Even if we don’t realize it, we are all familiar with the stages of life. Childhood is followed by the longest time of adulthood, with all of its concomitant development and progress. This, clearly, can continue decades and is connected with an exponential risk of mortality as individuals age. This ultimately leads to a third stage of life known as “late life,” in which people’s risks of dying strangely plateau before they die.
According to the BBC, recent study shows that rather than being confined to only three stages of life, there may be a fourth. Researchers claim to have identified the “death spiral” by examining how fruit flies mature, which has enabled them to forecast when a fly would die with an 80 percent accuracy. In another surprise, they even suggest that this phase may be present in people as well, but some are unconvinced.
The late life phase was found for the first time in the 1990s. Scientists discovered that, while the probability of dying from natural causes grew consistently as people aged, this relationship broke down as people reached extreme old age. They discovered that a 90-year-old had the same probability of dying as a 100-year-old. The researchers were taken aback by the leveling out in the pattern of mortality, and it is still unclear what caused it.
However, it was the revelation of one enigma that led to the discovery of another. A third set of researchers discovered an abnormality when studying the late life phase of fruit flies, which are frequently employed as model organisms by scientists due to their short generation period and rich understanding of their genetics and biology. They observed that regardless of a female fly’s age, her fertility decreased in the two weeks preceding her death. This was soon discovered to be true of the male fly’s fertility as well. It might be because generating eggs for a female fly is expensive, and if they are close to die, they may give up on it.
This decline in fertility was nicknamed the researchers’ “death spiral,” and by observing how individual female fly fertility declined over a three-day period, they were able to forecast – to a limited extent – when they would die. Other studies from different researchers have supported this relationship between fertility and death, albeit it is unclear how applicable this is to people.
[H/T: BBC]
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