I noticed then the abnormal shortness of their legs, and their lank, clumsy feet. All three began slowly to circle round, raising and stamping their feet and waving their arms; a kind of tune crept into their rhythmic recitation, and a refrain,—“Aloola,” or “Balloola,” it sounded like. Their eyes began to sparkle, and their ugly faces to brighten, with an expression of strange pleasure. Saliva dripped from their lipless mouths.
Suddenly, as I watched their grotesque and unaccountable gestures, I perceived clearly for the first time what it was that had offended me, what had given me the two inconsistent and conflicting impressions of utter strangeness and yet of the strangest familiarity. The three creatures engaged in this mysterious rite were human in shape, and yet human beings with the strangest air about them of some familiar animal. Each of these creatures, despite its human form, its rag of clothing, and the rough humanity of its bodily form, had woven into it—into its movements, into the expression of its countenance, into its whole presence—some now irresistible suggestion of a hog, a swinish taint, the unmistakable mark of the beast.
~ The Island of Doctor Moreau, H.G. Wells (1896)
Creatures that are neither human nor animal, but rather something in between, have probably been part scary stories since people began telling them around the campfire. However, what sets The Island of Doctor Moreau apart from traditional tales of werewolves and sphinxes, is that the humanized beasts are not the offspring of the gods or suffering from a curse. In H.G. Wells tale, his monstrocities were the product of science, rather than the supernatural.
Of course the Beast People of The Island of Doctor Moreau are not human at all. Instead they leopards and apes and hyenas and pigs surgically modified into human shape – "triumphs of vivisection". The Doctor even made some of his Beast People by combining parts from different animals:
You begin to see that it is a possible thing to transplant tissue from one part of an animal to another, or from one animal to another; to alter its chemical reactions and methods of growth; to modify the articulations of its limbs; and, indeed, to change it in its most intimate structure.
I don't doubt the Doctor would have eventually used human parts in his experiments, given the opportunity.
And I think it's partially that fear, that scientists will create monsters of dubious humanity in the blind pursuit of science, that had caused several US states (and countries like Canada) to pass laws banning creation of human-animal hybrids.
But when scientists create chimeras or hybrids of different species, they aren't interested in creating humanoids with animal characteristics like you see in science fiction-horror movies such as Splice. At least the scientists I know aren't trying to do that.
Instead, human and non-human genes and organs are combined to further biomedical research and treatments.
Organ transplantation has become a fairly routine part of medicine. The problem is that there are far more patients who need replacement organs - more than 72,000 on the active waiting list in the US - than there are healthy organs to transplant.
One potential solution is xenotransplantation - the transplant of organs from baboons, pigs or other animals into humans. While non-human animals seem to be a promising source of tissue for biological joint replacements, transplants of hearts, kidneys and other organs from animals to humans have had limited success. A major part of the problem is the rejection of the non-human tissue by the human immune system.
The solution? Engineer non-human animals to grow human organs. Sounds like mad science, right?
Here's a science fiction version:
Jimmy's father worked for OrganInc Farms. He was a genographer, one of the best in the field. He'd done some of the key studies on mapping the proteonome when he was still a post-grad, and then he'd helped engineer the Methuselah Mouse as part of Operation Immortality. After that, at OrganInc Farms, he'd been one of the foremost architects of the pigoon project, along with a team of transplant experts and the microbiologists who were splicing against infections. Pigoon was only a nickname: the official name was sus multiorganifer. But pigoon was what everyone said.
[... snip ...]
The goal of the pigoon project was to grown an assortment of foolproof human-tissue organs in a transgenic knockout pig host - organs that would transplant smoothly and avoid rejection, but would also be able to fend off attacks by opportunistic microbes and viruses, of which there were more strains every year. A rapid-maturity gene was spliced in so the pigoon kidneys and livers and hearts would be ready sooner, and now they were perfecting a pigoon that could grow five or six kidneys at a time.
