The dream of the revival of dinosaurs, mammoths and other extinct animals constantly pops up in the press, although the vast majority of scientists are very skeptical about this idea. Will people ever be able to walk in a park of any period?
Let's start with the bad news: Jurassic Park is pure fantasy. Not even a trace of DNA remained in the mosquitoes immured in amber, and even more so in the fossilized remains of dinosaurs. Most likely, even before the filming of the first film of the epic began, her scientific consultant, paleontologist Jack Horner, did not doubt this either. Although (probably not without the influence of working with Spielberg), he developed a project to create a creature that looks like a dinosaur, but more on that later.
And recently, the dream of dinosaurs was finally given up. Danish and Australian paleogeneticists analyzed DNA from the bones of more than one and a half hundred extinct New Zealand giant moa birds aged from 600 to 8000 years and calculated that (at least under conditions of storage of bones in the ground, and then in museums) the half-life of DNA is 521 years … The conclusion is unambiguous: even in permafrost, after one and a half million years, the strands of fossil DNA will become too short to obtain information about the sequences of its nucleotides. The remains of the last dinosaur 40 times older - dreamers can relax and dream of something more mundane. For example, about mammoths.
Mammoths: two approaches to the dream
Japanese geneticist Akira Iritani, one of the leaders of the Mammoth Creation Society, in the mid-1990s still hoped to find viable egg and sperm in the carcasses of Siberian mammoths, and plant the result of their fusion in the uterus of an elephant. Realizing the unreality of such a hope, this sturdy old man (now in his 80s) did not give up trying to get at least a nucleus of a somatic (preferably a stem) cell in order to get a mammoth by the classic "Dolly method" - transferring this nucleus into an elephant ovum.
It looks like this cannon won't fire for ten (maybe fifty) reasons. Firstly, the probability of finding a cell with intact chromosomes in tissues that have lain for 10,000 years in permafrost is virtually zero: they will be destroyed by ice crystals, residual enzyme activity, cosmic rays … Let us analyze some of the other reasons using another, less unrealistic idea.
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Family tree. Simplified family tree of the elephant family.
An international group of scientists read the mammoth genome almost completely back in 2008. Its chromosomes can be assembled "brick by brick" - to synthesize chains of nucleotides, and not even all more than six billion, but several thousand pairs of genes (out of approximately 20,000), which differ from similar DNA regions of the closest surviving mammoth relatives - the Asian elephant. It only remains to “just” read the genome of this elephant, compare it with the mammoth genome, obtain a culture of elephant embryonic cells, replace the necessary genes in their chromosomes - and go ahead, along the path beaten by Ian Wilmut, leading Dolly the sheep on a string.
A variety of animals, from fish to monkeys, have since been tilted by many. True, cells from donors were taken during life and, if necessary, stored in liquid nitrogen, and viable newborns are less than 1% of the eggs with the transplanted nucleus. And at the same time, if genes changed, then one or two, not thousands. And they transplanted eggs to animals of the same species or very closely related, and Indian elephants and mammoths are about the same "relatives" as people and chimpanzees.
Will the elephant be able to accept a mammoth embryo, carry it for two years and give birth to a live and healthy baby? It is highly doubtful. And what will you do with a single mammoth? To maintain the population even in the "Pleistocene park", a herd of at least a hundred heads is required.
And it is highly desirable that they are not siblings, otherwise the probability of hereditary diseases in their offspring is too high - and the last mammoths died out, among other things, because they could not adapt to the next warming due to too little variability of their genomes. Etc. But if they ever succeed in cloning mammoths, in the north of Yakutia they have long ago prepared both a table and a house.
Pleistocene park
Several tens of thousands of years ago, on the site of the present tundra, in the same climatic conditions as in our time, a savanna-like tundra steppe was growing, in which there were about the same number of bison, mammoths, woolly rhinos, cave lions and other living creatures as there are now elephants. rhinos, antelopes, lions and other animals in African reserves. The short northern summer was enough for the plants to accumulate enough biomass both for themselves and for feeding the herbivores during the polar night.
But during the last large-scale warming, about 10,000 years ago, the animals of the mammoth steppe became extinct (perhaps, primitive hunters accelerated this process a little). Without manure, the plants withered, the ecosystem began to rage, and after a few thousand years the tundra became formless and almost empty.
But in 1980, in a wildlife preserve near the town of Chersky at the mouth of the Kolyma, a group of enthusiasts headed by the head of the North-Eastern Scientific Station of the Russian Academy of Sciences, Sergei Zimov, began work to recreate the ecosystem of the mammoth steppe by introducing into the tundra the surviving Pleistocene animals or their modern counterparts that can exist in arctic climate.
They started with a fenced area of 50 hectares and a small herd of Yakut horses, which soon plucked and trampled almost all the vegetation in this “kraal”, which was too small for them. But that was only the beginning. Now (so far - on a slightly larger area, 160 hectares), elks, reindeer, musk oxen, marals and bison have already been added to the horses.
