The Evolution of Domestic Animals: Size Increased Drastically Over Time

It turns out that domestic animals became larger over time. Scientists have taken a closer look at the fossils of domestic species and found that as they grew closer to humans, they also grew bigger.

In this latest study, the scientists examined data taken from the remains of domestic animals, including cows, sheep and pigs, salvaged on archaeological sites across the Iberian Peninsula. The measurements came from a total of 41 sites dating between the Roman era and today.

So what did they find? It turns out there were successive changes in the size of domestic animals over time relating to changes in the landscape and production systems. More specifically, they became larger.

"The increase in animal size is normally linked to improvements of an environmental type (for example to new ways of feeding) or of a genetic type (for example, by importing larger animals," said Idoia Grau, one of the researchers, in a news release.

In Roman times, there was interest in improving cattle. During the first centuries after the fall of the Roman Empire, though, cattle largely stayed the same. Then between the 8^th and 9^th centuries, domestic animal size reached a minimum; this size condition could be linked to the spread of semi-free foraging practices during the Early Middle Ages. After the High Middle Ages and Late Middle Ages, the size of animals began to increase progressively, especially for that of sheep.

It's only in the modern era, though, that animal size reached its maximum. This reveals exactly what occurred over time and how animals changed size due to human practices during these time periods.

The findings are published in the journal Quaternary International.

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