What Happens When Science Clashes with the Public?: Crash Course Scientific Thinking #7

0:00 Smoking causes cancer.

0:01 I know that, you know that, and the tobacco industry definitely knows that.

0:05 But not all that long ago,

0:07 you couldn't even watch Saturday morning cartoons without being

0:10 bombarded with messages that cigarettes aren't that bad for you.

0:14 Tobacco companies ran ads in magazines and periodicals

0:17 saying that numerous scientists question smoking's risks,

0:21 that there are many possible causes of lung cancer,

0:24 and that there's no proof cigarette smoking is one of them.

0:26 So, if you had been there, how would you have figured out what was true?

0:31 Hi, I'm Hank Green, and this is Crash Course Scientific Thinking.

0:39 Before scientific knowledge reaches people like you and me,

0:42 it takes a long arduous journey,

0:44 and big stretches of it are dedicated to collecting,

0:47 testing, and scrutinizing empirical evidence.

0:50 Information collected through rigorous scientific methods

0:53 that either support or refute an idea.

0:56 The vast majority of scientific progress hums along quietly,

1:00 its evidence becoming widely accepted without much hullabaloo.

1:03 You won't hear pundits debate whether carbon has six protons,

1:07 and there won't be dramatic headlines about the mating behavior of sea slugs.

1:11 Though I, for one, definitely would and do read those articles.

1:14 But here's the thing,

1:15 sometimes science produces a nugget of knowledge that resists the status quo.

1:21 It challenges an economic system, or a hierarchy,

1:23 or a choice people make in their lives.

1:26 And when it lands with the public, tensions can flare.

1:30 Which is what happened in 1964 with smoking.

1:33 So, in this episode, we're going to do two things.

1:35 First, we'll peel back the curtain on how the scientific

1:38 process pieced together evidence about the risks of smoking,

1:42 and then we'll unpack why that knowledge got so much pushback,

1:46 and what we can learn from the tale

1:48 about the public consumption of science news.

1:54 At the beginning of the 20th century, lung cancer was so rare doctors treated

1:58 cases of it like once-in-a-lifetime learning opportunities.

2:01 But then in the 1920s and 30s, lung cancer rates started to spike

2:06 and scientists began working to figure out why.

2:09 There were a lot of early ideas about the possible cause.

2:12 Maybe it was atmospheric pollution or newly paved roads.

2:15 Maybe it was x-rays,

2:17 poison gas from World War I or the aftereffects of the 1918 flu pandemic.

2:21 Those were all correlations,

2:23 but as we learned in an earlier episode correlation doesn't mean causation.

2:27 So over two decades,

2:28 scientists tested different explanations and shared the results with each other.

2:32 Each study was like a pebble added to a pile of evidence.

2:36 Scientists had to weigh that evidence by examining

2:39 each study skeptically and asking things like, "How well was the study designed?

2:43 Did it find a strong or weak relationship to lung cancer?

2:47 And how directly did the methods actually get

2:50 at the question they were trying to answer?" For some explanations,

2:53 no evidence emerged.

2:55 You're off the hook, flu.

2:56 But eventually, four main lines of evidence pointed to one suspect.

3:01 Exhibit A, observational studies which had

3:03 followed groups of people over a period of time showed that smokers developed

3:08 lung cancer at higher rates than non-smokers.

3:11 But there were other factors in people's

3:13 lives that could be affecting cancer rates,

3:15 so these studies alone weren't enough.

3:17 Enter exhibit B, experimental studies were done on mice because you can

3:21 better control conditions in a lab and mice exposed to tobacco developed tumors.

3:27 But how?

3:28 What actually happens when lungs are exposed to smoke?

3:31 Exhibit C, further studies showed that cigarette smoke destroys cilia,

3:36 the tiny structures in lungs that keep out bad stuff.

3:40 And finally, exhibit D,

3:42 tobacco smoke itself contains a chemical compound that was previously

3:45 shown to cause cancer in people exposed to coal tar.

3:49 All that evidence, when weighed collectively, began to tip the scales.

3:53 By the late 1950s, scientists had reached a consensus,

3:57 widespread agreement given all of the evidence

3:59 that smoking was the leading cause of lung cancer.

4:02 So, in 1964, the US Surgeon General, himself a smoker,

4:07 announced to reporters that cigarettes cause lung cancer.

