Genetic resurrection: how ancient DNA is rewriting biology.

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A genetic resurrection It's no longer just a science fiction movie plot; it's become one of the hottest topics of the day. modern biotechnologyIn laboratories around the world, scientists are using Ancient DNA, cloning, gene editing, and synthetic biology. to recover characteristics of extinct species, create new medicines, and even recreate smells and processes from the distant past.

At the same time, this area known as "biology of resurrection" This raises profound ethical questions: to what extent is it sensible to reactivate viruses frozen for tens of thousands of years? Is it right to recreate an extinct species and insert it into a completely different modern ecosystem? And how do we balance the potential to save endangered species with the risk of unpredictable impacts on biodiversity and public health?

What is resurrection biology and genetic resurrection?

The call biology of resurrection It is a field of research that seeks to rebuild complex molecules, cells, and even entire organisms that no longer exist in the present.Within this umbrella emerges genetic resurrection, focused on using information from Extinct DNA to recreate genes, proteins, or physical traits in living organisms today.

In practical terms, researchers work with both isolated molecular chains (such as proteins and peptides from ancestral DNA) as well as with very ambitious projects, such as recreate part of the genome of woolly mammoths, dodos, or giant wolves in related extant species. These studies are accompanied by intense ethical debates, since they interfere with moral, ecological and biosecurity boundaries.

At the heart of this area are two main technical strategies, which complement each other:

• Reproductive cloning: It involves extracting DNA from an extinct organism (or from ancient samples) and using it to form an embryo in a living host, usually of a closely related species, using techniques similar to those used to create cloned sheep.
• Engineering and genetic editing: here the focus is on edit the genome of a living species (using CRISPR-Cas9 and related technologies) so that it begins to express characteristics that resemble an extinct species, without exactly reproducing the original genome.

In simplified terms, many projects follow a four-step roadmapFirst, the following is done: DNA extraction of fossils, bones, frozen tissues or museum samples; then comes the genome reconstruction old through sequencing and bioinformatics; then, we move on to embryo creation (via cloning or gene editing); finally, these embryos are conceived and created all the way to adulthood, if the goal is a complete organism.

Ancient DNA as a biological "time machine"

One of the driving forces behind this new revolution is the colossal expansion of genetic sequence banks of extinct or ancestral organismsToday, the DNA of woolly mammoths preserved in tundra icethe genome of dodo from museum specimens, in addition to thousands of ancient human genomes recovered from prehistoric skeletons.

Thanks to these banks, companies and academic groups are able to transporting genetic information through time: genes that have naturally disappeared from a lineage They can be reconstructed and inserted into modern cells. This type of "molecular time travel" opens doors to... save endangered species, to design plants that are more resistant to extreme climates and find out new drugs originating from organisms that lived during the Ice Age.

A prime example is the work of teams that study Human genes lost during evolutionResearchers at the University of Georgia, for example, analyzed a an enzyme that humans and other primates stopped producing millions of years ago., whose absence is linked to diseases such as gout. By reintroducing this gene into liver cells in the laboratory, they paved the way for potential targeted gene therapies for people who could benefit from regaining this metabolic function.

At the same time, organizations such as Revive & Restore They demonstrate that it is not always necessary to focus on completely extinct species. The group worked with the black-footed ferret, a critically endangered American carnivore, cloning individuals from frozen cells stored for decadesThe clones exhibit tens of thousands of genetic variants missing in the current population, which gives the species a way to cope with diseases and environmental changes.

"Zombie" viruses of the permafrost and health risks

One of the most controversial aspects of resurrection biology involves... reactivation of ancient viruses frozen in permafrostThe thawing of the ice sheet is a permanently frozen layer of soil found in regions such as Siberia and the Arctic. With global warming accelerating the thawing, there is growing fear that... Pathogens that have been dormant for tens of thousands of years become active again..

The virologist Jean-Michel Claverie, from Aix-Marseille University, became a reference on this topic by isolating and reactivating, in 2014, a virus that is approximately 30.000 years old, recovered from samples of Siberian permafrost. The virus was inoculated into amoeba cells in culture, becoming infectious again after millennia of inactivity, although it was not pathogenic to humans or animals.

In more recent studies, published in 2023, his team identified and reactivated several new families of old viruses from deep soil samples, including material collected 16 meters deep in underground lakes. One of the viruses dated back approximately 48.500 years, while others, found in the remains of animals such as the woolly mammoth, were about 27.000 years.

To reduce risks, Claverie focuses exclusively on viruses that infect single-celled amoebas, using them as models to estimate the persistence and potential dangers of other pathogens preserved in ice. Even so, the researcher warns that if amoeba viruses are still viable after so much time, There is no reason to rule out the survival of viruses capable of infecting humans or other animals..

This line of research, therefore, functions as a advance warning in public healthIn a warming planet, it is necessary to consider that old infectious agents may return to the environment, requiring monitoring, biosecurity protocols and response strategies appropriate.

Ice Age DNA in the search for new antibiotics

Another promising front in genetic resurrection lies in drug discovery from ancient DNAThe bioengineer Cesar de la Fuente, from the University of Pennsylvania, leads a group that uses artificial intelligence algorithms to to search through libraries of genomes of extinct humans and prehistoric animals In search of molecules with antibiotic potential.