~ Oryx and Crake, Margaret Atwood (2003)
Nothing like Atwood's pigoons currently exists. However, pigs are being genetically engineered to express human anticoagulants and human proteins that modulate the immune system. The resulting organs are not completely human, but they hopefully will be humanized enough to prevent the hyperacute rejection of the transplants.
Scientists in Japan have taken a slightly different approach. They used monkey stem cells to grow monkey organs in sheep. Presumably similar techniques could be used to grow human organs from human stem cells.
And it's not just big animals that are being engineered with human genes. Transgenic mice with functional human-like immune systems have been used to produce human antibodies for therapeutic purposes. A bit more oddly, tilapia have been engineered to produce human insulin as a potential source of transplanted islet cells to treat Type 1 diabetes.
Animal Models of Human Disease
For both ethical and practical reasons, it is often not possible to study the causes and potential treatments for disease directly in humans. Instead, animal models of human disease are used. A potential stumbling block to such research is that mice and other non-human animals aren't necessarily infected by the same microbes or afflicted with the same disorders as humans.
One way around that is to make the research animals more biologically similar to humans. For example, mice with humanized immune systems are being developed to allow screening of vaccine candidates for HIV and other viruses.
More controversially, mice were injected with human stem cells that ended up as functional components of the mouse brains. The hope is that the stem cell therapy research for brain diseases like Alzheimer's and Parkinson's.
There are many other examples: transgenic pigs used to study human retinitis pigmentosa, mice with humanized livers to study drug metabolism, and zebrafish engineered with human oncogenes to study cancer and so on.
Stem Cell Research
The biggest controversy over human-animal hybrids is not the creation of disease models or organ donors. It's research that touches on human reproduction.
While it may be possible for humans and chimpanzees to mate and have offspring, there is no evidence that this has ever happened. Instead, the great concern lies in the use of human-animal hybrid cells for cloning and stem cell creation. For example, the author of the recently passed Arizona law that bars the creation of a human-animal hybrid cited recent research in the UK that did just that:
Rep. Nancy Barto, R-Phoenix, who wrote the measure, said there's no evidence such research is going on in Arizona or any other state. But she noted that scientists in the United Kingdom reported putting human DNA into empty cow eggs.
So why create human-cow hybrids? The scientists' intention was not to create real-life minotaurs. Instead, cow egg cells had most of their DNA content removed, then replaced with nucleus and DNA from human skin cells. The idea is that such "cytoplasmic hybrid" cells can be stimulated to start dividing, then, after a few days, harvested for stem cells. The resulting stem cells would be for the most part human, since all of the nuclear DNA is derived from human cells.
Why use cow egg cells? For practical and ethical reasons. Human eggs are in short supply. I strongly doubt that people who oppose the development of the creation of human-cow stem cells would be any happier if they were entirely human.
Apparently human-animal hybridization has been used in the development of indy rockers:
A major advance in musical evolution? or a crime against nature and good taste?
- Frontline: Organ Farm
- Channel 4: Animal Farm (UK only)
- TED talk: Kevin Stone: The bio-future of joint replacement
- Bhan et al. "Human-animal chimeras for vaccine development: an endangered species or opportunity for the developing world?" BMC International Health and Human Rights 10:8 (2010) doi:10.1186/1472-698X-10-8
- Muotri et al. "Development of functional human embryonic stem cell-derived neurons in mouse brain" Proc Natl Acad Sci 102(51):18644-18648 (2005) doi: 10.1073/pnas.0509315102
Free science-fiction with human-animal hybrids (because who doesn't like some creepy SF?):
- "The Mind of a Pig" by Ekaterina Sedia
- "The Puma" by Theodora Goss
- "Winters are Hard" by Steven Popkes
- "The Dead Lady of Clown Town" by Cordwainer Smith
Top: ManBearPig from the South Park episode ManBearPig
Middle: Swine Flu by Chuck “Caveman” Coker, on Flickr, showing Patricia Piccinini's sculpture "The Young Family"
Bottom: Tondo Minotaur © Marie-Lan Nguyen / Wikimedia Commons