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. Women are slightly heavier, but shorter, than men due to a high level of hourglass figure.

They get this by way of a Second Puberty, which both genders have and is basically a glo 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?

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?