Hoffecker, the ‘super-brain’ and genetic similarity.

Today I came across a summary of a conversation with John Hoffecker, an American paleoanthropologist of the University of Colorado Boulder, about the relationship between the cultural explosion seen in human artifacts, especially art works, beginning at least 75,000 years ago and the evolution of the ‘modern human mind’. In the context of this particular piece, ‘human mind’ refers to our capacity to communicate abstract and novel ideas through speech or symbolism, not of course the brain, the physical size and structure of which had already been changing for a long time prior to the appearance of modern man.  This got me thinking about the idea put forward by Flannery in ‘Here on Earth’ that it may have been a reduction in genetic diversity in early H. sapiens that led to elevated levels of cooperation and altruism (much the same way as it does in ants or bees due to close genetic relationships). I wonder if a significant genetic bottleneck occurred at about the same time as this abstract cultural revolution? Could increasing cooperation and altruism have led to a greater capacity, or perhaps put more succinctly, need, to share thoughts?  I’m going to have a look at the literature and see what I come up with. I’d welcome the suggestion of any articles from readers that may broach this topic. Beware however that many articles in this area are filled with teology and science ruining anthropocentrism, so keep your Ockham’s razor and objective mindset at the ready.

Exciting stuff. It was after all, most likely this cultural paradigm shift (genetic in nature or otherwise) that led to agriculture, civilisation, government and technology advances like desktop computers and electric tea-kettles. Well worth the effort of investigation.

UPDATE: It just so happens that prevailing thought is that a bottleneck/s of some kind occurred around the 70,000 ya mark or more recently. Parsimony at work! I found the following papers relating to this;

http://ice2.uab.cat/argo/Argo_actualitzacio/argo_butlleti/ccee/geologia/arxius/4Gathorne-Hardy.pdf

http://rspb.royalsocietypublishing.org/content/277/1678/131.short

You can find the summary of the chat with Hoffecker here: http://www.sciencedaily.com/releases/2011/04/110420125510.htm

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~ by confusedious on May 19, 2011.

4 Responses to “Hoffecker, the ‘super-brain’ and genetic similarity.”

  1. Wasn’t it about 70k years ago that the Homo species almost went extinct? I hadn’t made the relationship between that event and the explosion of creativity before. Interesting thought.

    Homo erectus was pretty visual in his own way, with the advancement to Acheulian tools. Most of what I’ve read says he couldn’t have created those tools without the ability to visualize the unknown and unseen. ( “…H erectus of 700kya had a geometrically accurate sense of proportion and could impose this on stone in the external world. In effect, without open, paper or ruler, mathematical transformations were being performed. “ “Mental Abilities of Early Man: A L0ok at Some Hard Evidence” John A. J. Gowlett 1984, Academic Press, London)

    What do you think?

    • Yes well that’s the thing, data at this point indicates a bottleneck no more than 100,000 years ago, many attribute it to a volcanic winter that occurred as a result of the eruption at Lake Toba in Sumatra. This event was dated at around 73,000 years ago which would fit what you have mentioned. This being said, one author I respect greatly, John Hawks suggested back in 2000 that the data available wasn’t good enough for any kind of speculation on how or where a bottleneck took place, I’ll have to see if his stance has changed since then. Anyhow, any bottleneck reducing diversity within the last 100,000 years could have been sufficient to set things in motion for the amping up of altruism, cooperation and perhaps as a result communication. There is evidence that this time period also saw the beginnings of items being made for trade (various token items found in Africa, shells etc.). Any reduction in diversity increases the risk of a given allele being driven to fixidity, but this happens over subsequent generations after a bottleneck, so time would have been needed. I’m going to see if I can find the original sources that Flannery cited on the idea as they would no doubt make for fascinating reading.

  2. But on the other hand, if FOXP2 truly is implicated in the development of the “modern human mind” and namely language abilities, that sweep took place about 50,000… so there is still a substantial time gap between the presumed bottleneck and true communication with symbols. Interesting theory, although I tend to find a lot of the altruism-based explanations overrated.

    • Decreased genetic diversity leading to increased altruism/cooperation/tolerance/decreased territoriality etc. and the movement toward agricultural and in turn urbanised society would have of course happened in conjunction with other useful traits, nothing in evolution happens in a vacuum. As for FOXP2, Neanderthals had the same version of this gene and conservative estimates of when the divergence between their line and ours occurred put the event at around 500,000 years ago. Either this is a striking example of convergent evolution, they acquired this version of the gene from us via breeding later in the piece (the sample used for the Neanderthal genome was from around 38,000 years ago) or the gene has been present in genus Homo for much longer than many would suppose.

      I’m not sure about that considerable time gap. A reduction in population is assumed to have occurred ~73,000 ya with symbolic items appearing around ~70,000 years ago also.

      You are right to be cautious about theories that seem light on data and heavy on parsimony pleasing ‘sweep’, hopefully the future provides some more complimentary or contrary evidence.

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