Humans were once at risk of extinction

During 1 million years of history, human beings have had periods of "bottlenecks" in the development of numbers in certain periods where the number of deaths was greater than the number of births.

Scientists at the University of Utah (USA) have calculated that 1.2 million years ago, the period when our ancestors were scattered in Africa, Europe and Asia, the population worldwide only about 18,500 people (and cannot exceed 26,000), meaning less than chimpanzees (gorilla, a total of about 25,000) and gibbons (chimpanzee, about 21,000 individuals).

Modern humans, if based on genetic variables, are inferior to other primates. In the history of their existence, there have been times when they have met the "bottlenecks" in the development of numbers in certain periods where the number of deaths is greater than the number of births.

Humans have been in danger of extinction - Photo: blogspot.com

For example, the Toba 'super volcano' erupted in Indonessia 70,000 years ago, causing a nuclear winter, only 15,000 survived. Another calculation shows that during the past 2 million years, the number of people on the planet did not exceed 20,000.

The use of new methods based on genetic markers in genomics has enabled scientists to study Genetics not only to understand modern humans but also our earliest ancestors as Humans stand. straight (Homo erectus, often referred to as a direct ancestor of humanity), Home ergaster and ancient Homo sapiens. As a result, scientists have had enough information about DNA sequences from which to determine the population size in previous periods.

Human geneticist Lynn B. Jorde and colleagues studied segments of the genome, containing volatile elements, known as the Alu segment, which consisted of about 200 base pairs of DNA fragments, Randomly inserted into the genome. This is a rare case, because when inserted, they will pass down through generations, acting as a marker that reflects the period of human population increase and decrease.

Scientists have studied the mutation of DNA near those Alu markers in two modern and ancient genomes in prehistoric fossils, their mutations and the use of nucleotide diversity. to guess the age of regions in the genome. From these studies, they calculated the genetic diversity between our earliest ancestors and modern humans. They came to the conclusion that about 1 million years ago there had been major disasters, at least as large as the eruption of the Toba volcano, which had wiped out many species on Earth.

Professor Jorde hypothesizes that human beings and our direct ancestors have gone through cycles that include a period of population growth as well as a period of recession to the point of being in danger of extinction.

Jorge and his colleagues published their findings in the recent issue of the Proceedings of the National Academy of Sciences.