RFK Jr. is not a serious person. Don't take him seriously.

Well, president-elect Trump has announced that he will nominate Robert F. Kennedy Jr. to be the Secretary of Health and Human Services (HHS), putting him in charge of most of the nation's public health and medical research.

I can't say strongly enough how unqualified RFK Jr. is for this job. He isn't qualified to come anywhere within a thousand miles of any medical or science-related issue, much less to be in charge of health policy for the whole country. Virtually everything RFK says about science is wrong–actually, it's worse than that, because he speaks with such absolutely certainty, despite being wrong, that he convinces people to take actions that end up hurting themselves. To a normal person, someone not accustomed to lying so boldly, these claims can be convincing.

Since Trump's announcement of the nomination, I've been seeing columns in major media outlets (I'm looking at you, New York Times and Washington Post) saying things like "hey, some of RFK's ideas aren't entirely wrong." 

Just. Stop. Even a broken clock is right twice a day. Don't take RFK Jr., or his nomination, seriously.

I don't want to try to list all of RFK's mistaken views, which would require a book-length column, but here are a few. Just last year he said, on the Lix Fridman podcast, that "there’s no vaccine that is safe and effective," and that the polio vaccine did more harm than good. (Both of those statements are wildly wrong.) In 2005, he wrote a long essay for Rolling Stone and Salon which claimed that thimerosal-containing vaccines cause autism (they don't), and that the government knew about it and had been covering it up:

“The story of how government health agencies colluded with Big Pharma to hide the risks of thimerosal from the public is a chilling case study of institutional arrogance, power and greed.” [quote from RFK Jr.]

The article was full of dramatic claims like this one. The only problem was, all of them were false. Rolling Stone and Salon eventually retracted the article and deleted it from their websites. 

In 2019, Kennedy visited the island nation of Samoa to spread his anti-vaccine message, sponsored in part by his anti-vaccine organization, Children's Health Defense. (The name is highly misleading.) Vaccination rates plummeted, and just a few months later a tragic measles outbreak began, causing 83 deaths and 1,867 hospitalizations. Kennedy published an article afterwards calling it a "mild measles outbreak," and in the same article claims (falsely) that vaccines themselves, rather than measles, caused the deaths.

RFK Jr. is someone who never admits he was wrong, even (or especially) when his mistakes cause the deaths of innocent children. Instead, his conspiracy-addled brain blames someone else.

And that's only a tiny sample of RFK's misinformation. He also loves raw milk, which I wrote about in 2014 and again in 2023. Raw milk sometimes contains nasty bacteria and viruses, but fortunately Louis Pasteur solved this problem in the 1860s, when he invented what we now call pasteurization. As I pointed out in my 2023 piece, bacteria just love raw milk. And you know what else is in raw milk but not pasteurized milk? Cow poop. Just don't tell this to RFK Jr. 

By writing columns saying "RFK Jr. has some good ideas" (which I won't link to, since that's just feeding the beast), media organizations are falling into a trap: they're taking RFK seriously. I'd like to ask these journalists: if Trump nominated a first-grader instead, would you write similar stories? Maybe something like "hey, this nominee has some good ideas about nutrition!" 

Don't do it. This nomination deserves ridicule and scorn, nothing more.

I've written multiple columns (both on this site and at Forbes, my former site) warning about RFK Jr. and his dangerous anti-vaccine craziness, starting with this 2014 piece where I called him out for his efforts to lobby Congress against vaccines. His primary obsession then–and he still has this obsession–was the mistaken notion that thimerosal, a harmless preservative that isn't even used in vaccines today, causes autism. This claim has been thoroughly debunked in multiple studies. 

In 2017, I wrote about "Trump's lovefest with anti-vaxxer RFK Jr." – a lovefest that apparently still continues, seven years later. That column was about Trump's promise to put RFK in charge of a commission on vaccines. Fortunately, that vaccine commission never happened, but today we face a much more dangerous threat, if RFK Jr. is confirmed as Secretary of HHS.

I've also pointed out that Kennedy is one of the "Disinformation Dozen," a group of twelve people who, as reported by the Center for Countering Digital Hate, was responsible for 65% of all the anti-vaccine disinformation online. And earlier this year I asked how he could possibly be so arrogant as to think he's qualified to be President, given that his only claims to fame are his name, which he inherited, and his anti-vaccine notoriety.

