Costly signalling can be applied to situations involving physical strain and risk of physical injury or death. Research on physical risk taking is important because information regarding why people, especially young men, take part in high risk activities can help in the development of prevention programs. Reckless driving is a lethal problem among young men in western societies. A male who takes a physical risk is sending the message that he has enough strength and skill to survive extremely dangerous activities. This signal is directed at peers and potential mates. When those peers are criminals or gang members, sociologists Diego Gambetta and James Densley find that risk-taking signals can help expedite acceptance into the group.