This may well be the moment when an up-to-now entirely black modern humanity diverged in terms of skin color, as near-extinction reduced population numbers to the point that tiny genetic mutations become amplified in subsequent generations. This was very nearly the end of humanity here.
Another item to consider here is the loss of accumulated knowledge. The loss would be especially deep and wide if, as most circa 1999 AD experts believe, humanity's only conscious memory store and preservation technique at this time consisted of skills passed down from parent to child. With perhaps 70-90% of the population rapidly succumbing to the harsh environment, much knowledge would be lost.
Ever heard of nuclear winter? The scenario where a global nuclear war leads to such dense cloud cover worldwide that the world descends into a horrific winter lasting years or even decades, which kills off innumerable species, perhaps leading to the extinction of humanity itself?
Well, something similar can also be brought about by a sufficiently large asteroid or comet strike-- or even a sudden eruption of many small volcanos all at once (or one very big one).
Such a volcanic-inspired 'nuclear winter' may have been the final trigger which led to the appearance of modern human beings, 71,000 years ago (69,000 BC). Immediately following on the heels of that winter was the worst 1000 years of the most recent Ice Age (gosh, but this makes you wonder how anybody could tell the difference of one from the other, doesn't it?). All this killed off enormous numbers of humanity's ancestors, so that afterwards a relatively tiny group of survivors was responsible for the human diversity that emerged. You see, the smaller a starting group, the greater changes in the population that may occur from fairly small genetic mutations. In larger groups small genetic mutations usually get washed out or diluted by the law of averages. But in smaller groups they become much more important among progeny.
Some geneticists believe that"...no more than 15,000 to 40,000 people survived..." this period, worldwide. To put this into perspective, this is probably the current range of population for the small rural Tennessee county I live in today. Such numbers would seem to imply the survivors mostly consisted of isolated extended family groups of maybe a dozen to a dozen and a half persons, at the worst moments. In a worst case scenario this breaks down to 833 family groups spread over 52,500 square miles of dry land area on Earth. Each group would be separated by around 63 miles from their nearest neighboring family on average (distance between centers of occupied areas). These calculations assume no one is living in Antarctica at this time.
So a given person of this period could bump into a stranger within a few days of walking in a straight line (with a little luck).
AUTHOR'S NOTE: Take a good look at who the experts are talking about this drastic reduction in human numbers-- geneticists. This means they are likely talking about the breeding populations of the hominid line specifically leading to 20th century humanity. So their tally probably does not include those hominid lines which were already differentiated from 20th century humanity's predecessors by now. This means if some technologically advanced observers had performed their own survey at the time, they may have determined there was a considerably larger total population of such humanoid bipeds around than this. It could be that only our own direct ancestors suffered this disaster, while others thrived. For instance, a plague or other highly localized disaster could have been the affliction, based only on genetic information. It could even be that some other hominids were out-competing humanity's ancestors at this time-- and humanity only lucked out in the end by something catastrophic happening to the others in time to save humanity's line before it fell below critical mass in numbers. Or, one tiny group of human ancestors somehow obtained a survival advantage that so far outclassed all others that they rapidly swamped all their competitors in the reproductive race for some reason. If that was the case, total human numbers could actually have never declined at all-- only the reproductive rates of various lines would have changed drastically, with the winners suddenly having lots of children, and the losers virtually none. Even a quickie solar flare of sterilizing radiation flashing one region but not another (or a significant meteor impact or volcanic eruption) could have made the difference here, depending on the distributions of populations. Of course, there's also the real possibility of genocide: that one group realized sufficient advantage to wipe out all others-- and exploited that advantage to the fullest. END NOTE.
|-- Paleoanthropology (revised 16 December 1999) by Francis F. Steen, Department of English, University of California at Santa Barbara, http://cogweb.english.ucsb.edu/EP/Paleoanthropology.html|
One anthropologist (Stanley Ambrose) even thinks he knows of a single super-volcanic eruption perhaps substantially responsible for all this havoc: Mount Toba in Sumatra (the eruption of which lasted around 6 years and affected global climate for maybe 1000 years afterwards).
It may well be that things like present day skin color differences among human beings came from this near extinction of the whole species at that time. Before that, we may all have been black (since our common source was Africa).
Note that at this time it seems the only tools humanity possesses include its brains, hands, stones, clubs, fire, speech, and tamed wolves. All of these things must have become much more important during this challenging time.
Also note that these same conditions may well have helped decimate the populations of large predators in the americas-- thereby paving the way for an easier migration by more human beings to the new lands.
-- "Ancient 'volcanic winter' tied to rapid genetic divergence in humans", News From the University of Illinois at Urbana-Champaign, September 1998, News Bureau
University of Illinois at Urbana-Champaign
807 S. Wright St., Suite 520 East
Champaign, IL 61820-6219, found on or about 9-10-98
-- "History Of Humans And Great Apes Strikingly Different" University Science, 27-Apr-1999, UniSci Science and Research News, http://unisci.com
If an eruption of Mount Toba really is the instigating event for a massive die off of humanity at this time, part of the reason may be humanity's own preferences regarding migration and population densities up to this point. For humanity has mostly left Africa to populate the southern and southeastern asian coasts by this time-- with a strong preference for southeastern asia. Thus, when Mount Toba erupts and severely affects southeastern asia for maybe a thousand years, the enormous casualties there are enough to wipe out perhaps the majority of people on Earth at the time.