My problem with RFK Jr. is not just that he is wrong about vaccines, although that is the most immediate threat to public health. But he's also an idealogue, someone who holds onto his mistaken ideas despite mountains of contradictory evidence, and someone who simply makes up things to "prove" his points. 

And in that quote from him above, where he uses the phrase "institutional arrogance," highlights another danger: RFK Jr. is the one who is arrogant. He believes that he can substitute his own unsubstantiated beliefs for the knowledge of genuine experts, and why? Because he's a Kennedy, a man who has lived a life of great privilege, getting into Harvard as a "legacy" despite being expelled from prep school over his drug use, all the while pretending to be fighting against the system. He is too arrogant to listen to others, or to admit his mistakes.  

So no, I cannot take this nomination seriously. Children will die if RFK Jr. is put in charge of HHS. There are tens of thousands of people who are far, far more qualified than Kennedy, and I hope the Senate will refuse to confirm him. I'm not optimistic, but I hope a few Senators will look at the man's record and treat him with the scorn he deserves.

Political pollsters are pretending they know what's happening. They don't.

This week I have to explain a little statistics, because the political news media have failed so badly.

If you’re like me, you’re probably exhausted with all the so-called news stories about the latest U.S. presidential polls. After each poll, which seems to be a daily occurrence as the election draws near, news outlets report the results on their front pages with breathless excitement. The race is changing! Harris is pulling ahead! Trump is catching up! Swing states are swingier than ever!

To cite just one example, CNN just reported that “Polls show Harris’ numbers in Pennsylvania have shifted over the past month.” This story included a video featuring polling expert Harry Enten, who stated “there has never been a race this close in the polling since 1972!” OMG! (The “OMG” is from me, not Enten.)

Okay, now let’s get to reality (with a small dose of statistics).

A poll is nothing more than a tiny sample of voters’ opinions. A poll might ask, say, 1000 people who they plan to vote for, and then report the results. If you ask a truly representative sample of people, a poll can give you a pretty good idea of how the candidates stand.

The problem is, this is really hard to do accurately, and it’s become much harder since everyone switched to cell phones. Decades ago, pollsters would phone people, and those people would answer the phone. Not any more: many people won’t answer a call from a number they don’t know, and people who do answer might have a bias towards one party or the other.

So pollsters compile some numbers and then adjust them (more on that below), and then report the results with a “margin of error,” which goes something like this. Suppose that a poll finds Trump leading in Nebraska by 18%, with a margin of error of 4%. That means that he might be leading by anywhere from 14% to 22% – and that’s just one pollster’s guess. He might be leading by 30%, or even losing, if you ask a different pollster.

But a 4% margin means that if you run the poll again and again, the results will swing back and forth, randomly, in a pretty wide range.

That’s exactly what’s happening in Pennsylvania. The voters are split, but every poll shows a slightly different result, because that’s what random sampling does. It’s not news!

So let me give you some actual data. Let’s look at Pennsylvania because it seems to be the closest Presidential race, according to the polls. Here are the actual margins of victory from the past 9 elections - real numbers, not polls:

• 2020: Biden (D) won by 1.2%
• 2016: Trump (R) by 0.7%
• 2012: Obama (D) by 5.4%
• 2008: Obama (D) by 10.3%
• 2004: GW Bush (R) by 2.5%
• 2000: Gore (D) by 4.2%
• 1996: Clinton (D) by 9.2%
• 1992: Clinton (D) by 9.1%
• 1988: GHW Bush (R) by 2.3%

Clearly, Pennsylvania has been closely divided in recent years. Suppose the race this year will eventually be won, by either candidate, by less than 2%, as happened in 2016 and 2020. Then what would we expect polls to show us? Given their typical 4% margin of error, we’d expect polls to show a race that flips back and forth from one poll to another, even if no one is changing their mind.

And that, I argue, is just what we’re seeing. The polls aren’t accurate enough, statistically speaking, to tell us anything other than “we don’t know who will win Pennsylvania.” But the media reports each one as if it’s a revelation.

