Neanderthal life has been portrayed as historically highly stressful, shaped by constant pressure to survive in harsh ecological conditions, which may have contributed to their extinction. In a new study, paleoanthropologists analyzed the frequency of dental enamel hypoplasia, an indicator of growth impairment due to early life stress, in the largest sample of Neanderthals and Upper Paleolithic humans. Their findings support similar overall stress levels in both groups, but show that there are species-specific patterns in the distribution of its occurrence. They found that the likelihood of growth impairment increased during the weaning process in Neanderthal children and culminated in intensity after weaning, whereas growth impairment in Upper Paleolithic children was limited to the time of weaning and significantly decreased after its expected completion. These results may reflect differences in parenting and other behavioral strategies between the two species, including some that may be advantageous for long-term survival in modern humans.
Neanderthal family. Image courtesy of the Field Museum.
“Neanderthals have traditionally been depicted as living highly stressful lives, including pressures to survive in the harsh and highly variable ecological conditions of Pleistocene Eurasia, which have been thought to have contributed to their extinction,” said Dr Laura Rimmer from the University of Tübingen and her colleagues.
“Modern Upper Paleolithic humans faced similar environmental conditions, but it is generally assumed that they were better equipped to buffer such pressures through their behavioral repertoire.”
“This includes strategies such as greater flexibility and efficiency in resource use and more complex social organisation and networks.”
“Their behavioral repertoire is thought to have given modern humans a competitive advantage over Neanderthals during the Upper Paleolithic, allowing them to survive while Neanderthals became extinct.”
“However, several recent studies have cast doubt on this view, arguing that Neanderthals and modern Upper Paleolithic humans lived similarly stressful lives.”
For the study, the researchers analyzed the enamel of 423 Neanderthal teeth and 444 Upper Paleolithic human teeth.
The researchers investigated early life stress in these individuals by identifying thin horizontal grooves in the enamel that previous studies have demonstrated are associated with early life stressors such as illness, infection, malnutrition, nutritional deficiencies and trauma.
The researchers found that the overall likelihood of enamel defects was similar in the teeth of Neanderthals and modern Upper Paleolithic humans.
“However, we observed that the distribution of dental enamel defects varied across developmental stages: in modern humans, enamel defects were more likely to occur around the time of weaning,” Dr Rimmer said.
In Upper Paleolithic humans, enamel defects were more likely to occur around the age when weaning was estimated to have occurred (between 1 and 3 years) than after the estimated weaning period.
In Neanderthals, enamel defects began to appear during weaning (around 1 year of age), peaked during late weaning (between 2 and 4 years of age), and then tended to decrease.
Scientists hypothesize that the stress experienced by Upper Paleolithic human children during weaning may have been due to increased energy demands that increased their risk of malnutrition.
They propose that Late Paleolithic humans may have helped to reduce developmental stress in their offspring after weaning through strategies such as encouraging long-term dependency on parents, using resources more efficiently and providing offspring with access to food.
They suggest that these strategies may not have been used by Neanderthals, which may have contributed to the long-term survival advantage of modern humans compared to Neanderthals.
“Modern humans may have gained an advantage over Neanderthals by providing better support for their young during these difficult times, such as by protecting them for longer or by providing a better food supply,” said Dr Shireen El-Zaatari, a researcher at the University of Tübingen.
“Neanderthals lived in a particularly cold and harsh climate, which is often said to have led to their extinction.”
“But because over a period of time Neanderthals and modern humans were exposed to the same climatic conditions, we are investigating other explanations.”
of study Published in a journal Scientific Reports.
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LS Rimmer others2024. Differences in childhood stress between Neanderthals and early modern humans reflected in impaired dental enamel growth. Scientific Reports 14, 11293; doi: 10.1038/s41598-024-61321-x
Source: www.sci.news
