If "modern humans" had completed their evolution-al development hundreds of thousands of years ago, what stopped them from discovering "civilization"? Was it just a matter of animal husbandry being invented? I imagine the "leap" in thinking would be difficult at the time. I guess what I'm asking is, were older humans (hunter gatherer) "less intellectually capable" than "modern man" (Sumer, Greek, Egypt, and on) or was it simply a matter of deeply ingrained instincts having to be broken, which must've had a statistically low chance of occurring?