I think race should be divided based on blood types
I think blood types should be divided based on fingernail thickness.
So all the biologists and geneticists who have looked at the evidence and concluded that humans are all one sub-species are wrong and you know better?
It's not a matter of knowing better or not knowing as well. It's a matter of just being silly or not. Calling an entire species as it exists at a particular time a subspecies of itself just because it had slightly different predecesors isn't saying anything incorrect, because it isn't saying anything at all. Absolutely all living species had slightly different predecessors, so what's the point in bothering? If this kind of standard for subspecies declaration were actually used in biology, it would do nothing but squish "species" and "subspecies" into a single level because there'd no longer be even the
possibility of any species anywhere ever that isn't just a sub of itself. Fortunately for the sake of scientific non-goofiness (even without technical accuracy really being at stake on this one), this isn't a way that anybody ever does bother to look at other living species. It just became trendy to say it about humans at some point because somebody wanted to dramatize or exaggerate/emphasize something.
Humans are a single sub-species because there is comparatively little genetic variation between them and no clear dividing line between populations.
There's no amount of genetic variation at which to draw a line and say it's subspecies below and whole species above. (And if there were, it would be an arbitrary human-chosen line, not a real biological phenomenon.)
No. You are entirely off track. You can't take just any single gene and trace the ancestral line.
I think I need to see a definition/description of what you mean by "tracing the ancestral line" in as much detail as possible, because at this point, I don't get how you figure a gene on a nuclear chromosome other than Y is any different from a Y chromosome or a mitochondrial genome. How is a single gene NOT inherently a demonstration of its "ancestral line", if it is indeed inherited from one parent who inherited it from one parent and so on?
Unlike other chromosomes mtDNA is inherited solely from the mother...
mtDNA is inherited solely from the mother.
What difference does that make? Why does the ancestor you inherited something from need to be female? (Or, why would it need to be male?) What's so wrong with an "ancestral line" that has both men and women in it?
Mitochondrial DNA is inherited from people who can pass on mitochondria. Y chromosomes are inherited from people who can pass on Y chromosomes. All other genes in the nucleus are inherited from people who can pass on nuclear chromosomes other than Y. It's all the same thing: any coherent chunk of DNA is inherited from predecessors who were able to pass it on. Whether that happens to include just one sex or the other or both is merely further description, not a fundamental difference in what's going on, so how can it effect what you're calling "tracing"? The only way I can see for that to work is if we
define tracing as being only through all-male or all-female ancestries, which I don't think anybody does, and just wouldn't make any sense to do.
you are misunderstanding what I mean by "true biological division". Blood groups have a biological basis while you don't think they are 'race' divisions.
Right. The name "blood groups" is already quite a sufficient name for them. They don't need to annex some other thing's name.
For a taxonomic division the groups' divisions would be due to non-intermixing
...at or above the level "species". Below it, no, of course not. That would defy the way the word "species" is defined, at least for sexually reproducing plants & animals.
I'm talking about divisions below the division of species. A subspecies is a genetically isolated group that could interbreed
but doesn't.
Subspecies
You skipped the word "often" at that link. With species and subspecies, absolutely nothing is ever absolute.
(And some sets of distinct populations have been called separate species before based on geographic isolation alone even if they
could have reproduced if they mated... although the convention in more recent times has been to shift toward calling a case like that a single species anyway for the sake of retro-revised standardization.)
- There are observable differences between groups of people.
Yes...
- The differences between those groups is a cline (gradient).
Yes and no. One part of the "no" is that there would need to be multiple clines oriented in different directions. For example, among the three that happen to have had the most studies done on them, there'd be one cline from white to black, one from eastern Asian to white, and one from black to eastern Asian, rather than a single one with two of them at the ends and the third one in the middle between them. But that's just a quibble, in agreement with the basic idea.
More importantly, the other part of the "no" there is about the geographic distribution. To make an argument out of the fact is to imply that these clines/gradients are smeared out across the landscape so smoothly that anybody trying to divide it into separate units is making it up. That simply isn't the case in the real world. The clines you're talking about turn out in real life to be compressed into relatively narrow boundary zones between larger regions of internal consistency. The map I've included several times on this subject shows how much blending has actually been found, and where.
- There is no objective, a priori basis as to where to delineate when one group starts and the other ends.
No, there is. It's the trait clusters. The clustering effect is a structure built into the biology of the species, simply straightforward biological fact, not something anybody could possibly have chosen to invent or prevent.
And pretty much 'handedness' is not a continuum.
Actually, that's not a bad example of another phenomenon that works about the same as the human racial "gradient" thing. There are indeed people who aren't entirely left-handed or right-handed. They just aren't particularly common. It's not entirely one or the other, but it
mostly is. Now just imagine having someone argue that left-handedness and right-handedness are somehow unreal because that not-quite-left-or-right-handed minority exists.