8,000 years of human activities have caused wild animals to shrink and domestic animals to grow
Paul Arnold
contributing writer
Gaby Clark
scientific editor
Robert Egan
associate editor
Humans have caused wild animals to shrink and domestic animals to grow, according to a new study out of the University of Montpellier in southern France. Researchers studied tens of thousands of animal bones from Mediterranean France covering the last 8,000 years to see how the size of both types of animals has changed over time.
Scientists already know that human choices, such as selective breeding, influence the size of domestic animals, and that environmental factors also impact the size of both. However, little is known about how these two forces have influenced the size of wild and domestic animals over such a prolonged period. This latest research, in the Proceedings of the National Academy of Sciences , fills a major gap in our knowledge.
The scientists analyzed more than 225,000 bones from 311 archaeological sites in Mediterranean France. They took thousands of measurements of things like the length, width, and depth of bones and teeth from wild animals, such as foxes, rabbits and deer, as well as domestic ones, including goats, cattle, pigs, sheep and chickens.
But the researchers didn't just focus on the bones. They also collected data on the climate, the types of plants growing in the area, the number of people living there and what they used the land for. And then, with some sophisticated statistical modeling, they were able to track key trends and drivers behind the change in animal size.
The research team's findings reveal that for around 7,000 years, wild and domestic animals evolved along similar paths, growing and shrinking together in sync with their shared environment and human activity. However, all that changed around 1,000 years ago. Their body sizes began to diverge dramatically, especially during the Middle Ages.
Human impact
Domestic animals started to get much bigger as they were being actively bred for more meat and milk. At the same time, wild animals began to shrink in size as a direct result of human pressures, such as hunting and habitat loss. In other words, human activities replaced environmental factors as the main force shaping animal evolution.
"Our results demonstrate that natural selection prevailed as an evolutionary force on domestic animal morphology until the last millennium," commented the researchers in their paper. "Body size is a sensitive indicator of systemic change, revealing both resilience and vulnerability within evolving human–animal–environment relationships."
This study is more than a look at ancient bones. By providing a long-term historical record of how our actions have affected the animal kingdom, the findings can also help with modern-day conservation efforts.
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More information: Mureau, Cyprien et al, 8,000 years of wild and domestic animal body size data reveal long-term synchrony and recent divergence due to intensified human impact, Proceedings of the National Academy of Sciences (2025). .
Journal information: Proceedings of the National Academy of Sciences
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