Category:Middle-aged men in 1901 by country

 See also category: Middle-aged women in 1901 by country.

1. Babies (birth to 24 months)
2. Boys (2–13 years [puberty])
3. Adolescent boys (13–17 years)
4. Men (18+ years)
   • Young men (18–39 years)
   • Middle-aged men (40–59 years)
   • Old men (60+ years)

Definitions come from, but are slightly modified from, the Physical stages of human life as found at Wikipedia:Human development (biology).