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Why are GMOs bad? They aren’t. They just aren’t, not intrinsically, and certainly not for your health. We’ve been eating them for decades with no ill effects, which makes sense, because a genetically modified organism is simply an organism, like every other organism, produces hundreds of thousands of proteins, but one or two of them are proteins that were chosen specifically by humans.

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GMO Salmon

How are GMOs Made

Glycophosphate / Monsanto
Hank: Hello, I'm Hank Green & this is SciShow.

So, we made a video about this once before, but some of the studies we cited turned out to be bunk and in general I think we played our cards to close to our chest when it comes to how we really feel about genetic engineering here in SciShow.

So, why are GMOs bad? They're not. They just aren't, not intrinsically, and certainly not for your health.

We've been eating them for decades with no ill effects which makes sense because a genetically modified organism is simply an organism like every other organism, which produces tens 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 continued success of the human experiment here on planet earth, just like the advent of nitrogen fixing allowed for more fertile fields that saved millions from starvation, the fruits of genetic engineering, sometimes literally, will help us face the significant challenges of a world with more and more people and a climate that is less & less stable. 

Of course just like nitrogen fixing allowed Germany to build bigger bombs, genetic engineering in a tool that can be used for good or for evil, so yes, it must be studied and controlled and understood, but that understanding has to start with, like, us. Right now.

(intro plays)

If you live in the United States you almost certainly eat genetically modified organisms, or GMOs. Thus far it's just plants, though pretty 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 animals themselves 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 salmon & an eel like fish called the ocean pout. They concluded that the engineered fish was safe & opened up the discussion for public comment but still haven't announced a final decision.

GMOs are everywhere in the US, pretty much literally. 95% of sugar beets, 88% of corn and 94% of soybeans grown in the U.S contain traits like being insect resistant or herbicide resistant that were engineered to them.

And some crops are genetically modified simply for human benefit. Around 500,000 children go blind every year because of a vitamin A deficiency, so a strain of rice has been developed that, unlike normal rice, contains enough vitamin A to keep children healthy, or, healthier, anyway.

Now, the term genetically modified organism is actually somewhat of a misnomer. I mean, people have been genetically modifying organism since the invention of agriculture. Every plant and animals species has natural genetic variability and for thousands of years we harnessed this variability by practicing artificial selection.

We cultivate organisms to emphasize their most desirable traits. Cows that produce more milk and squash plants that survive droughts. Brassica oleracea, also knows as wild cabbage, has been bred so intensively that it is the wild ancestor of half a dozen garden staples, including broccoli, cabbage, cauliflower, brussel sprouts, kohlrabi and kale. Corn originally looked like THIS. Over years of selective breeding we have turned it into a massive crazy giants mutant version of itself that we happily throw in the grill without thinking of the centuries of breeding necessary to turn a grass seed into a sweet and starchy masterpiece. 

But when we talk about GMOs today we're actually talking about genetically ENGINEERED organisms or TRANSGENIC organism. We're talking about genes from one species being extracted and then fused into the genome of a different species. This is called transgenesis, and though not all GMO food is created this way, transgenic crops are by far the most common kind of genetically engineered organisms you come across.

But here's the thing, ENGINEERED organisms aren't new either, we've been tinkering with food in laboratories for nearly a hundred years. In the 1920s, scientists realized that they could cause mutations in plants thereby creating more genetic diversity and possibly more desirable traits by exposing them to X-rays and Gamma-rays and various chemicals.

Through the 1970s, these methods of mutation breeding were quite popular and completely unregulated and largely ignored by the public. 

Thousands of cultivars produced this way are currently on the market. It's the kind of brute force hack. Just mess the genes up, plant the seeds and see what happens and then breed the cool new traits back 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 spliced it into the genome of a tobacco plant. Now, of course, antibiotic resistant tobacco doesn't have any real purpose but it did prove that single gene transfer was possible. The new practice of transgenics was born.

Now the GM industry wasn't really able to take hold until 1994 when the USDA approved something called the Flavr Savr tomato, a fruit invented by a California biotech company that was altered so it took longer to ripen, giving it a longer shelf life. It was the first genetically engineered crop that was sold to consumers.

The Flavr Savr, though, didn't last very long, partly because people didn't like the taste and partly because others, mainly in Europe, were suspicious of it's genetical durations.

The Flavr Savr, and its non ideal flavor touched off a debate that continues to rage. Today, most GMOs aren't found in your produce section like the Flavr Savr was, instead, more than 90% of commercially grown GM foods are commodity crops, staples like feed corn and soybeans which have been modified to resist herbicides or insects. These crops are used to make the ingredients in lots of the processed foods we eat or are used as fodder for animals that we later enjoy consuming the flesh of.

