All I hear nowadays is your baby should be eating solid foods by 6 months.. your baby should be sitting up on their own by 8 months.. your newborn baby should be fed every 2-3 hours and sleep on their backs only.. etc But babies have somehow evolved from being strictly breastfed to, at some point, handling solid foods, and potty trained .. etc

Do we have evidence of prehistoric child rearing or even medieval times at what age did things begin to change and grow? Is there a reason, historically, why these current age milestones are what they are?