Scientists are still working to understand why Neanderthals went extinct while Homo sapiens established a lasting presence in Europe. The answer is not simple. It likely involves several overlapping factors, but a new study using techniques inspired by digital ecology is offering a clearer picture.
The research was led by Ariane Burke, a professor of anthropology at Université de Montréal and head of the Hominin Dispersals Research Group in Quebec. Building on work by her doctoral students, Benjamin Albouy and Simon Paquin, Burke adapted models commonly used to study the distribution of plants and animals and applied them to ancient human populations. The approach combines archaeological evidence with ethnographic data to better understand how early humans lived and moved.
The team focused on Europe during the last glacial cycle, between 60,000 and 35,000 years ago. This period was marked by dramatic climate swings, shifting between cold (stadial) and warmer (interstadial) phases. It was also the time when Homo sapiens first appeared in the archaeological record in Europe and when Neanderthals disappeared.
Their findings suggest that commonly cited explanations such as climate stress or direct competition alone cannot fully explain Neanderthal extinction. Instead, the outcome appears to have been shaped by a combination of climate, geography, population dynamics, and interactions between species, with conditions varying across different regions.
Modeling Ancient Human Habitats
In ecology, scientists use species distribution models to estimate where a species can survive based on known locations. Burke and her team applied this concept to ancient humans. Instead of modern observations, they used archaeological sites as "presence points" for both Neanderthals and Homo sapiens.
The researchers carried out several modeling steps. First, they built four habitat suitability models for each species using tools from conservation biology and geomatics. These models combined archaeological records with environmental data, including geography and measures of climate variability.
Next, Burke compared the results and developed additional models to identify "core" regions. These were areas large and productive enough to sustain stable populations and, importantly, connected to other such regions.
"Obviously, we don't have precise demographic data for populations living 35,000 years ago, so we used ethnographic data from better-documented ancient hunter-gatherer groups to set parameters for the geomatics tools and generate these models," Burke explained. "For example, these data show that the typical annual territory of a local group of 25 to 50 individuals, moving seasonally and maintaining regional connections with other groups, would be about 2,500 km2."
Social Networks and Survival Advantage
At this stage of the analysis, clear differences between Neanderthals and Homo sapiens began to appear.
Areas suitable for Homo sapiens tended to be more interconnected than those used by Neanderthals. According to Burke, this connectivity was critical. When populations are linked, they form networks that allow people to move between groups when facing environmental, ecological, or demographic challenges.
"These networks act as a safety net," explained Burke. "They allow for the exchange of information on resources and animal migrations, the forming of partnerships, and temporary access to other territories in the event of a crisis."
Burke emphasized that Neanderthals were not completely isolated. Archaeological evidence, such as the movement of materials across regions, shows they also maintained connections. However, the models suggest that these links were weaker and less reliable, especially in Central and Eastern Europe.
Climate Variability and Regional Differences
The study also found that climate variability, meaning how quickly and unpredictably conditions changed, had a stronger impact on populations than average temperature or rainfall alone.
"Climate variability appears to have played a major role. So it turns out that humans have been sensitive to environmental variability throughout our history," said Burke.
Even so, climate by itself cannot explain Neanderthal extinction. Fossil and archaeological records show that Neanderthals survived earlier glacial periods, indicating they were capable of adapting to harsh conditions.
According to the study, their disappearance likely resulted from a combination of climate instability, population pressures, and social structure. The exact mix of factors may have differed depending on the region.
For instance, Neanderthals in Europe appear to have been split into two main groups, one in the west and one in the east. In Eastern Europe, weaker connections between groups may have led to isolation as conditions worsened. In contrast, populations in the Iberian Peninsula, at the western edge of their range, may have lasted longer thanks to better-connected core areas.
The situation may have been even more complex.
"In western areas, the arrival of Homo sapiens may have added further stress, especially for Neanderthal populations that were already demographically vulnerable," said Burke. "Because the two species were capable of producing offspring together, their interactions were likely complex, involving competition, occasional interbreeding and other subtle population dynamics."
A Lesson About Human Connection
Burke believes these findings highlight something fundamental about human survival, both in the past and today.
"Human migration has always existed, facilitated by mobility and social networks," she noted. "Even today, despite the complexities of borders, population densities and social inequalities, humans continue to migrate for the same fundamental reasons: to find more favorable areas, reunite with loved ones and join mutual aid networks."
The research suggests that survival has never depended solely on intelligence or technology. As it was 40,000 years ago, it still depends on the ability to build and maintain connections with others.