• Question from:Greg

I recently got into a bit of a debate/discussion with friends as to what could be considered the threshold for biological adulthood. I was of the mind that reproductive potential was a fairly accurate benchmark, but some people argued that simply marks the beginning of adolescence and that adulthood occurs much later.

Is there a right answer as far as biology is concerned? Legally, socially, societally, I know that it varies by country and state, but I wondered if adolescence was considered a kind of early adult state. I am also of the mind that adolescence is a relatively new biological and social concept. Any input whatsoever would be greatly appreciated, if only to sate my curiosity.

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  • University of Exeter
  • Posts: 576

As a zoologist I typically distinguish between individuals in a population that are not sexually mature (juvenile) and those that are (adult). To me this also make sense for humans.

I don't think there's any threshold or line in the sand we can draw biologically, other than as you suggest the ability to reproduce. This is not to say that there aren't biological and psychological changes that happen before and after that - maturation is a process not an instantaneous event. We could of course pick something else to define being an adult if we wanted (getting married, leaving home, turning 18/21) but such thresholds are obviously societal not biological.

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  • Institut de Biologie du Développement de Marseille-Luminy (IBDML), Marseille
  • Posts: 79

I would add also that it depends on what you are measuring.  If you are only considering the ability to reproduce, then we're talking about puberty and early teens. If we are talking about brain development, the frontal lobe e.g., which controls executive decision making functions, doesn't fully mature until early to mid twenties.