age: the study of tooth fossils 3 million years ago showed that grandparents were common in the late stages of human evolution. The author calculated the proportion of the 4 groups of old people (the age of grandparents) and the number of young individuals. The 4 groups were the southern apes, the early members of the genus, the Neanderthal and the early European modern. The author found that the ratio of older individuals to young individuals increased slowly throughout the process of human evolution, and a leap was made until about 30 thousand years ago.
Wall Boff's research shows that Neanderthal people in the ruins of the Clara site are young when they die. After studying the evolution of life over several years, I decided in 2005 to re observe these samples with a new method. I want to confirm whether we have some old Neanderthal samples slipped out of our eyelids because of the inherent limitations of the wear analysis. I am with Yakov Radovi (Jakov Radovic) of National Museum in Croatia, Steven A Goldstein of the University of Michigan in the United States (Steven A. Goldstein), Geoffrey A Jeffrey A. Meganck) and Danner L. Dana L. Begun), together with a number of students from the central University of Michigan, developed a new nondestructive method, high resolution three-dimensional computer X ray tomography ("micro CT"), to reassess the death age of Neanderthals in the site of clarana. We observe a tooth for secondary dentine (secondary dentin) organization, content of this material will increase with the increase of age, when the crown is worn, is helpful to judge a person's age is how much of the content of secondary dentin.
with the help of the German Institute of evolutionary anthropology, our preliminary findings confirm Wall Boff's results, and the wear analysis has also stood the test: the death rate of the Neanderthals was very high in the clarinna site, and no one lived over 30 years (not all Neanderthals. Neither of them lived 30 years old. A few of the Neanderthal fossils at other sites lived to 40 years old.
according to today's standards, the situation of the Clara site is unthinkable. After all, for most people, the age of 30 is a strong year. The life expectancy of hunters living in recent times is over 30 years old. However, the Neanderthal situation at the site of the Clara site is not uncommon in early humans. Some of the other sites that have unearthed a large number of human fossils are similar to those of the Neanderthals, such as the heather rift site in the Atta Poka region of Spain, where the unearthed human fossils are about 600 thousand years ago. At this site, the mortality rate of young adults is very high. No one lives over 35 years old, and even a handful of people who live to this age are numbered. Perhaps the conditions of the disaster or the remains in petrochemical industry are not conducive to the preservation of the remains of the elderly in these sites. But after a wide survey of fossil records, my colleagues and I believe that in ancient humans, early death was a common phenomenon, not a case, because the fossils we investigated were not only from sites with unusual amounts of unearthed fossils, as well as sites with very small amounts of unearthed unearthed sites. In the words of Thomas Hobbes, Thomas Hobbs's prehistoric life is sinister, barbarous and ephemeral.
micro CT is a potential technology. Through it, we can study paleo human fossils carefully and deeply to determine the age of the elderly. But a few years ago, this technology had not yet appeared. When I and Li Xiangxi (Sang-Hee Lee) at University of California in the United States were ready to look at the history of human evolution and look for evidence of the evolution of human life, we used the best way we could find at the time: tooth wear analysis.
but we are facing a severe challenge. Most of the human fossils are not unearthed from the sites such as Clarina (with a large number of human fossils, and these fossils come from the same human population). The fewer samples, the less reliable statistics, and the less fossil samples excavated from a site, the harder it is to estimate the average death time of human individuals accurately.
, however, we can find another way to answer the general question when grandparents began to exist. We are not going to study how long the early humans lived, but we started from another question: how many people are there in these individuals? That is to say, we no longer pay attention to absolute age, but calculate relative age, and find out the proportion of adults who can live to grandparents. Our goal is to assess the change in the proportion of elderly people and young people, that is, ratio of older to younger adults (OY). In primates, including modern humans who appear very late, the third molars are usually sprouting up in adulthood and in reproductive capacity. According to the Neanderthals and the related data of the ancient humans of the same period with hunting hygiene, we estimate that in these ancient humans, about 15 years old, they had third molars and had the first child. After careful consideration, we intend to take the age of 30 as the age when ancient humans first became grandparents. As in today's case, some women may have a first child at the age of 15, and their children have the next generation at the same age, making their mother a grandmother.
in our view, any fossil human fossil over the age of 30 can be regarded as an elderly person, or a grandparent. The advantage of the OY value is that the number of older or younger individuals will not be affected regardless of age at age 10, 15 or 20, since the beginning of the age will change accordingly. Moreover, since we only divide the fossils into two categories of youth and age, we can analyze a variety of small fossil groups without considering the impact of uncertainty of absolute age.
we calculated the OY values of 4 large batch of fossil samples, which came from 768 ancient humans with a time span of about 3 million years. The first fossils were late Southern apes (australopithecines), both of the close relatives of "Lucy", living in East Africa and South Africa 1 million 500 thousand ~300 million years ago. Another group of early members belonging to human beings spread around the world 500 thousand ~200 years ago. The third group is the European Neanderthal (Neandertals) 30 thousand ~13 years ago. The last batch of modern people in the early stage of the late Paleolithic period lived about 20 thousand ~3 years ago, leaving us with exquisite cultural relics.
