If you didn't know any better, you might think that Star, Snuppy, CC and ANDi were just a few unfortunately named animals. You'd only be half right. These creative monikers actually belong to a pig, a dog, a cat and a monkey that were among the first clones of their species.
You're likely already familiar with Dolly -- the sheep that achieved near celebrity status as the first mammal to be cloned successfully using adult animal cells. But although Dolly has been one of the few cloned animals to attract widespread fame, she's not alone. The world's first clone -- a tadpole -- was actually created in 1952 [source: Human Genome Project]. And at least a dozen different species have been cloned since: everything from the common cow to the endangered guar, a type of wild ox. You can learn more about the science behind cloning in How Cloning Works.
Animal cloning has come a long way since that first tadpole more than 50 years ago. The U.S. Food and Drug Administration's (FDA) declaration in early 2008 that food products derived from the clones of cows, pigs and goats are safe for human consumption intensified an already growing interest in the process.
Cloning has additional uses besides its ability to help farmers breed consistently top-notch burgers and bacon. Other potential applications include the preservation of species, biomedical research, drug and organ production and even commercial ventures that aim to keep little Fido (or at least a convincing substitute) in the family forever.
The possibility of having carbon copies of man's best friend bounding around the house leaves some people giddy and others understandably edgy. It may also leave you wondering just how many of these walking photocopies already exist. Or perhaps more importantly, did the hamburger you just finished eating get its start in a petri dish?
It seems that finding out exactly how many cloned animals have been produced is almost as difficult as producing them in the first place. There's no official registry of clones, and laboratories aren't required to report every single tadpole or mouse they create. The only species that anyone seems to be keeping track of are those whose progeny might make it into your grocer's deli case.
Armed with a bit of knowledge concerning animal cloning and its most prevalent uses, it's possible to narrow down the contestants to a viable field. While no one can say with any certainty that the animals in this article are the five most cloned animals in the world, they're at least worthy of mention.
Animal 5: Cloned Pets
In 2005, scientists in South Korea announced they had produced the first dog clone -- an Afghan hound named Snuppy. Several years earlier, in late 2001, the world's first cloned kitten, CC (short for Copycat), entered the world. Since then, at least 40 dogs and an unknown number of cats have been replicated [source: Keim].
In July 2008, BioArts International auctioned off four dog cloning spots to the highest bidders. The program, aptly titled "Best Friends Again," also offered up one, all-expenses-paid spot for a lucky winner in its Golden Clone Giveaway contest. That spot has since been won by a heroic Sept. 11 rescue dog, dubbed the world's most "clone-worthy" dog [source: BioArts International].
Hundreds of people pay upward of $1,000 a year to preserve tissue from their cat or dog for future cloning [source: Shiels]. Despite the high demand for commercially cloned pets, BioArts states on its Web site that its Best Friends Again program is a limited service that may or may not be continued.
Surely someone will step up to the plate, which is why pets merit a spot on this list. With thousands of potential customers having expressed interest in duplicating their beloved pets, it's only a matter of time before the technology advances enough to support a commercial venture.
Indeed, the Seoul-based company RNL Bio recently opened its doors for business and after the birth of five cloned puppies in August 2008, announced itself as the "first successful commercial canine cloning service." The team has already cloned more than 20 dogs and has plans to clone about 300 per year [source: CNN]. So if you have $150,000 to spare and a beloved pug to duplicate, you may want to take a trip to South Korea.
Animal 3: Cloned Pigs
If all pigs were as good at spelling as Wilbur, you might be a little more stoked about this particular selection. But while pigs can't spell -- it was Charlotte's doing, after all -- they do make some pretty mean bacon. If meat isn't your thing, cloned pigs are also sought after because of the suitability of their organs for human transplantation.
Transferring cells, tissues or organs from one species to another is known as xenotransplantation and is viewed as a potential solution to the shortage of organs and cells for lifesaving transplants. By tweaking the genetic makeup of pigs, a biopharmaceutical company named PPL Therapeutics has fine-tuned the animals' DNA so some of their organs and cells can be used successfully in people. These genetically altered pigs can be cloned to mass-generate things like insulin-producing cells for the treatment of type 1 diabetes and organs like hearts and kidneys [source: PPL Therapeutics, Inc.].
According to the European Food Safety Authority (EFSA), which recently conducted a study on the safety of products obtained from cloned animals and their offspring for consumption, there are already at least 500 cloned pigs in existence worldwide [source: EFSA]. And like goats, porcine foodstuffs also got the green light from the FDA, so it's likely that the number of pigs being cloned will increase. As advancements continue to be made with the treatment of human disease and xenotransplantation, pigs should continue to stake out a pretty prominent spot on the list of most cloned animals.
Animal 1: Cloned Mice
These ever-popular laboratory animals, mice are in even greater demand with the advent of reproductive cloning. The first cloned mouse, Cumulina, was born in July 1998 -- more than 10 years ago. And she wasn't alone: While it took Dolly's creators 277 tries before they had any success, Cumulina was the firstborn of ten identical siblings. Within five months, her creators had manufactured more than 60 clones [source: Caldwell].
Since mice are usually the most desirable animals for biomedical research, the possibility of having an endless supply of genetically identical rodents has caused quite a stir. Since Cumulina, the cloning process for mice has become even more successful. A study in 2007 discovered a cloning technique that achieved almost five times the success rate as the typical method [source: HHMI].
Mice, along with rats and birds, make up around 95 percent of the animals currently used in research [source: AAVS]. That will likely translate into thousands upon thousands of little cloned mice. Although there aren't any official numbers since facilities aren't required to report the number of animals they clone (or even use), it goes without saying that scientists will make use of cloning technologies in their studies. While that may not be good news for the mice, or for those individuals who oppose animal research, at least it earned the little guys a top spot on the list of most cloned animals.
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