Thursday, July 18, 2019

Maternal Secrets from 3 Million B.C.E.

A stunning new research result published in Nature reveals for the first time the breastfeeding and weaning habits of an early human ancestor that lived between 3 and 2 million years ago in South Africa.

Credit: La Trobe University

As part of an international research team – led by Southern Cross University and Monash University – Professor Andy Herries, Head of La Trobe University’s Archaeology and History Department, helped analyse more than two-million-year-old teeth from Australopithecus africanus fossils found in South Africa.

The research team revealed that infants were breastfed continuously from birth to about one year of age. In addition, the study has shown nursing appears to have continued in a cyclical pattern in the early years for infants, as seasonal changes and food shortages caused the mother to supplement gathered foods with breastmilk.

“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 breastmilk when resources were scarce,” said geochemist Dr Joannes-Boyau from the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University.

“Australopithecus africanus was the first human species to inhabit what was likely a relatively harsh limestone landscape in South Africa. This research potentially shows that living in these environments was difficult for our early ancestors, particularly as climate began to change around 2.3 to 2 million years ago and this may have led to their ultimate extinction not long after this time,” said Professor Andy Herries, Head of La Trobe University’s Archaeology and History Department.

“These finds suggest for the first time the existence of a long-lasting mother-infant bond in Australopithecus. This makes us to rethink on the social organisations among our earliest ancestors,” said Dr Fiorenza, who is an expert in the evolution of human diet at the Monash Biomedicine Discovery Institute (BDI).

“Fundamentally, our discovery of a reliance by Australopithecus africanus mothers to provide nutritional supplementation for their offspring and use of fallback resources highlights the survival challenges that populations of early human ancestors faced in the past environments of South Africa,” said Dr Adams, an expert in hominin palaeoecology and South Africa sites at the Monash BDI.

For decades there has been speculation about how early ancestors raised their offspring. With this study, the research team has opened a new window into our enigmatic evolutionary history. Australopithecus africanus lived from about two to three million years ago during a period of major climatic and ecological change in South Africa, and the species was characterised by a combination of human-like and retained ape-like traits. While the first fossils of Australopithecus were found almost a century ago, scientists have only now been able to unlock the secrets of how they raised their young. 

Teeth grow similarly to trees; they form by adding layer after layer of enamel and dentine tissues every day. Thus, teeth are particularly valuable for reconstructing the biological events occurring during the early period of life of an individual, simply because they preserve precise temporal changes and chemical records of key elements incorporated in the food we eat. Specialized laser sampling techniques were used to vaporize microscopic portions on the surface of the tooth. The gas containing the sample is then analysed for chemical signatures with a mass spectrometer – enabling researchers to develop microscopic geochemical maps which can tell the story of the diet and health of an individual over time.

“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,” Dr Joannes-Boyau said.

“This likely reduced the potential number of offspring, because of the length of time infants relied on a supply of breastmilk. 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,” he said.

“This finding underscores the diversity, variability and flexibility in habitats and adaptive strategies these australopiths used to obtain food, avoid predators, and raise their offspring,” Dr Adams emphasised.

“This is the first direct proof of maternal roles of one of our earliest ancestors and contributes to our understanding of the history of family dynamics and childhood,” concluded Dr Fiorenza.

Dr Joannes-Boyau conducted the analyses at the Geoarchaeology and Archaeometry Research Group at Southern Cross University in Lismore NSW and at the Icahn School of Medicine at Mount Sinai in New York. This work was conducted as part of an ARC Discovery Project led by Professor Herries at La Trobe University, looking at what drove changes in human species, and their diversity between 2.6 and 1.8 million years ago in South Africa.

The team will now work on species that have evolved after 2 million years, including the cave site of Drimolen where Professor Herries runs an international field school in Palaeoanthropology each June, to develop the first comprehensive record of how infants were raised throughout a critical time in our evolutionary history at the extinction of Australopithecus and the first occurrence of our genus, Homo.

Read the full paper in Nature titled Elemental signatures in Australopithecus africanus teeth reveal seasonal dietary stress.

Contacts and sources:
Claire BowersLa Trobe University

Crystalline ‘Artificial Muscle’ Makes Paper Doll Do Sit-Ups (Video)

Scary movies about dolls that can move, like Anabelle and Chucky, are popular at theaters this summer. Meanwhile, a much less menacing animated doll has chemists talking. Researchers have given a foil “paper doll” the ability to move and do sit-ups with a new material called polymer covalent organic frameworks (polyCOFs). They report their results in ACS Central Science. Watch a video of the material in action here.

Youtube ID: YLmqBmsnV3g

Scientists make conventional COFs by linking simple organic building blocks, such as carbon-containing molecules with boric acid or aldehyde groups, with covalent bonds. The ordered, porous structures show great potential for various applications, including catalysis, gas storage and drug delivery. However, COFs typically exist as nano- or micro-sized crystalline powders that are brittle and can’t be made into larger sheets or membranes that would be useful for many practical applications. Yao Chen, Shengqian Ma, Zhenjie Zhang and colleagues wondered if they could improve COFs’ mechanical properties by using linear polymers as building block

The researchers based their polyCOF on an existing COF structure, but during the compound’s synthesis, they added polyethylene glycol (PEG) to the reactants. The PEG chains bridged the pore space of the COF, making a more compact, cohesive and stable structure. In contrast to the original COF, the polyCOF could be incorporated into flexible membranes that were repeatedly bent, twisted or stretched without damage. 

To demonstrate how polyCOFs could be used as an artificial muscle, the team made a doll containing the membrane as the waist and aluminum foil as its other parts. Upon exposure to ethanol vapors, the doll sat up; when the vapors were withdrawn, it laid down. The researchers repeated these actions several times, making the doll do “sit-ups.” The expansion of polyCOF pores upon binding the gas likely explains the doll’s calisthenics, the researchers say.

The authors acknowledge funding from the National Natural Science Foundation of China, Tianjin Natural Science Foundation of China and the National Science Foundation.
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