Posted on 01/17/2007 9:58:32 PM PST by FLOutdoorsman
The idea that humans and chimps interbred causes discomfort in some circles, even as science explores the potential benefits of hybrids and the blurring of what was once a bright line between species.
In 1997, developmental biologist Stuart Newman did something relatively unusual for a scientist: He submitted a patent application for a technology he hoped never to use. In it, he laid claim to the humanzee, a chimera made by combining the embryonic cells of humans with those of chimpanzees. Though it was hypothetically possible to manufacture such a creature, he vowed to put the patent in a drawer for twenty years, ensuring that a proper public debate occurred before such information could fall into the hands of mad scientists or corporations that might exploit it. After years of legal wrangling, his application was officially denied in 2004. Newman let the appeal period lapse in 2005, putting an end to the matter for the time being. Or so he thought.
Recent research suggests that Mother Nature had other ideas. In May, scientists at the Broad Institute in Cambridge, Massachusetts, released a study comparing human and other primate genomes with more intense scrutiny than ever before, down to the letters of each base pair. The striking similarities between humans and chimpanzees, especially on the sex-determining X chromosome, led the scientists to a pair of astounding conclusions. First of all, chimps and humans likely diverged from the same evolutionary tree less than 6.3 million years ago, more recently than previously thought. Secondly, the break might not have been a clean one: Early humans and chimps quite possibly interbred for a period of about 4 million years before they split for good. This type of on-again, off-again speciation had formerly been documented in plants and other animals, but never in humans.
The implications sent shock waves through our anthropocentric culture, cuing mental footage of the interspecies monstrosities in The Island of Dr. Moreau. The fear and revulsion some feel at the thought of interbreeding with our simian ancestors is echoed in the expressed objections to modern biotechnologies that blend human and animal parts. President George W. Bush, for one, called for a ban on human-animal hybrids in his 2006 State of the Union address. Yet scientists have already infused mice, sheep, pigs, and other animals with human cells, and a closer look at the boundaries between species reveals the lines to be much more fluid and amorphous than commonly thought, even between humans and nonhumans. If what the Broad Institute scientists suggest is true, we likely descended from humanzees, and if the pace of progress continues, humanzees may be what we once again become.
Most people would probably say they know what species are—different kinds of animals that look alike, act alike, and have babies that follow the same path. As far as biologists are concerned, though, the matter is much less settled. For decades, most scientists have relied upon what’s called the “biological species concept”: Two animals are of the same species if they can interbreed and produce offspring that are fertile. Two breeds of domesticated dogs are the same species if they can produce a litter of fertile pups, as opposed to horses and donkeys, which beget sterile mules. This understanding, however, leaves out a few critical points. Much of the plant kingdom and some of the animal kingdom don’t breed at all; many organisms, such as bacteria, reproduce asexually. In addition, some creatures that can interbreed and produce viable hybrids, such as certain varieties of orchids, are still considered separate species.
With those difficulties in mind, a newer, more nuanced view of species has evolved—one subscribed to by, among others, Massimo Pigliucci, an evolutionary biologist at Stony Brook University in New York. “Sex is only part of the definition; there are other things going on,” he says. “Species may be distinct because of their ecology, or they may be distinct because of other aspects of their genetics. Fixating oneself on sex is just a little too narrow. It just wouldn’t work for some species.”
The definition of species is not purely an academic question; there are clear moral, legal, and ethical implications for scientists and laypeople alike. The Endangered Species Act, for instance, depends on precise enumerations of individual species to determine which animals to protect and which are left to fend for themselves. The protection of animal research subjects can be mandated by species, with primates often more heavily regulated than birds, insects, or rodents. Our personal, less technical species classifications frequently dictate our diet—many people eat fish, but not mammals— and, to some extent, determine our treatment of the creatures around us. The everyday understanding of species also encompasses the moral and technical difficulties inherent in blending them. The occasional entertaining zoo hybrid aside, most people pretty much agree that dog is dog, cat is cat, and there’s not much room for crossbreeding. This is especially true when it comes to our favorite species: Homo sapiens.
For researchers, however, “there’s nothing sacramental about the boundaries between the species,” and interbreeding, therefore, “is just moving around cellular or genetic materials in the world,” says Arizona State University bioethicist Jason Robert. Esmail Zanjani, an animal biotechnologist at the University of Nevada School of Medicine, has grown sheep with human livers; Irving Weissman, director of the Institute for Stem Cell Biology and Regenerative Medicine at Stanford University, has created mice with human brain cells; and many researchers are taking the first steps toward stem cell therapy by injecting human cells into mice, monkeys, and other animals. Evan Snyder of the Burnham Institute in La Jolla, California, argues that these sorts of experiments allow scientists to work out the kinks in such therapies on a monkey or rat rather than “your child or grandmother.”
Like Snyder, most biologists working to combine species aim to help humans or to advance scientific knowledge, not to selfishly cook up a Frankensteinian manimal. Zanjani, for instance, hopes human organs grown in animals could help shorten transplant waiting lists. Still, the intermingling makes many uneasy. Robert and other bioethicists have identified some potential underlying reasons for these fears: In essence, man-animal chimeras and hybrids could lead to a type of moral confusion, leaving us unsure of how we are supposed to treat the resulting creatures and whether we should be performing medical research on them at all. Regardless of their religious beliefs or lack thereof, most people do find something “special” about the human species, Robert says. “For people of faith, it’s going to be a metaphysical difference between humans and nonhuman animals. For others, it’s going to be something else, such as culture or self-consciousness, that explains the differences between human and nonhuman animals.”
