If you insist your baby has to breastfeed for a year you have a cultural heritage to justify it. Extinct species such as
Australopithecus africanus likely breastfed for that long.
How could scholars determine how long
A. africanus
breastfed? Like trees, teeth contain growth rings that can be counted to estimate age. Teeth rings also incorporate dietary minerals as they grow. Breast milk contains barium, which accumulates steadily in an infant's teeth and then drops off after weaning.
In a new study, researchers analyzed trace minerals in two sets of fossilized
A. africanus teeth from the Sterkfontein Cave outside Johannesburg, South Africa.