Is it possible to revive the dinosaurs?

The dream of the revival of dinosaurs, mammoths and other extinct animals is constantly emerging in the press, although the overwhelming majority of scientists are skeptical about this idea. Can people ever walk in the park at least some period?

Let’s start with the worst news: Jurassic Park – pure fantasy. Neither traces of DNA left in immured in amber mosquitoes, nor even in the petrified remains of dinosaurs. Most likely, even before the filming of the first film of the epic, this was not doubted by her scientific consultant – paleontologist Jack Horner. Although (certainly not without the influence of working with Spielberg), he developed a project to create a creature resembling a dinosaur, but about this later.

And recently, at the dream of a dinosaur, the cross was finally put. The Danish and Australian paleogeneists analyzed DNA from the bones of one and a half hundred new extinct New Zealand giant birds with moa from 600 to 8000 years old and calculated that (at least in the conditions of storing bones in the ground and then in museums), the half-life of DNA is 521 years . The conclusion is unambiguous: even in the permafrost in 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 once in 40 years older – dreamers can relax and dream about something more mundane. For example, about mammoths.
 

 
Mammoths: two approaches to the dream
 
The Japanese geneticist Akira Iritani, one of the leaders of the Mammoth Creation Society, in the mid-1990s still hoped to find a viable egg and sperm in the carcasses of Siberian mammoths, and the result of their merging would be planted in the womb of an elephant. Realizing the unreality of this hope, this strong old man (now he is just over 80) did not give up trying to get at least a somatic (preferably stem) cell nucleus in order to get the mammoth by the classic “Dolly method” – transferring this nucleus to an elephant egg.

It seems that this gun will not fire for ten (and maybe even fifty) reasons. First, there is virtually no chance of finding a cell with intact chromosomes in tissues that have lain 10,000 years in permafrost: they will be destroyed by ice crystals, residual activity of the enzymes, cosmic rays … Some other reasons will be analyzed with the example of another, less unrealistic idea.
 


Simplified family tree of the elephant family
 
The mammoth genome was read by an international group of scientists almost in 2008. Its chromosomes can be assembled “on a brick” – synthesize nucleotide chains, and not even all of six and a half billion, and several thousand pairs of genes (out of about 20,000) that differ from analogous DNA sites of the closest surviving mammoth relatives – an Asian elephant. There will be “just” read the genome of this elephant, compare it with the mammoth genome, get the culture of elephant embryonic cells, replace the necessary genes in their chromosomes – and forward, along the road beaten by Jan Wilmut, leading on a string Dolly lamb.

The most diverse animals, from fish to monkeys, have since been tipped to the set. True, cells from donors were taken during life and, if necessary, stored in liquid nitrogen, and viable newborns receive less than 1% of the eggs with transplanted nucleus. And genes at the same time if they changed, then one or two, not thousands. And the eggs were transplanted to animals of the same species or very closely related, and Indian elephants and mammoths are about the same “relatives” as humans and chimpanzees.

Can an elephant accept a mammoth embryo, bear it for two years and give birth to a live and healthy baby? Very doubtful. And what will you do with a single mammoth? To maintain the population, even in the “Pleistocene Period Park,” a herd is needed, at least in the hundreds of heads.
 

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 have died out because they could not adapt to the next warming because of the too small variability of their genomes. And so on. But if one ever clones mammoths still succeed, in the north of Yakutia they have long been prepared and a table and a house.
 
Pleistocene Park

Several tens of thousands of years ago, in the place of the present tundra, in the same climatic conditions as in our time, there was a tundra-steppe similar to the savannah, in which bison, mammoths, woolly rhinoceroses, cave lions and other living creatures were about the same as now – elephants, The rhinoceroses, antelopes, lions and other animals in the African reserves. The short northern summer was enough for plants to accumulate enough biomass for themselves, and for the feeding of herbivores for the time of the polar night.

But during the last large-scale warming, about 10,000 years ago, the animals of the mammoth steppe died out (perhaps primitive hunters speeded up the process a little). Without manure the plants withered away, the ecosystem went wild, and after a few thousand years the tundra became invisible and almost empty.

But in 1980, in a reserve near the town of Chersky in the mouth of the Kolyma, a group of enthusiasts led by the head of the North-Eastern Scientific Station of the Russian Academy of Sciences, Sergei Zimov, began work on recreating the mammoth steppe ecosystem by introducing tundra survivors of Pleistocene survivors or their modern counterparts capable of arctic climate.

They began with a fenced plot of 50 hectares and a small herd of Yakut horses, which soon plucked and trampled almost all the vegetation in this “kraale” too small for them. But that was only the beginning. Now (while – on a slightly larger area, 160 hectares), moose, reindeer, musk ox, maral and bison have already settled on horses.

Modest achievements

The last of the dingoes destroyed by dogs, natives and, finally, European sheep breeders of the Tasmanian marsupial wolves – thylacinus (Thylacinus cynocephalus) died in the zoo in 1936. In 2008, researchers from Melbourne University isolated one of the regulatory genes that strengthen the synthesis of another gene’s protein, which is responsible for the development of cartilage and bones, from the alcohol-bound tissue of museum specimens of tilatsin, and replaced them with a similar gene regulator in mouse ovules. In two-week-old mouse embryos (no potential ugly creatures were born to be born), it was not the murine but the tylacin protein Col2A1 that was synthesized. But about the revival of the marsupial wolf on a mouse basis, one should not even dream of it – it’s just a genetic focus, the results of which, perhaps, will someday be useful, for example, to study the functions of the genes of extinct species.

