The Neanderthals began weaning their newborns around the fifth or sixth month of age, a period similar to that of modern humans. The discovery comes from the work of an international research group that carried out geochemical and histological analyses on three milk teeth that belonged to Neanderthal children who lived between 70,000 and 45,000 years ago in north-eastern Italy.

Thanks to these results, published on the journal PNAS, the researchers could reconstruct the growth rate and weaning times of Neanderthal newborns. In a similar way to what happens in trees, the growth process of the teeth produces "growth lines" from which it is possible to obtain information through histological analysis techniques. By combining this information with chemical composition data obtained by mass spectrometry, the researchers have been able to establish that the children to whom the analysed teeth belonged started eating solid food between five and six months of age.

"The beginning of weaning is more related to the physiology of newborns than to cultural factors", says Alessia Nava of the DANTE − Diet and ANcient TEchnology Laboratory at the Department of Oral and Maxillo-Facial Sciences of Sapienza, now "Marie Curie" researcher at the University of Kent (UK) and co-author of the study. "For modern humans, regardless of the type of culture and society, the introduction of solid food into the diet takes place around the sixth month of age, when the child begins to need a greater supply of energy: now we know that the same timing also applied to Neanderthals."

"If we make a comparison with other primates − adds Federico Lugli, researcher at the University of Bologna and co-author of the study − it is very likely that the high level of energy resources required for the growth process of the human brain leads to the need for an early introduction of solid foods into the baby's diet."

This new information makes it possible to reconstruct the important characteristics and behaviour of Neanderthals. In particular, it allows the researchers to exclude that the small number of Neanderthals could be linked to longer weaning times than Homo sapiens, which would have led to lower fertility.

"The results of this study show that Neanderthals and Homo sapiens share a similar energy demand during early childhood and a similar rate of growth", says Stefano Benazzi, professor at the University of Bologna, one of the study coordinators. "These elements suggest that Neandertal infants must have a similar weight to our newborns: this would also indicate a similar gestational history, a similar process of development in the early stages of life and perhaps even a possible shorter interval between pregnancies than previously thought."

The three milk teeth at the centre of the study were found in a limited area of north-eastern Italy, between Vicenza and Verona: at the Riparo del Broion, in the Grotta di Fumane and the Grotta de Nadale. The analysis of the finds, together with information on the diet and growth process of the children, also made it possible to obtain information on the movements of the Neanderthal groups living in that region.

"They moved less than previously assumed", says Wolfgang Müller, professor at Goethe University Frankfurt (Germany), one of the coordinators of the study. "An analysis of the strontium isotopes found in the studied teeth indicates that these children spent most of their time in the vicinity of their birthplace: a behaviour that denotes a modern mentality, probably linked to a careful use of the resources available in that region."

"Although there was a general drop in temperatures during the period analysed, north-eastern Italy has almost always remained a region rich in resources, in terms of food, diversity of natural environments and the presence of caves: all elements that help explain the survival of the Neanderthals in this area up to about 45,000 years ago", says Marco Peresani, professor at the University of Ferrara, one of the coordinators of the study and in charge of the excavations in the Grotta de Nadale, Grotta di Fumane and, together with Matteo Romandini researcher at the University of Bologna, at the Riparo del Broion.

Published in the journal PNAS under the title "Early life of Neanderthals", the study was promoted and guided by Stefano Benazzi, professor at the Department of Cultural Heritage at the University of Bologna and Principal Investigator of the European research project SUCCESS (ERC Starting Grant No. 724046), which aims to understand when modern humans arrived in Southern Europe, the bio-cultural processes that favoured his adaptive success and the causes that led to the extinction of Neanderthals.

Researchers from the University of Bologna, the University of Kent (UK), Goethe University Frankfurt (Germany), the University of Ferrara, the University of Modena and Reggio Emilia, the Institute of Environmental Geology and Geoengineering (IGAG) - CNR, the International Centre for Theoretical Physics "Abdus Salam", the University of Florence, the Sapienza University of Rome, the Natural History Museum of London (UK) took part in the project.

References:

Early life of Neanderthals − Alessia Nava, Federico Lugli, Matteo Romandini, Federica Badino, David Evans,  Angela H. Helbling, Gregorio Oxilia,  Simona Arrighi, Eugenio Bortolini, Davide Delpiano, Rossella Duches, Carla Figus,  Alessandra Livraghi, Giulia Marciani, Sara Silvestrini, Anna Cipriani, Tommaso Giovanardi, Roberta Pini, Claudio Tuniz, Federico Bernardini, Irene Dori, Alfredo Coppa, Emanuela Cristiani,  View ORCID ProfileChristopher Dean, Luca Bondioli,  Marco Peresani, Wolfgang Müller, and Stefano Benazzi – PNAS, 2020. DOI https://doi.org/10.1073/pnas.2011765117

Further Information

Alessia Nava
Department of Oral and Maxillo-Facial Sciences
alessia.nava@uniroma1.it