The linked paper doesn't obviously support the claim you're making here. Maybe I've missed something?
"The median age at menarche was 14.5 years (95% CI=14–15; Nindividuals=128; Nobservations=199), which is within the range of variation of modern populations."
"The median age at menarche was 14.5 years (95% CI=14–15; Nindividuals=128; Nobservations=199), which is within the range of variation of modern populations."