STUDY: How animal agriculture and hunting reshaped the animal world across the globe

After farming began about 10,000 years ago, just a handful of livestock species spread along with humans and scrambled natural boundaries forever. Examining archaeological records, the researchers found just 12 domesticated species — including cattle, sheep, pigs, horses, donkeys, goats, and some birds —  fundamentally altered the composition of animal communities. Since domesticated farm animals monopolize food resources wherever they are in high numbers, many wild mammals went extinct…

New fossil research shows how human impacts, particularly through the rise of agriculture and livestock, have disrupted natural mammal communities as profoundly as the Ice Age extinctions.

Fossil bones from six continents have revealed how people have fundamentally transformed mammal communities across the globe, according to new research that traces 50,000 years of animal history.

The international study, published last month in Biology Letters, shows that during the last Ice Age, mammal communities formed distinct patterns across continents based on natural climate zones and geographic barriers. But after farming began about 10,000 years ago, just a handful of livestock species spread along with humans and scrambled those natural boundaries forever.

“The study shows how agriculture and hunting combined as powerful global forces to reorganize ecosystems, which still creates conservation challenges today,” says Associate Professor John Alroy from Macquarie University, a co-author on the study…

Examining archaeological records, the researchers found just 12 domesticated species—including cattle, sheep, pigs and horses—appeared in roughly half of the global sites studied, fundamentally altering the composition of animal communities.

“After farming began, just a handful of livestock species spread with humans and scrambled those natural boundaries, reshaping mammal communities worldwide,” says Professor Brook.

Domesticated animals which had an outsized impact included familiar farm animals.

“All domesticated species had an impact, including donkeys, sheep, goats, pigs and dogs,” Associate Professor Alroy says. “Large ungulates like horses and cows are important because they monopolize food resources wherever they are in high numbers.”

While the study excluded birds from the main analysis due to their erratic fossil record, Associate Professor Alroy says that domesticated chickens were also found at 29 of the 350-plus sites, mostly in Europe and the Middle East.

The researchers developed a new computer-clustering method to show that domesticated animals link Holocene archaeological sites thousands of kilometers apart. At the same time, many wild mammals went extinct, in each case following human arrival — not during a particular worldwide climate change episode…

Some researchers link past species extinctions deep in Earth’s history to human hunting or major shifts in climate, despite major climate changes in the Pleistocene being either mostly beneficial to mammals or not coinciding with extinctions.

However, this study shows hunting-related Pleistocene species extinctions were complemented by very different agricultural impacts in the Holocene.

“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,” Associate Professor Alroy says. LISA LOCK

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