Now back to those “adjustments” that pollsters make. In 2016 and 2020, the polls were off by quite a lot. In 2016, as everyone knows, pollsters were highly confident that Hillary Clinton would win, and they were wrong. They were almost as confident that Joe Biden would win in 2020, and they were right–but the race was closer than they predicted, and their estimates were once again off. In the 2022 midterm elections, though, they were wrong again, but in the opposite direction, and Democrats did better than forecast.

Did they over-correct after 2020, and is that why they predicted much bigger Republican gains in 2022? And have they fixed that now, so that polls this year will be spot on? Who knows?

The thing is, it’s very hard to figure out who will actually show up to vote, and who might answer the phone when a pollster calls, and whether they’re even telling the truth. So pollsters make statistical adjustments based on past experience, weighing some voters more than others. In general, they don’t tell the public precisely how they do this.

Are these adjustments accurate? Well, here’s the kicker: we won’t know until after the election! But one thing is almost certainly true: the changing polls are overstating the number of people who are changing their mind.

So I have a suggestion to the media: stop reporting every poll as if it’s news. Instead, tell us where the candidates stand on issues that really matter: support for Ukraine, support for Israel, health care policy, immigration, respect for the rule of law, stuff like that. I know, crazy stuff, right?

I realize that my plea will fall on deaf ears. It’s so much easier for The Washington Post, CNN, The New York Times, Fox News, and others to write about and talk about polls, and pretend these are actual news. It’s also lazy.

Don't tell me they found Tyrannosaurus rex meat again!

It seems that some scientists are still claiming they can find bits of dinosaur meat clinging to the fossilized bones of ancient dinosaurs. Don’t sharpen your dinner knives yet.

I thought this story, which first appeared in 2007, had died long ago, but it has just reappeared. Before I get to that, though, let me explain the original claims. Back in the late 2000’s, a couple of paleontologists managed to publish two articles in the journal Science claiming they had found traces of original dinosaur proteins in 68-million-year-old Tyrannosaurus rex fossils, and in an even older 80-million-year-old fossil from another dinosaur, a hadrosaur.

This would have been shocking news if it was true, but alas, it wasn’t (even if Jurassic Park fans wished otherwise). Organic material survives only a very short time after an animal dies, usually just a few years. Bones and teeth can last far longer, though. Scientists have extracted DNA from the bones of Neandertals and cave bears that are over 50,000 years old, which is pretty extraordinary.

But 68 million years is far, far longer than 50,000 years. Those fossils are one thousand times older than bones from Neandertals.

But maybe proteins can last longer than DNA? Well, perhaps, but not that long. The oldest known protein fragment, which was preserved in an exceptionally cold environment, is about 3 million years old. The T. rex fossils studied in the Science paper were found in a warm climate, where any proteins must have degraded far more quickly.

I wrote about this way back in 2008, expressing my disappointment with the journal and explaining some of the problems. Nature ran a news story about the controversy as well.

But wait, you’re probably thinking, that T. rex study was published in a prestigious journal, so how can it be wrong? Well, what seemed to happen was this: one of the editors at Science back in 2007 simply believed the study, or maybe he just wanted to believe it, so he ignored the reviewers. How do I know this? Well, when the first paper appeared, in 2007, two of the scientific reviewers, both experts in the field, contacted me to tell me that they had both recommended rejecting the paper, but the editor went ahead with publication anyway. (They contacted me because I had published papers in Science before, and they wanted my advice on what they could do.)

My guess is that the Science editor wanted to get headlines along the lines of “T. rex tasted like chicken.” (To explain: the tiny fragments of protein that the first paper found appeared to be similar to proteins from birds.) The editor got exactly that, in stories that ran in the Washington Post, the New York Times, Smithsonian Mazazine, and elsewhere back in 2007 and 2008.

After the original T. rex paper appeared, at least two letters were sent to Science explaining why it was wrong. Science published them as a “technical comments,” which weren’t nearly as prominent as the original paper.

