Januari 04, 2017
hello! i'm hank green, and this is scishow!so, we made a video about this once before, but some of the studies we cited turned outto be bunk, and, in general, i think we played our cards too close to our chest when it comesto how we really feel about genetic engineering here at scishow. so, why are gmos bad? they're not. they justaren’t, not intrinsically, and certainly not for your health. we’ve been eating themfor decades with no ill effects, which makes sense, because a genetically modified organismis simply an organism, like any other organism, that produces hundreds of thousands of proteins,but one or two of them are proteins that were chosen specifically by us humans.
genetic engineering is necessary for the continuedsuccess of the human experiment here on planet earth. just like the advent of nitrogen fixingallowed for more fertile fields that saved millions from starvation, the fruits of geneticengineering (sometimes literally) will help us face the significant challenges of a worldwith more and more people and a climate that is less and less stable. of course, just like nitrogen fixing alsoallowed germany to build bigger bombs, genetic engineering is a tool that can be used forgood or for evil. so, yes, it must be studied and controlled and understood. but that understandinghas to start with, like, us. right now! [intro]
if you live in the united states, you almostcertainly eat genetically modified organisms, or gmos; thus far, it’s just plants, thoughpretty much every kind of meat on the market was likely fed with gm corn at some point. and it won’t be long before the animalsthemselves are genetically modified. in 2012, the fda reviewed a new kind of atlantic salmon,engineered to have higher levels of growth hormone, using the genes of pacific salmonand an eel-like fish called the ocean pout. they concluded that the engineered fish wassafe and opened up the discussion for public comment, but still haven’t announced a finaldecision. gmos are everywhere in the us, pretty muchliterally. 95% of sugar beets, 88% of corn,
94% of soybeans grown in the u.s. containtraits -- like being insect-resistant or herbicide-resistant -- that were engineered into them. and some crops are genetically modified simplyfor human benefit. around 500,000 children go blind every year because of vitamin a deficiency.so a strain of rice has been developed that, unlike normal rice, contains enough vitamina to keep children healthy. or, healthier, anyway. now the term “genetically modified organismâ€is actually somewhat of a misnomer. i mean, people have been genetically modifying organismssince the invention of agriculture. every plant and animal species has natural geneticvariability, and for thousands of years, we’ve
harnessed this variability by practicing artificialselection. we cultivate and breed organisms to emphasize their most desirable traits - cowsthat produce more milk and squash plants that survive drought. brassica oleracea, also knownas wild cabbage, has been bred so intensively that it is the wild ancestor of half a dozendifferent garden staples, including broccoli, cabbage, cauliflower, brussel sprouts. kohlrabiand kale. corn originally looked like this. over theyears of selective breeding, we have turned it into a massive, crazy giant mutant versionthat we happily throw on the grill without thinking of the centuries of breeding necessaryto turn a grass seed into a sweet and starchy masterpiece.
but when we talk about gmos today, we’reactually talking about genetically engineered organisms or transgenic organisms. we’retalking about genes from one species being extracted and then fused into the genome ofa different species. this is called transgenesis, and though not all gmo food is created thisway, transgenic crops are by far the most common kind of genetically engineered organismsyou come across. but here's the thing: engineered organismsaren’t anything new either -- we’ve been tinkering with food in laboratories for nearlya hundred years. in the 1920s, scientists realized that theycould cause mutations in plants -- thereby creating more genetic diversity and possiblymore desirable traits-- by exposing them to
x-rays, gamma rays, and various chemicals.through the 1970s, these methods of mutation breeding were quite popular, and completelyunregulated and largely ignored by the public. thousands of cultivars produced this way arecurrently on the market. it's a kind of brute-force hack, just messthe genes up, plant the seeds, and see what happens and then breed the cool new traitsback into various strains of crop. then in 1983, scientists pioneered a new tactic,where they successfully took a gene from an antibiotic-resistant bacterium and splicedit into the dna of a tobacco plant. now, of course, antibiotic-resistant tobacco doesn'thave any real purpose, but it did prove that single-gene transfer was possible. the newpractice of transgenics was born.
now the gm industry wasn’t really able totake hold until 1994, when the usda approved something called the flavr savr tomato, afruit, invented by a california biotech company, that was altered so that it took longer toripen, giving it a longer shelf life. it was the first genetically engineered crop soldto consumers. the flavr savr, though, didn’t last verylong -- partly because people didn’t like the taste, and partly because others, mainlyin europe, were suspicious of its genetic alterations. the flavr savr, and its non-idealflavr touched off a debate that continues to rage. today, most gmos aren’t found in your producesection like the flavr savr was. instead,
more than 90 percent of commercially growngm foods are commodity crops, staples like feed corn and soybeans, which have been modifiedto resist herbicides or insects. these crops are used to make the ingredients in lots ofthe processed foods we eat, or are used as fodder for animals that we later enjoy consumingthe flesh of. probably the most well-known of these transgeniccrops are the so-called roundup-ready crops -- foods like soybeans, corn, sugar beets,cotton, alfalfa and canola that are engineered to resist the herbicide roundup. these crops provide us with some, you mightsay, digestible examples of how transgenic foods are engineered, why they’re made theway they are, what they do as well as what
they don't do. let’s start with why they were made in thefirst place. the active ingredient in the herbicide roundup is glyphosate, a chemicalthat inhibits an enzyme plants use to synthesize amino acids. by blocking this enzyme, roundupstops plants from making what they need to grow and metabolize food, thereby killingthem. and it pretty much takes no prisoners. so much so that it can be hard to use aroundplants that you don’t want to kill, like your crops. so in the early 1990s, the company that makesroundup, monsanto, decided to develop crops that were resistant to glyphosate, so farmerscould spray the herbicide over their whole
crop, but only kill the weeds. see, there are microorganisms that producean enzyme that is unaffected by glyphosate. all monsanto had to do was transfer thosebacteria genes to food plants, and farmers could use roundup to protect their crops withoutkilling them. so they extracted small pieces of bacterial dna that were responsible formaking the enzyme and set about introducing them into plants. but how do you get the genes of a bacteriuminto the nucleus of a plant cell? on the tree of life, plants and bacteria aren’t evenon the same branch! well, it turns out there are a couple of pretty interesting ways.
