A devastating hurricane that killed over 3,000 humans also possibly had an unusual effect on a local monkey population.
Making ground in Puerto Rico in September 2017, the deadly weather event also struck the nearby “Monkey Island” of Cayo Santiago, where a group of rhesus macaques has long been studied by scientists.
Examining molecular changes in the rhesus macaques after the storm hit, the researchers found that the storm's impact may have accelerated the aging of the monkeys’ immune systems.
The findings suggest that extreme weather could have a similarly negative impact on human biology, a concerning insight in the context that climate change could trigger an uptick in severe events like this.
"While everyone ages, we don’t all age at the same rate, and our lived experiences, both negative and positive, can alter this pace of aging," said corresponding author Noah Snyder-Mackler, an assistant professor at Arizona State University’s School of Life Sciences, in a statement.
"One negative life experience, surviving an extreme event, can lead to chronic inflammation and the early onset of some age-related diseases, like heart disease. But we still don’t know exactly how these events get embedded in our bodies leading to negative health effects that may not show up until decades after the event itself."
The study, published in the Proceedings of the National Academy of Sciences, looked at blood samples from the rhesus macaques to test if (or how) Hurricane Maria influenced immune cell gene regulation and aging. They then compared the insights from these to age-matched samples collected before the hurricane.
A global analysis of immune gene expression showed that four percent of the monkeys’ immune cell genes were altered after the hurricane. The highest expressed genes were also found to be those connected to inflammation, while genes related to important immune functions were dampened. These included those connected to T cells, adaptive immune response, protein translation, folding, and refolding.
One of the worst affected were the heat shock genes, whose downregulation has been linked to Alzheimer’s and cardiovascular diseases. The results spell bad news for the monkeys. However, given rhesus macaques share behavioral and biological traits with humans, and age similarly, it likely spells bad news for the health of humans following extreme weather events too.
"On average, monkeys who lived through the hurricane had immune gene expression profiles that had aged two extra years, or approximately seven or eight years of human lifespan," said lead author Marina Watowich Watowich, who believes the research may have, at least in part, answered how negative events can get embedded in our bodies and trigger worsening health.
"We [have identified] a critical mechanism – immune cell gene regulation – that may explain how adversity, specifically in the context of natural disasters, may ultimately ‘get under the skin’ to drive age-associated disease onset and progression."
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