Hey! You got your sheep in my DNA! Well, you got your DNA in my sheep! Two great parts of nature that go great together. Or do they?
SO LONG, SPIDER-MAN
In 2009 senators Sam Brownback (R-Kansas) and Mary Landrieu (D-Louisiana) introduced an interesting piece of legislation: the Human-Animal Hybrid Prohibition Act. Just like it sounds, the bill would have made it illegal for scientists—mad or otherwise—to create creatures that are part human and part…something other than human. The reasoning went, if you made a “catwoman” in your basement laboratory, you could go to prison for 10 years and be fined up to $1 million. (Though that would be totally worth it.)
The bill was mostly laughed at, and it never made it to the Senate floor for a vote, but, as silly as it seems, it’s not as farfetched as it might sound. All around the world, scientists are hard at work trying to do just what the bill sought to outlaw. Here are just a few, and the creatures they’ve created.
I Am the Egg-Cow-Man: In April 2008, a team of scientists at Newcastle University in England extracted an unfertilized egg cell from a cow, removed its nucleus—where most of a cell’s DNA resides—and replaced it with the nucleus of a cell taken from another animal. They then gave the egg a tiny electric shock, which “activated” it, meaning that the inserted DNA began to do its work, and the cell started dividing. In other words, it was alive. And the DNA they inserted into the cow egg was human (taken from a skin cell). The Newcastle scientists had successfully cloned a human-animal hybrid, possibly for the first time in history. (There have been a handful of unverifiable claims since 2003.) Did it go on to become a cow with hands and feet? Or a human with horns and hooves? No—the cells stopped dividing after about three days. But the team hopes to repeat the experiment and get an egg to keep dividing for about six days—at which time it should begin creating embryonic stem cells (ES cells), the “building block” cells found in embryos that go on to become more than 200 different types of cells in the body. The cells would be almost completely human—they’d have 99.99% human DNA and only .01% cow DNA. But, if successful, the procedure would allow scientists to skirt around laws forbidding or restricting the use of “normal” human embryos for stem-cell production. The scientists performing such experiments say they would never allow the cow-human hybrids to divide for more than a few days, and would never implant such an egg into a cow and attempt to bring it to term.
Every July, people gather along the railroad tracks in Laguna Niguel, CA, and drop their drawers for “Moon Amtrak Day.” More than 8,000 mooners participated in 2008.
I Squeak, Therefore I Am: Stanford University professor Irving Weissman and a team of researchers have created mice with brains that are part human. Hoping to learn more about brain cancers, Weissman extracted human embryonic brain stem cells—the kind that go on to become various types of brain cells—and injected them into the brains of adult mice. The cells survived and even traveled to different areas of the brains and matured into different types of brain cells. (The researchers created special markers that allowed them to keep track of the injected human cells.) The tests resulted in mice with brains whose cells were about 1% human. The next step: inject human brain stem cells not into adult mice but into fetal mice still in the womb. That, Weissman says, would result in mice that have much higher human brain content…perhaps as much as 100%. Before moving ahead, Weissman went to Stanford’s ethics department to make sure he wasn’t crossing any lines. Law professor Hank Greely, chair of the school’s ethics committee, gave the study the go-ahead with one condition: If the mice started showing any humanlike behaviors, they’d have to be destroyed immediately.
I’d Like Some Mutton and a Little Liver: In March 2007, Professor Esmail Zanjani of the University of Nevada-Reno announced that he had successfully injected sheep fetuses with human stem cells. The result: sheep that grew organs that were part human. Some had livers, for example, that were made up of as much as 40% human liver cells. Zanjani hopes the research may one day lead to sheep being raised only for the human organs in their bodies—which could be transplanted into humans who need them. The scientists could conceivably create sheep that are tailor-made for specific people. For example, a sheep could be injected with your bone marrow in order to grow organs suitable just for you. Zanjani insists that the work is ethical and medically necessary, and that the sheep are not monsters. “We haven’t seen them act as anything but sheep,” he says.
Piggy, Bloody Piggy: Jeffrey Platt, director of the Mayo Clinic Transplantation Biology Program in Rochester, Minnesota, performed similar human stem cell injections into fetal pigs, and now has a group of pigs that have pig blood cells and human blood cells running through their veins. But it gets weirder: Some of the blood cells are both. Their DNA contains both human and pig genes. Platt hopes the work might lead to pigs being raised for their human blood and organs, but there are several hurdles, including the fact that some porcine (pig) viruses can be passed on to humans.
Just Call Me “Babe”: Human/animal hybrids are actually nothing new. If you know anyone with an artificial valve in their heart, then there’s a good chance you already know a human/animal hybrid. Thousands of people each year receive heart valves harvested from either pigs or cows. That, technically, makes these people hybrids.
Evan Balaban, a behavioral neuroscientist at McGill University in Montreal, has produced bird-bird hybrids: He took brain cells from embryonic quails and transferred them into the brains of embryonic chickens. When the chickens later hatched and grew up, they didn’t “cluck” or “cock-a-doodle-doo” like normal chickens…they trilled like quail. And they bobbed their heads just like quail do. Balaban said the work upended the long-held belief that these behaviors are learned, showing conclusively that they are not only hard-wired—but that they can be transferred to entirely different species.
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Q: What do you get when you cross a turkey with an octopus? A: Drumsticks for everyone!