That letters gave far more plausible explanations for the data from the paper: first, one letter explained that it was very likely that the tiny, tiny trace of chicken-like protein was simply contamination from a modern bird, maybe as benign as someone’s turkey sandwich. That letter also pointed out that the supposed T. rex protein appeared to be modern in origin, because it lacked the signs of aging that an ancient protein fragment should have. (The details are very technical; follow the link if you want to learn more.) The other letter pointed out errors in the statistical analysis, pointing out that the result could easily be a statistical artifact.

A later paper, published independently, re-analyzed the T. rex data itself and found that the sample appeared to contain “common laboratory contaminants, soil bacteria, and bird-like hemoglobin and collagen.” In other words, no ancient proteins at all.

I should note that the experiments used to detect the dinosaur proteins, using a technology called mass spectrometry, are notoriously plagued by contaminants. Even a tiny trace of a modern bird in the mass spectrometry lab (e.g., someone eating a turkey sandwich) is liable to produce a few protein fragments that show up in the experiment. Scientists at the time pointed out that the very same lab had done experiments using ostrich bones around the same time as the dinosaur fossils.

And if that wasn’t enough, yet another published paper argued that the “soft matter” found in some fossils by the paleontologists was likely to be a bacterial biofilm. Fossils, I should explain, are highly porous, and it’s easy to imagine how bacterial could infiltrate them over the millenia.

In fact, you don’t have to imagine that at all: another scientific paper from 2019, published in the journal eLife, described finding “an abundant microbial community” in dinosaur fossils.

All of this skepticism did not deter the original scientists. It was less than two years before they’d published a second report (also in Science, with the same editor) claiming that they’d found similar proteins in another, even older dinosaur fossil, an 80-million-year-old hadrosaur.

And yes, the paleontologists continued to insist that they found “soft matter” that must have originated from the original dinosaurs. Dinosaur meat! The highly regarded CBS news program 60 Minutes was so impressed that they aired an entire segment on this finding:

Alas, there’s just no way that fossils contain any soft matter from 62 million years ago. It was likely just bacteria. But we can’t let that get in the way of a good story.

So how long can animal proteins survive? In temperate regions (such as those where the T. rex fossils were found), most organic matter decays in a few decades. If the animal happens to die in a very cold place, and its body is encased in ice, it seems that some organic material can survive up to one million years, and possibly even longer. Cool! (Pun intended.)

But the T. rex fossils from the original Science study were found in temperate climates. They were not frozen in deep permafrost or ice, and the original organic material was almost certainly long gone many millions of years ago.

I thought this story was dead, but apparently I was wrong: a small cadre of scientists continues to believe that dinosaur fossils–which are made entirely of stone, not bones–contain detectable traces of the original dinosaur proteins. Unbeknownst to me (because I wasn’t following it), another paper appeared in 2017 that claimed to find signs of dinosaur proteins in a 195-million-year-old fossil, more than twice as old as the previously reported claims.

Astounding, if true. And just this month, a chemistry professor at MIT reported that he has the explanation for how these proteins survived so long. This finding, though, is more about how the chemical bonds in collagen–the protein that bones are built upon–are exceptionally stable. That’s interesting, but it doesn’t at all prove that collagen can last for nearly 200 million years.

So count me as deeply skeptical. The science of dinosaur “meat” has from the beginning been fraught with wishful thinking. Multiple papers appeared refuting the original claims, and none of those were effectively rebutted; it seems they were just ignored by scientists who preferred a more fanciful story. I wish it were otherwise, but fossilized bones from Tyrannosaurus rex and other dinosaurs lost any traces of the original organic material eons ago.

The Hayflick Limit: why humans can't live forever

 A scientific legend, Leonard Hayflick, passed away at the beginning of August. Most non-scientists probably don’t recognize his name, but he made a remarkable discovery in the early 1960s. Back then, while doing experiments on human cells, he and a colleague, Paul Moorhead, discovered that our cells can only divide a limited number of times.

This discovery, although made at the level of an individual cell, has a dramatic implication: humans cannot live forever.

What Hayflick discovered was that after 40 to 60 rounds of splitting in two, cells simply won’t divide any more. At that point, they enter a phase called senescence, and they eventually die. The number of divisions that a cell can go through is now known as the “Hayflick limit.”

