Science Sundays: Early Modern Human Cultural Revolution?

By: Meradeth Houston on 10:02 AM

Welcome to Science Sundays everyone! One quick side note: I had a fun little interview yesterday which was all kinds of fun--stop on by if you're so inclined :)

Today I thought I'd tackle a topic that I've been learning more and more about lately. I have to teach a whole class on it next semester, so I've been gearing up to do that (and in all honesty, kind of freaking myself out!). I normally hit on this topic for about one lecture every year, and it's a personal favorite. And, what might that be? Well, the emergence of modern human culture of course!

Okay, so here's the big mystery: modern humans show up ~150kya--and by that, I mean they look like modern humans do. They have chins (random fact--no other species that is ancestral to humans had a chin, and we really don't know why modern humans do), have our same limb proportions, look like us, have the same brain size, etc etc. But it's not until ~60kya, or almost hundred thousand years later, that we see this massive explosion of things that *culturally* look like modern humans.

What do I mean by that? Well, I mean more advanced tools, jewelry, art, cave paintings, exploiting new and more difficult resources (like fishing), and the list goes on and on. Before this cultural explosion there seemed to be very little of this stuff associated with the human remains and archaeological sites.

The question then is: what changed at this time? Why do we suddenly see so much cultural activity? Was there a shift? Or was it just a gradual accumulation of technology over a long period of time that just became more visible because at ~60-50kya people were leaving Africa and we have a better archaeological record?

Attempts to explain this shift tend to fall into two general camps:

The atlatl--a much more effective early tool :)
Also, illegal in some states!

1. Gradual accumulation of cultural traits. This school of thought has been gaining steam recently with lots of new archaeological findings. Basically what the researchers are saying is that modern humans emerged and had the ability for complex, symbolic thought, and it slowly grew and grew over time. Early finds of art-like artifacts, more complex tools, and other traits that have been deemed to "only" come later in human history have bolstered this thinking. So, there was no cultural "revolution" but a slow and steady growth of modern human traits.

Early beads.

2. Cognitive shift allowing for complexity. This school of thought sees the shift in cultural traits in archaeological sites as being quite dramatic and much more complex than anything that came before (they do have a point--but there are also quite a few more sites that date to this time period, too). They suggest that what happened was that there was some kind of mutation or other change in modern humans that allowed for them to use more complex symbolic items (art) and technology. Suggestions for this have included a mutation in the FOXP2 gene, for example, as we know that when a person had a mutation in this gene they are unable to use higher cognitive function, so possibly ancient humans had a different form of this gene. (Ancient DNA analysis has shown that Neanderthals had the same form of FOXP2 as us, however we don't know if it was regulated differently than our own.)

The jury is still out on what exactly happened with this cultural shift. It is still a really interesting thing to consider though, and I can't help but be drawn to the allure of there being a mutation that explains modern human cultural understanding, though the gradual accumulation of traits probably has a more firm (and simpler) explanation for what occurred.

So, tell me, what do you think? Which seems more likely?