Early ancestral asphyxia nearly wiped us out!

The basic syntax of our new inference method is shown. The image depicts a cliff painting, showing hominid populations coming together to escape an unknown danger in the dark during a severe ancient bottleneck. Credit: Shanghai Institute of Nutrition and Health, CAS

A new method of inferring ancient population size has revealed a severe bottleneck in the human population, which nearly wiped out the chance of humanity as we know it today.

The unexplained gap in the African/Eurasian fossil record can now be explained thanks to the team Researchers from China, Italy and the United States. Using a new method called FitCoal, the researchers were able to accurately identify demographic inferences using recent human genome sequencing from 3,154 individuals. These results indicate that early human ancestors went through a long and severe bottleneck phase, in which approximately 1,280 individuals were able to maintain the population for approximately 117,000 years. While this research has shed light on some aspects of early to middle Pleistocene ancestors, there are many questions to be answered since this information has been revealed.

FitCoal methodology

A large amount of genomic sequences were analyzed in this study. However, “the fact that FitCoal can detect such a severe ancient bottleneck even with only a small number of sequences is quite an achievement,” says lead author Yun-Shin Fu, a theoretical population geneticist at the University of Texas Health Science Center at Houston.

The researchers will publish their findings online Sciences On August 31, 2023 (US Eastern Time). Results mapped using FitCoal to calculate the probability of the current genome sequence finding that early human ancestors experienced a massive loss of life, and thus a loss of genetic diversity.

The fossil hiatus of African hominins and the estimated time period of chromosome fusion are shown on the right. Credit: Science

Fossil Gap Interpretation

“The gap in the African and Eurasian fossil records can be explained by this bottleneck in the Early Stone Age in historical terms. It coincides with this proposed time period for a significant loss of fossil evidence,” says senior author Giorgio Manzi, an anthropologist at the Sapienza University of Rome. Reasons Proposed for this decline in hominin numbers is mostly climatic: glaciation events at this time lead to temperature changes, severe droughts, and loss of other organisms. classifyIt was likely used as a food source for ancestral humans.

Genetic diversity and human evolution

The repercussions of this bottleneck are staggering. An estimated 65.85% of current genetic diversity may have been lost to this suffocation in the early to middle Ice Age, and the prolonged period of reduced reproductive numbers threatened humanity as we know it today. However, this bottleneck appears to have contributed to a speciation event in which two ancestral chromosomes may converge to form what is now known as chromosome 2 in modern humans. With this information, the last common ancestor of Denisovans, Neanderthals, and modern humans (Homo sapiens).

Discover new questions

We all know that once a question is answered, more questions arise.

“The new discovery opens a new field in human evolution because it raises many questions, such as where these individuals lived, how they overcame catastrophic climatic changes, and whether natural selection through a bottleneck accelerated the evolution of the human brain,” says the lead author. Yi Hsuan Pan, an evolutionary and functional genomics specialist at East China Normal University (ECNU).

Now that there is reason to believe that ancestral conflict occurred between 930,000 and 813,000 years ago, researchers can continue searching to find answers to these questions and reveal how this small population survived in difficult and dangerous circumstances. The control of fires, as well as the climate becoming more hospitable to human life, may have contributed to the subsequent rapid population increase about 813,000 years ago.

“These findings are just the beginning. With this knowledge, future goals aim to paint a more complete picture of human evolution during this transitional period from the Early to the Middle Pleistocene, which in turn will continue to unravel the mystery of early human origin and evolution.” Theoretical population geneticist and scientist Computational Biology at the Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (SINH-CAS).

Reference: “Genomic Inference of Human Severe Bottleneck During the Early to Middle Pleistocene Transition” by Wangji Hu, Ziqian Hao, Pengyuan Du, Fabio Di Vincenzo, Giorgio Manzi, Jiang Cui, Yun-Xin Fu, Yi-Hsuan Pan, and Haiping Li 31 August 2023 Sciences.
doi: 10.1126/science.abq7487

This research was co-led by Haipeng Li at SINH-CAS and Yi-Hsuan Pan at ECNU. Their collaborators, Fabio De Vincenzo from the University of Florence, Giugio Manzi from Sapienza University in Rome, and Yun Shin Fu from the University of Texas Health Science Center at Houston, made important contributions to the results. The first authors of the paper are Wangjie Hu and Ziqian Hao who used to be students/trainees of SINH-CAS and ECNU. They are currently affiliated with the Icahn School of Medicine at Mount Sinai, Shandong First Medical University and Shandong University Academy of Medical Sciences, respectively. Pengyuan Du of SINH-CAS and Jialong Cui of ECNU also contributed to this paper.