True, bison are inhabitants of deciduous forests, and if they fail to adapt in the Arctic, they are planning to replace them with a more suitable species - forest bison. We just need to wait until their small herd grows, sent by colleagues from the reserves of northern Canada and assigned to a post in a nursery in the south of Yakutia.
When (and if), instead of a large park, the project receives an area sufficient to organize a nature reserve, it will be possible to release wolves and bears from the enclosures and even try to introduce Amur tigers - the most suitable replacement for cave lions available. But what about mammoths? And mammoths later. If this works out.
Fly, pigeons?
The project to revive the American wandering pigeons (Ectopistes migratorius) has nothing to do with ecology. On the contrary, at the beginning of the 19th century, in eastern North America, wandering pigeons flew in flocks of hundreds of millions of birds, devouring forests like locusts, and leaving behind an inch layer of droppings, arranged colonies of hundreds of nests in the trees and, despite all the efforts of predators, Indians, and then the first white settlers, did not diminish in number.
But with the advent of railways, hunting pigeons has become a profitable business. Shoot without looking at the cloud flying over the farm, or collect chicks like apples and hand them over to the buyer - a bunch for a piglet, but bunches - how many you can drag. In just a quarter of a century, several thousand of the billions of wandering pigeons remained - too few to restore the population of these collectivists, even if it had occurred to someone in those days. The last wandering dove died at the zoo in 1914.
The young American geneticist Ben Novak flared up with the dream to revive the wandering pigeon. He even managed to get funding for his idea from the Revive and Restore Foundation, one of the branches of the Long Now organization founded by the writer Stuart Brand, which supports extravagant, but not too crazy projects in various fields of science.
Ben plans to use the eggs of the striped pigeon, the species most closely related to the wandering pigeon, as material for gene shuffling. True, they are separated from their common ancestor by 30 million years and the number of mutations is much greater than between mammoths and elephants. And the experiment with replacing genes in bird embryos has been more or less worked out only on chickens, and so far no one has dealt with pigeons …
But the genome of the wandering pigeon has already been read from a tissue sample provided by one of the museums, and in March 2013 Novak began work on the reconstruction of the extinct bird at the University of California at Santa Cruz. True, even if the project ends in success, its results will live in zoos: in nature, wandering pigeons can exist only as part of multimillion flocks. What will happen to the US corn belt if these flocks can adapt to new conditions of life?
Although, even if it is not possible to recreate the wandering pigeons, the results obtained will be useful for attempts to revive dodo (funny Dodo birds), New Zealand moa, Madagascar Aepyornis similar to them and other recently extinct bird species.
In January 2013, incredible news spread around the world media: the famous geneticist George Church from Harvard University is looking for a brave woman to be a surrogate mother for cloning a Neanderthal. A day later, all the respectable publications that took the bait published a refutation: it turned out that the journalists from the Daily Mail made a little mistake when translating an interview in the German weekly Spiegel. Church, who had never dealt with the Neanderthal genome, was just speculating that theoretically it would be possible to clone it someday, but is it necessary?
Kurosaurs: forward into the past
Now back to the scientist we started with, Jack Horner of Montana State University, author of How to Build a Dinosaur. True, it will be more likely a kurosaurus: the project is called Chickenosaurus, and its implementation, according to the author, will take only five years. To do this, you need to "wake up" in the chicken embryo the preserved, but not active genes of dinosaurs. We can start with the teeth: Archeopteryx and other first birds had quite good teeth. True, the maximum that researchers working in this field could achieve is 16-day-old chicken embryos with several conical teeth in the front of the beak, but the road of a thousand li starts with the first step …
This is exactly how, in several stages - step by step, gene by gene, protein by protein - Horner plans to grow his kurosaurs. Remove the fourth toe, turn the wings into paws … And the first stage of the project will take five to seven years of work and a couple of million dollars. However, there is no information yet that the Kurozavry project has received funding. But there will surely be a patron of the arts: it is not so important that these will not be quite real dinosaurs, and for a start - the size of a chicken. But it's beautiful.
Speaking of beauty, the dark coloring and scales of the dinosaurs in Jurassic Park make them more scary, but most likely not true. Horner and many other paleontologists have long held that most, if not all, terrestrial dinosaurs were warm-blooded and covered in brightly colored feathers. Including the Terrible Regal Lizard - Tyrannosaurus rex. Warm-bloodedness is still a controversial issue, but the undoubted traces of feathers on the fossilized remains of close relatives of the tyrannosaurus - Yutyrannus huali (translated from Latin-Chinese - "Handsome tyrant with feathers", weight - almost 1.5 tons, length - 9 m) - recently discovered expedition of Chinese paleontologists. And what if the structure of its primitive feathers up to 15 cm long look more like chicken fluff, and not the complex feathers of modern birds? Well it can't beso that they are not beautifully painted!
And if future mammoths, dodos, dinosaurs and other extinct animals are not quite real, but almost identical to natural ones - which of you would refuse to walk in the park of a period that at first glance is indistinguishable from the Jurassic or Pleistocene?
Alexander Chubenko