How far back in the line of descent does it have to take before a person’s ancestor cannot be considered a member of the homo sapiens species but rather an antecedent species?
Is it possible to figure it out, or am I asking an impossible question?
Is it possible my future descendants somehow, after millions of years of minor mutations in the DNA, not be a human being but some other species? When does this happen?
If you define “human being” as a member of our own genus, Homo, the origin was about 2.3 million years ago. Modern humans, Homo sapiens, originated about 200,000 years ago.
If we consider a generation to be about 20 years, then humans originated about 100,000 generations ago. Modern humans originated 10,000 generations ago. (Of course, generation times were probably shorter earlier in our history.) So any relative more remote than 100,000th cousin would not be a human being, and any more remote than 10,000 cousin would not be a modern human.
Golly! I would be more surprised, if that cousin were alive to this day!
Is it possible to track down my genealogy back to my great-great-great-[truncated]-grandfather and grandmother, 1,000,000 generations ago?
Chimps and the human lineage split about 6 million years ago. Using a shorter average generation time of 15 years, this gives us about 500,000 generations since the split. So your closest living non-human relative, a chimp, would be your 500,000th cousin.
I think you’re confusing the idea of cousin with great-great-great…great grandparent. The chimp or orangutan or whatever other ape that might be all our 100,000th cousin wouldn’t have to have existed a long time ago, and could certainly be contemporary with us. Indeed, since we know chimps, etc. are related to us distantly and exist now, we all have very, very, very (repeat many times) distant cousins in that magnitude alive today.
ETA: OK, so it probably wouldn’t be 100,000th.
When does speciation occur? Can a modern-human being mate with a modern-day chimpanzee, or are they completely unable to reproduce with one another?
(Not that I am interested in that sort of thing, but still, I find it remarkable that after so many generations, reproduction can cease due to speciation.)
I believe that the answer is that no one knows, because it hasn’t been tried.
I have no doubt that it’s been tried. Some dudes will have sex with a vacuum cleaner.
But there’s no chance of it working outside of a lab, (and very slim chance there*) and I think that’s what you mean as no scientist would do such a thing.
It was tried once in the 20’s by a Soviet scientists. It was unsuccessful, but wasn’t really extensive enough to rule out the possibility.
Chimps have 48 chromosomes. Humans have 46. So while a child might happen at the extreme limits of possibility, it’s not very likely.
The line leading to modern man and the line leading to chimps diverged many millions of years ago. There have not only been many new species since, but also many new genuses.
The cousin thing is confusing. I could be your millionth cousin. That just means our parents were 999,999th cousins, and their parents were 999,998th cousins, and etc until you get down to 1, which are just normal first cousins. So, isn’t the question just how many generations back did homo sapiens start existing?
Wouldn’t it be 10,000 generations?
Oh, I’ve tried…
But there’s no species that has branched off since then that has surviving members. Since a nth cousin needs to have as many generations between itself and your common ancestor as you do, I doubt any now extinct species would have survived long enough to make “cousins” of modern humans.
It’s been tried in jokes. You know, the ones with punchlines like “Ok, but the baby’s gotta be raised Catholic!”
Yeah, but chimps have standards, even if some of their more evolved cousins don’t.
And as we have already discussed at length on these boards, there is no way any single human could make an unwilling chimp co-operate with such an act (and I really doubt they are going to get help, but maybe that is an unwarranted assumption).
Si
Bonobos, on the other hand … might be more cooperative.
Well, I’ll be a monkey’s uncle!
Not sure what you mean by this. Ancestors are ancestors, no matter what species they are. Every bit of life on earth is related because it all shares the same basic DNA structure. We are cousins to trees and fungi as well as dinosaurs. It is obviously theoretically possible to move back through parent after parent to get to the common ancestor of humans and chimps even if that is not a human or a chimp.
My comment was also aimed at SDMBKL, who wrote “Not that I am interested in that sort of thing, but still, I find it remarkable that after so many generations, reproduction can cease due to speciation.” I’m not sure I understand that either, but in general the point is that reproduction ceases fairly quickly with divergence, and the more divergence the less likely that successful births can occur. This is not remarkable, it is exactly to be expected.
Out of curiosity, is it known whether we’ve lost 2, or chimps have gained 2?
Alternatively, perhaps our common ancestor had 47 chromosomes, and both species changed?
As far as the nth-cousin thing is concerned . . . don’t forget that with cousins, you have to go back that many generations to the appropriate pair of ancestors, then back to the present to include all their descendants. If the number is high enough, every other human being on the planet is, roughly, your nth-cousin, as well as possibly being your parent, child, sibling, first cousin, etc. as well. And If the number is even higher, every other primate on the planet is your cousin. And eventually, every living thing is your cousin.
And then there are theories about the origins of life on earth. You may have cousins in some very distant places.
