Why there's no such thing as a Stone Age Tribe

This post has been percolating for many months, so I decided to go ahead and give it a go now, but subject it to revision as I continue to ponder the question.
Two videos have brought about this rush to print: one a series actually, to which I will get shortly; the other being this National Geographic Special about the Waorani tribe of Ecuador. In a documentary like this, the narrator typically gushes that they live as they did 20,000 years ago, and are just now finally emerging from the Stone Age.
These claims not only have no historical basis; they defy logic. The lifestyle of the Waorani is totally incompatible with the evolutionist's claim that they are descended from people who crossed the Bering Straight tens of thousands of years ago. They make their living by using darts (made from one palm) dipped in poison (scraped from the bark of a certain vine, and only deadly if injected) shot through a blowgun (made from another palm). That, for their meat supply; their vegetable staple is manioc, a domesticated crop that only grows in the tropics. Granted, they have been doing this from time immemorial, but only since their ancestors took up residence in the rain forest of the Amazon. It's impossible that their ancestors could have lived any such way before arriving there--and the forensic evidence from this video series (especially beginning with video #10) indicates that their ancestors only arrived there a few centuries earlier than the conquistadors--and that the people whom they displaced were accomplished agrarians.
Just one of the bits that jumped out at me from the movie was that the "uncontacted" Waorani no longer use stone axes or earthen pots--they trade for steel versions of the same. Only the oldest man in the community can even remember how to use a stone axe, and he made a startling revelation---the tribe had no knowledge of where stone axe heads even came from!  They found the heads abandoned in the jungle by a previous civilisation--just as my sons like to comb newly plowed fields every spring for stone arrowheads--and assumed that they fell from heaven or something. A "stone age" tribe equally dependent on outside civilisation for their axe heads, whether they be of stone or steel--incredible!
Elisabeth Elliot, half of the first team of outsiders to live among the Waorani and record their culture, reported that the Waorani told her their ancestors also had worn clothes, but had eventually abandoned all clothing but for a single string around their loins, and perhaps--to dress up--one around each arm. Obviously their ancestors would have needed quite a bit more than that to make the trek to North America!
The native ability of evolutionists to suspend the use of logic continues to astound me.
Another bit that jumped out to me: an anthropologist, who learned the language from the Waoroni civilised by their contact with Elisabeth Elliot and Rachel Saint, led the documentary team eastward to contact their downriver relatives. His research indicated that 70% of the males in the past five generations had died of homicide (oral history traces this murderous tendency back to a falling out over a tribal celebration about ten generations back). Clearly outsiders who bring in diseases that kill off a quarter, a third, or even half of the population are not the major threat to their continued existence. And those who do survive modern diseases will tend to pass their resistance to the following generations.
Again, a wee bit of logic would be helpful. How could a tribe that has lived on this land, disease-free for centuries, still only number in the hundreds--while the descendants of just a couple dozen men on the Mayflower now number in the tens of millions? Obviously murder, from conception onward, is a serious threat to population growth--in the case of "uncontacted tribes" still numbering only a few hundred individuals, clearly the greatest threat. It is notable that, the documentary reports, word filtered back to the uncontacted members of the tribe--along with the steel pots and axes--that there's no need to kill each other any more; so they've stopped the carnage (else, obviously the team would have never made it back out alive with their footage). Note: Mincaye, who had been one of, if not the oldest man in the tribe for over sixty years, has finally died of old age in his 90's. He manged to live long enough to give up his murderous lifestyle shortly before his life expectancy ran out, and "walk Waogongi's path" for the next two-thirds of his life, and on into the hereafter.
Everything in the documentary trumpets the same thing: this is not an ancient tribe peacefully perpetuating the lifestyle of their ancestors--a way of life under threat only by outside intrusion--but instead, a degenerate community in serious danger of completing the process of self-extinction if they are NOT contacted by outsiders.