This sense of specialness also underlies many of the negative responses the researchers at the Broad Institute received. “The reason there is all this discussion is because a lot of people still today simply can’t wrap their minds around the idea that we’re animals,” says Pigliucci, who has a particular interest in the way we think about evolutionary theory. “We may be special animals, we may be particular animals with very special characteristics, but we’re animals nonetheless; we have cousins and relatives all over the animal world, and, therefore, by implication of course, we were not created from nothing by an intelligent designer. That really hurts a lot of people.”
Sara Via, an evolutionary biologist at the University of Maryland, echoed this sentiment in a recent AAAS talk on speciation: “Many people don’t want to accept that humans aren’t on the top of the heap evolutionarily and certainly not that humans may have evolved from something that resembles a lowly monkey.”
Scientists are not immune to illusions of distinct separation, says Pigliucci. “I am certainly not going to claim that at a subconscious level, there’s been no bias amongst scientists themselves in terms of human biology,” he says. “I’m sure that it is difficult to look not only at humans, but at our closest relatives, in a completely detached way. I know several primatologists, and I don’t know any of them who doesn’t feel more than just a scientific curiosity toward their subject of investigation. They clearly understand and they feel that they’re dealing with very special animals because they’re so closely related to us.” But new information, such as the complete sequence of human and some animal genomes, is allowing scientists to factually confirm, again and again, our similarities to other species. We share with chimpanzees more DNA than previously thought; other primates, known as bonobos, have constructed societies in which they display moral rules; and elephants and other long-living species are now believed to suffer from psychiatric conditions like post-traumatic stress disorder. The ability to uncover these commonalities—and to be surprised by them—highlights the true benefit of the scientific worldview, Pigliucci says: its flexibility.
“Your regular person on the street thinks of a scientist as someone who’s certain. Scientists know facts. They’re objective. But that’s not science at all,” says Via. “Science is a view of life in which new information is admitted, not denied, and we use that information to always make that view better.”
That doesn’t mean scientists are always right or, as Robert points out, that they should be free to concoct hybrids and chimeras without public knowledge or oversight. It does suggest, however, the ways in which modern science can cast new light on the origin of species and the battle over the humanzee. If we open our minds to the fact that the humans of today descended from something akin to the man-animal hybrids of yesterday, perhaps we can live more comfortably with the idea of mixing animal and human parts and genes. Ultimately, maybe we can draw a new, more nuanced line between what is natural and what is taboo, between that which will hurt us and the genetic exploration that might help us improve life moving forward.
Pigman, coming to a lab near you soon! Oh, wait, Bill Clinton already has the patent on that.
one gorilla of a ping
Mythology is filled with chimera. One can't help but wonder if we've been down this road before. How much physical evidence of a technological civilization would survive an ice age? Would some tales of old survive as a dim distorted oral history?
Everyone has heard or even personally known beasts in human shape and humanzees. Nothing new here, move along.
The idea that humans and chimps interbred causes discomfort in some circles...particularly among those who hesitate to visit a topic like this, for fear there will be a picture of Helen Thomas...
"My family tree really does go back a long way..."
In May, scientists at the Broad Institute in Cambridge, Massachusetts, released a study comparing human and other primate genomes with more intense scrutiny than ever before, down to the letters of each base pair. The striking similarities between humans and chimpanzees, especially on the sex-determining X chromosome, led the scientists to a pair of astounding conclusions. First of all, chimps and humans likely diverged from the same evolutionary tree less than 6.3 million years ago, more recently than previously thought. Secondly, the break might not have been a clean one: Early humans and chimps quite possibly interbred for a period of about 4 million years before they split for good. This type of on-again, off-again speciation had formerly been documented in plants and other animals, but never in humans.Fascinating claim, considering humans have 23 chromosome pairs and chimps have 24 (as do gorillas, gibbons, and orangutans).
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Think big.
The great science fiction author pseudonymously known as Cordwainer Smith argued eloquently in favor of the generation of chimeras.
Progressive's despair about the current extinction event will almost certainly be remedied by human creativity. And after all, as we are informed in Genesis, humanity is charged with the Divine right to dominion over the Planet.
Throwing raw meat to tigers, I now stand back to see if anyone takes the bait...or even understands the implications.
too late, islam beat us to it!
Graincollections: Humans' Natural Ecological Niche -- A Review by Roger W. Wescott
Sergio Treviño is an independent-minded scholar who has made use of two troublesome anomolies of primate evolution to create a highly original model of homonid phylogeny. The first of these anomolies is the total absence of chimpanzee and gorilla remains from the fossil record of Quaternary Africa. The second is the apparent ineffectiveness of pre-Levalloisian choppers and hand-axes as weapons of the chase or butchering tools.
Back to the drawing board...
"Use tools - feel human"
If his does, mine does, too. I'm a second cousin of his.
The Interstate Highway System is creating tens of thousands of new species of snakes and squirrels as we speak.
Humanzee hybrids make Gunter sad.
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