The latest research shows:Millions of years ago, humans nearly became extinct.The three questions of philosophy are, "Who am I? Where do I come from? Where am I going?" It is difficult to answer. Among them, "where do we come from" particularly troubles archaeologists. In the past, through archaeological results, scientists have determined that human evolution began with the primate forest ape, and then passed through four stages: Australopithecus, Homo habilis, Homo erectus, and Homo sapiens. About 1 million years ago was the critical period when Homo erectus gradually evolved into Homo sapiens.
But previously, there has been little research on this critical period of human evolutionary history. An important reason is the lack of key fossil evidence.
Fossils are an important part of evolutionary research. Through fossil analysis, ancient DNA sequencing technology, etc., scientists can relatively accurately explore the evolutionary history of humans through fossils. But in the past, paleontologists faced a problem:
Fossils from 950,000 years ago and within 650,000 years ago are relatively abundant, but fossils between 950,000 and 650,000 years ago are extremely scarce. also,African Homo erectus fossils also suddenly disappeared during this period.
The many African Homo erectus fossils discovered so far all date from about 900,000 years ago, but none have been discovered since then, and they have been replaced by another new human species.
What happened 900,000 years ago? Why did key fossil evidence disappear during this period?
The "history of human evolution" in genes
On September 1, a research paper titled "Genomics inference of asevere human bottleneck during the Early to Middle Pleistocene transition" was published online in the international academic journal Science, which solved this huge mystery in the evolutionary history of human groups.
This research team led by Chinese scientists has created a new theory and method of population genetics and computational biology - Fast Minimum Time Ancestry (FitCoal). This method can avoid the problem of missing fossils and find another way to accurately estimate the existence time and size of ancient human breeding populations directly through the analysis of mutation patterns in modern human genes.
It allows scientists to conduct an unprecedented "census" of ancient humans across the time dimension of millions of years.
In the study, the researchers used FitCoal to analyze and calculate the genome sequences of 3,154 modern human individuals and found:From about 930,000 to 813,000 years ago, extreme cold weather killed about 98.7% of the human population in a short period of time, and the number of individuals dropped sharply from nearly 100,000 to 1,280.
Moreover, this period of population decline lasted for about 117,000 years, and it was not until about 800,000 years ago that the human population suddenly and rapidly rebounded to about 27,000 people. Based on previous research results, the researchers believe thatMaybe it's because humans learned to use fire, was able to survive in a desperate situation in a harsh environment.
In addition, the researchers conducted further verification using sample individuals from two southern African groups. The results still detected the bottleneck period of this ancient human group, and this bottleneck period coincided with the missing link in the fossils of African human ancestors, the disappearance of African Homo erectus fossils, the formation of new ancient human species, and the fusion stage of the two ancient human chromosomes 2.
To put it simply, it was precisely the loss of human groups caused by this mass extinction that led to this blank period of missing fossil evidence. This study directly skipped the problem of missing fossils and used a new FitCoal analysis method to find a unique explanation, and this answer happened to solve the mystery of missing fossils.
The revelation of this history is of great significance to the evolution of human groups. During this huge human bottleneck period, we not only lost 92.8% of human individuals, but also lost approximately 65.85% of genetic diversity, which has had a profound impact on the life and health of modern humans.
Looking Ahead: Solving Diabetes
By using FitCoal to conduct in-depth research on this period of history, scientists may be able to find more key information about modern human health and provide new solutions to some modern human health problems.
Now, researchers have identified a gene that may be related to human susceptibility to diabetes. By tracing the mutation history of this gene, it may help us study the mechanism of diabetes and the reasons why modern people are susceptible to diabetes, thereby preventing or solving the problem of diabetes.
In addition, FitCoal will also be used to reveal key health issues such as the evolution of tumors and the molecular mechanisms of rapid brain volume growth.
In addition, as the most accurate method to estimate the history of effective population size so far, FitCoal can also be applied to infer the historical living conditions of multiple species, including animals, plants, and microorganisms. In the future, further use of FitCoal may bring us greater surprises.