FEB 16, 2020 8:25 AM PST

West African Genomes Reveal 'Ghost' Population

WRITTEN BY: Carmen Leitch

Fossils of modern humans have been found that are around 200,000 years old. But fossils of humans with a mix of modern and ancient features have been recovered that are, relatively speaking, much younger at 35,000 years old. Recent work reported in Science Advances has now shown that ancient humans living in West Africa around 50,000 years ago interbred with another group of humans that scientists have never found before - a so-called ghost population of ancient people. The evidence for their existence is not found in fossils; it is carried in the DNA of modern West Africans.

Neanderthals are thought to have disappeared around 40,000 years ago, and we know that humans and Neanderthals interbred; up to two percent of the genome now carried by Europeans and East Asians is made up of Neanderthal DNA.

The Denisovans are another example of an ancient species of human that is thought to have reproduced with humans. There aren't as many Denisovan fossils compared to Neanderthals, so we don't know as much about them. The DNA of modern Melanesians, who live in a part of Oceania that includes New Guinea and Tonga, is up to six percent Denisovan.

This new research shows that there's more to learn about the formation of the modern human.

"It's almost certainly the case that the story is incredibly complex and complicated and we have kind of these initial hints about the complexity," study author Sriram Sankararaman, a computational biologist at UCLA, told NPR.

In this work, the scientists were analyzing the genomes of 405 West Africans, using statistics to comb through the DNA and find portions that are not characterized as modern. The portions of DNA that were found don't belong to Neanderthals or Denisovans, either. The researchers suggested that it comes from a population that has not been discovered yet.

"We don't have a clear identity for this archaic group," Sankararaman added. "That's why we use the term 'ghost.' It doesn't seem to be particularly closely related to the groups from which we have genome sequences from."

We may start to find more populations like this as more high-quality genetic data is generated from larger groups of modern humans.

"I think as we get the genome sequences from different parts of the world at different points in time, there is always the possibility that we might discover these as-yet-unidentified ghost populations," Sankararaman continued.

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JAN 16, 2020
Genetics & Genomics
JAN 16, 2020
Sequence the Kraken! The Genome of the Giant Squid is Revealed
Giant squid, which can weigh over 900 kilograms and grow to thirteen meters, are the stuff of legend....
JAN 28, 2020
Cell & Molecular Biology
JAN 28, 2020
A Rare Genetic Disorder is Effectively Treated With Modified Stem Cells
A clinical trial used stem cell gene therapy to treat a rare genetic disorder called X-CGD. Image credit: UCLA Broad Stem Cell Research Center/Nature Medicine...
FEB 07, 2020
Neuroscience
FEB 07, 2020
People with Autism have Fewer Fatty Sheaths Between Neurons
Myelin, a fatty substance, accelerates the delivery of electrical signals between neurons in the brain. Now, researchers have found that people with autism...
FEB 23, 2020
Genetics & Genomics
FEB 23, 2020
Revealing More About the Genetic Mechanisms Underlying Down Syndrome
Down syndrome impacts around 6,000 live births in the US every year. Around 95% of affected individuals have a type called trisomy 21....
MAR 27, 2020
Genetics & Genomics
MAR 27, 2020
Expanding the Genomic Regions That Can Be Targeted With CRISPR
CRISPR gene-editing technology has sparked a revolution in biomedical research and is poised to have far-reaching applications in medicine....
MAR 31, 2020
Cell & Molecular Biology
MAR 31, 2020
A Genetic Edit Shields Cells That Are Usually Destroyed by Type 1 Diabetes
Diabetes is a disorder in which the body cannot properly regulate blood sugar levels because of a problem with insulin....
Loading Comments...