July 15 (UPI) -- New analysis of ancient hominin teeth suggests Australopithecus africanus, one of the earliest human ancestors, breastfed their children for the first year of life.
By analyzing the elemental makeup of two-million-year-old baby teeth found in South Africa, scientists confirmed that Australopithecus africanus babies predominantly consumed breast milk from infancy through their first birthday.
After the first year, scientists identified a cyclical nursing pattern. The findings, detailed Monday in the journal Nature, suggests moms supplemented gathered foods with breast milk.
"For the first time, we gained new insight into the way our ancestors raised their young, and how mothers had to supplement solid food intake with breast milk when resources were scarce," Joannes-Boyau, a geochemist at Southern Cross University in Australia, said in a news release.
The findings have offered scientists new insights into the evolution of "extended parental care" among early human ancestors.
"These finds suggest for the first time the existence of a long-lasting mother-infant bond in Australopithecus," said Luca Fiorenza, an expert in the evolution of human diet at Monash University's Biomedicine Discovery Institute. "This makes us to rethink on the social organizations among our earliest ancestors."
To study the ancient teeth, scientists used a laser to vaporize microscopic bits from the surface of the tooth. The researchers used a mass spectrometer to identify the chemical signatures of the vapor samples.
Because teeth develop in layers, just as trees add rings of growth, year after year, scientists can analyze how the chemistry of the tooth changed over time, layer by layer.
"We can tell from the repetitive bands that appear as the tooth developed that the fall back food was high in lithium, which is believed to be a mechanism to reduce protein deficiency in infants more prone to adverse effect during growth periods," Joannes-Boyau said. "This likely reduced the potential number of offspring, because of the length of time infants relied on a supply of breast milk."
Australopithecus africanus lived in southern Africa between two and three million years ago. The species displayed a unique combination of human- and ape-like traits. The early hominin species sported a slender build, some human-like facial features and a more human-like cranium, capable of housing a larger brain.
During their time in southern Africa, the region experienced dramatic shifts in climate -- changes that would have presented a variety of challenges for early hominins. The latest findings suggest Australopithecus africanus possessed impressive adaptive abilities.
While the use of breast milk helped insulate their children from the difficulties of life in a dangerous, rapidly-changing world, it also likely reduced the number of offspring early hominins were able to produce.
"The strong bond between mothers and offspring for a number of years has implications for group dynamics, the social structure of the species, relationships between mother and infant and the priority that had to be placed on maintaining access to reliable food supplies," Joannes-Boyau said.