New research suggests Australopithecus africanus mothers, one of the earliest human ancestors, breastfed their children for almost the first year of life.
These findings were presented Monday in the journal Nature. Scientists analyzed the elemental makeup of two-million-year-old baby teeth found in South Africa. They confirmed that Australopithecus africanus babies predominantly consumed breast milk from infancy through their first birthday, likely strengthening the mother-child bond.
Scientists identified a cyclical nursing pattern suggesting moms supplemented gathered foods with breast milk, according to Fox 43.
"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.
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 vapour samples. Since teeth develop in layers, scientists can analyze how the chemistry of the tooth changed over time, layer by layer. The teeth were also compared with those of modern great apes.
"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."
According to The Conversation, geochemical analysis of teeth shows they exclusively breastfed infants for about 6-9 months, before supplementing breast milk with varying amounts of solid food until they were 5-6 years old. This helps understand the particular biological and behavioural adaptations of Australopithecus africanus compared to other extinct human ancestors and modern humans.
Breastfeeding for that long required a certain amount of calories for the lactating mother. Using milk as a supplemental food for older offspring may have hampered the ability of the A. africanus species to successfully survive during a period of dramatic shifts in climate. Also, the meager resources available during the dry winters may have contributed to the extinction of Australopithecus.
Australopithecus africanus lived in southern Africa between two and three million years ago. The species had 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 accomodating a larger brain.
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-evolving world, it also likely reduced the number of offspring early hominins were able to produce.