Chances of bringing mammoth and dodo back to life are low – 03/11/2023 – Science

Is it possible to bring extinct species back to life?

The question, which would have sounded like science fiction a few decades ago, is getting closer to reality due to advances in recent years in DNA editing techniques and manipulation of embryos in the laboratory.

The American company Colossal Biosciences announced, in 2021, the desire to reintroduce in the tundra steppes of Siberia and Alaska the woolly mammoth (Mammuthus primigenius) that became extinct 10,000 years ago, in the last Ice Age. And he managed a considerable effort for this: about US$ 15 million (or approximately R$ 78 million).

The technique to “de-extinct” the mammoth consists of reconstructing its DNA based on fragments obtained from frozen fossils and filling in the gaps in the genome with genetic material from the Asian elephant (Elephas maximus). The DNA would then be introduced into embryonic cells from this animal and the embryo implanted in the uterus of an elephant. So far, however, no pups have been viable.

Now, the same company has announced that it wants to bring back the dodo (raphus cucullatus), a giant flightless bird that originated from Mauritius in the Indian Ocean and was last seen in 1662.

The dodo “de-extinction” process will combine primordial pigeon germ cells with dodo DNA recovered from specimens in scientific collections. The modified cells would then be introduced into an unfertilized egg where the “pigeon dodo” chick would grow.

For ornithologist Luís Fábio Silveira, a professor at USP’s Museum of Zoology, this is extremely unlikely to work. “It is very difficult to carry out this procedure and, in addition to having the body’s own barriers, no one has ever seen a dodo egg, we have no idea how big it is.”

Silveira points out that even if it succeeds in crossing this border, the animal will never actually be a dodo. “Obviously you will have an animal that is not a dodo, or an animal that is not a mammoth, but which are hybrids. What is cool, however, is seeing the leap in intelligence and technological investment, especially with genetic manipulation, which will be very interesting.”

According to Beth Shapiro, a paleogeneticist hired by the company to run the dodo project, tests are still being carried out to obtain these primordial cells, but “the final version of the dodo will hatch from the pigeon genetically modified to be the size of a dodo, and the eggs will then be of adequate size”.

In a response sent to the report, Ben Lamm, one of the company’s co-founders, said that the company’s mission is to reintroduce species produced in the “de-extinction” process back to their natural habitat.

According to him, the mammoth is important because it is a species “critical for combating the effects of climate change”, while the dodo is “emblematic because it represents a species that disappeared due to changes caused in its habitat by man”.

Lamm also said that the company’s advances in the “de-extinction” process could represent new tools to correct the de-extinction process in some circumstances.

The company’s CEO also said that technological advances in embryology and genetic manipulation can help in the conservation of living species, such as the Asian elephant, and possible applications in the future can be made for human health and diseases.

Although it seems to work in theory, in practice “de-extinction” is criticized by experts, who say they see the project as more publicity than actual science.

“It’s iconic species that bear a burden of this human-caused extinction [no caso do dodô]so it’s an attempt to attract investment”, says Taissa Rodrigues, paleontologist and professor at the Federal University of Espírito Santo. “What I believe to be more likely is to use this new technology to save species that are currently at risk of extinction. “

One of the points raised is that extinct animals no longer have their natural habitats (in the case of the mammoth) or else they will suffer intense modifications that will make them look like the species, but they will not be exactly the same as the natural species.

An argument for the recreation of the mammoth disclosed in a Colossal video is that “de-extinction” can help to contain global warming: the permafrost, the layer of ice that covers the Siberian tundra, suffers from melting due to global warming, releasing more methane gas in the atmosphere.

Mammoths previously helped to control this temperature by consuming vegetation and also by condensing the pasture, keeping the temperature below -40°C. “But this is much more utopian than reality”, assesses Rodrigues.

Another critical point is that mammoths are highly social animals, like elephants, and depend on ecological interactions that are not possible to create in the laboratory.

“Even if the procedure is feasible, we have no way of knowing whether those behaviors that are learned by the chicks will be there”, reflects ecologist Gustavo Burin, postdoctoral fellow at the Museum of Natural History in London.

Burin also questions how much the process of extinction, which is natural, can suffer interference, positive or negative, from human activity. “The time since the extinction of that species has already led to a new adaptation of that community or ecosystem. And then reintroducing the species can cause a change in the organization of that habitat with a species that no longer exists.”

There are some indications that mammoths were hunted by humans, but the end of the Ice Age ended up causing effects on the climate that did not allow their existence in various parts of the world.

In the case of the dodo, the company raised more than US$ 150 million (about R$ 777 million) to rescue a bird that may have been extinct directly by human action, hunting, or indirectly, by the introduction of exotic species on the island and ecosystem modification.

Although there are few scientific accounts of what the dodo looked like in life, as it was mostly seen by sailors, it is believed that the lack of natural predators on the island led these animals to be more “docile”. But even characteristics about the social behavior and biology of these animals are scarce, evaluates Silveira.

For Rodrigues, an example of an animal that can be more successful in “de-extinction” is the Tasmanian wolf (also called Tasmanian tiger or thylacine), last seen in a zoo in 1936. Originally from Australia, this marsupial was also extinguished by hunting.

“The Tasmanian tiger is more interesting [trazer de volta] because there is documentation of his behavior in captivity, in addition to having enough DNA from individuals in museums. And his habitat still exists.”

Silveira agrees. “We know that the thylacine became extinct through predatory hunting, and these techniques may even help to improve genetic variability and manipulation in the laboratory for studies of reproduction with endangered mammals and birds.”

In any case, bringing extinct species back to life can be a considerably greater effort than conserving current species that are at risk of extinction.