With advances in DNA recovery techniques from fossils, it is now possible to reconstruct, with good accuracy, gene sequences of Neanderthals, woolly mammoths, giant sloths and other Ice Age inhabitantsDe la Fuente's team analyzes these sequences to identify small proteins and peptides with antimicrobial properties which have never been found in living organisms today.

The reasoning behind this strategy is simple and powerful: how Modern bacteria have never come into contact with these "resurrected" molecules.The probability of prior resistance is very low. This opens up room to conceive... new antibiotics capable of fighting superbugs that no longer respond to conventional medicines derived from fungi and bacteria found in the soil.

According to estimates from the World Health Organization, almost Five million deaths annually are associated with antimicrobial resistance.Given this scenario, non-traditional approaches, such as mining ancient genomes with the help of AI, have become extremely attractive because They expand the chemical universe accessible to medicine. beyond what the current biosphere offers.

Reviving extinct species: dodo, mammoth, and giant wolf.

No facet of genetic resurrection attracts as much public attention as the attempt to... to bring back extinct charismatic speciesHere, the biotechnology company Colossal Biosciences He gained attention by announcing plans to recreate the woolly mammoth, thylacine (Tasmanian tiger) and dodo, an icon of extinctions caused by humans.

The dodo project, in particular, involves combining ancient DNA sequencing, precise gene editing, and synthetic biologyResearchers at Colossal identified in Nicobar's dove, the closest living relative of the dodo, primordial germ cells (PGCs) that give rise to eggs and sperm. These cells are able to develop into chicken embryos, creating a curious experimental system.

The plan is to compare the genomes of dodo and Rodrigues's solitary confidant (another extinct and related bird) to map important differences. Then, the PGCs of the Nicobar pigeon would be edited to express the physical features of the dodo.These modified cells would then be inserted into sterile chicken and rooster embryos, which, when they reproduced, would generate offspring with characteristics similar to those of the original dodo.

Even if the project is successful, the scientists themselves acknowledge that the outcome will be a A hybrid functionally similar to the dodo....and not a perfect genetic copy of the bird that lived in Mauritius in the 17th century. Even so, Colossal has already partnered with... Mauritian Wildlife Foundation to study the feasibility of reintroducing these birds into a suitable habitat — a complicated task, since The island has changed profoundly since the extinction of the species..

Another noteworthy effort involves giant wolf (Aenocyon dirus), famous for series like “Game of Thrones”. Researchers at Colossal analyzed highly degraded DNA fragments of this species, which lived in North America between approximately 2,5 million and 600.000 years ago, and identified genetic regions related to key morphological characteristics.

Using CRISPR and other gene-editing toolsapproximately 20 modifications in 14 genes of the modern gray wolf, attempting to replicate traits such as coat color and skull shape of the extinct wolf. The result is a modern wolf with a partially "dirus" appearanceThis is not a literal resurrection of the species, but a useful living model for studying its biology and testing conservation strategies.

Experts in evolutionary genomics, such as Juliana ViannaThey emphasize that this type of work goes beyond mere curiosity: the knowledge generated about genomes of past and present species can support projects like the "1000 Genomes", which seeks to sequence endemic and threatened Chilean species. With this information, it becomes possible to plan genetic interventions to increase the resilience of animals to disease and global warming..

Resurrection plants and agriculture in a drier world

While some researchers try to revive extinct animals, others look at species that are still alive but have almost "miraculous" abilities. This is the case with... resurrection plants, who manage survive months with virtually no water and "come back to life" when they are watered again.With increasingly severe and erratic droughts, these plants have become a source of inspiration for more resilient agriculture.

The South African scientist Jill Farrant He observed since childhood, in the 1970s, that certain plants that appeared dead, completely dry, would turn green again shortly after receiving water. Later, he discovered that it was not a simple seasonal cycle, but a... survival strategy based on extreme reversible dehydrationToday, Farrant is considered one of the world's leading authorities on resurrection plants and teaches at the University of Cape Town.

These species are extremely rare among the angiosperms (flowering plants)Of the more than 352.000 known species, only about 240 have extreme tolerance to desiccation.They arise in different evolutionary branches, which indicates that this ability has evolved independently several times.particularly in rocky or poor-soil environments in South Africa, Australia, and South America, where rainfall is unpredictable and dry seasons are severe.

From a physiological point of view, these plants are able to lose more than 95% of the water in your tissues without dying, while common agricultural crops generally collapse when they lose weight. 10% and 30%One of the secrets is the so-called cellular vitrification, in which the internal contents of the cells form a glassy matrix rich in sugars such as sucrose and trehalose, stabilizing membranes and proteins during extreme dryness.

Furthermore, resurrection plants They temporarily dismantle their photosynthetic apparatus., including chloroplasts, to prevent the overproduction of reactive oxygen species (ROS) Under intense light without water. In parallel, they accumulate LEA (Late Embryogenesis Abundant) protective proteins and other molecular chaperones, which help maintain the structure of essential proteins even under conditions of severe stress.

