Scientists find possible clue to ancient 'ghost species' of humans

File photo: Hyperrealistic face of a neanderthal male is displayed in a cave in the new Neanderthal Museum in the northern Croatian town of Krapina February 25, 2010. (REUTERS/Nikola Solic)

By studying saliva, researchers at the University of Buffalo have found clues to a possible ancient 'ghost species' of humans.

The search shows that human ancestors living in Sub-Sahara Africa may have had trysts with other early hominins.

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“It seems that interbreeding between different early hominin species is not the exception — it’s the norm,” said Omer Gokcumen, PhD, an assistant professor of biological sciences in the University at Buffalo College of Arts and Sciences in a press release.

Gokcumen added that when you looked for the mucin protein known as MUC7 that's found in saliva, the evidence is there for interbreeding.

“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 new findings, which were published on July 21 in the Molecular Biology and Evolution journal, appear to be part of a trend. Other similar studies have concluded that humanity's ancestors in Asia and Europe may have interbred with other early hominin species, including the Neanderthals and Denisovans.

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Saliva has become an important finding for researchers, espeically the MUC7 protein, as it gives spit its consistency and also may also get rid of disease-causing bacteria.

In a previous study, MUC7 was shown to have evolved to serve an important purpose, holding six copis of gene intructions enabling the body to build the protein for some people. Other people have a code for five instructions.

“From what we know of MUC7, it makes sense that people with different versions of the MUC7 gene could have different oral microbiomes,” said  Stefan Ruhl, DDS, PhD, a professor of oral biology in UB’s School of Dental Medicine. “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.”