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It all seems to be luck , Yichel . Over 90 % of all the species that ever existed have gone extinct , and as you say , many others , including man have come very close . Cheetah DNA is virtually identical for all , showing that at some point not too long ago , the population got down to only a couple of breeding pairs .Maybe our whole theory of man's development from one line in Africa is wrong . Maybe there were other lines of man that existed but went extinct .

this is the visual I heard take the entire population of LA. that was the human population pre toba. Post Toba enough to fill one movie screen in a megaplex. luck, a flip of one environmental factor who knows? this has gotten me rginking big time.

It's somewhat strange that weak Cheetah genes (and I accept that fact) are due to too few breeding pairs yet ranged from Africa to India (or maybe to America since the pronghorn evolved fast legs to evade a Cheetah-like predator long before the last sub-Ice Age) when Toba blew its top and yet other animals had to have faced the same dilemma without apparently showing such inbred weaknesses. Wolves introduced into Yellowstone should show the same soon despite their alpha leaders without further introductions or meerkat males that rove around the Kalahari so as to not should eventually be having cousins mating with each other. Of course, being non-climbing lightweights, cheetahs had it tougher to keep their downed prey than leopards or lions or their litters protected from other predators.

what i hav always thought facinating about the reintroduction of wolves into yellowstone was they immediately are top of the food change and initially found coyote an easy prey. i wder if that i still occuring without coyotes a lot more cacasses are to be around. they tried to reintroduce Elk into Maine have not been here for 300 years. what a mess 10 breeding pairs flew them in by helo. 3 dies from shock. first winter another dies one shot by hunter as a moose jerk? i think one male suvived has this long territory in the area behind baxter(jhundred of miles of nothing and into quebec of course will be last elk.

Canids have a very definite pecking order . Wolves kill and eat coyotes and keep the coyote population very much in check wherever they are present , and coyotes do the same to foxes .

What is interesting about human DNA is that we can only trace it in unbroken male , or unbroken female lines . Thus if a particular family reproduces only one sex offspring in any particular generation , the DNA line of the other sex is lost . In other words , mitochondrial DNA only traces one's lineage in the female line from daughter to mother to grandmother , etc. etc.

that is how jews of the kohanim can trace their dna all the way back to brother of moses, Aaron the guy who started my line. funny thing he was such a wimp is that passed along with dna?

I might add that it's speculated in a recent NatGeo presentation that the indigenous population with favorable conditions neared 100, not 19, million in 1491, almost as much as in crowded plagued Europe. Despite many areas appearing devoid of life, as along the Mississippi basin and New England hinterland, the means of sustenance in the Americas was there, as in the Amazon basin where still multiple hidden plots of land still have mysterious means of being self-fertile. Most likely, fatal European diseases spread ahead faster than the actual presence of the newcomers. From the scattered few crossing the Bering land bridge (and elsewhere), in 15,000+ years they multiplied. So, too, despite the Toba bottleneck, populations bounced back.

The Mississippi Basin was far from devoid of life at that time , especially in the Southern reaches .

Actually, bottlenecks are an integral part of the evolutionary process. Take the supervolcano, Toba for example. It is estimated that before the last super-eruption of the caldera, there were approximately 1 million homo sapiens living on the continent of Africa. After about 10 years after the eruption it is estimated that only 10,000-100,000 of our ancestors survived the volcanically induced global winter. It in effect had narrowed the gene pool considerable, leaving behind only those who possessed the intellectual wherewithal and ingenuity to survive such a global catastrophe. Many scholars believe that this is what led to the relatively rapid development of civilizations after this event.

After the Permian mass extinctions, the lifeforms that survived developed very rapidly into more and more complex organisms. The same thing occurred when "snowball" Earth came to an end approximately 700 MYA by the volcanic activity that resulted when the super-continent Rodinia began breaking apart . And during the Jurassic, when a rift, which we now refer to as the mid-Atlantic ridge, broke apart the super-continent Pangea, the runaway greenhouse effect which resulted from volcanic activity the ensued on a monumental level produced an environment that led to the dinosaurs becoming the gigantic behemoths that they were during the Cretaceous period.

So, far from being something that almost "stopped" the evolutionary process, bottlenecks have greatly assisted the evolutionary process. Had it not been for bottlenecks in Earth's history, we probably wouldn't be here having this discussion....which I'm not exactly sure is a good or bad thing, considering what human beings have done and are still doing to each other and to the world in which they have been living throughout their existence.