For many peopleipl365, aging feels like it happens in stops and starts. After a period of smooth sailing, one day, seemingly out of the blue, you have achy knees.

“You wake up in the morning and you suddenly feel old,” said Dr. Steve Hoffmann, a computational biology professor at the Leibniz Institute on Aging in Jena, Germany. “That’s sort of the takeaway.”

It turns out there may be a scientific basis for this experience. By analyzing age-related markers, such as proteins and DNA tags in the bloodstream, some scientists are coming to understand that aging in adulthood is not a linear process, but perhaps one that jumps dramatically at certain points in one’s life.

Here’s what they’ve learned so far, and what it could ultimately mean for your health and life span.

Scientists have long suspected that aging may happen in bursts, but they only began using molecular signals to measure the pace of aging in the past decade or so.

A widely covered Stanford study published last year tracked several molecular changes associated with aging in blood samples gathered from 108 adults between age 25 and 75. By comparing samples from different subjects of different ages, it found that people seemed to age more rapidly around age 44,66jogo and again around 60. The clusters of changes in the first spike appeared to be mostly related to fat and alcohol metabolism, as well as muscle function, and the second spike mostly to immune dysfunction and muscle function. The first spike could help explain why people seem to have more trouble processing alcohol starting in their 40s, and why they become more prone to illness in their 60s, said Michael Snyder, a professor of genetics at Stanford Medicine and study coauthor.

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In an interview, Mr. Bonta said plastic pollution was “fueled by the myth of recycling, and the leader among them in perpetuating that myth is Exxon Mobil.”

But the victory was hard fought by Scott. After Billboard certified a victory for Carpenter, who had released her “Short n’ Sweet” on the same day as “Days Before Rodeo,” the rapper’s team revealed that they had sent a four-page letter in the days before the chart — which would credit Carpenter with 362,000 sales and Scott with 361,000, in rounded numbers — was finalized. The letter called the chart process “unreliable and incomplete.”

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