Imagine this: As you wait for the train, someone commits suicide by jumping onto the tracks. Weirder yet, this person looks like you. In fact, this person is you. And that’s just the beginning.
Orphan Black, the new BBC America sci-fi show premiering Saturday, opens with this premise and hurls headlong into conspiracy. Sarah, the survivor, eventually pieces together that she and the dead woman are clones and that an untold number of women with her face and her DNA are systematically being killed off.
While we’re a long way from an Orphan Black scenario, scientists across the globe continue to develop techniques that, theoretically, would be used to clone humans. So how close are we?
First, the basics. Cloning can be divided into three major categories: DNA cloning, reproductive cloning, and therapeutic cloning. DNA cloning involves producing genetic sequences not present in biological organisms by combining material from different sources. It’s used for gene therapies, including the production of insulin, hepatitis B vaccine, and human growth hormones, as well as insect- and herbicide-resistant crops and genetically modified foods.
But hype and headlines usually refer to reproductive cloning, the making of an exact genetic replica of an organism. The process, somatic cell nuclear transplantation, involves taking DNA from somatic cells (which, unlike sperm or eggs, contain two copies of the genes that comprise an organism’s DNA) and inserting it into an egg that has had its nucleus removed. Implanted now with two copies of DNA, the enucleated egg becomes an embryo, which scientists transfer to a female host where it develops until birth. In 1997, this technology produced Dolly the sheep, the first mammal cloned from an adult cell. (The very first species to be cloned was a tadpole in 1952.) But it wasn’t a wholesale success: It took scientists at Edinburgh’s* Roslin Institute 277 attempts to produce Dolly, and in the end she was euthanized at age 6, half the average life span for a domestic sheep, after developing lung cancer and arthritis. It’s unclear whether the cloning process contributed to these conditions, but cloned animals do tend to die young and suffer from numerous ailments.
Given the inconsistent and low success rates of animal cloning, for years, many scientists thought primates would be too complex to clone. Then, after 10 years of attempts, a team at the Oregon Health and Science University cloned Rhesus monkey embryos in 2007. However, cloning an embryo is not the same as producing an actual clone of a species. Later, the same team tried reproductive cloning again, transferring 77 cloned embryos in various stages of development into 12 different surrogates. None of them survived more than three weeks in the womb.
Experiments in human cloning haven’t fared any better, generating far more controversy, skepticism, and unsubstantiated claims than success stories. Depending on your bioethical persuasion, you may be underwhelmed. But here are the highlights.
1998: South Korean scientists claimed to have cloned an embryo from a 30-year-old woman, but they destroyed it early in development. Their findings were never published or verified.
2001: Advanced Cell Technology, a Massachusetts company, announced that it had cloned human embryos for medical research, causing a storm of publicity that culminated in George W. Bush’s condemnation of and restrictions on embryonic stem cell research. (Obama removed these restrictions in 2009.) Later, ACT clarified that it never got as far as creating actual embryos— only creating a “ball of cells” that stopped developing a few hours later.
2002: An organization called Clonaid claimed to have delivered the first cloned baby, and since then has bragged that it’s “helped a number of patients have their own children through [their] cloning technology.” Clonaid’s claims have never been verified, and its ties to Raëlism, a religion founded upon belief in UFOs and the idea that cloning will pave the way to immortality, don’t exactly help its credibility. They also apparently perform pet cloning (they’re not the only ones), a service featured on a recent TLC show.
2004: A team led by fertility expert Panos Zavos claimed to have implanted a cloned human embryo into a 35-year-old woman (it’s unclear where this procedure might have happened), but she didn’t become pregnant. The team resolved to continue trying, but no success has been documented.
That same year, a South Korean team published a paper in Science magazine claiming to have derived embryonic stem cells from cloned a human embryo. But two years later, Science retracted the paper due to lack of proof.
You get the idea. Even Ian Wilmut, lead scientist of the team that produced Dolly, dismissed such attempts as publicity stunts.
Science isn’t the only hurdle here. While not expressly prohibited by federal law, many states have enacted bans on human cloning, as have many countries. Some also prohibit research cloning, while others, such as California, Massachusetts, Rhode Island, as well as China, the United Kingdom, and India specifically permit it. The United Nations, unable to reach consensus because of the differences between reproductive and therapeutic cloning (in which an embryo grows for just a few days before stem cells are harvested for medical purposes), adopted a nonbinding declaration against human cloning in 2005.
So for now, those in favor of human cloning will have to satisfy themselves with Orphan Black and maybe this classic episode of The X-Files. But perhaps the plight (or danger) of these look-alikes might be one good reason to champion genetic uniqueness.
Correction, March 30, 2013: This blog post originally misspelled Edinburgh.