Prior to Hayflick’s experiments, many scientists believed that cells could divide forever. After all, every cell in our body comes from one original cell, and that cell came from our parents, and from their parents before that, and so on back through the ages. So it stood to reason that cells could continue to divide without limit. What’s more, in the early 20th century, Alexis Carrel (a Nobel laureate) claimed to have grown cells in his labs that continued to divide for decades, with no sign of decline.

(Aside: Jan Witkowski explained in an article back in 1980 that it was likely that Carrel’s seemingly immortal cells had been quietly replenished, without Carrel’s knowledge, by members of his lab who were eager to keep the boss happy.)

Back to the Hayflick limit: because all of our organs are destined to wear out, our bodies will simply die unless we can intervene and restore cells to their youthful state. That would require technology that has not yet been invented. Hayflick himself estimated that the limit of the human lifespan is 125 years.

Hayflick’s limit raised an intriguing puzzle: how does a tiny, microscopic cell keep track of how many times it has divided? In other words, how can a cell know how old it is? Don’t all of our cells have identical DNA? Hayflick himself didn’t have a solution for this, but a few decades later, others figured it out.

The answer to this cellular “clock” puzzle resides, it turns out, in our DNA. More specifically, it depends on the DNA sequences at the very ends of our chromosomes, which are called telomeres.

Telomeres don’t really do anything, and they appear very simple: they consist of a long stretch of six DNA bases, TTAGGG, repeated hundreds of times, end-to-end. All our chromosomes end with telomeres, on both ends.

So here’s the thing: when a cell divides, it has to copy all of its chromosomes. The mechanism for copying isn’t quite perfect, and it can’t go all the way to the end of the chromosome, so the new copy is a little bit shorter. The telomere gets shorter! Fortunately, we have a special enzyme, called telomerase, that fixes this problem by adding a few extra copies of TTAGGG to the end of each chromosome, restoring the proper length. Problem solved, right?

Well, no. Telomerase doesn’t work perfectly, and chromosomes sometimes do get a bit shorter each time they divide. When the chromosomes get too short, the cell can’t divide any more, and it eventually dies.

And yes, scientists have explored the question of whether telomere length might be the key to longevity. No one has figured out a way to keep telomeres long, and it’s not clear that would help anyway. On the contrary, as my Hopkins colleague Mary Armanios reported in a study last year, long telomeres might help individual cells stick around, but they don’t seem to prevent aging.

Does the Hayflick limit mean we really can’t live forever? Well, not necessarily. Some types of stem cells can produce “fresh” cells that could, in theory, replenish our old cells. Perhaps some day we’ll have the technology to replace our organs with new ones, possibly grown in a lab, that will have the youth and energy of a 20-year-old. But without replacing our parts, we are destined to wear out, even if we manage to avoid cancer, infections, and the many other perils that humans face.

Leonard Hayflick made it to 96, a ripe old age by today’s standards. It would have been fitting if he’d reached 125, the limit that he estimated, but no human has ever done that. Yet.

Can you use the gut microbiome to diagnose autism? I think not

Last week, the New York Times published a story claiming that we might be able to use the gut microbiome to diagnose autism. The Times story was based on a just-published scientific paper that claimed the same thing.

This report set off all my skeptical alarm bells. My initial reaction was “oh no, more bad science around autism.” For one thing, as most scientists studying autism are aware, the modern anti-vaccine movement started with a scientific paper, back in 1998, that claimed, falsely, that childhood vaccines caused autism. That paper in The Lancet was later shown to be fraudulent and was eventually retracted, but not before a huge amount of damage was done. Its lead author, Andrew Wakefield, went on to become a hero to the anti-vaccine movement, and he continues to promote anti-vaccine misinformation to this day.

The new paper (from the journal Nature Microbiology) is not making outrageous claims like that, nor was the New York Times. However, anyone claiming autism is caused by microbes in the gut should know that the notorious Lancet study was based on a hypothesis about a “leaky gut,” a hypothesis that was discredited long ago. (I don’t want to give it any credibility, but that hypothesis held that virus particles in some vaccines somehow “leaked” from the gut and made their way to the brain. It was nonsense at the time and still is.) That’s one reason why the suggestion that microbes in the gut might cause autism (or even be used to diagnose it) raises so many alarm bells.

