Editing Signalling theory (section)

=== Physical risk ===
{{anchor|Physical risks as a costly signal}}
[[File:Motorcycle racing.jpg|thumb|Young men may take part in risky sports like [[motorcycle racing]] to signal their strength and skill.]]

Costly signalling can be applied to situations involving physical strain and risk of physical injury or death.{{sfn|Bliege Bird|Smith|Bird|2001}}{{sfn|Farthing|2005}} 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.{{sfn|Nell|2002}}{{sfn|Farthing|2005}} Reckless driving is a lethal problem among young men in western societies.{{sfn|Nell|2002}} 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.{{sfn|Zahavi|1975}} When those peers are criminals or [[Gang|gang members]], sociologists [[Diego Gambetta]] and [[James Densley]] find that risk-taking signals can help expedite acceptance into the group.{{sfn|Densley|2012}}{{sfn|Gambetta|2009}}

In a study of risk-taking, some types of risk, such as physical or heroic risk for others' benefit, are viewed more favorably than other types of risk, such as taking drugs. Males and females valued different degrees of heroic risk for mates and same-sex friends. Males valued heroic risk-taking by male friends, but preferred less of it in female mates. Females valued heroic risk-taking in male mates and less of it in female friends. Females may be attracted to males inclined to physically defend them and their children. Males may prefer heroic risk-taking by male friends as they could be good allies.{{sfn|Farthing|2005}}

In western societies, voluntary [[blood donation]] is a common, yet less extreme, form of risk-taking. Costs associated with these donations include pain and risk of infection.{{sfn|Schreiber|Schlumpf|Glynn|Wright|2006}} If blood donation is an opportunity to send costly signals, then donors will be perceived by others as generous and physically healthy.{{sfn|Zahavi|1975}}{{sfn|Lyle|Smith|Sullivan|2009}} In a survey, both donors and non-donors attributed health, generosity, and ability to operate in stressful situations to blood donors.{{sfn|Lyle|Smith|Sullivan|2009}}