Footprints

Got into a long, protracted, and productive discussion with a friend concerning Aurignacian Cave Art. I'm not use to this being the normal sort of divisive issue, but it was productive in that I had to isolate my core princples to uphold my argument, those being:

1. That the preserved archaeological record can tell us about past human behavior and,
2. Absence of evidence is not evidence of abscence and,
3. To make worthwhile statements we must base them on "facts", which I define as a piece of evidence everyone can agree on. In other words, I may disagree with a creationist on how the Elephant standing before us came to be, but we can both be reasonably sure that there is an elephant present standing before us, and that is the "fact". Everything else is either theory or belief.

So, concerning Aurignacian Cave Art, I stated that before Aurignacian Cave Art I couldn't say if humans produced or had the ability to produce art. She argued that they could, as all humans can produce art today, so they must have been able to yesterday, and that "primitive" cultures (wherever, whoever they are) are an indication of what people lived like 100,000 years ago.

So, in sum, I realize that the driving basis for extrapolationg past known data sets (in this case our data being intricate drawings on cave walls), are largely due to affections for what we want to be true. Hitler wanted the archaeological record to reveal Aryan dominance. Malcolm X wanted the archaeological record to show a large, complex Nubian civilization. Before 1950 people wanted Neandertals to be primitive and brutish. After 1960 people wanted Neandertals to be the same species. And now, people want our ancestors to be exactly like us.

Of course, all of the above is bunk. Evolution may alow phenotypic stasis through strong selection, but it hardly ever stops. On average, each human has 1.6 new mutations in their genome... (Alcock, Freeman, 2002). Think about it, that is pretty strong genetic change. Evolution is simply this genetic change over time. The presumption that humans from 100,000 years ago were the same as us is just as ridiculous that we are the same as our parents in traits and abilities. But, hell, let's use some big numbers.

At http://www.prb.org/Content/ContentGroups/PTarticle/0ct-Dec02/How_Many_People_Have_Ever_Lived_on_Earth_.htm, Some guy runs some calculations to show that, since 50,000 BC, roughly 106, 456, 367,669 people have lived and died. This is based on rough historical estimates compounded by estimated growth rates based on known data for hunder-foraging groups of people (and here's the kicker, he uses an Adam and Eve population of 2, so the real number would be much, much higher). So, 1.6 X 106, 456, 367, 669 = 170,330,188,270.4 new mutations And that's 50,000 years ago. In context of the aforementioned argument, which my opponent suposed that humans were the same 100,000 years ago in genotype and capabilities, we must factor that other half of population. The base formula is P * (1+r)^t (P = initial population, r = rate of growth, t = unit of time). Of course this doesn't factor for carrying capacity in any given environment (substantially different for the Yanamamo of the Amazon than for the !Kung Bushmen of Southern Africa). But if any of you out there are ambitions that equation is: dP(t)/dt = rP(t)[1 - P(t)/K(t)] (P = population, t = time, K = carrying capacity). This means that bad genes (a few thousand) would move out of the genome rapidly, and good genes (let's say a few hundred) would stay in the population, while neutral repeats (Most of the 170+ billion) would be passivly spread and thus subject to Kimura's Neutral theory. Of course, we must realise that the human genome has roughly 20 - 25,000 genes, so our capacity to carry genes is limited. There will be rapid spread of these genes.

Well, off to lunch, hope this inspires some thought. We are unique and special snowflakes!