Climate change spurs weight gain in owl monkeys

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. The science-journalism coverage adds useful context, while the strongest evidential footing still comes from the underlying data, papers or institutional documentation.

That matters because Earth science becomes stronger when local observations can be placed inside a broader physical pattern that spans time and geography. The planet operates as a coupled system in which atmospheric, oceanic, cryospheric and solid-Earth processes interact across timescales from days to millions of years. A measurement that captures one variable at one location and one moment has limited interpretive value until it is embedded in the longer series and wider spatial coverage that allow natural variability to be separated from forced change. This article has been reviewed according to Science X's editorial process and policies. 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.

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. The weight gain coincided with a period when daily mean temperatures in the region increased by more than 1 degree Celsius.

We found that owl monkeys today weigh more, not less, than they did in 1999, even though average temperatures have increased since then," said lead author Jonathan Pertile, a Ph. The new findings are based on data collected by the Owl Monkey Project over 24 years from 180 owl monkeys at a field site on a privately owned cattle ranch in Formosa, Argentina.

The mean daily temperatures in the region over the course of the study period increased from 22.2 degrees Celsius in 1999 to 23.8 degrees Celsius in 2023, according to the study. They also measured the animals' body lengths, from the crown of their skulls to the base of their tails.

The broader interest lies in linking the observation to climatic, geophysical or environmental dynamics that extend well beyond the immediate event or location. Earth science is unusual in that its most important questions operate on timescales that no single research career can observe directly, making the archival record, whether in ice, sediment, rock or satellite data, as important as any new measurement. Results that can be embedded in that record, and that either confirm or challenge the patterns it reveals, carry disproportionate scientific weight.

(Some individuals were measured repeatedly over the years. ) Discover the latest in science, tech, and space with over 100, 000 subscribers who rely on Phys. org for daily insights. Jonathan Alexander Pertile et al, Rapid weight increases in a primate population: evidence of a plastic response to climate change, Proceedings of the Royal Society B: Biological.

Because this item comes through Phys. org Biology as science journalism, it should be treated as contextual reporting rather than primary evidence. Good science reporting can identify why a result matters, connect it to the wider literature and make technical work readable, but the decisive evidence remains in the original paper, dataset, mission release or technical record. That distinction is especially important when a story is later repeated by aggregators, because repetition increases visibility, not evidential strength.

The next step is to place the result inside longer time series and to compare it with independent instruments and independent sites. Earth system observations gain most of their interpretive power from network density and temporal depth, not from any single measurement however precise. Model simulations that assimilate the new data will help clarify whether the observation fits comfortably within known natural variability or represents a shift that existing models do not reproduce.

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