Analysis of growth rings in Australopithecus africanus teeth may tell us about prehistoric hominin’s breastfeeding habits. A recent analysis looked at four teeth, recovered from South Africa’s Sterkfontein Cave, belonged to two individuals who lived between 2.6 and 2.1 million years ago. The results suggest that they exclusively breastfed for the first six to nine months of life.
Although other foods were added around the 1st birthday, milk intake also ramped up again each year, over a period of four or five years. Why this yearly return to breastmilk? Perhaps during times of food scarcity, mothers would return to breastfeeding, to ensure their children got enough to eat.
The analysis found an additional piece of evidence suggesting that breastmilk was a starvation-food used to keep young children nourished. Levels of lithium in the teeth rose right before the period of breastfeeding began each year. Such a distinctive biological time-stamp connected to the later-life breastfeeding suggests that the breastfeeding began again each year in the same season, likely corresponding to the time of year when food was scarcest. One can speculate that lithium was high in a specific food source which became available only during a certain season each year (like apples in autumn) – or which Australopithecus africanus only resorted to when other foods were scarce (like tree bark in winter).
