This is the last in a series of reports from the Edinburgh International Science Festival. The talk What Makes Us Unique? was held at the Museum of Scotland.

Professor Robin Dunbar, head of the Institute of Cognitive and Evolutionary Anthropology at the University of Oxford and director of the innovative programme 'From Lucy to Language,' took his audience through a brief history of the evolution of the social brain - how cognition has contributed to our social development from being 'primate brained' to 'human brained'.

He asked why it was that we developed from primates rather than great apes, given that one sub-species of gorilla has more DNA in common with humans than other gorillas. He also suggested that two aspects of human behaviour, story-telling and religious worship, could give important clues about how we developed.

The 'Social Brain' hypothesis arises from chimpanzees and other primates living in a social world, which is essentially tribal and inter-dependent. Mutual defence coalitions arise for both extra and intra tribal protection, and mutual grooming is an important reinforcement of these links.

Pair-bonded monogamy arises not only to foster bi-parental care (which isn't the case with all pair-bonded species), but essentially to promote co-ordination of activities and 'behavioural sychronicity' (if one parent is foraging, the other is needed to care for young, sit on eggs, protect the nest). To this extent, pair bonded animals have a 'theory of mind' and awareness of others.

Primates exhibit more pair-bonded social systems - the pair bond is part of a tribal society. Tribes, however, form only one element of a complex hierarchy of groupings in humans, the upper limit of effectiveness being around 150 persons.

Thus village populations in England (and presumably elsewhere) remained at around 150 from the Doomsday Book survey in the 11th century to the mid 18th. The Goretex company operates successfully with specialist units of production with about 150 employees in each. Elephants, chimpanzees and other primates as well as Orca whales are all capable of dealing with 'degrees of relatedness', recognising a large number of species members over geographical space and time, but relating to these differently from tribal or family members.

This implies that an emotional or relationship tie is important to cognition, that our heart in some sense rules our brain. This in turn can reinforce how we relate to and construct our worlds - cognition can depend on relationship up to the 5th order (I believe because Fred told Freda, who told Harry, who told Harriet who told me).

When cognition is direct - we think the problem through ourselves - the neurons demonstrably work harder to achieve this. The implications of this are several - women tend to be better at mentalising tasks, and it may be worth noting from elsewhere that the corpus collosum, the network of neurons lying in front and between the two lobes of our brains, is more dense and rich in neurons in women than in men. Equally, the distribution of rods and cones in the female eyeball affords greater sideways vision - very useful if you're watching out for predators or venturesome young.

In the context of primate behaviour, grooming is not only a social bonding exercise, it also releases endorphins, relaxing participants and creating a psycho-pharmacological effect of building trust. Primates can spend up to 1/5 of every day on grooming activity. Humans would thus need to spend 43% of their time doing this. Instead, language becomes the human substitute for grooming, as humans use language to bond.

What, however, gives humans the opiate kick primates gain through grooming? Professor Dunbar suggests laughter lead to music (Inuit and other women ululate to one another, the first to laugh being the loser of the contest), and that music in this form lead to language, and the combination was crucial to forming religious expression.

It's known music and religious expression are both effective in releasing endorphins - vide the 'Whirling Dervishes' of Sufi Islam, the singing Chassidim of Judaism, the choral singing of Wales. There is, of course, more to this, and embodied activity conducted as part of a group leads to both feelings of well-being and group solidarity less immediately dependent on 'endorphin kick.

Humans are capable of recognising 5th order intention, as stated before. Primates on the other hand are probably only capable of recognising 2nd order intention (i.e. that of one other immediate primate). A larger corpus collosum and retinal field have obviously helped humans, but our increased cognitive ability and social networking skills have to be seen as a result of our cognitive past, the echo of which can be found among our nearest relatives - the primates.

Published on EdinburghGuide.com 2008

Copyright Bill Dunlop 2008