I’ve now looked at the study, and frankly I don’t believe a word of it. Let me be clear, though: I’m not trying to prove scientifically that the study is wrong, which would require many months of effort and a much more detail than I can put into a column anyway. Fortunately, though, there’s an earlier study that did that job for me, which I’ll get to below.

However, the science behind this study is closely related to my own work, so I feel pretty comfortable offering my opinion. So what did the authors do?

Well, as the new study explains, they collected poop (”faecal samples”) from 1,627 children, some of whom had been diagnosed with autism and some who hadn’t, and they sequenced DNA from the poop. Then they looked for bacteria, viruses, and other microbes in the DNA sequence data.

That’s right: the “gut microbiome,” is really just a polite term for bacteria that live in the intestines and the colon, some of which come out in poop. Of course, some bacteria in poop might come from the food that a person ate, but mostly these are so-called gut bacteria.

I’ve been involved in many studies like this myself, so I’ve seen that these experiments yield hundreds of different species from every sample. The data sets are very complex, and a widespread problem in the field is that these data are often misinterpreted. In the Nature Microbiology paper, the authors took these very complex data sets and fed them to a machine learning program, and voila! The AI program was able to do a pretty good job (far from perfect, I should note) identifying the autistic children, based on the melange of microbes in their poop.

Right. I don’t believe any of this, as I wrote above. Why not? Well, first of all, machine learning programs are really good at telling apart two sets of subjects (such as children with and without autism) if you give them enough data. It sometimes turns out that the learning programs are keying in on irrelevant features that the scientists didn’t intend.

For example, this 2021 paper looked at over 400 studies that used machine learning to predict Covid-19, all of which had claimed some success, and found that all of the studies were essentially useless “due to methodological flaws and/or underlying biases.” Of course, the gut microbiome study wasn’t one of those, and some machine learning experiments do work, but we should be very skeptical.

Another reason for skepticism is that the new paper doesn’t even try to tell us what the machine learning models actually learned–it just treats the programs as a “black box” that we should trust.

Perhaps the biggest flaw in the study of autism and children’s gut microbiota is this: children with autism tend to be finicky eaters, and their parents try all sorts of diets in the hope that they can at least alleviate the symptoms of autism with food. There are countless websites–many of them scams, unfortunately–claiming that special diets can help these children. Why is this important? Because a special diet will alter your gut microbiome, sometimes quite significantly.

Thus even if the machine learning models in the new study are correct, the causality almost certainly goes the other way: children with autism might have a different microbiome because they’re eating different foods. Thus it’s autism that indirectly affects the microbiome. Unfortunately, both the New York Times and the scientific paper suggested the opposite.

Now on to that earlier scientific paper I mentioned above. It turns out 3 years ago, a group of researchers in Australia published a major study in the journal Cell that addressed precisely the problem I just pointed out. In that study, the scientists collected and sequenced poop from 247 children both with and without autism. They found “negligible direct associations between ASD [autism spectrum disorder] and the gut microbiome.“

On the contrary, the authors warned: “microbiome differences in ASD may reflect dietary preferences ... and we caution against claims that the microbiome has a driving role in ASD.”

In other words, three years ago a study in a major scientific journal found that there was no connection between autism and the contents of the gut microbiome. They went on to warn that if you see differences in the gut microbiome in autistic kids, those are caused by their diet, so don’t go claiming that the microbiome causes autism. The authors of the newer study, and the reporters at the New York Times, apparently decided otherwise.

So no, the gut microbiome can’t be used to diagnose autism.

A randomized controlled trial of parachutes had a surprising outcome. Anti-vaxxers, take note.

One of my themes in this column over the years has been that you need to be skeptical of many of the claims out there about science and medicine. A healthy dose of skepticism can be a good thing, especially when someone is telling you something that seems surprising.

On the other hand, anti-science forces often pretend that they too are just being skeptical, or “just asking questions,” when what they’re doing is actually science denialism. Denialism is what someone is doing when the science is basically settled, but they refuse to accept it.

Let’s consider perhaps the clearest example of denialism, and the one that causes the most harm to public health: vaccine denialism. The anti-vaccine movement, which has grown alarmingly fast during the Covid-19 pandemic, insists that vaccines don’t save lives, and even more they insist that vaccines cause neurological damage. The latter claim is a favorite of Robert F. Kennedy Jr., as he’s proclaimed in multiple books and articles, and of his VP running mate Nicole Shanahan as well.

