Death has always been regarded as the inevitable destination of all life and an inescapable fate. Darwin wrote so many books and discussed all aspects of life science, but he didn't waste a drop of ink on the issue of death. It seems that this problem is not worth discussing at all.
However, with more and more knowledge of nature accumulated by human beings, this problem becomes more and more uncertain. Bacteria, for example, seem to be immortal and will split forever as long as conditions permit. Moreover, the division of bacteria is divided into two on average, so it is difficult to distinguish who are parents and who are children, so it is difficult to define the life span of bacteria.
If the surrounding environment is not good, bacteria will become spores, suspend all life activities and wait patiently for rebirth. This cycle can last forever, without end.
Cells of higher animals and plants may never die, such as human cells used by scientists for experiments. You have the ability to live forever. You can reproduce in a Petri dish forever. Most of these cell lines are taken from patients' malignant tumor tissues. For example, the famous Hella cell line was taken from a black American woman named Harriet Lax, whose cancer cells are still alive and spread all over the world. In a sense, she also won eternal life. However, the traditional sense of immortality seems a bit out of place when discussing multicellular higher organisms, because harsh nature always thinks of various ways to kill them, such as hunger, drought, fires and earthquakes, storms and infectious diseases.
Suppose an alien wants to study how long humans can live. He randomly selected 65,438+000 people from the earth, put them in cages and ate delicious food every day. What do you think will happen to him?
Perhaps we should look at the aging speed of various creatures from another angle, and only in this way can we more accurately reflect the fate of different species. The measurement of aging speed has been explained in detail above, but when we turn our eyes to the whole biosphere, the measurement method of aging speed will change. It is impossible to measure the methylation biological clock of each organism, and even their metabolic rate is difficult to measure. So scientists changed their ways and took mortality as a measure of aging. In other words, the higher the death rate of an organism in nature, the higher its aging degree.