///since modern humans came about in less time than that (20,000 year)

GUEST,josep

I don't suppose you have a source for this?

My understanding is that genetically we have been "Homo sapiens" the species we are now for for longer than 100,000 years.///

Yes, it's a bit confusing. I agree that H. sapiens has been around closer to 200,000 years but I was referring to us specifically--the present human race and the only surviving primates of the Homo line.

"Are we genetically different from our Homo sapiens ancestors who lived 10-20,000 years ago? The answer is almost certainly yes. In fact, it is very likely that the rate of evolution for our species has continuously accelerated since the end of the last ice age, roughly 10,000 years ago. This is mostly due to the fact that our human population has explosively grown and moved into new kinds of environments, including cities, where we have been subject to new natural selection pressures. For instance, our larger and denser populations have made it far easier for contagious diseases, such as tuberculosis, small pox, and the plague, to rapidly spread through communities and wreak havoc. This has exerted strong selection for individuals who were fortunate to have immune systems that allowed them to survive. There also has been a marked change in diet for most people around the globe since the last ice age to one that is less varied and now predominantly vegetarian with a heavy dependence on foods made from cereal grains. It is likely that the human species has been able to adapt to these and other new environmental pressures because it has acquired a steadily greater genetic diversity. A larger population naturally has more mutations adding variation to its gene pool simply because there are more people. This happens even if the mutation rate per person remains the same. However, the mutation rate may have actually increased because we have been exposed to new kinds of environmental pollution that can cause additional mutations.
It is not clear what all of the consequences of the environmental and behavioral changes for humans have been. However, it does appear that the average human body size has become somewhat shorter over the last 10,000 years, and we have acquired widespread immunity to the more severe effects of some diseases such as measles and influenza."

http://anthro.palomar.edu/homo2/mod_homo_4.htm