Genetic studies suggest that part of this desiccation tolerance gene network It can exist in a latent form in many other plants, including... important food cropsThe difference is that these genes are usually only active in the seeds and are silenced after germinationThis opens up a fascinating possibility: instead of inserting external DNA, we could reactivate endogenous genes “dormant” in leaves and stems, creating varieties that better withstand drought without being legally classified as genetically modified organisms in some countries.

From the laboratory to the field: sweet potato, tobacco, Arabidopsis, and the microbiome.

The practical application of this knowledge has already begun in specific cultures. In 2018, researchers from Kenya and Sweden introduced a gene from a South African resurrection plant, the Xerophyta viscosa, at morning glory (Ipomoea batatas)The gene, called XvAld1It is associated with antioxidant defense and helps plants cope with water stress.

In laboratory tests, XvAld1-modified fennel plants were subjected to a 12-day artificial drying. They They retained more chlorophyll, lost fewer leaves, and grew taller. than unmodified plants, suggesting superior resistance to water deficit. Under normal conditions, these transgenic lines were practically indistinguishable from conventional plants, indicating that the additional gene did not disrupt standard development.

Similar experiences in Arabidopsis thaliana (classical model of plant biology) and in tobacco (Nicotiana tabacum) They reinforced the idea that resurrection plant genes could work effectively in other species, expanding the range of possible tools to address the global water crisis.

But it's not just the genome that matters. The so-called rhizosphere microbiomeThe microbiome associated with water stress, that is, the community of microorganisms that lives near the roots, is gaining prominence as a key factor in resistance to water stress. Myrothamnus flabellifolia, a shrubby resurrection plant, revealed more than 900 unique microbial groups in the soil around its roots.

For soil specialists such as Timothy GeorgeThis finding suggests that a significant portion of the ability to withstand extreme droughts may have a... microbial component transferable to agricultural crops with relative ease, perhaps even simpler than introducing multiple desiccation tolerance genes. Hence the idea of ​​developing "plant-based probiotics" or microbial consortia specifically designed to improve plant performance in arid environments.

An interesting case is that of teff (Eragrostis tef)Teff is a traditional grain from Ethiopia. It has a wild relative, the... Eragrostis nindensis, which is a true resurrection plant. Because the two species are very closely related, genome and gene expression comparisons allow us to identify active genes in E. nindensis that remain silent in teff, as well as differences in the production of anthocyanins and antioxidants, pigments that protect against UV radiation and oxidative damage during dry periods.

These findings point to a necessary transition in agricultural systems: abandoning a model based exclusively on extremely high performance under ideal conditions and move towards systems where the priority is... Crop stability even in years of extreme weather.As Jill Farrant summarizes, more rustic varieties may not achieve record yields, but they allow the subsistence farmer to... Have guaranteed food, whether it rains in ten days or in two years..

Personalized gene editing, embryonic selection, and ethical dilemmas.

Genetic resurrection directly relates to other advanced areas of biotechnology, such as... Personalized gene editing in humans and genetic selection of embryoswhich also raise complex moral discussions. In 2024, for example, a newborn in the United States with a rare metabolic disorder He received an experimental gene-editing therapy specifically designed to correct the mutation in his genome, avoiding the urgent need for a liver transplant.

After three doses, the baby began to to present significant improvements...how to take your first steps and be discharged from the hospital to spend Christmas at home. The team in charge plans... trials with other newborns carrying different mutations, with the ambition of establishing a regulatory model in which a A single medication can be genetically tailored for each patient. without repeating all clinical trials from scratch.

The US regulatory agency (FDA) is already discussing Approval pathways for highly personalized therapieswhich could reduce costs today in the house of millions of dollars per treatmentResearchers like Fyodor Urnov, from the University of California, Berkeley, see this as an important step towards treating rare diseases, but warn that it also requires... new ethical and equity standards in access.

At the other end, the genetic selection of embryos It is no longer limited to the pre-implantation diagnosis of serious hereditary diseases. Currently, some companies offer couples the possibility of classifying embryos by probabilities associated with height, eye color, or even scores linked to cognitive traits.The science behind this is highly uncertain, because Complex traits depend on hundreds of genes and environmental factors.But the mere fact that it is technically feasible already fuels fears of a a step backward towards eugenics.

Many experts advocate for clear limits to prevent these tools from being transformed into... instruments of social selectionEven though companies argue that they are merely expanding parents' freedom of choice, the genetic resurrection of extinct animals and the possibility of modifying wild species to resist disease or extreme weather raise analogous questions within this context. who decides which characteristics are desirableWhich species deserve to be "brought back," and what risks are we willing to take in the name of progress?

Overall, the biology of resurrection paints a picture in which Ancient DNA, next-generation gene editing, cloning, and tailor-made microbiomes. They converge to rewrite parts of the history of life on the planet and to try to prevent future losses of biodiversity. Between viruses that awaken from the ice, plants that survive almost without water, partially recreated giant wolves and hybrid dodos in the planning stages, it is clear that the boundary between past and future in biology is becoming increasingly blurred, requiring society to keep pace with this progress. Informed public debate, responsible regulation, and a healthy dose of prudence..