the first involves gene guns. yeah, you heard me! gene guns! gene guns do pretty much what they sound like-- literally and kind of haphazardly, blasting dna into plant cells. most commonly used toengineer corn and rice species, they start with tiny particles of gold that are coatedwith hundreds of copies of a desired donor gene, called a transgene. cells from the plantthat’s gonna receive the new genes are put into a vacuum chamber and then, fire away!the gene-covered gold particles are shot at the cells using high-pressure gas. once inside the nucleus of a plant cell, thegold dissolves, and the scientists cross their
fingers and hope that the dna is taken upby the chromosomes in the nucleus, which it sometimes it. once the transgenes have beenincorporated into the plant’s dna, it can then be bred into offspring plants. not exactly elegant, but it's a heck of alot more subtle than just bombarding the seed with radiation and hoping for the best. another more recent, and more effective, wayto create transgenic organisms involves using a soil-dwelling bacterium called agrobacterium.this is a plant parasite and a natural genetic engineer – it has an extra, and quite special,piece of dna called a plasmid that can move outside the bacterium and implant itself intoa plant cell.
in nature, the agrobacterium uses this lil'trick to re-code plant cells to grow food for it. but in the lab, engineers can usethe plasmid as a kind of carrier for fancy transgenes, using it to infuse plant cellswith new genetic material. so -- whether you’ve used the agrobacteriumor the gene guns, you now have a new engineered crop plant. but you can’t just put thatthing into the ground -- you have to introduce this new genetic material into existing, traditionalstrains of the crop. this last step, called backcross breeding,involves repeatedly crossing the new transgenic plant with breeding stock, over and over again,until you wind up with a new transgenic crop. at the end of the process, monsanto had apatented plant that could be sprayed with
glyphosate and survive. previously, plantswould have to be seeded far enough apart that machines could till away competing weeds,increasing soil loss and costs to the farmer, not to mention fuel consumption. plus, monsantogets a whole new, massive customer base for glyphosate. it’s a long process – the whole thingcan take as long as 15 years – but that’s how just about all genetic engineering isdone to your food, whether scientists are putting a bacterium’s antibiotic resistanceinto a tobacco plant, or an eel’s growth pattern into a salmon. of course, then there’s the process of gettingthe crop or animal approved for use, which
can also take quite a number of years. atthe moment, it’s extremely expensive, though there are some technologies on the horizonthat might make it cheaper. the fact that it’s so expensive and yetstill economically worth doing indicates how extremely useful gm crops can be. it alsomeans that the companies that produce them closely guard and restrict the patents andsale and growth and even research done on the crops. one of the reasons engineered foods are attackedso viciously is not because of the scientific consequences of their existence, but the economicand cultural consequences of placing so much power over our food supply into the handsof very few very large companies.
the gmo debate has become something of a surrogatefor a much larger debate about economics that, frankly, is out of our league. there are scientific concerns about geneticallymodified food. how does inserting a single gene, for example, rather than swapping outhuge hunks of genetic material, affect the genome at large? we used to think “not atall,†but it turns out, the genome is more complicated than that. additionally, many farmers save non-patentedseed for next year's crop, something you can't do with patented gm crop seed. but if yourpublic domain seed was unintentionally fertilized by a patented strain, you might find thatsuddenly the seed you saved from last year's
harvest to plant next year has genes ownedby someone else. someone who is, it turns out, suing you. and if your livelihood dependson selling certified organic crops or selling into markets where gmos are prohibited, theconsequences can be even more dire. and, of course, the traits we're engineering intocrops might have potential ecological effects, like if we're engineering in insect resistance,we want to make sure that we're not harming the insects we do like, like bees and butterflies. but after having been consumed in hundredsof millions of meals by me and probably by you, and having been studied for decades,there has been zero implication that genetically modified food poses a danger to human health.
that has not stopped an extremely vocal oppositionfrom funding poorly-designed studies and publishing misleading papers. we here at scishow even reported on a studyindicating that gmos caused an increase in cancer in rats. this study, led by a guy whowas not-coincidentally publishing a book on the topic that same week was published ina peer-reviewed journal and was initially taken at face value. but cherry picked data,a lack of dose-response, small sample groups, and a strain of rat that has an 80% chanceof developing cancer in its lifespan eventually combined to completely discredit the study. of course, as with any new technology, itcan have unintended consequences; it can be
controlled and monopolized and even weaponized,so there is plenty of reason to keep an eye on the companies making these advances. but when considering the number of hungrypeople on the planet, we have an obligation to explore every possible avenue to increasecrop yields and to decrease the amount of herbicide, pesticide, energy and water neededto produce a crop. traditional and advanced breeding methods need to be a part of that,and so does genetic engineering. thanks for watching this episode of scishow,and thank you to the people who pushed me to write up a more complete and accurate versionof this episode. if you want to continue getting smarter with us, you can go to youtube.com/scishowand subscribe.
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