Using the large number of human fossils found in Ice Age Europe, paleoanthropologists have identified a population turnover in Western Europe 28,000 years ago, isolation between western and eastern refugia between 28,000 and 14,700 years ago, and a bottleneck during the most recent Ice Age.
Artistic reconstruction of an Ice Age hunter-gatherer group. Image courtesy of Tom Björklund.
“Around 45,000 years ago, the first modern humans migrated into Europe during the Ice Age, marking the beginning of the so-called Late Paleolithic period,” said Dr Hannes Lassmann, a researcher at the University of Tübingen.
“These early populations continuously inhabited the European continent, even during the so-called Last Glacial Maximum about 25,000 years ago, a time when glaciers covered much of northern and central Europe.”
“Archaeologists have long debated how climate change and the resulting new environmental conditions affected the demographics of hunter-gatherers at the time.”
“The limited number of available fossils and the often poor molecular preservation for ancient DNA analysis have made it very difficult to draw conclusions about the influence of climatic factors on migrations, population growth, decline and extinction.”
Because teeth make up a large part of the fossil record and preserve genetic traits in their morphology, Dr. Rathman and his colleagues compiled a large dataset of 450 dentitions dating from 47,000 to 7,000 years ago.
They focused on morphological features of the teeth – small variations within the dentition, such as the number and shape of cusps on the crowns, the pattern of ridges and grooves on the chewing surfaces, and the presence or absence of wisdom teeth.
“Because these traits are heritable, they can be used to trace the genetic relationships of Ice Age humans without the need for well-preserved ancient DNA,” Dr Lassman said.
“These features are visible to the naked eye, so we also looked at hundreds of publicly available photographs of the fossils.”
The results show that between about 47,000 and 28,000 years ago, during the Middle Glacial Period, populations from Western and Eastern Europe were well connected genetically.
During the subsequent Late Glacial Period, between 28,000 and 14,700 years ago, the researchers found no genetic link between Western and Eastern Europe.
Furthermore, the analysis shows that both regions have experienced significant declines in population size and loss of genetic diversity.
“This dramatic population shift was likely caused by major climate change,” Dr Rathman said.
“Temperatures during this period fell to their lowest values for the entire Upper Paleolithic, culminating in the Last Glacial Maximum, when ice sheets reached their maximum extent and covered large parts of northern and central Europe.”
“The worsening climate changed the vegetation from steppe to primarily tundra, affecting the habitat of prey animals and, consequently, the hunter-gatherers who depended on them.”
“Our findings support the long-held theory that humans were not only pushed southward by the advancing ice sheet but also isolated into isolated refugia with more favourable environmental conditions,” said Dr Judith Beier, also from the University of Tübingen.
Another notable finding of the study is the discovery that Western European populations became extinct during the transition from the Middle to Late Neoglacial and were replaced by new populations migrating from Eastern Europe.
After the Late Glacial Period, temperatures rose steadily again, the glaciers retreated, grassland and forest vegetation returned, and previously abandoned areas could be recolonized for the first time.
The team observed that during this period, the populations of Western and Eastern Europe, which had previously been isolated and significantly declining, began to grow again and migration between the regions resumed.
“Our new method makes it possible for the first time to reconstruct complex prehistoric demographic events using morphological data,” said researcher Dr Maria Teresa Vizzarri from the University of Ferrara.
“To our knowledge, this has never been accomplished before.”
“Our study provides important insights into the demographic history of Ice Age Europeans and highlights the profound impact that climatic and environmental change had on prehistoric human life,” Dr Lassmann said.
“If we want to tackle the complex environmental challenges of the future, we need to urgently learn from the past.”
of Survey results Published in the journal Scientific advances.
_____
Hannes Lassmann others2024. Human demography in Late Paleolithic Europe inferred from fossil dental phenotypes. Scientific advances 10(33);doi: 10.1126/sciadv.adn8129
This article has been edited based on the original release from the University of Tübingen.
