“You assume the birth and survival rate from the average was applicable to the early periods, when they certainly were not.”
No, I haven’t assumed that. If you’re going to try to claim I did, then back it up and quote me.
“You wrongly assume the pandemics did not affect enough people in the short term of a few centuries or less to have a significant enough effect to preclude a millenia eqrlier exponential population explosion like the one that occurred in the last two or three centuries.’
Again, quote where I made that claim.
“You ignore how reducing a population to zero in the space of only one year has the effect of extinction despite the average population growth which erroneously assumes a continued population growth into the future years of a populaton that no longer exists at all.”
No, you ignore the words I wrote, specifically: “unless those contractions were extraordinarily severe”. An extinction event is by definition an extraordinarily severe contraction.
“It doesn’t do much good to have 120,000 years of bare existence and miniscule increases in population when something like an asteroid impact comes along and reduces your population to barely more than a thousand individuals who must eke out a barely sustainable existence for survival for millenia to come as the environmental conditions recover.”
It seems like you are probably ignoring the fact that such events kick in a survival response in all sexually reproductive organisms, and a change in their breeding patterns. After any such event, there will be a population growth explosion, so you can’t simply say the graph was reset to zero at all these points and then continued as usual. That doesn’t get you the nearly flat-line growth that you need.
My response was based directly upon what you had written. for example:
“A few centuries IS insignificant, if you posit a 100,000 year plus time scale, unless those contractions were extraordinarily severe.”
You made the exception only for “contractions” and wrongly assumed “A few centuries IS insignificant” in the absence of such contractions, which is manifestly untrue. Expansions of human population were inhibeted by a plethora of circumstances for millenia. Limitations in human technologies kept their ability to expand population to less than a certain number of individuals per square mile or per square kilometer very low on average. Regardless of changes in the birth rate, child mortality and adult mortality rates kept the population relatively static or slowly increasing until the next catastrophe contracted the total population and the growth had to resume all over again.
You wrote, “It seems like you are probably ignoring the fact that such events kick in a survival response in all sexually reproductive organisms,....” On the contrary, the changes in birth rates are implicit in the final composited population numbers. The birth rates though increased were often unable to keep pace with the increased mortality rates or achieved a relative parity with the mortality rates. Under such conditoins, the only way in which the birth rates could exceed the mortality rates was whenever the population was able to expand into new territories formerly uninhabited or when the development of new technologies permitted the population to exploit more food resources in the existing territories.
An example can be found among the Amerindian cultures of the new World. The Amerindian populations were reduced to a small fraction of its former numbers by a series of pandemics and other catastrophes before and after the Columbian colonizations. The peculiarities of the Amerindian circumstances severely inhibited the birth rate and increased the mortality rate. Amerindian women had to sucle the children for a period of years, during which the women were not fertile and unable to give birth. Whereas Old World populations could see one mother give birth to one child per year or a little sooner, the Amerindian mother was unable to give birth to one child in two or more years. This was due to the severe deficiencies in suitable food supplies. The mothers had to suckle their children longer, whereas Old World mothers supplemeted their childrens’ food supplies with bovine milk and goat milk. Prehistoric human populations predating the advent of such animal husbandry and their associated food supplies kept the birth rates limited and the child mortality rates extremely hhigh. It wans’t until the human development of animal husbandry and agriculture on an advanced scale that human populations were able to breakloose from the earlier constraints on populaton growth imposed by the resources of the habitat experienced by the pre-agricultural populations.