Sunday, February 25

“We are all mutants” | Today


We resort to color to characterize our peers. To that redhead with very light skin, that black teenager with jet hair, that girl with spots on her skin, that blond baby with blue eyes… Around skin, hair and eyes orbit ‘Genes de colores’ ( Next Door Publishers), work of the geneticist Lluís Montoliu. A book full of curiosities in which this researcher from the National Center for Biotechnology (CNB-CSIC) and the illustrator Jesús Romero guide the reader through the most human rainbow, the one that makes us different, but only in appearance.

“The differences are anecdotal. They are very scandalous – in that they change the color of our hair, our skin, our eyes – but in essence we are more equal than we are willing to assume, “says Montoliu. It doesn’t matter where we were born and the color of our skin, the color that throughout history, and still today, has served to justify all kinds of atrocities. “Races do not exist,” emphasizes the Catalan geneticist. We are so equal that “any human being resembles any other in 99.9% of their genome” and that the majority (85%) of that 0.1% difference occurs between individuals, not between populations. The consequence is counterintuitive. «If you compare a Nordic with an African and two Spaniards with each other, intuition leads you to believe that the former are more different from each other than the latter. However, the reality is that, two by two, any of them are just as different and just as similar.

The color genes that give the title to Montoliu’s latest outreach work – also author of ‘Editing genes: cut, paste and color’ (2019) and ‘Albinism’ (2019) – are 662 of the 20,465 counted so far . “A not insignificant 3.2% of our genome is dedicated to pigmentation.” They are the genes that make us blond, dark-haired, brown-eyed, albino, red-haired, black… A small number of genes in an instruction book in which no one is free from variations. “We are all mutants. We all carry a multitude of mutations, changes, in our genes, which establish how we are. Some of them affect color genes”, says the CNB-CSIC researcher.

redheads

The fascination with difference

They attract us. We can’t help it. “A red-haired person walks into a room and, inevitably, everyone, fascinated, turns to look at her,” writes the Catalan geneticist. They are 2% of the world’s population and, as in the case of the other human colors, their hair ranges from orange to intense red. «In our country, there are more redheads in the north of Spain than in the rest of the peninsula due to the historical flow of sailors between the United Kingdom and Ireland and the Cantabrian coast, from the Basque Country to Galicia».

For the corresponding chapter of ‘Genes de Colores’, Jesús Romero has drawn a scene in which the occupants of an elevator, including a dog, look fascinated at a red-haired girl. A certain Pheomelanin is calling her on her mobile. “We only have two types of melanin: eumelanin (brown, dark) and pheomelanin (reddish, yellowish),” explains Montoliu. Mutations in the MC1R gene mean that redheads only produce pheomelanin, which makes their hair red and also lightens their skin to the point that “they should protect themselves more from the sun even than people with albinism.” Redheads can develop skin cancers more easily than the rest because “pheomelanin is photoactive and that causes more damage to cells than not having melanin.”

Albinism

Rejection due to lack of color

Albinos do not go unnoticed either, in their case due to the lack of pigmentation, a consequence of the fact that they do not produce melanin. In some African countries they are persecuted, killed and mutilated to use parts of their bodies in rituals and as amulets. Montoliu has been studying this genetic condition and the social rejection towards it for 30 years, which he believes is probably based “in the association of our fears with ghosts and spirits that are always usually white. In fact, one of the nicknames that albino children suffer from is ghost. There are also the disturbing albino children from the horror classic ‘The Village of the Damned’ (1960) and the evil monk Silas from ‘The Da Vinci Code’ (2006).

“People with albinism only need one letter of the genome changed, out of place, to lose all pigmentation,” says the geneticist. One among the 3,096 million pairs of chemical letters in our genome. Scientists have so far identified some twenty genes whose mutations cause twenty-one types of albinism. The main problem with this condition – “which does not worsen over time, but does not improve either” – is not the absence of pigmentation, but the visual impairment that it entails: albinos have very low visual acuity – “10% or less” –, they do not distinguish “between close objects and those further away” –they see the world in two dimensions– and they suffer from photophobia.

A mutilated African albino boy, with an albino rabbit. /

Jesus Romero

Europe

The cradle of chromatic variability

“Europe has been the cradle of pigmentation variability, while in other parts of the world some parameters that have spread to the entire population have triumphed. This is where the different colors of hair, eyes and skin evolved”, says Montoliu. Stop to think: have you ever seen a blond, red-haired, green-eyed Asian, African or Native American…? It is neither good nor bad, just one more example of human variability from those of our ancestors, blacks, who arrived in Europe from Africa tens of thousands of years ago and whose pigmentation adapted over time to the different levels of insolation.

“We have from southern Europeans, who could pass for Berbers, to Nordics who have white hair and in whom it is difficult to detect albinism,” illustrates the author of ‘Genes de colores’. Red hair originated in northern Europe and the same goes for blonde hair. This and light eyes attract our attention in the Mediterranean world, while in northern Europe black hair and eyes do. The ‘weird’ in our community always catches our attention.

the black skin

Life insurance against the sun

“Having dark, pigmented skin, practically black, is life insurance if you are constantly exposed to the sun,” Montoliu points out. Just as there is a wide range of whites, there is a wide range of blacks. «A guy from Cádiz and one from Oslo are very different, and a guy from Sudan and one from South Africa too. It is in the tropics, where the highest solar radiation is recorded, that you find the people with the highest level of pigmentation, with darker skin.” As you travel south or north, the skin lightens.

“The color of the skin has an evolutionary explanation,” says the geneticist. Our closest relatives, the chimpanzees, have a white under their hair that protects them from the sun. When our ancestors lost that protective fur in Africa, their skin darkened to cope with solar radiation. The first of our kind were black, although later their descendants paled as they migrated to more northern latitudes, where radiation is less intense but is still needed to synthesize vitamin D.ne

An African with varying shades of dark skin from neck to forehead. /

Jesus Romero

vitiligo

humans with spots

In general terms, we like animals with spots –cats, dogs…– and even albinos –such as rabbits and red-eyed spiderlings–, but when it comes to humans… «I know many people with vitiligo who are hardly discovered by the rest because they are made up to avoid rejection. There are people who refuse to shake their hands because they think they are going to get infected. It is an absurdity that can happen in Europe, but in India it is worse, women with vitiligo are rejected, they are social outcasts”, laments the author of ‘Genes de colores’.

Vitiligo is characterized by “the unpredictable appearance of white, non-pigmented patches on the skin.” It is an autoimmune disease that affects between 0.2% and 2% of the population and can cause “a profound emotional and psychological disorder in those who suffer from it”. 80% of cases are due to genetic factors; the remaining 20%, to environmental causes. «Michael Jackson suffered from it and used a mixture of makeup and whitening creams, which made him lose pigmentation. “He was criticized for ‘giving up his black skin’ when, in reality, what he was doing was trying to treat and compensate for the appearance of non-pigmented spots due to the vitiligo he suffered from and that he had inherited from his father,” Montoliu explains. .


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