4:10 But for the public, that message got drowned out by a lot of noise.

4:15 So, let's rewind the tape and this time,

4:17 let's look at what was going on in the public view.

4:20 Even in the 1930s, people suspected smoking wasn't exactly great for you,

4:25 but tobacco companies worked to stay ahead of the narrative,

4:28 boasting that their cigarettes were healthier,

4:31 safer, gentler, fresh as mountain air.

4:37 The RJ Reynolds Tobacco Company ran ads citing studies

4:41 that claimed more doctors smoke Camels than any other cigarette.

4:44 And you want to know how they got that statistic?

4:46 By giving doctors free Camel cigarettes and then

4:50 asking them what kind of cigarettes they smoked.

4:52 I mean, come on.

4:54 By the 1950s, tobacco companies knew about the mounting scientific evidence,

4:58 but they were still invested in selling their product,

5:01 so they changed the message.

5:03 Instead of our cigarettes are better for you,

5:05 the ads became we don't know yet if cigarettes are bad for you.

5:09 And by doing so, they manufactured a controversy that didn't actually exist.

5:14 This is where things get wild.

5:16 In 1954, a committee called the Tobacco Industry Research Committee,

5:19 which was formed by the tobacco companies,

5:22 released a statement claiming the link between smoking and lung

5:25 cancer wasn't settled and they would be researching the issue themselves.

5:29 These people would have thrived on social media.

5:32 This went on for decades, long after the scientific consensus had been settled.

5:36 The tobacco industry distracted from smoking's harms by funding

5:40 and publicizing research looking into alternative explanations for lung cancer.

5:45 They suppressed and criticized studies that found smoking was bad for you,

5:49 and all the while they publicly denied that smoking was risky or addictive,

5:53 and blasted ads that made cigarettes seem as enticing as possible.

5:57 They did all of this knowingly and strategically to keep making money.

6:01 A 1969 internal memo at the tobacco company Brown& Williamson stated,

6:06 "Doubt is our product, since it is the best means of competing with the body

6:10 of fact that exists in the mind of the general public.

6:13 It is also the means of establishing a controversy." Wow, they just said it.

6:18 And selling that doubt worked.

6:20 The tobacco industry preyed upon people's cognitive biases,

6:24 those predictable patterns our brains tend to take

6:27 that can sway us away from accepting valid information,

6:29 especially when it challenges something we already do or think.

6:33 The news that smoking causes cancer just didn't

6:36 vibe with a world where smoking was common,

6:38 widely accepted, and everybody did it.

6:41 Doctors, astronauts, movie stars.

6:43 Plus, cigarettes are highly addictive.

6:45 When you're addicted to something,

6:47 you pay more attention to reasons to keep doing that thing,

6:50 and the tobacco industry was willing to give smokers those reasons,

6:54 even though the reasons were made up.

6:56 They systematically attacked the widely accepted scientific explanation

7:00 in order to sow doubt among the public.

7:02 But here's what finally turned the tide against smoking.

7:05 In the 1990s, scientists uncovered evidence of exactly how cigarette

7:09 smoke can trigger a normal cell to become a cancerous cell.

7:13 Then, in 1998, a major settlement required the tobacco industry

7:17 to pay up billions of dollars for the damage they had caused.

7:20 The writing was on the wall,

7:22 but the tobacco industry still tried to spin the narrative.

7:25 The message this time,

7:26 they claimed they'd always been transparent about the risks of smoking,

7:31 and said that it had always been an individual's choice to take those risks,

7:35 which brings me to another common point

7:37 of tension that can make scientific knowledge seem controversial.

7:41 Sometimes, scientific knowledge clashes with people's values.

7:45 There's stuff science can tell us,

7:47 like the precise mechanism that causes a cell to become cancerous,

7:51 or how much smoking increases your individual risk of developing cancer.

7:55 But, science can't tell us what to do with that knowledge.

7:59 It's on us, as individuals and as societies,

8:02 to decide what to do now that we know what we know.

8:05 For example, in the early 2000s,

8:07 as the dangers of secondhand smoke became more widely smoking in public places.

8:14 Not everybody agreed with the move,

8:16 but the disagreement wasn't over the science,

8:18 it was about how that knowledge should mesh with the values.

