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 out
to be bunk, and, in general, I think we played our cards too close to our chest when it comes
to how we really feel about genetic engineering here at 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 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 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
and less stable.
Of course, just like nitrogen fixing also allowed Germany to build bigger bombs, genetic
engineering is 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]
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 and an eel-like fish called the ocean
pout.
They concluded that the engineered fish was safe and 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, 94% of soybeans grown in the U.S. contain traits -- like being
insect-resistant or herbicide-resistant -- that were engineered into them.
And some crops are genetically modified simply for 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 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 organisms since the invention of agriculture.
Every plant and animal species has natural genetic variability, and for thousands of
years, we’ve harnessed this variability by practicing artificial selection.
We cultivate and breed organisms to emphasize their most desirable traits - cows that produce
more milk and squash plants that survive drought.
Brassica oleracea, also known as wild cabbage, has been bred so intensively that it is the
wild ancestor of half a dozen different garden staples, including broccoli, cabbage, cauliflower,
brussel sprouts.
kohlrabi and kale.
Corn originally looked like this.
Over the years of selective breeding, we have turned it into a massive, crazy giant mutant
version that we happily throw on 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 organisms.
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 anything 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, 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 a 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 DNA 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 that it took longer to ripen, giving it a longer shelf life.
It was the first genetically engineered crop 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 its genetic
alterations.
The flavr savr, and its non-ideal flavr 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 percent 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-known of these transgenic crops 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 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 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 that you don’t want to kill, like
your crops.
So 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.
See, there are microorganisms that produce an enzyme that is 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
and 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 aren’t even on 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 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 it.
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 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 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 scientific concerns about genetically modified food.
How does inserting a single gene, for example, rather than swapping out huge hunks of genetic
material, affect the genome at large?
We used to think “not at all,” but it turns out, 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 can 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 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 implication 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 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% 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 is 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 to 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 youtube.com/scishow and
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