problem:
“Species” are not very well defined. Paleontologists work from bones, naturalists work with dead specimens, geneticists work with DNA, and ecologists work with living communities. Each group has its own definition, and very often they are in conflict with the others.
Take for example, a mule. The horse has 64 chromosomes, the donkey 62, and the hybrid mule has 63. Mules are usually sterile, but every once in a great while a mule gets pregnant. Are horses and donkeys two species? Are hybrids a new species? Could pregnant mules start a new species? After all, even if only 5 mules were fertile in the past 200 years, think of what might happen in 5 million years.
Just to make it more interesting, the wild horses of Europe, thought to be the predecessors of the domesticated horse, had 66 chromosomes. Did domestication make new species? Or are we just looking at the natural variations in a horse baramin (to use a non-standard category)?
And this story is not the exception–it’s the rule. All the Galapagos finches can cross-breed. Lizards on some Caribbean islands seem to have 3 isomorphs that fluctuate in a semi-regular pattern. Some shorebirds appear to have 4 sexes or two intermingled species. If “evolution” is about changes in species, then it piles uncertainty on uncertainty, ambiguity upon ambiguity.
It’s not just biology.THere can even be uncertainty in mathematics. For example, mathematicians in the 1700’s kept finding paradoxes in mathematics, which you would have thought was well-defined. For example, what is the answer to this infinite sum: 1+ (-1) + 1 + (-1) …? If we group them in pairs, then the first pair =>0, so the sum is: 0+0+0… = 0. But if we skip the first term and group it in pairs, we get 1 + 0+0+0… = 1. So which is it?
Mathematicians call these “ill-posed” problems and argue that ambiguity in posing the question causes the ambiguity in the result. If we replace the numbers with variables, do some algebra on the sum, we find the answer. It’s not 0 and it’s not 1, it’s 1/2. By the 1800’s a whole field of convergence criteria for infinite sums was well-developed, and the field of “number theory” extended these results for non-integers etc. The point is that a topic we thought we had mastered in first grade–the number line–turned out to be full of subtleties and complications.
Someday we will have to abandon the naive definition of “species” if for no other reason than it has been defined improperly for so long. Perhaps “baramin” will replace it, perhaps some other word.
Certainly in microbiology, the easy transfer of DNA means that bacteria are losing their distinctive species label. Shigella is just a pathological version of E. coli. If one subspecies makes you better and one subspecies makes you sick, then what is the point of differentiating bacterial species anyway? Or to put it another way, these species are not distinguished by their intrinsic character differences, but their extrinsic effect on humans.
Now see how this plays out in higher animals. “There are two species of humans: those who vote like me, and those who don’t”. At this point, I think you would agree with me that “species” just is not a useful word any more.
Note: Evolutionary biologists will want to find a term other than baramin, due to its association with creationism, but we assume that Rob is just giving their chain a tug there.
See also: Neanderthal woman, Denisovan man Two longstanding Darwinian myths are threatened by these types of finds: One is the “missing link,” the not-quite-human, that we hardly expected to interbreed. The second myth is the notion that life is a war of all against all, such that current humans got where we are by exterminating other lineages.
Nothing says “Darwin snob” like indifference to the mess that the entire concept of speciation is in.