Tech UPTechnologyCarles Lalueza-Fox:

Carles Lalueza-Fox:

At just 39 years old, Carles Lalueza-Fox has made a name for himself among the great world experts in the study of ancient DNA. He currently works as an associate professor in the Anthropology unit of the University of Barcelona. Two years after recovering, for the first time in history, the DNA of the moa, a species of bird that was extinct 400 years ago, this young researcher has just scored the triumph of having participated in the discovery of the mitochondrial DNA of two fossils of the man from Cro-Magnon. The work has been published by the magazineProceedingsfrom the United States Academy of Sciences. Lalueza-Fox is also the author of other books: Razas, racismo y Diversidad. Science a weapon against racism, which has been awarded the 2001 European Prize for Scientific Dissemination Estudi General;Messages from the pastYThe color under the skin.

-Why hasn’t DNA from Cro-Magnons been recovered until now?
-There are several ways to investigate the origin and evolution of our ancestors. Until a few years ago, everything was based on observing fossils but, luckily for our specialty, the informative value of genetic material was discovered. Many scientists thought that the first thing was to recover DNA from Neanderthals, to compare it with our own. Thus, after great efforts, in 1997 the first Neanderthal DNA was recovered. In the first 40 attempts, DNA was only recovered in 4 cases. For the Cro-Magnons, we had the added difficulty of not having enough fossils, but our team has succeeded.

-Why has your team been successful?
-We have had the wisdom to study the remains of two individuals buried at the bottom of the Paglicci cave, in southern Italy. We do not know if those humans lived comfortably in the cave, but their remains were perfectly preserved. One of the individuals was an adult woman who lived 23,000 years ago and the other, a young boy from 24,700 years ago. Neanderthals were only recently extinct.

-What have you discovered in these two individuals?
-The study we have done indicates that genetically Paglicci’s Cro-Magnons were individuals of the human species as we know it now. In contrast, despite having shared European territory for some 10,000 years, Paglicci’s Cro-Magnons had no genetic characteristics in common with Neanderthals.

-Why didn’t they interbreed sexually?
-We cannot assure that there was no mating or a hybrid was born. But, if there was any crossing, there was no evidence in the mitochondrial DNA of the Cro-Magnons, as we have been able to verify with our study. In other words, the possible sexual encounters were sporadic and did not have genetic repercussions. Our study confirms that Neanderthals became extinct without leaving any inheritance.

– Were there confrontations between both human species?
-Neanderthals were morphologically different from Cro-Magnons, and they belonged to lineages that had been separated for at least half a million years, but perhaps they were not seen as individuals of another species, but only as a little different. We have no proof that there were any great battles between Cro-Magnons and Neanderthals.

– Until now, which is the oldest species from which DNA has been recovered?
-DNA has been recovered from 42,000-year-old mammoth bones, precisely because they lived in an area that was covered by ice.

-With this DNA could mammoths be revived?
– Normally we recover mitochondrial DNA, but in the case of mammoths, some fragments of some nuclear genes have even been rescued. The problem is that the mammoths had 30,000 or 35,000 genes, we don’t even know … At the moment, it is not possible to think about rehydrating a mammoth cell and cloning it. It is impossible. If we want to be imaginative, we can still think about sequencing the genome of an elephant and changing some of the genes that we can recover from the mammoth … But we would have very little chance of success and it would be difficult to justify an investment like this. With this money we could help conserve the endangered species that still live.

-You have participated in the sequencing of the first complete mitochondrial genome of an extinct species, the moa, perhaps the largest bird that has ever existed on Earth …
-The moa was a giant bird, about three meters high, that lived in New Zealand and that became extinct about 400 years ago because of the hunting of the Polynesians who came to these islands.

