How Neanderthal is your nose?

Improvements in genetic analysis have allowed us to know the comings and goings of our species and even glimpse, at an individual level, from which populations on the planet our ancestors come. But, can you imagine being able to do the same with the different parts of the body and identify their origin? Due to the multiplicity of genes involved in the development of some anatomical traits, this is simply a chimera, but such interesting approximations can be made, such as the one just published by a team of researchers led by University College London (UCL).

Lluís Montoliu: “The mutation that leads you to be redhead involves a toll, and it is not always good”

Further

In a magazine article Communications Biology, Kaustubh Adhikari and his team have used data from more than 6,000 volunteers from Latin America, of mixed European, Native American and African descent, to try to find a correlation between physical facial features and the expression of their genes. What they did was take photographs of the participants, identify a series of key points on their faces (such as the distances between the eyes, lips, and nose) and cross-check that information with the genetic data of each individual, to which a genome association study complete (GWAS). In this way, and somewhat by brute force, the researchers looked for striking values ​​that presented matches with specific genetic markers.

legacy stuff

What they have discovered is a particular genomic region, called atf3, which is associated with a greater height of the nose among the individuals studied. When analyzing this region, the scientists saw that it is a DNA fragment inherited from Neanderthals and that it shows signs of natural selection, which suggests that it gives an advantage to those who carry it in their genome. And not only that, but they also found that many of the people in whom the double circumstance occurred (higher nose and genetic marker) had Native American and East Asian ancestry.

Our ancestors inherited genetic material from Neanderthals that affected the shape of our nose.

This means that, during hybridization with Neanderthals, our ancestors A wise man they inherited genetic material from these evolutionary relatives that affected the shape of our noses. And this trait, unlike others that have been diluted over the thousands of years of mixing between our own species, must have had some adaptive value, because it lasted and has reached our days.

“Here we discovered that some of the DNA inherited from Neanderthals influences the shape of our faces,” says Adhikari. “This could have been useful to our ancestors as it has been passed down for thousands of generations,” she adds. For Qing Li, a researcher at Fudan University in China and first author of the article, this trait could have been preserved because it helped our human ancestors adapt to colder climates when they left Africa. “It has long been speculated that the shape of our noses is determined by natural selection,” he explains in a press release, “how our noses can help us regulate the temperature and humidity of the air we breathe; differently shaped noses may be better suited to the different climates in which our ancestors lived.”

A cold ‘nose’

The geneticist Carles Lalueza-Fox, a researcher at the Institute of Evolutionary Biology (IBE) in Barcelona who did not participate in the study, considers that this is a striking result, because this genetic region had not been described in general nor had it been associated with craniofacial morphology. “What they see is a correlation between the height of the nose and this genomic region,” he explained to elDiario.es. “And when they go to look at chromosome 1, they see that it falls into a fragment inherited from Neanderthals.”.

Lalueza Fox, a specialist in the analysis of ancient DNA, recalls that there is abundant literature in which the wide nose of Neanderthals is attributed to adaptation to cold climates. “That Neanderthals had a wider nose has been associated with the environment in which they lived, colder environments,” adds Óscar Lao, also an IBE researcher. “One of the hypotheses is that, since they were breathing very cold air, the first barrier to moisten and warm the air was more developed.”

From the result, it is striking that it is the East Asian and South American populations that present this specific trait, when the Neanderthals had a presence in Europe and Central Asia. “Interestingly, this intogression is quite prevalent in Native Americans, but not in Europeans,” Lalueza Fox emphasizes. “I find it curious that it is so, unless there is something that has been selected. Native Americans eventually entered [en el continente] through a very cold area 20,000 years ago, through the Bering Strait, they were there for thousands of years and perhaps there was something that was selected ”, he speculates.

“When our ancestors meet Neanderthals, they hybridize and from there comes 2% of the inherited Neanderthal genome that we preserve,” Lao points out. “There are many current human phenotypes that have traces of this Neanderthal introversion, and health risk factors associated with these DNA fragments have been identified.” Throughout evolution, traits that were highly detrimental to survival were lost, while others were beneficial and/or no longer beneficial.

“Another paradigmatic case is the adaptation to altitude in Tibet,” says the expert. “In the populations of this region of the planet, genomic regions have been identified that are of Denisovan origin and that contribute to adaptation to heights,” he recalls. In fact, the authors of the present study found in previous work 32 regions of the genome associated with the shape of the face and regulated by a gene, the TBX15which intervenes in the shape of the lip.

Is my nose Neanderthal?

What we should not interpret from this result, clarifies Óscar Lao, is that because we have a wider nose we have more Neanderthal features, since what is indicated here is a trend over thousands of years of evolution and selective pressure on the populations. “To have a concept of what a face is at the genetic level, it would not be enough to look at marker by marker, but sets of markers and see what association they give you,” he points out. And that requires a level of complexity that is beyond our reach, at the moment. “We have to settle for this type of approximation, which serves to start scratching,” he says.

Knowing the genetic origin of our face in detail is beyond our reach

Oscar Lao — IBE researcher

In any case, says Lalueza Fox, the study is interesting because until now the implications for health issues of possible inherited Neanderthal genes had been described. “This is one of the few studies that I have seen that looks for a morphological meaning and this is curious because we can imagine that part of our physical appearance derives from what we have inherited from Neanderthals.” Whether this influence was large or small is, in his opinion, an interesting question. “Because the same thing happens with the other genes that affect health,” he concludes, “it is very difficult to know how determinant they were for our survival 50,000 years ago, when there were not even the same pathogens and our environment was so different.”