We all know that death is inevitable. But if you had a choice: find out the date of your own death or remain in the dark, which option would you prefer? Some researchers believe they have found a clue to the mystery. So how do you predict death?
Experiments with fruit flies have revealed a new phase of life - one that heralds the approach of death. This stage is called the death spiral. Perhaps people could experience the same.
Childhood
Since the mid-20th century, scientists have qualified only two stages of life: childhood and adulthood. This division is clear to everyone. Childhood is caused by the rapid growth of bones and tissues, as well as the development of internal organs and systems. Starting from the moment of reaching puberty, a person goes into adulthood. At this time, the likelihood of death is extremely small.
Adult state
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Now we need to complete the main mission and leave behind offspring. Therefore, in youth, the body is insured against serious and prolonged diseases. But the years go by inexorably. And along with them, the physical aspects of aging are manifested. Bones and internal organs wear out, and the likelihood of death only increases every year.
Third phase of life
At the end of the 20th century, scientists realized that there was another phase of life. The most senior members of society pass through it. The so-called late life differs from the two previous phases in the highest probability of mortality risk. Curiously, however, a 60-year-old is much more likely to die than a 50-year-old. If we compare an individual who has lived to be 90 years old and someone who managed to celebrate his 100th anniversary, their chances of death are regarded as approximately equal. This is what Laurence Mueller of the University of California says. According to the expert, in old age the mortality rate levels off.
Death plateau
This is what distinguishes "late life" from the rest of the adult state of man. The ratio of annual growth to mortality rates does not work at the very end of the human journey. Scientists are still debating why we are seeing this phenomenon. So far, there is no generally accepted conclusion. Lawrence Mueller and his colleague Michael Rose decided to shed light on this issue. They began looking for signs of why biological markers of mortality flatten out at the end of life.
Drosophila fruit flies as test subjects
The scientists set to work in the laboratory. The choice of biological test subjects fell on the fruit flies of Drosophila. More than 2,800 females were selected, each of which was individually housed in a bottle with two males. Each new day, scientists moved on to the next female to calculate how many eggs were laid. The observation continued until every one of the flies died. It was a tedious job, but fruit flies have a short lifespan - only a few weeks. But in order to count, scientists had to take dozens of students to help.
This is how the fourth phase of life was discovered
Despite all the titanic efforts, the results were disappointing at first. Before the start of the experiment, scientists assumed that female fertility follows the same pattern. Therefore, they decided to look for answers in the reproduction of offspring. However, they were expected to fail: the birth rate did not equalize, while the females entered the final phase of life. With each new day, the number of eggs decreased and decreased.
But then the researchers looked closely at the data and realized something mysterious was happening. Laurence Mueller says: "I noticed that when females close to death were separated and compared with other individuals, there was a dramatic difference in fertility." A fly's fertility rate (the number of eggs she laid per day) plummeted two weeks before her death. Thus, the organism of the individual showed a completely predictable death spiral.
Most surprisingly, fertility declines can occur at any age. The inevitable end follows very soon.
Death spiral
This universal feature of life, or the new, fourth stage, is fundamentally different from infancy, maturity, and later life. Scientists have called this phenomenon a death spiral. The experiment was carried out in 2007, and all the following time, researchers have been working to study this issue. So, in 2012, they found that male fruit flies also go through a reproduction decline several days before death. A large number of data collection cycles have been carried out. In the end, scientists learned how to correctly predict about 80 percent of deaths.
As the male gets older, his ability to reproduce drops dramatically. But if an individual prepares to die (whether young, mature, or old), her ability to reproduce is reduced to a critical point.
Conclusion
There is evidence that people doomed to die of natural causes enter a death spiral - this is a natural inevitability. And this does not necessarily happen at the end of life. The human end is associated with age, but for the most part it is associated with fertility. This observation may lead biologists to rethink their theories.