Probably the most well knows of these transgenic crops are the so-called roundup ready crops. Foods like soybeans, corn, sugar beets, cotton, alfalfa & canola are engineered to resist the active ingredient in the herbicide "roundup". These crops provide us with some, you might say, digestible examples of how transgenic foods are engineered, why they're made the way they are, what they do, as well as what they don't do. Let's start with why they were made in the first place. 

The active ingredient in the herbicide "roundup" is glyphosate, a chemical that inhibits an enzyme that plants use to synthesize amino acids. By blocking this enzyme, "roundup" stops plants from making what they need to grow and metabolize food, thereby killing them. And it pretty much takes no prisoners. So much so, that it can be hard to use around plants you don't want to kill, like your crops.

In the early 1990s, the company that makes "roundup", Monsanto, decided to develop crops that were resistant to glyphosate so farmers could spray the herbicide over their whole crop but only kill the weeds. There are microorganisms that produce an enzyme that's unaffected by glyphosate. All Monsanto had to do was transfer those bacteria genes to food plants and farmers could use "roundup" to protect their crops without killing them. So they extracted small pieces of bacterial DNA that were responsible for making the enzyme & set about introducing them into plants.

But how do you get the genes of a bacterium into the nucleus of a plant cell? On the tree of life, plants and bacteria are not even on the same branch. Well, it turns out that 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 to engineer corn and rice species, they start with tiny particles of gold that are coated with hundreds of copies of a desired donor gene, called a transgene. Cells from the plant that'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, the gold dissolves and the scientists cross their fingers and hope that the DNA is taken up by the chromosomes in the nucleus, which it sometimes is. Once the transgenes have been incorporated into the plant's DNA, it can then be bred into offspring plants. Not exactly elegant, but it's a heck of a lot more subtle than just bombarding the seed with radiation and hoping for the best.

Another more recent and more effective way to create transgenic organisms involves using a soil-dwelling bacterium called a 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 into a 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 use the plasmid as a kind of carrier for fancy transgenes, using it to infuse plant cells with new genetic material.

So, whether you've used the agrobacterium or the gene guns, you now have a new engineered crop plant. But you can't just put that thing into the ground, you have to introduce this new genetic material into existing, traditional strains 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 a patented plant that could be sprayed with glyphosate and survive.

Previously, plants would 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 Monsanto gets a whole new massive customer base for glyphosate.

It's a long process, the whole thing can take as long as 15 years, but that's how just about all genetic engineering is done to your food, whether scientists are putting a bacterium's antibiotic resistance into a tobacco plant, or an eel's growth pattern into a salmon.

Of course, then there's the process of getting the crop or animal approved for use, which can also take quite a number of years. At the moment it's extremely expensive, though there are some technologies on the horizon that might make it cheaper.

The fact that it's so expensive and yet still economically worth doing indicates how extremely useful GM  crops can be. It also means that the companies that produce them closely guard and restrict the patents and sale and growth and even research done on the crops.

One of the reasons engineered foods are attacked so viciously is not because of the scientific consequences of their existence, but the economic and cultural consequences of placing so much power over our food supply into the hands of a very few very large companies. The GMO debate has become something of a surrogate for a much larger debate about economics that frankly is out of our league.

There are some scientific concerns about genetically modified food. How does a single gene, for example, rather than swapping out huge chunks of genetic material affect the genome at large. We used to think not at all, but it turns out that the genome is more complicated than that.

Additionally, many farmers save non-patented seed for next year's crop, something you can't do with patented GM crop seed. But if your public domain seed was unintentionally fertilized by a patented strain, you might find that suddenly the seed you saved from last year's harvest to plant next year has genes owned by someone else. Someone who is, it turns out, suing you. And if your livelihood depends on selling certified organic crops or selling into markets where GMOs are prohibited the consequences could be even more dire.

And of course, the traits we're engineering into crops 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 that we do like like bees and butterflies. But after having been consumed in hundreds of millions of meals by me and probably by you, and having been studied for decades, there has been zero indication that genetically modified food poses a danger to human health.

That has not stopped an extremely vocal opposition from funding poorly designed studies and publishing misleading papers. We here at SciShow even reported on a study indicating that GMOs caused an increase in cancer in rats. This study, led by a guy who was not coincidentally publishing a book on the topic that same week was published in a peer reviewed journal and 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% chance of developing cancer in its lifespan eventually combined to completely discredit the study.

Of course, as with any new technology it can have unintended consequences, it can be controlled and monopolized and even weaponized so there's plenty of reason to keep an eye on the companies making these advances. But when considering the number of hungry people on the planet, we have an obligation to explore every possible avenue to increase crop yields and decrease the amount of herbicide, pesticide, energy, and water needed to 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 version of this episode. If you want to continue getting smarter with us, you can go to and subscribe.