The State of Cloning 20 Years After Dolly the Sheep

Dolly was the first cloned mammal created from an adult cell.


Twenty years ago on July 5, 1996, the world’s most famous sheep was born. Brought into existence by a technique called somatic cell nuclear transfer, she became the first mammal to be successfully cloned from an adult cell. Named Dolly after Dolly Parton, she was named so because she originated from a cloned mammary cell and even scientists love boob jokes.

Dolly began her life in a test tube, was transferred as an embryo into a surrogate sheep mom, and was born at the Roslin Institute in Scotland. The whole affair captured the attention of people around the world when it was announced almost a year later, shocking leading researchers who had previously thought it couldn’t work.

“It’s unbelievable,” Dr. Lee Silver, a biology professor at Princeton University, told the New York Times in 1997. “It basically means that there are no limits. It means all of science fiction is true. They said it could never be done and now here it is, done before the year 2000.”

Okay, maybe not all of science fiction became true but it was undeniably cool. Dolly was at the time a unique drop of cells in a world of biodiversity: Of 277 attempts at cloning, Dolly came from the only embryo that was carried to term. Unfortunately, she had to be put down at the age of 6 due to a progressive lung disease — a death that’s about 5 years short from the average life span of a sheep. Today, Dolly’s body is on display at the National Museum of Scotland.

A member of the National Museum of Scotland staff views Dolly the Sheep .

Getty Images / Jeff J Mitchell

Where are we now twenty years after Dolly broke into the cloning scene? Here’s a timeline demonstrating what scientists have achieved since 1996, effectively turning the once fantastical into scientific milestones.

1998: Mice Clones Revealed

While tests showed that Dolly’s DNA matched that of the adult ewe that supplied her DNA, some researchers still had doubts that somatic cell nuclear transfer meant she was really a clone. Those doubts were set aside two years later in 1998, when clones of mice were created using the same technique. Dr. Ryuzo Yanagimachi and his then-postdoctoral student, Dr. Teruhiko Wakayama of the University of Hawaii, created a total of 50 mouse clones — 22 that were clones created from adult mammal cells, seven of which were clones of clones. This discovery meant that Dolly wasn’t a fluke, and heralded a new era of an unprecedented cloning process. Within ten years, somatic cell cloning was applied to a myriad of other animals, including cats, deer, horses, and rats.

It only took a few months for scientists to create dozens of mouse clones.

Global Panorama/Flickr

2001: Scientists Claim to Clone Human Embryo

Researchers from the privately financed biotechnology company Advanced Cell Technology announced in 2001 that they had created the first human embryos produced by cloning. These researchers used a technique called nuclear transplantation and believe their discovery represented, as said to Scientific American, “the dawn of a new age in medicine.”

But the experiment was, by most accounts, unsuccessful. While three of the cloned embryos divided to the four- to six cell stage, all died before they reached eight cells. While the experiment was never intended to result in a baby (the goal was to create a new way to make embryonic stem cells that could be matched to medical patients) it did add to the debate over the ethical boundary of human cloning. At the time of this experiment, then President George W. Bush planned to outlaw human cloning. Today there are no federal laws specifically regarding human cloning, but the Food and Drug Administration does have the authority to veto any experiments to explicitly create a cloned human baby.

2009: First Extinct Animal Cloned

Moving on to 2009, when a team of French and Spanish scientists successfully birthed the first extinct animal created from cloning techniques, the bucardo, a subspecies of the Pyrenean ibex. Unfortunately the clone only survived ten minutes after birth due to a large extra lobe that had grown attached to its lung. Still, with the baby’s DNA taken from the frozen skin of an extinct animal, this animal was (and still is) the closest thing scientists have gotten to maybe reversing extinction.

That certainly doesn’t mean that scientists aren’t trying. In March 2016, a team of South Korean researchers announced their plans to bring back an ancient cat species known colloquially as Cave Lions, by using the tissue from 10,000 year old cubs found frozen in Russian permafrost. The woolly mammoth has been a particular focus for researchers hoping to bring back extinct species; biologists at the University of Chicago, Harvard, South Korea’s Sooam Biotech, and Russia’s North-Eastern Federal University are all racing to clone the ancient beast.

The first (and only) extinct clone was a Pyrenean ibex.

Wikimedia Commons

2013: Human Embryonic Stem Cells Are Created From Cloning Techniques

The cloning technique used to create Dolly the sheep led to the first successful creation of human embryonic stem cells in 2013. Reproductive biology specialist Shoukhrat Mitalipov and his team were the first to create patient-specific human embryonic stem cells through cloning techniques, although a South Korean research claimed to do the same in 2005 (those claims turned out to be false).

This advancement is specified as therapeutic cloning, where the goal is to create stem cells for patients in need, not to create an actual living being. Mitalipov actually was able to derive embryonic stem cells from a monkey in 2007, but had to spend years working through United States medical regulations before he was able to achieve the same results with human cells.

2016: Massive Clone Projects Are Coming

While the exact date is still a mystery, the Chinese company BoyaLife announced in 2015 plans to open the “world’s largest” cloning facility by the end of 2016. Their first goal is to use cloning techniques to produce one million cows by 2020. The objective here has moved beyond scientific exploration — they want to create thousands of cows to satisfy the meat demand of 1.4 billion Chinese people. The facility will be a bit of a tourist attraction as well, with a gene bank, cloned animal center, and science education exhibit hall in the works.

Cows won’t be the only focus of the facility, though. According to The Guardian, BoyaLife also intends to clone “champion racehorses and sniffer dogs” — a far cry from one little lamb born from a common ewe in Scotland.

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