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In 1871, a farmer named Heurtin abandoned five cows on Amsterdam Island, a 54-square-kilometer French territory lost in the southern Indian Ocean.
That small founding group became a herd of thousands of animals that survived for more than a century in extreme conditions. In 2024, geneticists analyzed their DNA — preserved decades before their extinction — and the results dismantled a theory that science had taken for granted.
The study was published in July 2024 in Molecular Biology and Evolution, led by geneticist Mathieu Gautier with researchers from INRAE and the University of Liège.
The team worked with samples taken from animals in 1992 and 2006, before the last specimen was removed in 2010 as part of an ecological restoration program.
What scientists discovered by analyzing the DNA of the remote island cows
The cattle genome showed two clearly differentiated lineage groups. Most of it — about three quarters — came from European taurine breeds related to today’s Jersey, historically adapted to cold, wet, and windy climates. The remaining quarter corresponded to Indian Ocean zebu, linked to cattle from Madagascar and Mayotte.
That combination, already present before arriving on the island, would explain why five animals were able to thrive in such a hostile environment.
What the DNA confirmed
- Mixed origin: ~75% European taurine (Jersey-like) + ~25% Indian Ocean zebu
- No accelerated dwarfism: no genetic signal of selection for reduced size
- Origin-based advantage: the genetic diversity was present from the five founders
- Rapid expansion: the herd grew to nearly 2,000 animals in 1952 and recovered after a disease collapse in 1988
The study’s central finding refutes a 2017 study published in Scientific Reports, which claimed the herd had experienced accelerated island dwarfism: a reduction of up to three quarters of its original size in just over a century.
The genetic analysis found no sign of selection for reduced body size. The data suggest that the founders were already small when they arrived, and that their dual lineage gave them from the outset the biological tools to adapt to Amsterdam Island’s hurricane-force winds, cold, and lack of fresh water.
How five cows survived 130 years on a remote island
With so few founders, inbreeding was inevitable for generations. The researchers estimated inbreeding levels close to 30%, a threshold that in most animal populations triggers inherited diseases and can lead to extinction.
However, the herd did not collapse: no signs were detected of an accumulation of harmful genetic variants or population decline.
What prevented collapse was the speed of growth. The herd expanded quickly enough to maintain genetic diversity before inbreeding could erode it.
This analysis was possible because researchers preserved biological samples in the decades before eradication — without there being a formal preservation program when the last animals were removed in 2010 — allowing them, decades later, to reconstruct the complete genetic history of a herd that began with five cows on a remote island.
Why the herd was eliminated
- The cattle threatened endemic species such as the Amsterdam albatross and the Phylica arborea tree
- In 1987, a fence was built and more than a thousand animals were removed from the southern sector
- The last specimen was removed in 2010 as part of an ecological restoration plan
- In 2019, UNESCO declared the French Southern Lands and Seas a World Heritage Site