[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So this is a talk about gene drives,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but I'm going to start by \Ntelling you a brief story.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,20 years ago, a biologist\Nnamed Anthony James
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,got obsessed by the idea\Nof making mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that didn't transmit malaria.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,It was a great idea,\Nbut pretty much a complete failure.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,For one thing, it turned out to be\Nreally hard
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,to make a malaria resistant mosquito.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,James managed it, finally,\Njust a few years ago
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,by adding some genes\Nthat make it impossible\N
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,for the malaria gene\Nto survive inside the mosquito.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,But that just created another problem.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Now that you've got malaria-resistant\Nmosquito,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,how do you get it to replace\Nall the malaria-carrying mosquitos?
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,There are a couple options,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but plan A was basically to breed up\Na bunch of the new genetically-engineered mosquotos,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,release them into the wild,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and hope that they pass on their genes.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The problem was that you'd \Nhave to release
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,literally 10x the number of native\Nmosquitos to work.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So in a village with 10,000 mosquitos,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,you release an extra 100,000.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,As you might guess, this was not\Na very popular strategy
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,with the villagers.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Then, last January, Anthony James\Ngot an email\N
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,from a biologist named \NEthan Bier.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Bier said that he and his grad student,\NValentino Gantz,\N
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,had stumbled on a tool that could not only\Nguarentee
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that a particular gene trait\Nwould not be inherited,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but that it would spread\Nincredibly quickly.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,If they were right, it would basically\Nsolve the problem\N
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that he and James had been\Nworking on for 20 years.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,As a test, they engineered\Ntwo mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,to carry the anti-malaria gene
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and also this new tool,\Na gene drive,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,which I'll explain in a minute.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Finally, they set it up so that\Nany mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that had inherited the\Nanti-malaria gene
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,wouldn't have the usual white eyes,\Nbut would instead have red eyes.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,That was pretty much just \Nfor convenience
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,so they could tell just at a glance\Nwhich was which.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So they took their two \Nanti-malarial, red eye mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and put them in a box with 30\Nordinary white-eyed ones
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and let them breed.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In two generations, \Nthose had produced 38,000 grandchildren.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,That is not the surprising part.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,This is the surprising part:
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,given that you started with just\Ntwo red-eyed mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and 30 white-eyed ones,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,you expect mostly white-eyed\Ndescendents.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Instead, when James opened the box,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,all 38,000 mosquitos had red eyes.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,When I asked Ethan Bier\Nabout this moment,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,he became so excited, tht he was\Nliterally shouting into the phone.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,That's because getting only\Nred-eyed mosquitos
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,violates a rule that is the\Nabsolute cornerstone of biology,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Mendelian genetics.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,I'll keep this quick, but Mendelian genetics\Nsays when a male and female mate,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,their baby inherits half of its\NDNA from each parent.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So if our original mosquito was aa\Nand our new mosquito is aB,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,where B is the anti-malarial gene,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,the babies should come out\Nin four permutations:
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,aa, aB, aa and Ba.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Instead, with the new gene drive,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,they all came out aB.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Biologically, that shouldn't\Neven be possible.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So what happened?
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The first thing that happened\Nwas the arrival
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,of a gene-editing tool\Nknown as CRISPR in 2012.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Many of you have probably heard\Nabout CRISPR,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,so I'll just say briefly that CRISPR\Nis a tool that allows researchers
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,to edit genes very precisely,\Neasily and quickly.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,It does this by harnessing a mechanism\Nthat already existed in bacteria.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Basically, there's a protein\Nthat acts like a scissors
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and cuts the DNA,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and there's an RNA molecule\Nthat directs the scissors
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,to any point on the genome you want.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The result is basically a word processor\Nof genes.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,You can take an entire gene out,\Nput one in,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,or even edit just a single letter\Nwithin a gene.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And you can do it in nearly any species.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Okay, remember how I said \Nthat gene drives
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,originally had two problems?
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The first is that it was hard\Nto engineer a mosquito
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,to be malaria resistant.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,That's basically gone now,\Nthanks to CRISPR.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,But the other problem was \Nlogistical.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,How do you get your trait to spread?
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,This is where it gets clever.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,A couple years ago, a biologist\Nat Harvard named Kevin Esvelt
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,wondered what would happen\Nif you made it so that
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,CRISPR inserted not only\Nyour new gene,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but also the machinery \Nthat does the cutting and pasting.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In other words, what if CRISPR\Nalso copy and pasted itself.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,You'd end up with a perpetual\Nmotion machine for gene editing.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And that's exactly what happened.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,This CRISPR gene drive\Nthat Esvelt created
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,not only guarantees that a trait \Nwill get passed on,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but if its used in the germline cell,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,it will automatically copy and paste\Nyour new gene
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,into both chromosomes of every\Nsingle individual.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,It's like a global search and replace,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,or in science terms,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,it makes a heterozygous trait\Nhomozygous.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So, what does this mean?
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,For one thing, it means we have\Na very powerful,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but also somewhat alarming new tool.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Up until now, the fact that gene drives\Ndidn't work very well
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,was actually kind of a relief.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Normally when we mess around\Nwith an organisms's genes,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,we make that thing less evolutionarily fit.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So biologists can make all the mutant\Nfruit flies they want
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,without worrying about it.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,If some escape, natural selection\Njust takes care of it.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,What's remarkable and powerful\Nand frightening about gene drives
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,is that that will no longer be true.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Assuming that your trait does not\Nhave a big evolutionary handicap,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,like a mosquito that can't fly,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,the CRISPR-based gene drive\Nwill spread the change relentlessly
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,until it is in every single individual\Nin the population.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Now, it isn't easy to make\Na gene drive that works that well,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but James and Esvelt think\Nthat we can.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The good news is that this opens\Nthe door to some remarkable things.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,If you put an anti-malarial gene drive\Nin just 1 percent
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,of anopheles mosquitos,\Nthe species that transmits malaria.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Researchers estimate that it would\Nspread to the entire population
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,in a year.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,So in a year, you could virtually \Neliminate malaria.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In practice, we're still a few years out\Nfrom being able to do that,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,but sitll, a 1,000 children a day\Ndie of malaria.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In a year, that number could be\Nalmost zero.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,The same goes for dengue fever,\Nchicken genuang (?), yellow fever.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And it gets better.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Say you want to get rid \Nof an invasive species,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,like get Asian Carp out of\NThe Great Lakes.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,All you have to do is release \Na gene drive
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that makes the fish produce\Nonly male offspring.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In a few generations, there'll be\Nno females left, no more carp.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In theory, this means that we \Ncould restore hundreds
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,of native species that have been\Npushed to the brink.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Okay, that's the good news,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,this is the bad news.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Gene drives are so effective,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,that even an accidental release \Ncould change an entire species,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and often very quickly.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Anthony James took the precautions.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,He breed his mosquitos in\Na bio-containment lab
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and he also used a species\Nthat's not native to the US
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,so that even if some did escape,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,they'd just die off,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,there'd be nothing for them\Nto mate with.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,But it's also true that if \Na dozen Asian Carp
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,with the all-male gene drive accidentally\Ngot carried from The Great Lakes
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,back to Asia,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,they could potentially wipe out \Nthe native Asian Carp population.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And that's not so unlikely, given\Nhow connected our world is.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,In fact, it's why we have \Nan invasive species problem.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And that's fish.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Things like mosquitos and fruit flies,\Nthere's literally no way to contain them.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,They cross borders and oceans\Nall the time.