As stated by Benjamin Franklin, in the world are known for only two things: death and taxes. However, while the inevitable nature of death is indisputable, so far, few were willing to predict when it will occur. A watershed can be research scientists from California, who claim to have discovered the fourth phase of life “spiral of death”.
The subject of the research carried out by a team of Laurence Mueller of the University of California in Irvine was the life of fruit flies. Based on many observations, scientists have found that it is possible to extract in the life cycle of the fourth phase, which heralds death. Researchers have identified it as the “death spiral” and claim that there are bases to believe that this phenomenon also applies to people.
Two, three or maybe four steps?
About 25 years ago, biologists argued that human life consists of two stages: childhood and adulthood. The first phase is characterized by rapid growth and development, and the other begins with the attainment of sexual maturity. Around 1990 the Division was, however, the modified-biologists have determined that it is necessary to extract the third period-old age. What distinguishes “late life” from maturity, is a unique model of mortality.
In the case of adulthood increase in the risk of death is visible from year to year. This diagram does not, however, apply at the end of his life. In other words, the 60-year-old is much more vulnerable to the risk of imminent death, than the 50-year-old. An interesting relationship appears, however, in those who manage to cross the border. Namely: 90-year-old has more or less the same chance that he would die, like the 100-year-old.
Scientists argue over how such a relationship, however, so far no one has provided a coherent and satisfactory explanation. Lawrence Muller and Michael Rose decided to look for other outside mortality indicators, where the level is lowered in the late period of life. Put on fertility.
“Spiral of death”
To research used more than 2800 female fruit flies. Each of them were placed in a vial with two males, each day moved to the next vial and counted how many eggs female left in the previous. The study was carried out until the death of the insect. Mueller acknowledged that the scale of the experiment was enormous, but the results initially seemed disappointing. There have not been a clear decline in the birth rate at a time when the flies come into phase “late life”.
Over time, however, the researchers found something quite different. “When I sent the females that were near death and I compared them with others of the same age, surviving even the next few weeks, I noticed the difference in fertility,” said in an interview with BBC Mueller. In other words-fertility much decreased clearly two weeks before their death. What’s even more important, the accuracy was observable whatever the age of the insect. Just as decreased fertility flies 60-day that was coming to the end of life, as well as 15-day, just before his death. These studies, conducted in 2007, led their authors to the hypothesis of the existence of the fourth phase of life, which they called as the “spiral of death”.
In the following years, further research was carried out. Parvin Shahrestani in 2012, he discovered that a similar decline in fertility in the days leading up to the death can be observed also in male fruit flies.
How “spiral of death” apply to people?
In 2016, Mueller and Rose once again returned to research on the “spiral of death”. This time have already the results of experiments carried out in the four independent laboratories. Again, after their examination, they found that you can extract in the life cycle of flies fourth stage. Based on the observation of fertility rates flies three days, regardless of its age, the researchers were able to largely cases to determine when you will be her death. “In about 80% of the cases correctly anticipated, when there will be death,” said Mueller.
Scientist argues that the “spiral of death” can be observed in people who die of natural causes. Although the relationship between fertility and death on fruit flies has been shown by other scientists, not all are convinced that this diagram also works in humans and other animals. Against such extension of this regularity, as well as the same concept of “spiral of death” is James Curtsinger from the University Looked, which ran similar studies and achieved similar results.
Mueller, however, weapons of their hypothesis, citing research carried out at home for the elderly in Denmark in a group of 90-year-old volunteers. Tested their efficiency, coordination and mental acuity. After a few years, scientists have tested that test before people are still alive. It was found that the old couple who have had worse test results, died. People who died were those who coped less well in tests-indicated Mueller. As he added, “in the run-up to the death, a noticeable decrease of physical capabilities.”