Many ``real-world'' networks are clearly defined while most ``social''
networks are to some extent subjective. Indeed, the accuracy of
empirically-determined social networks is a question of some concern because
individuals may have distinct perceptions of what constitutes a social link.
One unambiguous type of connection is sexual contact. Here we analyze data on
the sexual behavior of a random sample of individuals, and find that the
cumulative distributions of the number of sexual partners during the twelve
months prior to the survey decays as a power law with similar exponents α≈2.4 for females and males. The scale-free nature of the web of human
sexual contacts suggests that strategic interventions aimed at preventing the
spread of sexually-transmitted diseases may be the most efficient approach.Comment: 7 pages with 2 eps figures. Latex file. For more details or for
downloading the PDF file of the published article see
http://polymer.bu.edu/~amaral/WebofContacts.html . For more results on teh
structure of complex networks see http://polymer.bu.edu/~amaral/Networks.htm