Genetically modified plants and animals are often feared as "Frankenfoods," but is there really anything dangerously new about manipulation of DNA? People have been creating extreme genetic mutants with plants and animals for tens of thousands of years.
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Today, using biotechnology, humans can directly manipulate the genetic code of plants and animals, making them resistant to crop-decimating diseases (GM papaya), tolerant to insect pests (Bt Corn), or incapable of breeding, thus reducing disease transmission (GM mosquitoes). But there is growing concern about GMO technology — a number of people, ranging from grassroots groups to scientific societies, worry that eating GMOs could lead to health risks and worse.
These worries ignore the long history of humans manipulating the genetic code of our foods and other organisms in the environment. In the past, we manipulated the DNA of animals and plants through selective breeding and heavy inbreeding. And we did it for the same reason we create GMOs today: People wanted plants and animals to work better for people. We want our pigs to be as close to 100% bacon as possible, our cows to secrete pure butter, and our wolves to bark shrilly and uselessly from our handbags. High-tech forms of genetic manipulation are just the logical next step forward in millennia-long, transformative relationship between humans, animals and plants.
And in a world facing a rapidly shifting climate, GM crops may represent our best chance at feeding humanity.
The domestic dog is probably our longest-running genetics experiment. Through the process of selective breeding, humans have altered the genome of the domestic dog incredibly. The earliest evidence of changes to the dog occurs in well preserved remains buried in a cave about 33,000 years ago. Investigations of these remains indicated that the skull and jaws of the dog were much more like those of a modern dog (shorter, wider, and with crowded teeth), than of a wolf.
Such changes actually come unintentionally as a result of domestication; Dmitry Balyaev demonstrated this with some of the best designed, longest-running domestication studies. Working with silver foxes from a fur farm, Balyaev, selected only the friendliest foxes for breeding. As a result, Balyaev was able to produce very friendly foxes with piebald coats, floppy ears, and short, broad muzzles, even though he wasn't selecting for any traits other than friendliness toward humans. Surprisingly, this selection has altered the personality of the foxes at a genetic level. When embryos from friendly foxes are transplanted into, and then raised by unfriendly mothers, pups from friendly lineages were still friendly. In essence, these foxes are mutants for friendliness towards humans (a trait that would surely doom them in the wild).
Modern dog fanciers have taken this sort of selection to incredible extremes, genetically manipulating the wolf through selective breeding into specimens that are are barely identifiable as canines. Take the English bulldog. Originally, this breed was created for the sport of bull-baiting. The genetic mutations causing wide mouths and short muzzles, coupled with enormous strength, allowed the bulldog to clamp on to the nose of a bull and not let go. This sport fell out of favor in the Victorian era, but the bulldog remained.
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With no job to do, breeders focused on exaggerating the unique characteristics of this breed through intense inbreeding. Within a few decades, the bulldog had been transformed. The modern bulldog's unique structure is actually due to an inherited form of dwarfism, a mutation which causes an extremely large head and broad chest with short, dwarfed legs, malformation of the cartilage (hence the crumpled, shrunken tail of the bulldog), and a protruding lower jaw. 80% of these dogs have to be delivered by c-section because their heads are too large to be born naturally, and a staggering 71% of dogs suffer severe joint issues.
If you found a bulldog skull in the woods, you would probably suspect you had encountered a chupacabra. Much like genetically-modified creatures created in a lab, these dogs would not and could not exist without the direct manipulation and support of humans.
Dogs are a pretty extreme example of our genetic manipulations — our focus on intensively breeding strange-looking individuals has caused them to exhibit the greatest variation of any domesticated species. But we have developed some pretty incredible mutants in other species, too. Especially species we like to eat.
In the name of making more ever more delicious steak, humans have created what can only be referred to as the Hulk of the cow world. The mutant Belgian blue cow and a handful of other breeds have a mutation that reduces production of myostatin in the body, a protein which would normally limit muscle growth. When you flip this switch in the genome, you get incredible, cartoonish muscle production, basically from birth. This mutation occurred naturally in some individuals that formed the Belgian Blue breed, but intensive linebreeding (e.g. daughter to father) and use of artificial insemination in the 1950s led this mutation to become fixed in the breed.
