Clues to Ghost Species of Ancient Human Discovered
Topic: Anthropology and Disability
Author: University at Buffalo
Published: 2017/07/21 - Updated: 2024/06/05
Publication Type: Anthropology News - Peer-Reviewed: Yes
Contents: Summary - Introduction - Main - Related
Synopsis: Scientists discover hints that ghost species of archaic humans may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today. In saliva, scientists have found hints that a "ghost" species of archaic humans may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today. The research adds to a growing body of evidence suggesting that sexual rendezvous between different archaic human species may not have been unusual. Our research traced the evolution of an important mucin protein called MUC7 that is found in saliva. When we looked at the history of the gene that codes for the protein, we see the signature of archaic admixture in modern day Sub-Saharan African populations.
Introduction
The evolutionary history of a salivary protein may point to interbreeding between humans and an enigmatic ancient relative.
Main Digest
In saliva, scientists have found hints that a "ghost" species of archaic humans may have contributed genetic material to the ancestors of people living in Sub-Saharan Africa today. The research adds to a growing body of evidence suggesting that sexual rendezvous between different archaic human species may not have been unusual.
Past studies have concluded that the forebears of modern humans in Asia and Europe interbred with other early hominin species, including Neanderthals and Denisovans. The new research is among recent genetic analyses indicating that ancient Africans also had trysts with other early hominins.
"It seems that interbreeding between different early hominin species is not the exception - it's the norm," says Omer Gokcumen, Ph.D., an assistant professor of biological sciences at the University at Buffalo College of Arts and Sciences.
"Our research traced the evolution of an important mucin protein called MUC7 that is found in saliva," he says. "When we looked at the history of the gene that codes for the protein, we see the signature of archaic admixture in modern day Sub-Saharan African populations."
The research was published on July 21 in the journal Molecular Biology and Evolution. Gokcumen and Stefan Ruhl led the study, DDS, Ph.D., a professor of oral biology in UB's School of Dental Medicine.
A Tantalizing Clue in Saliva
The scientists came upon their findings while researching the purpose and origins of the MUC7 protein, which helps give spit its slimy consistency and binds to microbes, potentially helping to rid the body of disease-causing bacteria.
As part of this investigation, the team examined the MUC7 gene in more than 2,500 modern human genomes. The analysis yielded a surprise: A group of genomes from Sub-Saharan Africa had a version of the gene that was wildly different from versions found in other modern humans.
The Sub-Saharan variant was so distinctive that Neanderthal and Denisovan MUC7 genes matched more closely with those of other modern humans than the Sub-Saharan outlier did.
"Based on our analysis, the most plausible explanation for this extreme variation is archaic introgression - the introduction of genetic material from a 'ghost' species of ancient hominins," Gokcumen says. "This unknown human relative could be a species discovered, such as a subspecies of Homo erectus, or an undiscovered hominin. We call it a 'ghost' species because we don't have the fossils."
Given the rate that genes mutate during evolution, the team calculated that the ancestors of people who carry the Sub-Saharan MUC7 variant interbred with another ancient human species as recently as 150,000 years ago, after the two species' evolutionary path diverged from each other some 1.5 to 2 million years ago.
Why MUC7 Matters
The scientists were interested in MUC7 because, in a previous study, they showed that the protein likely evolved to serve an important purpose in humans.
In some people, the gene that codes for MUC7 hold six copies of genetic instructions that direct the body to build parts of the corresponding protein. In other people, the gene harbors only five sets of these instructions (known as tandem repeats).
Prior studies by other researchers found that the five-copy version of the gene protected against asthma, but Gokcumen and Ruhl did not see this association when they ran a more detailed analysis.
The new study did conclude, however, that MUC7 appears to influence the makeup of the oral microbiome, the collection of bacteria within the mouth. The evidence for this came from an analysis of biological samples from 130 people, which found that different versions of the MUC7 gene were strongly associated with different oral microbiome compositions.
"From what we know of MUC7, it makes sense that people with different versions of the MUC7 gene could have different oral microbiomes," Ruhl says. "The MUC7 protein is thought to enhance the ability of saliva to bind to microbes, an important task that may help prevent disease by clearing unwanted bacteria or other pathogens from the mouth."
About the Research: Authors and Funding
In addition to Ruhl and Gokcumen, the research team included:
Duo "Erica" Xu, the study's first author and a UB Ph.D. student in biological sciences.
Pavlos Pavlidis, Ph.D., and Nikolaos Alachiotis, Ph.D., of the Foundation for Research and Technology - Hellas in Greece.
Colin Flanagan, a UB undergraduate who has completed his degree in biological sciences.
Ran Blekhman, Ph.D., of the University of Minnesota.
Michael Degiorgio, Ph.D., of Pennsylvania State University.
The research was funded primarily by the University at Buffalo Research Foundation, with additional support from InnovCrete and the National Institute of Dental and Craniofacial Research.
- Skull Study on Human and Neandertal Interbreeding
- Foundations of Human Health: A Genetic Checkup
- Research Confirms Humans Are Part Neanderthal
- Will Dragon Man Fossil Replace Neanderthals as Humans Closest Relative
- How Neanderthals Influenced Human Genetics at the Crossroads of Asia and Europe
Attribution/Source(s):
This peer reviewed publication was selected for publishing by the editors of Disabled World due to its significant relevance to the disability community. Originally authored by University at Buffalo, and published on 2017/07/21 (Edit Update: 2024/06/05), the content may have been edited for style, clarity, or brevity. For further details or clarifications, University at Buffalo can be contacted at buffalo.edu. NOTE: Disabled World does not provide any warranties or endorsements related to this article.
Page Information, Citing and Disclaimer
Disabled World is a comprehensive online resource that provides information and news related to disabilities, assistive technologies, and accessibility issues. Founded in 2004 our website covers a wide range of topics, including disability rights, healthcare, education, employment, and independent living, with the goal of supporting the disability community and their families.
Cite This Page (APA): University at Buffalo. (2017, July 21 - Last revised: 2024, June 5). Clues to Ghost Species of Ancient Human Discovered. Disabled World. Retrieved September 13, 2024 from www.disabled-world.com/disability/education/anthropology/muc7.php
Permalink: <a href="https://www.disabled-world.com/disability/education/anthropology/muc7.php">Clues to Ghost Species of Ancient Human Discovered</a>: Scientists discover hints that ghost species of archaic humans may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today.
Disabled World provides general information only. Materials presented are never meant to substitute for qualified medical care. Any 3rd party offering or advertising does not constitute an endorsement.