En esta noticia
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 obtained from animals in 1992 and 2006, before the last specimen was removed in 2010 as part of an ecological restoration program.
What did scientists discover when they analyzed the DNA of the cows from the remote island?
The cattle genome showed two clearly differentiated lineages. Most of it — approximately three quarters — came from European taurine breeds related to today’s Jersey cattle, historically adapted to cold, wet, and windy climates. The remaining quarter corresponded to zebu from the Indian Ocean, 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.
The study’s central finding refutes a 2017 study published in Scientific Reports, which maintained that the herd had experienced accelerated insular 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 indicate that the founders were already small when they arrived, and that their double lineage gave them from the outset the biological tools to adapt to the hurricane-force winds, the cold, and the scarcity of fresh water on Amsterdam Island.
What the DNA confirmed
- Mixed origin: ~75% European taurine (Jersey-type) + ~25% Indian Ocean zebu
- No accelerated dwarfism: no genetic signal of selection for reduced size
- Origin advantage: genetic diversity was present from the five founders
- Rapid expansion: the herd reached nearly 2,000 animals in 1952 and recovered after a disease collapse in 1988
How did they survive 130 years on a remote island with just five cows?
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 hereditary 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.
That this analysis was possible is due to the fact that researchers preserved biological samples in the decades prior to eradication —without there being a formal preservation program when the last animals were eliminated in 2010—, which made it possible to reconstruct, decades later, 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 tree Phylica arborea
- In 1987, a fence was installed and more than a thousand animals were removed from the southern sector
- The last specimen was eliminated in 2010 as part of an ecological restoration plan
- In 2019, UNESCO declared the French Southern Lands and Seas a World Heritage Site