-Just 400 years?
-Yes. In fact, New Zealand was one of the last places on the planet to be colonized by humans, around the year 1200. Since his arrival in New Zealand, man has dedicated himself to hunting defenseless animals such as the moa, which became extinct around the year 1600. I participated in this study when I was at Oxford University, together with Professor Alan Cooper. We use as a reference the work already carried out on the ostrich to gradually assemble the more than 100 fragments of mitochondrial DNA from moa that we were able to recover, until we complete the functional genome of this extinct species. It was the first time, and so far the only time, that the genome of a disappeared species had been recovered. But, as in the case of the Cro-Magnons, it must be clear that we have analyzed mitochondrial DNA, genetic information that is found outside the nucleus of cells and that is only 0.0005 percent of the length of a genome. of the cell nucleus.

-And what is the use of a study of this type?
-In this case, for example, we were able to confirm that the moa were birds that were distributed throughout the planet when the entire earth’s surface was united in the supercontinent known as Gondwana. We were able to reconstruct the phylogenetic tree of the moa and confirm that they were direct relatives of the kiwi, ostrich or emu. In general, ancient DNA studies are used to reconstruct the genealogical tree of species, works that until 15 years ago were unthinkable. The most important contribution of our specialty has been precisely to confirm the differences between humans and Neanderthals. Right now, with this technique, disappeared human populations are being studied. Knowing the ancient DNA helps to rebuild the tree of life and to know ourselves.

-Can we recover the DNA of a species, an insect, for example, that has been preserved in a drop of amber?
-I don’t think we should have too much hope, although there are contradictory results. The studies that were done 10 years ago with insects preserved in amber were not done correctly either, especially since they were carried out in laboratories that worked with insects similar to the old ones and, therefore, the contamination of the sample was very simple. Amber is porous and the oxygen that enters it degrades DNA. As with mummies, the tissue may look good but the genetic material is degraded.

-With DNA recovery from people who died a few dozen years ago, have you been more successful?
-The ancient DNA techniques allow expanding the work carried out in forensic medicine. For example, with our techniques we have helped solve historical unknowns, such as the identification of the remains of Tsar Nicholas II of Russia and his family. When, in 1991, the bodies of the supposed members of the Tsar’s family were found, it was necessary to resort to the ancient DNA technique to verify that they really were their remains. Instead, it could be shown that Anna Anderson was not Anastasia, the daughter of the Tsar, as she claimed for many years.

-Another unknown solved was that of Josef Mengele …
-Yes, the Auschwitz angel of death, the terrifying Nazi researcher who intended to clone humans, accidentally drowned in Brazil in 1979. The Israeli intelligence services thought that this death was a setup so that the real Mengele could flee and, In 1992, it had to be resorted to the ancient DNA technique to discover that the corpse was really that of Hitler’s famous scientist.

-What color was the skin of the first hominids?
-The skin does not fossilize and therefore there is no evidence of its color. But we can speculate. It has been explained that the first hominids had dark skin, but I think they did not. If we talk about the first lineage that separated from the chimpanzees and that came to us, probably those first hominids had light skin; because chimpanzees also have it light, although their hair is dark. Perhaps two million years ago, when the first individuals of the genus Homo appeared, of similar proportions to some present-day populations in East Africa and without much body hair, they must have had pigmented skin.

-Why were they black?
-Otherwise, living in that area of Africa and without hair on their bodies, they would have died of skin cancer.

-Was skin color a protection factor?
-In part, but it also happens now. Fair-skinned people who have gone to live in areas with a lot of sun, such as the British who have settled in Australia or Europeans from South Africa, have the highest incidence of skin cancer.

-Why did the skin color change occur? What advantage does white skin have for the inhabitants of Europe?
-The main one is the assimilation of vitamin D. Humans need sunlight to synthesize vitamin D, to control the absorption of calcium in the body and to form the skeleton correctly. Highly pigmented people who have moved to the Nordic countries have calcification problems due to lack of vitamin D.

-Will the ancient DNA technique allow us to show what color the skin of our ancestors was?
-I think so. We will end up knowing the genes that are involved in all external features, not just pigmentation. In this way, we can infer the skin color of the first humans.

Joaquim Elcacho

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