All Belgian Blues now exhibit myostatin deficiency, which is great, if you want giant walking steak machines. It is not so great, however, if you are a female Belgian Blue trying to give birth to baby Hulk. C-sections are regularly performed on these cattle, and the mutation is so extreme that some European countries have considered eliminating this breed altogether.
In the name of giving consumers what they want, turkeys have also been modified to the point where they look almost nothing like their wild progenitors. To create the Chesty La Rue birds we have all come to know (and eat), breeding emphasized enormous pecs on your standard meat turkey, the Broad Breasted White. Created through selective breeding in the 1950's, this turkey fit the needs of consumers and farmers. It produces a ton of breast meat quickly, and when slaughtered young, fits nicely in a fridge. Unfortunately, the mature male Broad Breasted is so bulky that he can't mate without mashing his partner under his Herculean chest, so nearly all breeding of Broad Breasted turkeys happens via artificial insemination.
The enormous musculature of these turkeys (which can reach up to 50 lbs) also leads to shortened lifespan, as dragging around all of that tasty breast meat leads to heart failure, respiratory illness, and joint problems. In an effort to get around this, breeders have also focused on increasing the number of viable eggs produced by parthenogenesis, or the formation of an embryo without fertilization. That's right, no male is necessary. Through careful selective breeding, humans have created a turkey that clones itself. And this bird was developed long before GMO technology.
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Other human-created bird mutants include Cornish cross chickens, which grow at an incredible rate, producing birds of adult weight in as little as six weeks. This modern marvel is really a combination of two mutants. The Cornish chicken, which, like the Broad Breasted White, grows enormous pectoral muscles, and the Plymouth Rock, which is a tall bird with long bones to carry excess weight. This hybrid mutant grows twice as fast as other chickens. The downside is that these birds can barely walk, as their weight-gain outstrips their ability to hold themselves up.
Humans have carefully created mutant plants over thousands of years, resulting in most of the crops we take for granted as "natural" today. But nearly all of our staple crops are radically different from their wild ancestors. Grain crops like wheat have much larger seeds than their wild counterparts. Domestic corn is derived from a wild grass called teosinte, which produces grains that look more like a sad centipede than an ear of corn. All of these changes have taken place sometime in the last 12,000 years, after humans began seriously engaging in agriculture.
We also figured out how to graft two different trees together to maintain tasty fruit mutants without having to worry about breeding. The popular, juicy navel orange can only be grown from cuttings, which means we've been eating clones for decades.
However, sometimes people just don't have the time to wait for plant mutations to arise through selective breeding. Using a very comic-bookesque technique, scientists in the 1930s began blasting plant seeds with gamma rays and X-rays, inducing many new mutations and creating a number of delicious plant varieties. These induced mutations could alter the growth rate, flesh color, and chemical composition of plants, which in turn alters their productivity, taste and appearance, as well as their susceptibility to disease. Chances are, if you have eaten an American grapefruit, you have probably eaten a mutagenic variety.
Humans have been manipulating the genes of other species for a very long time. And for the most part, these manipulations have worked well for us — although they aren't always great for the mutated creatures. Genetic modification represents the next step in our manipulation of other species, and may actually help us overcome the shortcomings of artificial selection. GMO crops have been shown to be efficient, with no evidence of causing direct harm to humans in the form of increased allergies or the ability to cause cancer.
That isn't to suggest that GM crops should be green-lighted without investigation. GM crops raise a number of ecological concerns — for example, the impact of GM salmon on wild fish is only beginning to be investigated.
But the fact that there are no documented cases of negative health impacts from GM ingestion, and scientific groups ranging from the National Academies of Science, to the American Association for the Advancement of Science have declared GM crops safe from a human health perspective, should bolster the confidence of those who are suspicious of GM technology.
Arguments against genetic modification often rely on an appeal to nature: GMOs are unnatural! But our "natural" forms of tinkering have yielded plants and animals that couldn't perform even the most basic of functions without human interference. We have been in the genetic manipulation game since the dawn of agriculture. Many of the foods you buy from the organic section at your grocery store are genetic mutants created by humans. What you think of as a "natural" product may have had its genome scrambled far more than most GMOs ever will.