Team assembly – seven is a lucky number
Roger Guimera et al. (Science, 308, pp. 697-702, 29 April 2005)
provide a fascinating and strongly grounded analysis of professional
networks in business and science as an aspect of human interactions.
Guimera et al. show, in their Figure 1, that the Broadway team size
grows to and settles at an optimum of around seven. Twenty years ago,
Bryan Shorrocks and I published an article on the tendency for group size
in many different networks often to settle around this size (1). We found
this among clusters of fast-food restaurants in Florida and Oklahoma,
children’s networks in the school yard, and military units from Rome to
the present day. Our interest arose because it also seems to be the
typical diversity of animal species in ecological guilds, as a way of
achieving structured resource exploitation. Elsewhere, George Miller (2),
at Harvard, showed that seven was a common limit to human ability to
handle bits of information. Median committee size seems to be about the
same.
We noted that networks in ecology, economics, and society are driven
by energy, money, and knowledge, which all correspond to a common currency
of “information.” These networks are scale free at some stage (that is,
some are very much larger), but more mature networks or structures settle
around the median – perhaps because this is the scale at which information
processing is most efficient. Bryan and I offered no more complex theory,
but now Guimera et al.’s success suggests that network theory might
provide the framework to draw even more diverse observations together.
Jonathan Adams
Dean for Strategic Development, University of Leeds, LEEDS
Managing Director, Evidence Ltd, LEEDS LS2 9DF, UK
Jonathan.adams@evidence.co.uk
References
1. J. Adams, B. Shorrocks, New Sci. 1465, 41 (18 July 1985).
2. G. A. Miller, Psychol. Rev. 63, 81 (1956).
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