Farming transformed mammal communities worldwide over 50,000 years

Fossil evidence from six continents shows that humans reshaped global mammal communities over the last 50,000 years, according to new research published in Biology Letters. During the Ice Age, animal distributions reflected climate zones and geographic barriers. But after the advent of farming 10,000 years ago, livestock species spread with people, permanently disrupting those natural patterns.

Associate Professor John Alroy of Macquarie University, a co-author of the study, explained that agriculture and hunting acted together as powerful forces of ecological reorganization, creating conservation challenges that continue today.

The study revealed that just 12 domesticated species, including cattle, sheep, pigs and horses, appeared at roughly half of the archaeological sites studied, fundamentally altering the makeup of mammal communities.

Lead author Professor Barry Brook from the University of Tasmania said the team examined species records from hundreds of archaeological and palaeontological sites spanning multiple continents and tens of thousands of years.

"All domesticated species had an impact, including donkeys, sheep, goats, pigs and dogs," Alroy noted. "Large ungulates like horses and cows are important because they monopolise food resources wherever they are in high numbers."

Using a new computer-clustering method, researchers showed that domesticated animals connected sites thousands of kilometres apart, while many native wild mammals disappeared after human arrival.

"Over the last 10,000 years or so, humans have overseen the wholesale replacement of native mammal communities with a very limited set of domesticated species," Alroy said. "National parks in the hardest-hit regions, such as Australia and the Americas, lack over half of the native large mammal species that would have been present if not for humans."

Research Report:Late Pleistocene faunal community patterns disrupted by Holocene human impacts