2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Reconstruction of the appearance of the African Australopithecus (Australopithecus africanus)
The researchers found that African australopithecines, who lived in southern Africa about 2, 1–2, 6 million years ago, breastfed babies for up to about a year, as modern humans do, according to Nature. At the same time, over the next several years, the young Australopithecus still continued to suck on their mother's milk seasonally, during the lack of other food, as today the cubs of orangutans and baboons do.
African Australopithecus (Australopithecus africanus) lived in South Africa from 2, 6-3 to 2, 1-2, 3 million years ago. Compared to Australopithecus Afar, which inhabited East Africa, it had more advanced features in the anatomy of the skull, but a more primitive skeletal structure. For example, the fingers were still like monkeys, adapted for climbing trees. African Australopithecines were highly mobile compared to other hominid species, and the morphology of the teeth showed that their diet was much more varied. It included fruits, roots, leaves, herbs. Scientists suggest that African Australopithecus lived in areas with a mixed landscape: in forests and savannas. This explains the richness of their diet. However, little is known about how adult hominids experienced seasonal fluctuations and what they ate during this time, and even less is known about how Australopithecines cared for nursing infants.
To answer these questions, Luca Fiorenza and colleagues from Australia, the United States and Germany analyzed the ratio of strontium isotopes and trace elements in the molars of two African australopithecines that lived in the period of 2.07–2.61 million years ago. Their remains were found in Sterkfontein Caves, located 40 kilometers northwest of Johannesburg. The mobility of individuals could be determined by the ratio of strontium isotopes, which varies depending on the region and allows you to determine where the individual was born and spent the first years of life. By the composition of trace elements, scientists hoped to determine how Australopithecus fed infants. Recently, it has been shown that the content of the trace element barium in teeth shows how the diet of an infant has changed, and it can be used to determine when the mother switched from breastfeeding to solid food. After birth, the barium content in the teeth increases rapidly, and then slowly begins to fall and reaches a minimum level when the child is transferred to solid food.
As shown by the content of barium in the teeth of both Australopithecus, apparently, they were fed mainly with breast milk for 6–9 months after birth, and after nine months and up to about a year, a large amount of complementary foods were added to the milk. The content of barium in teeth soon after birth became maximum, then dropped and for several years changed cyclically, with a frequency of 4–6 months for one Australopithecus and 6–9 months for another. The same cyclical pattern is observed, for example, in modern orangutans during the first nine years of life, and researchers believe that it reflects the seasonal availability of food. During those periods when the number of fruits in the forest decreases, the young often return to breast milk. Probably, Australopithecines also had to change their diet in dry seasons, and this was reflected in the amount of trace elements.
The authors tested this assumption by analyzing the teeth of modern mammals that live in the same regions of South Africa where the African Australopithecus lived two million years ago. Baboons also had a cyclical nature (the cycle lasted about eight months), while in carnivorous animals it was less pronounced. Apparently, this indicated that their diet did not change as noticeably as that of omnivorous hominids.
The ratio of strontium isotopes in the teeth of Australopithecus showed that at an early age they lived in dolomite karsts, surrounded by grasses and bushes. Resources were scarce here. Apparently, during the rainy seasons, the young Australopithecines switched to solid food and allowed the mother to recover herself. And in the dry season, when there was not enough other food, they began to feed on mother's milk again.
At the end of 2017, paleoanthropologists finished assembling the skeleton of the Australopithecus "Little Foot", which took 20 years. Australopithecus fossils have been found in Sterkfontein Cave. It belonged to the subspecies of African Australopithecus, and lived about 3.67 million years ago.