Imagine you are in the Siberian tundra–the sky is grey, the land is covered in soft snow–but off in the distance you see something moving, something big. A woolly mammoth! Its 6 metric tons of furry girth and 10 ft. long tusks tower over you. A whole herd lumbers past towards a barely exposed tuft of grass. Many thousands of years ago during the last ice age, this would have been a common sight across northern Asia, Europe, and parts of North America.
Today the wooly mammoth is very much extinct, though it’s closest living relative is the Asian elephant. But amazingly intact mammoth carcasses are still being unearthed today. With such well-preserved tissue samples, the question on everyone’s mind is this: Can we clone a woolly mammoth?
This is a question addressed by Beth Shapiro, PhD who recently wrote the book How to Clone a Mammoth: The Science of De-Extinction. She recently gave a talk at UCSD through the Institute of Practical Ethics. Her answer?
“No, we will never, ever, ever clone a woolly mammoth,” she told the crowd, followed by a picture of a baby crying. Indeed we were all disappointed. But she went on to explain in great detail the reason for her answer and it has everything to do with the science of cloning.
Cloning is a much simpler process than you might expect. First, you take a living cell from the animal you want to clone and isolate the nucleus, which contains its DNA. Then, you harvest an egg from a related donor animal and remove its nucleus. Next, you take the nucleus of the animal you want to clone, put it in the donor egg, and insert the newly formed zygote into the womb of a host mother. Now you have an embryo that will begin to grow like a naturally conceived fetus and after some number of months, you end up with a brand new baby clone. Tada!
So if we are trying to clone a woolly mammoth, the first thing we need is a living cell. And therein lies the problem. Because even though we have many metric tons of preserved mammoth tissue, not a single one of those cells is still alive. But why won’t any of the other cells work? That has to do with DNA.
DNA is the molecule that tells our cells how to be cells. It’s kind of like a recipe book that gives us the instructions for how to make all of our key components. In a normal living cell, the DNA is like a long roll of streamers. It is tightly wrapped up most of the time, but can be expanded to form a long, intact strand. There are a whole set of other molecules in our bodies that help make sure that strand doesn’t get damaged or degraded.
After you die, however, those molecules stop working. Instead, other molecules come in and cut those strands in to small pieces, so that instead of streamers you have confetti. “The DNA inside of preserved mammoth cells,” Dr. Shapiro explains “isn’t just like confetti. It’s like the confetti left in a gutter the day after a parade when it rained.” Without a perfect copy of mammoth DNA, there is no way to clone a woolly mammoth.
That doesn’t mean people aren’t still trying to bring back mammoths. There are researchers who have managed to glue together those dirty pieces of confetti and sequence a whole mammoth genome. As it turns out, this genome is actually pretty similar to the Asian elephant genome. With modern gene editing technology, it could be possible to make a new mammoth by many generations of breeding gene-edited mutants starting from a modern Asian elephant.
If there is anything I learned from watching Jurassic Park, however, it’s that just because we can do something doesn’t mean we should.
Much of Dr. Shapiro’s seminar was about the ethical issues around bringing back extinct animals, a concept called de-extinction. The world today is a very different place than it used to be. The habitat that woolly mammoths used to roam is mostly gone. And if not gone, it is drastically changed. There is a simple question of where we would put them. Zoos? Perhaps. But we already know that modern elephants don’t fair particularly well in captive breeding programs, so what do we expect for a species that lived even before we had the concept of domestication?
Some would say that these are questions for philosophers and ethicists. But given the many cultural tropes of mad scientists who create monsters in a laboratory, I think it is about time that scientists themselves begin to take a more practical look at where their science is going. Scientists need to take more responsibility for the roles they play in altering society as a whole. De-extinction is just one of many concepts that we scientists will have to face going forward so that it is not so much a question of can we bring back woolly mammoths, but should we.