Parents are acutely aware of the influence that friends exert over their children's behavior -- how they dress, how they wear their hair, whether they drink or smoke. And now a new laboratory-based study has shown that friends may also influence how much adolescents eat.

The study appears online in the current issue of Annals of Behavioral Medicine and involved 54 overweight and non-overweight youth -- 24 boys and 30 girls -- between the ages of 9 and 11.  Each was assigned randomly to bring a friend or to be paired with an unfamiliar peer. Study
participants worked on a computer game to earn points exchangeable for food or time to spend with their friend or with an unfamiliar peer.

Why should we bother building mathematical models of biological systems? Scientists from other fields might wonder why one would as such a question - physicists, climate scientists, economists, engineers, and chemists all use mathematical models to understand the world.

Some biologists do too - individual proteins are studied with quantum mechanical models by biophysicists, enzyme reactions are modeled by biochemists, physiologists have mathematical models of the circulatory system, and population geneticists model the evolution of gene frequencies in populations.