origin: Sina integrated global science WeChat public number writing Rachel card Spari (Rachel Caspari) translation Lu Yan Li Hui
nowadays people usually live long enough to have the chance to become grandparents, but this is not always the case in history. Until 30 thousand years ago, grandparents were common in early modern European families. The surge in the number of older people has become the driving force of new tools and innovations in Europe at the same time. This is perhaps the secret of our success.
1963 summer, when I was 6, my family started from Philadelphia and went to visit relatives in Losangeles. I am very familiar with my grandmother because she helped my mother take care of me and my twin brother 18 months younger than me. Grandma lived with her mother before she lived with us. This summer, I met my grandmother's mother for the first time. I came from a long life family. My grandmother was born in 1895, and her mother was born in 1860. Two people finally lived 100 years old. I got along with two old people for a few weeks, and from the stories they told me, I knew where my roots were and where I was in this four generation of social networks. Along with their memories, I seem to have come to the end of the American Civil War, the reestablishment of the beginning of the period, the hardships that my grandparents have experienced, and their insistence on the faith of the heart.
this is not my unique story. In the human society, the elderly play an important role. They speak and teach, transmit wisdom, and provide economic and social support for their families and larger family groups. In modern society, people's life expectancy is usually longer, and in the end they will become grandparents. But in the history of mankind, the role of grandparents is not always there. So when did grandparents become popular and how did they influence human evolution?
research by my colleagues and I showed that grandparents' elderly talents began to become popular until the relatively early period of prehistory. Moreover, with the emergence of this change, human culture has changed at the same time, and it is obviously moving towards the direction of modern behavior. For example, the communication between each other depends on the character symbol, and the symbolic communication is the basis of art and language. These findings suggest that longevity has a profound impact on population, social and early modern people, and can even explain why modern people are able to compete in the competition with Neanderthals, such as the ancients.
age evidence on the tooth
to find out when grandparents began to become a fixed group in the human society, we must first know that in the past, the percentage of the population of all age groups, namely, the percentage of the parents of children, the childbearing age and the young adults. It is very difficult to reproduce the population of ancient human beings. On the one hand, there is no fossil record of the entire ancient human race. Paleontologists are more interested in studying individual fossils. On the other hand, the rate of maturation of early humans is different from that of modern humans, even in modern humans. But in some ancient human sites, scientists have unearthed a large number of human fossils from the same stratum, and they can accurately estimate the age of death of these ancient humans - which is crucial to understanding the population of prehistoric human populations.
in the town of Clara, about 40 kilometers northwest of Zagreb, Croatia, there is a rock shed site. About a century ago, the Croatia paleontologist Dragutin Joyanovich - clam Berg (Dragutin Gorjanovic-Kramberger) discovered fragments of about 70 Neanderthal remains, most of which were in the same stratum, about 130 thousand years ago. Many fossils are very close to each other, and it is easy to see that this soil layer is rapidly accumulating. In addition, the unique genetic characteristics of many remains suggest that the fossils of the Clara site are likely to come from the same Neanderthal population. Like most fossils, the best preserved tooth in the cave is the tooth fossils, because the mineral content in the teeth is high and it is not easy to degrade. Fortunately, tooth fossils are the best material to identify the age of death by analyzing the wear and tear of the surface, as well as the age - related changes in the internal structure. In
1979, before I began to study the evolution of grandparents, Milford H Wall Boff of University of Michigan in the United States (Milford H). Wolpoff) published an article using tooth fossils to study the death time of Neanderthals in the ruins of Cola Pina. As the molar tooth erupted in a certain order, the Milford reference record, the earliest time for modern people to germinate teeth, estimated that the eruption time of the first, second and third molar teeth of Neanderthals were about 6, 12 and 15, respectively. In human life, the wear and tear produced by chewing will accumulate at a stable rate, so when the second molar has just erupted, the first molar has experienced 6 years of wear and tear. When the third molar just erupted, the second molar has gone through 3 years of wear.