In the same Australia in the spring of this year, bioengineers from the University of New South Wales tried to grow a frog Rheobatrachus silus, extinct only 30 years ago, a small animal, curious that its females were carrying caviar in their mouths. The nuclei from the frozen tissues of R. silus scientists introduced the frogs closest to it, Mixophyes fasciolatus, and even waited a few oocyte divisions, and then the embryos died. But dashing trouble began, although for the public this amphibious detail is not at all what dinosaurs are.

Failure, albeit much less, ended and the experiment of researchers from the University of Zaragoza on cloning pyrenean mountain goat, the last of which died in 2000. The first two attempts to achieve the birth of kids from embryos derived from cell nuclei frozen during the life of the last individual, and eggs of a domestic goat, resulted in miscarriages at best. For the third time (in 2009), Spanish scientists created 439 chimeric embryos, 57 of which began to divide and were implanted into the uterus of surrogate mothers. Unfortunately, of the seven pregnant goats, only one child has survived until the baby, and the goat died a few minutes after birth due to breathing problems.

True, the bison are inhabitants of broad-leaved forests, and if they fail to adapt in the Arctic, they plan to replace them with a more suitable species – forest bison. We just have to wait until their small flock is sent, sent by colleagues from the reserves of northern Canada and determined to stay in a nursery in the south of Yakutia.

When (and if) instead of a large park the project will receive an area sufficient for the organization of the 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. Well, how about mammoths? And mammoths – then. If possible.

Fly, doves?

The project of the revival of American wandering pigeons (Ectopistes migratorius) with the environment is not connected. On the contrary, as early as the beginning of the nineteenth century, in the east of North America, wandering pigeons flew flocks of hundreds of millions of birds, eating forests as locusts, and leaving behind an inch of the droppings, planting colonies of hundreds of nests in trees, and despite all the efforts of predators, Indians, and then the first white settlers, did not decrease in number.

But with the advent of railways, hunting for wandering pigeons has become a profitable business. Shoot without looking at the cloud flying over the farm or collect chicks, like apples, and hand over to the buyer – a bunch for a penny, but beams – how much to drag. In just a quarter of a century, from the billions of wandering pigeons, a few thousand are left – too little to restore the population of these collectivists, even if it occurred to someone in those days. The last wandering dove died in the zoo in 1914.

The dream of reviving the wandering pigeon was inflamed by the young American geneticist Ben Novak. He even managed to get funding from the Revive and Restore fund, one of the branches of Long Now, founded by writer Stuart Brand, supporting extravagant but not too crazy projects in various fields of science.

As a material for the rearrangement of genes, Ben plans to use the eggs of a striped tailed pigeon, the species most related to the wandering pigeon. True, from a common ancestor they are separated 30 million years and much more than between mammoths and elephants, the number of mutations. And the experience with the replacement of genes in the embryos of birds more or less worked only on chicken, and with pigeons, so far no one had anything to do …

But the genome of the wandering pigeon has already been read on the basis of tissue samples provided by one of the museums, and in March 2013 Novak began work on the reconstruction of extinct birds at the University of California in Santa Cruz. True, even if the project ends with luck, its results will live in zoos: in nature, wandering pigeons can exist only as part of multimillion packs. What is the “corn belt” of the USA waiting for, if these flocks can adapt to the new conditions of life?

Although, even if you can not recreate the wandering pigeons, the results obtained will be useful for attempts to revive dodo (funny Dodo birds), New Zealand moas, Madagascar epihorns similar to them and other recently extinct bird species.
 

 
In January 2013, the world’s media has flown incredible news: a well-known geneticist George Church of Harvard University is looking for a brave woman to act as a surrogate mother for cloning Neanderthals. Every other day, all the decent publications that bite on this bait published a refutation: it turned out that the journalists from the Daily Mail were a little mistaken when translating the interview in the German weekly Spiegel. Church, which the genome of the Neanderthal man has never dealt with, just argued that theoretically cloning it will someday be possible, but is it necessary?
 
 
Kurosaurs: forward, into the past!

And now back to the scientist from which we started, – Jack Horner from the University of Montana, author of the book How to Build a Dinosaur (How to Build a Dinosaur). True, it will be more like a chimpanzee: the project is called Chickenosaurus, and for its implementation, according to the author, it will take only five years. To do this, you need to “wake up” in the chicken embryo surviving, but not active genes of dinosaurs. You can start with teeth: in Archeopteryx and other pervaptic teeth were quite good. True, the maximum that the researchers working in this area could achieve was 16-day-old chick embryos with several conical teeth in the front part of the beak, but the road to a thousand li begins with the first step …

That’s right, in several stages – step by step, gene for the gene, protein for protein – Horner and plans to grow his kurozavrov. The fourth finger is removed, the wings are turned into paws … And it will take five to seven years of work and a couple of million dollars for the first stage of the project. However, there is no information that the project “Kurozavry” received funding. But the patron will surely be found: it is not so important that they will not be real dinosaurs and for the beginning – the size of a chicken. But it’s beautiful.

By the way, about beauty: the dark coloring and scales of dinosaurs in “Jurassic Park” makes them more terrible, but, most likely, not true. Both Horner and many other paleontologists have long held the view that most if not all terrestrial dinosaurs were warm-blooded and covered with bright feathers. Including the Terrible Regal Lizard – Tyrannosaurus rex. Warmth-keeping is still a controversial, but doubtless traces of feathers on the petrified remains of close relatives of the tyrannosaurus – Yutyrannus huali (translated from the Latin-Chinese – “A beautiful tyrant in 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 longer like a chicken fuzz, rather than the complex feathers of modern birds? Well, it can not be that they are not beautifully colored!

And if the future mammoths, dodos, dinosaurs and other extinct animals are not quite real, but almost identical to natural ones – which of you refuses to walk through the park of a period that at first glance is indistinguishable from Jurassic or Pleistocene?