Attack of the Clones
Hello, and welcome to part three of my series of posts on de-extinction. To all those who saw this title and expected a Star Wars post, I am deeply sorry. I also love Star Wars. But if you’re a Jurassic Park fan, which I am as well, then you’re in the right place.
The topic of this post is cloning. Cloning is the process of producing similar populations of genetically identical individuals. This is a process that happens in nature in the case of many plants and single celled organisms that reproduce asexually. Even some animals can reproduce via cloning, though that is usually a secondary method of reproduction. Starfish are a good example. While they can reproduce sexually, they can also reproduce via self cloning. If a star fish loses an arm, not only will it regrow its arm, but the arm will grow into a new starfish, a clone of the original. Some snails and other animals are also known to be capable of asexual reproduction. Even more advanced animals such as frogs and lizards have been known to reproduce asexually.
But when most people say cloning, they are not referring to natural processes. They are talking about using genetics and biotechnology to artificially clone an animal that would not be capable of producing a clone in nature. The first successful mammal clone was Dolly the sheep, in 1996. Since then, many successful mammal clones have been produced in several species including sheep, cattle, pigs, and deer.
In layman’s terms, artificial cloning of a mammal (reptiles and birds would be a bit different since they use eggs, but it would still be a similar process) works by removing the nucleus from an egg cell, and fusing it with a donor cell stem cell from the animal you wish to clone, and stimulating the cell so that it starts to divide and develop. The embryo is then implanted in a surrogate animal, and when it is finished developing, will be born like a normal animal, except that it is a genetic copy of the animal from which it’s DNA was taken.
In the Jurassic Park films, Dinosaurs were brought back via cloning from DNA stored in fossilized mosquitoes. Sounds pretty cool, right? Yeah, but it’s fake. Yep, that’s right. Jurassic Park’s Mr. DNA has lied to us all. I thought he looked shifty. In real life, cloning dinosaurs is impossible. That’s because DNA has a half-life of only 521 years. So in a 65+ million year old DNA sample, there would be virtually no DNA. Now this isn’t to say that there aren’t other ways to create an animal that exactly resembles the extinct non-avian dinosaurs, but it just won’t be through cloning. If you’ve read my previous two posts, you can find some information about these other methods. Also, if you’re really curious, like me, I’d recommend reading “How to Build a Dinosaur: Extinction Doesn’t Have To Be Forever” by Jack Horner. It’s a very interesting read.
But I digress. So, cloning can’t give us a Jurassic Park, but that’s not to say it won’t be useful in other de-extinction efforts. Animals that have died more recently have left DNA behind that can be used in cloning. DNA’s half life is 521 years, but it’s decay can be increased or decreased based on environmental and preservation factors. For instance, the DNA of an animal that dies and is immediately buried will be at least somewhat useful for a few hundred years. If the animal is frozen, DNA can maintain fairly good integrity for several thousand years. But an animal that isn’t preserved in a way like that will likely have a much faster DNA decay rate, and it may only take a few years or less for the DNA to degrade beyond any usefulness.
Among the candidates for cloning are recently extinct species that have been brought to extinction by humans, such as the Thylacine and the Passenger Pigeon. Also in line is the Woolly Mammoth, made a possibility because of specimens deep-frozen in glacial ice. But even though these species are far more recent than dinosaurs, it’s still not super straight forward. With the exception of the Mammoths, these other species were not preserved in ice. So it might be questionable as to how much viable DNA can actually be recovered from the few remains we have left of these animals. And while Mammoths have been well preserved in ice, they are still 10,000 years old, which is old for DNA, and thawing will also speed up DNA decay. So even if somewhat or even mostly complete DNA can be recovered from Mammoths and other recently extinct animals, it still falls short. Mostly complete is not the same as complete, and you need a complete strand to make an animal.
However, there are potential ways to fix that. Let’s go back to Jurassic Park. In Mr. DNA’s scientifically inaccurate rundown of how to make dinosaurs, he did get a few things right. He said that the dinosaur genetic code was “full of holes”. While realistically there wouldn’t be any DNA left, at least he admitted that it was incomplete. The solution to this problem was to fill in the “holes” with DNA from related animals, including crocodiles, birds, and frogs, though frogs are in no way closely related to dinosaurs, but whatever. But regardless of InGen’s choice of DNA filler, Mr. DNA hits on an actual bit of real science. He doesn’t say it, but what he’s talking about is transgenics, the transferring of genetic material from one organism into the genome of another, or in this case, the incomplete genome of a dinosaur. But of course we’ve already established that cloning isn’t even a remotely viable method to bring back dinosaurs. But let’s look at recently extinct animals again. For the sake of simplicity, and because they’re some of my favorites, from here on out we’ll be mostly focusing on the Mammoth.
Viable Mammoth DNA can and has been recovered, but in this case “viable” is less of a 100% literal term and more of a vague term meaning, “not completely hopeless”. Mammoth DNA is able to be sequenced an mapped, but before it can be used to create a baby Mammoth, it’s more than likely that it’ll need some work done on it. Luckily, the Mammoth has a very close living cousin: the Asian Elephant. Asian Elephants and Mammoths are very closely related. And a Mammoth actually looks a lot like an Asian Elephant. Their overall body shape and head shape are about the same (and yes, it differs slightly from the less closely related African Elephant), though Mammoths were more robust and had their iconic huge curved tusks, which modern elephants lack. And while some species of Mammoths grew much larger, the Woolly Mammoth would have actually stood at about the same height as an Asian Elephant. They just would have been stockier, tuskier (yes I made up that word), and of course, woolly.
My point is, most of the Mammoth genome is the same as the Asian Elephant, and the two are very phenotypically similar, so if there are “holes” in the Mammoth genome, there is a prime candidate to fill them, or to form a starting point in reconstructing the Mammoth genome. This is promising for the Mammoth. But really, is it possible?
The short answer: yes. Has anything like this been done before? Also yes. In 2000, the Pyrenian Ibex went extinct. But in 2003, some preserved tissue was used to clone one. Unfortunately, the clone only lived a few minutes before dying from a lung defect, making it the first species to go extinct twice, but it proved that de-extinction via cloning is possible. And our technology and genetic research have only improved since then.
So where are we on the Woolly Mammoth? It is estimated that Mammoths could be back within a decade, governments permitting. And there are a few different efforts to clone one currently going on, each using slightly different methods. Probably at the forefront of these projects is the project being conducted here in the United States, lead by Harvard professor George Church. Some reports estimate that he could have viable Mammoth embryos within two years. Now, before everyone gets too excited, that might be an exaggeration, and the estimate may not have come from Dr. Church himself, and may be more a product of sensationalist reporting. In any case, more research and experimentation still needs to be done, and you can’t rush that. It’ll happen when it happens. Maybe it’ll be this decade. Maybe it’ll be longer.
But the real question is the ethics. Before Nature gets its clone army, there are some questions that may need to be asked and some discussions that may need to be had among lawmakers. To quote Ian Malcolm from Jurassic Park: “Your scientists were so preoccupied with whether they could, they didn’t stop to think if they should.”
Until next time, sayonara.