Humans Acquired 20% of Increased Brain Functions Due to a 'Ghost Population' That Coexisted With Our Ancestors
The origin of humanity has been a long-debated and discussed topic amongst experts. A new study formulates a genetic model that gives some insights regarding the development of human anatomy, stated Live Science. Findings regarding this model have been published in the journal Nature Genetics.
The study claims that human ancestors split from a group 1.5 million years ago, and again rejoined them 300,000 years ago. This unknown group supposedly contributed 20% of modern DNA and improved human brain function. Researchers attributed modern technology for this breakthrough. "The fact that we can reconstruct events from hundreds of thousands or millions of years ago just by looking at DNA today is astonishing, and it tells us that our history is far richer and more complex than we imagined," said study co-author Aylwyn Scally, a geneticist at the University of Cambridge, stated Live Science.
Researchers associated with the study created their model using the method "cobraa." The method was subjected to DNA data provided by the 1000 Genomes Project and the Human Genome Diversity Project. The results indicated that the division happened 1.5 million years ago. Researchers labelled the resultant groups as Population A and Population B. Experts found that Population A possibly suffered a 'bottleneck' event after division. The incidents that cause an enormous reduction of numbers in a population are called a 'bottleneck' event. This reduction led to a significant loss of genetic diversity. Population A recuperated, and over time, Neanderthals and Denisovans branched out from this section.
Some 300,000 years ago, Population A again came together with Population B. Present-day human DNA is composed of genes given by this combined group. The model suggests that 80% of the genomes in modern humans are from Population A, while the rest is the contribution of Population B. Experts think that 20% of the genomes that came from Population B had a positive impact on brain function and neural processing.
The identity of these populations is still a mystery for researchers. "What is interesting about this paper is that the pattern in the model is a deep African structure that is shared by everyone living today," John Hawks, a biological anthropologist at the University of Wisconsin-Madison who was not involved in the study, said. "It is not 'ghost populations' contributing to one particular group, it is one big ghost that merged in with the African source population for all modern humans." 'Ghost population' is a term given by experts to ancient human groups that branched off in the past and then reconnected again at some point, stated Live Science.
The study is another proof in a long line of evidence that asserts that human evolution was not linear, and instead had many complex twists and turns that are yet to be figured out by experts. "What's becoming clear is that the idea of species evolving in clean, distinct lineages is too simplistic," study co-author Trevor Cousins, a postgraduate student in genetics at the University of Cambridge, said. "Interbreeding and genetic exchange have likely played a major role in the emergence of new species repeatedly across the animal kingdom," added Trevor.