Early in the twentieth century william mcdougal proposed that there were human instincts.

18

Explanation:

Scientific development of the instinct theory consisted mainly of drawing up lists of instincts. In 1908, William McDougall (1871-1938) postulated 18 human instincts and within 20 years, the list of instincts had grown to about 10,000.

Although instinct theory has long been abandoned, sociobiologists have adopted its evolutionary perspective considering the new wide range of human behavior, from the standpoint of natural selection, from aggression to interpersonal attraction, and the survival of humans as species.

yes i think there would be volunteers

depends on the age of the teen, many believe by the age of 16 a person should know the strong difference between right and wrong along with the difference between risky and immediate death. swimming with sharks might be dangerous but swimming with sharks while bloody meat is attached to you is just insane. even more if you have no idea what you're doing. however, no matter the age, as long as the person is skilled enough and has the mental and physical capacity to control their actions doing whatever sport they put their mind to is all that matters.