Why do the young take more risks?

Matt Yglesias claims he is defective and asks:

Are there good reasons for young people to be designed as more risk-friendly than older people? …Is there some more general logic to this?

After all, teenagers can do some very stupid things, and for no apparent benefits.  Why?  I see a few major hypotheses:

1. The young take risks to signal they are strong and thus good potential mates.  We are biologically programmed so that this motivation declines with age.  This also helps explain why the young are most foolish amongst their peers.  Note that under this hypothesis, the default setting must be that a non-risk-taker doesn’t reproduce very much (otherwise why take risks?).  If polygamy was once common, this might explain why young men are more reckless than young women.

2. The young have greater need for some skill which is biochemically correlated with risk-taking behavior.  The risk-taking itself performs no useful functional role.  Read Randall Parker on this.

3.  When it comes to the kind of risks that were most prevalent in early hunter-gatherer societies — such as facing hostile large animals — today’s young are still quite risk-averse.

4. The young have fewer commitments and thus less to live for.  This is related to yesterday’s discussion of theism and risk-taking.

I view #4 as an underrated hypothesis, but I have turned on the comments function for your ideas.  And here is my earlier post on risk-taking and life extension.