IS THE SAME FUNDAMENTAL MECHANISM AT PLAY?
Dinosaurs are still around: they are called birds. Birds are those dinosaurs which enjoyed high metabolism. In difficult circumstances, those who acted quick could stay warm, and make the slow, or their eggs, into lunch. Mammals, too, and probably even more, exerted deadly pressure on dinosaur reproduction.
Dinosaurs were big (the smallest, like Velociraptors, were feather covered, and turkey sized). To create the same number of average individuals dinosaurs may have required a thousand times more energy as for the average bird: obvioulsy after a disaster, their population would not rebound as fast.
[As we can read DNA like a printed book, Paleontology is becoming history, complete with written documents! Represented above: the 40,000 years old Homo Sapiens jaw which was sequenced, and found to be a Sapiens Sapiens- Sapiens Neanderthal hybrid.]
Much spectacular progress is made in paleontology, every month. In the latest, some dinosaur protein would have been isolated. Sequencing and making a Jurassic Park, someday, is not science fiction anymore. Such was the truth, in June 2015. (In the preceding month, that would have sounded like science-fiction.)
Now we have a new fact supporting the theory I hold that Neanderthal’s traits were outbred. Here is yesterday’s recap from Nature:
Neanderthals are also still around. Or more exactly Neanderthal genome: 1% to 3% (although some claim up to 9% of combined Neanderthal and Denisovan ancestry!). And more so in East Asia and among Native Americans. Some find strange that Neanderthal genome disappeared more in Europe, where Neanderthal reigned so long.
But it just means that genetic competition between Sapiens Neanderthal and Sapiens Sapiens traits was more in favor of the later there… Perhaps simply because winters are milder in Europe.
Neanderthals had evolved from Archaic Homo Sapiens, and ruled Europe for 300,000 years. Most of the time, the continent was in the grip of glaciation. Neanderthals evolved genetic adaptations to these Arctic conditions, such as a larger body mass, and a more compact, more muscular, powerful body.
However technological advances such as clothing, burning coal (!), the propeller (to launch javelins further), and the bow made those Neanderthal genetic modifications obsolete, moot, duplicative. A prime defect was higher mass. Reproducing the same number of Neanderthals required more energy than the same number of more gracile forms of Homo Sapiens.
When in competition, the reproductive advantage of the more gracile traits grow exponentially in time:
It is not about Homo Sapiens Sapiens enjoying superior traits relative to Neanderthals.
The disappearance of Neanderthals is about most Sapiens Neanderthal traits having become excess evolutionary baggage. So the traits got out-selected. One should expect that the heavy, Arctic genetic traits were weeded out, and only superior traits (the 3%) were kept. As observed. And more so in Europe, as winters are milder there than in the rest of the Eurasian land mass (South Asia excluded). As observed. In other words, after an Arctic excursion, Neanderthals transmutated back into what they came from, keeping some useful mutations (many having to do with skin).
The tree of evolution is rather a network (with a non-trivial topology).
A case in point is Homo itself. The first prototypes (so to speak) may have separated from chimpanzee like ancestors, ten million years ago. But the official theory has it, at this point, that there was some interbreeding with chimpanzees, around six million years ago again.
BTW, it is not true that no Neanderthal DNA is found in sub-Saharan Africa. That’s so yesteryear, 2014. Neanderthal DNA has been found all the way down to South Africa’s tip (2015 discovery), and the migration route traced.