8:22 What's more important?

8:23 A person's freedom to make their own choices with their own body,

8:26 or a person's freedom to protect their body

8:29 from the choices someone else is making?

8:31 Science can't answer those questions,

8:33 and I can't answer these questions for you.

8:35 So, you might be wondering, why did I even tell you all this?

8:38 You can think of the war over smoking as a kind of fable.

8:41 It's a story that can teach us something, like the tortoise and the hare,

8:44 or the boy who cried wolf, except it really happened.

8:47 And there are three lessons we can take away from this story

8:50 that can help us navigate the wilderness where science and public opinion meet.

8:54 First, follow the scientific consensus.

8:57 When a certain idea is backed by broad agreement among experts,

9:00 it is already cleared an extraordinarily high bar of skepticism.

9:03 I trust the experts for a reason.

9:05 Like, when I notice an electrical outlet is broken,

9:07 I could try to fix it myself, but I will at best spend much more time

9:11 and do a much shabbier job than an electrician would.

9:14 At worst, I'll look like this.

9:16 The same is true with science.

9:17 You'll have better information and get better

9:19 outcomes when you trust the process of science.

9:22 So, when there is scientific consensus, pay attention to it.

9:25 Second, when there isn't yet consensus,

9:28 we should be skeptical of science-related claims we encounter

9:31 and keep in mind that a single study doesn't settle anything.

9:35 The studies we do hear about, the ones that make headlines,

9:38 are the ones that have a surprising or attention-grabbing angle.

9:42 But a single study is just one pebble of evidence on the pile.

9:45 You should look to what other experts say about it

9:48 to understand how that study compares to the rest of the evidence,

9:52 and how much it actually changes what we know.

9:55 Third, in science, challenging or debating an idea has

9:58 a very different meaning than it often has in everyday life.

10:01 Even with a strong consensus,

10:02 not every scientist agrees on every detail of an issue.

10:06 But scientists don't hold evidence back or try to keep

10:10 other scientists from finding the flaws in their argument.

10:13 They put it all on the table.

10:15 They share everything they know, all of the evidence in good faith,

10:19 so that their ideas can be challenged well.

10:22 That's the whole point.

10:25 See, kids, you like arguing.

10:26 You can make a whole career of it.

10:28 Sage, I don't think you were scheduled for today.

10:30 I just had to say goodbye to the people, eh?

10:32 It's been a pleasure to have you along, Sage.

10:34 Oh, I'll be back.

10:37 Oh, is that a teaser?

10:38 Yeah, it might be.

10:39 Bye, people.

10:39 Hope you enjoyed your Sage advice.

10:42 Thanks, Sage.

10:43 There are times when scientific knowledge seems controversial to the public eye,

10:47 but actually isn't controversial among the experts who know it best.

10:50 That's why the argument that smoking causes

10:53 cancer wasn't just an opinion among other opinions.

10:56 Often, when a scientific idea sparks controversy among the public,

11:00 it's because it challenges our biases, our values, or powerful interests.

11:05 Scientific consensus is so impactful because

11:08 it happens independent of those external considerations.

11:12 And it's why science, the process,

11:14 is so powerful at helping us become less wrong over time.

11:19 As we wrap up this series, I'll leave you with this.

11:22 When we recognize how science really works, the world makes so much more sense.

11:27 We can be skeptical of individual studies,

11:29 yet place trust in the collective process.

11:32 We can appreciate the long journey an idea

11:34 takes before it becomes widely accepted knowledge,

11:37 yet be open to ideas changing with new evidence.

11:40 And we can know that if an idea is wrong,

11:43 there's a good chance scientists will find out.

11:47 From all of us here at CrashCourse, thanks for watching.

11:51 This episode of CrashCourse Scientific Thinking

11:52 was produced in partnership with HHMI BioInteractive,

11:56 bringing real science stories to thousands

11:58 of high school and undergraduate life science classrooms.

12:01 If you're a teacher, visit their website for resources that explore

12:04 the topics we discussed in the video today.

12:06 Thanks for watching this episode of CrashCourse Scientific Thinking,

12:09 which was filmed in Missoula,

12:10 Montana, and made with the help of all of these nice people.

12:12 If you'd like to help keep CrashCourse free for everyone forever,

12:15 you can join our community on Patreon.