My coursera essay for 'Human Evolution: Past and Future'
Dualisms's dysgenic disruption of endocranial displacement,
or: Dude, where's the rest of my brain?
by A philosophical Doggerlander
"I would be willing to wager that if an average citizen from Athens of 1000 BC were to appear suddenly among us, he or she would be among the brightest and most intellectually alive of our colleagues and companions." Gerald R. Crabtree from 'Our fragile intellect'
This is a disturbing idea at odds with the standard narrative of humankind becoming steadily more intelligent and I shall address one of the many possibilities for a cause of this phenomenon - the rise of dualism as concomitant with the appearance of consciousness. I shall produce data in the form of endocranial displacement trends, and my own "research" into the fecundity of the acknowledged geniuses of history.
The subject is enormously complex and hotly debated, in order to narrow the scope to fit in the confines of this essay, I shall make a number of assumptions which I shall declare at the beginning; each is in itself a topic for discussion some aspects of which I shall mention; for the interested reader I point to a paper supporting each respective assumption. I consider a mainly eurocentric (local) viewpoint though I believe a global argument could be made.
A1. That there is a correlation between the size of the brain (measured through endocranial volume) and intelligence.
This is at least partially the case, complications arise through modern brains having a different structure as well as the effects of better education, also a diminishing body mass. We may wish to ask how we would be today with these advantages AND a bigger brain.
Decrease Female 17.4% (from 94% to 87% of male brain size)
From 'Decrease of human skull size in the Holecene' Henneberg, Maciej 1988.
The decline as seen above is in sharp contrast to the steady increase seen in the last 2,000,000 years. The start of decline slightly predates the agricultural revolution indicating a cause other than natural selection due to domestication, though this probably is a major contributor post neolithic (limited food and unsanitary birthing conditions compared to the wild).
I postulate that the decline is marked by the replacement of sexual selection on an animal basis to a system of cultural mate allocation - through complex language and the idea of ownership.
Property prior to this time simply did not exist, stone tools were disposable, but now we see various objets d'art (statues; flutes; pottery), dogs, dwellings, and particularly grave goods. It is probably at this point that the patriarchy is established and the female role is reduced to dutiful daughter - note how much more marked the female reduction is - a sign of stronger selection pressure on the female. Whilst female selection appears to have favoured big brains, males were clearly focusing their attention elsewhere - towards neoteny; body fat in other areas and possibly docility, clearly there is a story to be told here - but not now.
When man put in place (albeit unwittingly) the parameters for cultural sexual selection what were the chances that he would have hit upon a better method than nature (A4) had already provided? Given that he based his method on a number of erroneous assumptions, not least of which involved ignoring half the population's wshes, the chance must be vanishingly small. But it is those early 'methods' that set us upon our way to 'civilisation'. Probably male mates were allocated that were considered fit for a particular culture and the various niches that such a society has to offer (chief, henchman, soldier, labourer etc..).
Rather than speculate on the exact forms of primitive beliefs in prehistory, it could be instructive to work backwards from our early written history. Firstly in early classical times we find Pythagoreans extolling the virtue of celibacy for mystic reasons, moving backwards from there there appear to be a mix of cults and beliefs, some of which deny the pleasures of the flesh to priests and shamen - in particular 'Earth mother' cults may expect the shaman to be available to the goddess and none other. The shaman moves in the spirit world at a remove from the body, not to see the sun not to touch the earth, his person is different from others.
Joseph Campbell in 'Primitve Mythologies' shows this to be the beginning of the schism between sex and intellect - quoting Hamlet:
....thy commandment all alone shall live
Within the book and volume of my brain,
Unmixed with baser matter. Yes, by heaven!
O most pernicious woman!...
Chris Stringer in his book 'The origin of our species' claims that sects which do not allow the shaman to reproduce or even castrate their priests are doomed to die out, but clearly if a society can give up just a few individuals for this purpose it can still thrive and benefit from their wisdom - but with a reduction in genetic variety. It is the cerebral who become the shamen and wise men and it is their genes removed from the pool (A3). The trade-off for the shaman is reward in the spirit-realm (pre/post-mortem).
“The most spiritual men, as the strongest, find their happiness where others would find their destruction...Their joy is self-conquest: asceticism becomes in them nature, need, and instinct" Nietzsche 'The Anti-Christ'
These two streams merge in the christian religion which dominated European culture for perhaps 50 generations. The first written mandate requiring priests to be chaste came in AD 304. Canon 33 of the Council of Elvira stated that all "bishops, presbyters, and deacons and all other clerics" were to"abstain completely from their wives and not to have children." The less venal clerics and more serious thinkers have been honour-bound by this. Around 1 in 50 men were clerical during the middle ages. This seems about the level we might expect for a shaman in the mesolithic - perhaps one plus an acolyte in a clan of 200?
With its monopoly on education and its providing the only chance of social mobility in a single generation (prime examplehttp://en.wikipedia.org/wiki/Thomas_Wolsey ), the church was able to select the best and brightest..
Here are some figures for reproductive success of some of the best known thinkers. There are many 'toptens' on the internet, but they seem to have some names in common (Goethe is invariably #1), I have chosen one at random so not to be guilty of cherry-picking, but I maintain that a similar result will crop up on any list.
Table 2: We are standing on the shoulders of giants, but are they our ancestors?
Goethe--------->1---None of his 3 grandchildren reproduced
Galileo--------->1---2 became nuns
Philosophers (Chapters from B.Russell 'History of Western Philosophy', chosen because this is my field)
Descartes--------->0-----daughter died age 5
Rousseau--------->0----all 5 abandoned to die
Kierkegaard------>0---in honesty missing form Russell but a prime example
Conclusion Clearly this hypothesis requires more work, especially the maths, but I think it points towards a recognisable trend in our recent evolution. We should avoid making the assumption that we are steadily improving with time and accept that we may have taken a wrong turning somewhere.
If mankind aspires to longer more fulfilling life it may need bigger brains with space to preserve individual histories and identities. Current trends showing an inverse relation between intelligence and fecundity.
We can stop self harming by: 1. Respect for diversity 2. Education - history;science;philosophy, not divinity;dogma;devotion 3. Equality of the sexes