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Lucy's fossil is the best-known example of Australopithecus, a species that lived between 2 and 3 million years ago. And as chimpanzees, their children have grown rapidly and reached adulthood must be faster than modern humans.
Previously, research has shown that Australopithecus have a varied diet, consisting of fruits, leaves, grass and roots. Because of their habitat, seasonal changes have resulted in periods of abundance and shortage of food. The wet summers provided many food resources, but dry winters had the opposite effect.
Two sets of fossilized teeth discovered in the Sterkfontein cave near Johannesburg, South Africa, were studied to better understand the response of these early human ancestors to seasonal food changes.
Teeth have growth rings, just like trees, which determine age as well as minerals derived from the individual's diet. Barium is a mineral in breast milk that can be seen in the rings to determine when a child is breastfeeding and when he or she has been weaned.
The barium accumulation in both sets of teeth showed stable patterns of barium accumulation after three months of age, indicating that the behavior lasted for about a year. Then there were signs of supplementation of other foods. Breastfeeding has probably helped infants survive during a seasonal food shortage.
Cyclical signs of lithium in the teeth have also been highlighted, suggesting a shortage of food because it can vary depending on body mass. The food shortage could last six months, which could have led to more breastfeeding or looking for other sources of food.
"For the first time, we gained new insights into how our ancestors raised their offspring and how mothers may have adapted to seasonal food shortages due to breastfeeding," he said. Renaud Joannes-Boyau, lead author of the study and head of geoarchaeology. Archeometry Research Group of Southern Cross University in Australia.
The teeth have been compared to those of the modern great apes. The researchers also found that infants were more dependent on breast milk during times of food shortage.
Researchers believe that meager resources available during dry winters may have contributed to the extinction of the Australopithecus.
"Seeing the evolution of breastfeeding over time can shed light on best practices for modern humans by integrating evolutionary medicine." Our results show that this species is a little closer to the average. Man that other great apes who have such different breastfeeding behaviors, "said Christine Austin, co-authored study and assistant professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai. "These are important evolutionary discoveries because humans have a long childhood and short periods of breastfeeding while monkeys have longer breastfeeding periods than humans do." We still do not know why or when we made this change and what the effects of the recent major changes in breastfeeding, along with agriculture and industrialization, could have consequences for the future. health of mothers and babies. "
Who was Lucy?
When Lucy, the world's best-known fossil, was discovered in 1974 over a shallow Ethiopian riverbed, she provided a new glimpse into the lives of the earliest human ancestors 3,18 millions of years. The image of his skeleton – estimated at 40% complete and considered The best representation of its species, Australopithecus afarensis – has become emblematic. Lucy's skeleton is represented by elements of the skull, upper limb, hand, axial skeleton, pelvis, lower limb and foot.
Lucy was small, about 3 feet tall and 60 pounds. The analysis of her skeleton and teeth shows that she has reached maturity, but her species is similar to that of chimpanzees. The researchers estimate that she was 15 or 16 years old.
She was standing upright with her feet, knees and hips similar to ours. If you saw her walking from a distance, you would think that Lucy was human by her figure. But up close, she had a small head, a brain of size comparable to that of a chimpanzee, arms and longer hair that covered her body.
A 2016 study proposed that she died after falling from a tree, stretching her arms to break her fall in a manner that seemed distinctly human.
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