Yet another question for this world: Rail Transportation with Races Described Below - Specifically, Seating

One race specifically, the Phanerae.

They are 6-8 feet tall, and 250-300 pounds as adults. Females are slightly heavier, but shorter, than males due to a high level of hourglass figure.

They get this by way of a Second Puberty, which both sexes have and is basically a 'glow up' puberty. Phanerae have a First Puberty, which gets them ready for reproduction, from 10 to 13 years of age. The Second Puberty kicks in at 16 and ends at 20 years of age, which has them gaining muscle mass, height (a few spare inches), and some sexually attractive features, mostly in women gaining an hourglass shape.

How and why would a species evolve a second puberty, which only sexualizes them?

  • 6
    $\begingroup$ How is that different from what happens in humans? Teens can reproduce, but they get their final adult look after the hormonal storm. $\endgroup$
    – L.Dutch
    Commented Dec 11, 2020 at 14:37
  • $\begingroup$ I'd echo the question from @L.Dutch-ReinstateMonica - this just sounds like...normal puberty. But somehow divided into two stages. $\endgroup$
    – VLAZ
    Commented Dec 11, 2020 at 14:38
  • $\begingroup$ Stage 1 = Puberty, Stage 2 = Sexual Maturity. It's human psychology that equates sexual maturity with "Me Tarzan, you Jane". So your question as it stands (and as has been states), just mirrors human sexual maturity stages. $\endgroup$
    – user80989
    Commented Dec 11, 2020 at 14:47
  • $\begingroup$ In humans, the transformation of children into adults begins at 10 to 12 years of age and ends at 18 to 20 years of age. Just like in the fictional Phanerae. (Note: the Greek word phaneros means "visible", "evident"; hence, phanerogams, i.e., seed plants, plants with clearly visible process of reproduction.) $\endgroup$
    – AlexP
    Commented Dec 11, 2020 at 14:52
  • 1
    $\begingroup$ I think the human glow up kicks in at 31 and goes until late 50s and has us gaining mass (a lot), girth (many spare inches) and additional sexually attractive features if you are into cash reserves, lack of subtlety and rampant body hair. At least that's how we do it in Murica! USA! USA! $\endgroup$
    – Willk
    Commented Dec 11, 2020 at 22:42

1 Answer 1


As pointed out in the comments below the question, this isn't really different from human puberty.


If you explicity want this to be two separate processes, I would look at amphibians. Typically amphibians reach sexual maturity when they undergo metamorphosis from larval to adult form, as we see with frogs, for example.

There is, however, this guy, the axolotl:

an axolotl

Axolotls exhibit neoteny - as humans do - which means they reach sexual maturity while still in larval form. Many members of the Ambystoma genus are entirely neotenic species, which means they spend their entire life as larvae, and don't undergo metamorphosis.

Your species may have evolved in similar way, and your second puberty would be actually metamorphosis into adult form, while the first one would mean becoming sexually mature through neoteny.

You could even make it so that your species only undergoes metamorphosis through the wonders of medicine, if you wish, by receiving a shot with appropriate hormones. (lack of metamorphosis in Mexican axolotl, for example is caused by lack of thyrotropin).

  • 2
    $\begingroup$ Good idea! I probably won't do the medicine part, though. But it's a good idea, still! $\endgroup$ Commented Dec 11, 2020 at 15:12

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