Warmer Temps, Heavier Owl Monkeys: Climate Linked to Weight Gain in Primates

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Azara’s owl monkeys, a small primate species found in South America, are heavier today than those that lived a quarter-century ago, and evidence suggests that rising temperatures might have driven the weight gain, according to a Yale-led study of a wild population.

Azara’s owl monkeys, a small primate species found in South America, are heavier today than those that lived a quarter-century ago, and evidence suggests that rising temperatures might have driven the weight gain, according to a Yale-led study of a wild population.

The study — the first to link climate change to weight changes in living primates — is based on 287 weight measurements of 180 owl monkeys collected between 1999 and 2023 in Formosa, Argentina. The researchers found that the monkeys were about 50 grams (1.8 ounces) heavier in 2023 than in 1999, an increase equivalent to 4% of the mean adult weight of 1,300 grams (2.87 pounds).

The weight gain coincided with a period when daily mean temperatures in the region increased by more than 1 degree Celsius. The researchers also found that that warmer temperatures in a monkey’s first year of life predict heavier weights when they’re older.

Read More: Yale University

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