The claim that vaccines cause autism was first promoted in a bogus 1998 article in The Lancet by Andrew Wakefield. That article was later shown to be fraudulent, and the journal retracted it, but not before it spawned the modern anti-vaccine movement and made Wakefield one of their heroes. I’ve written many columns on this topic, and others have written far more, but the movement persists.

Scientists and doctors have pointed out, over and over again, that vaccines have saved millions of lives, and are one of the greatest medical advances in the history of civilization. The rapid development of the Covid-19 vaccine was a triumph, and it undoubtedly saved tens of millions more lives.

In defending their denialism, anti-vaxxers frequently ask this question: “where are the randomized controlled trials for vaccines?” They imply that scientists haven’t run such trials because they (the scientists) know that vaccines don’t really work.

That’s nonsense, of course. Scientists have conducted hundreds of studies, involving millions of people, showing how vaccines prevent disease and death.

But we don’t have any randomized controlled trials for childhood vaccines, and we never will, for an obvious reason: it would be deeply unethical. Let me explain.

A randomized control trial (an RCT) works like this: first, you identify a large group of people whom you want to treat, say by giving them vaccines. Then you divide them at random into two groups: the treatment group, who get the vaccine, and the control group, who get nothing. To prevent bias, you might also “blind” the subjects and experimenters so that no one knows who’s getting treated. For example, you could use shots filled with saline solution for the control group, so they think they’re getting a vaccine.

Once you’ve administered the treatment, you follow everyone for some period of time and see who does better. If the treatment group does better, then we say that the treatment worked.

Obviously, we cannot run an RCT for childhood vaccines, because withholding vaccines from children could grievously harm or even kill them. Instead, we can use data collected over time from millions of children, some of them vaccinated and some not, and measure vaccines’ effects from that. It’s not perfect, but these observational data show overwhelming evidence that vaccines for diseases including measles, mumps, rubella, polio, and smallpox are incredibly effective.

Yet anti-vaccine activists continue to call for RCTs, and they pretend that scientists who point out what I just wrote are not to be trusted.

Now to those parachutes in the title of this piece. We know that parachutes work, right? And yet where are the randomized controlled trials? Maybe we shouldn’t use parachutes until some scientists conduct that study? Hmm.

Well, if you’re thinking of skydiving and wondering about this question, you’re in luck! Because a few years ago, a group of scientists at Harvard, UCLA, and the University of Michigan ran an RCT on parachutes! And they published it, too, in the highly regarded British Medical Journal, now called BMJ.

I’m sure you’re curious about how they did this study, and how it turned out. Well, I’m going to tell you.

It was a small study: they approached 92 aircraft passengers and enrolled just 23 people. They randomized them into two groups, with 12 people wearing parachutes and 11 jumping with just an empty backpack.

What happened? Amazingly, there was no difference! Also amazingly, no one died! How could that be?

Well, reading the details of this (ahem) well-executed study, one learns that “randomized participants ... could have been at lower risk of death or major trauma because they jumped from an average altitude of 0.6 m on aircraft moving at an average of 0 km/h.”

In other words, participants did jump from a plane, but they were jumping from less than a meter off the ground and the plane wasn’t moving. A figure from the study illustrates the experiment:

Representative study participant jumping from aircraft with an empty backpack. This individual did ... [+]

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So as you see, this particular RCT of parachute use didn’t prove anything. Even so, the authors note, tongue in cheek, that “Beliefs grounded in biological plausibility and expert opinion have been proven wrong by subsequent rigorous randomized evaluations. The PARACHUTE trial represents one more such historic moment.”

In case you’re wondering how on earth the BMJ would publish a study like this, I can explain that the date of publication was Christmas 2018. The BMJ has a long tradition of publishing satirical but seemingly serious articles on Christmas, and this was a particularly good one.

On the other hand, though, my larger (and serious) point is that the public shouldn’t lose trust in science. Even when science gets things wrong–and it does–it’s still the best toolkit we have for figuring out whether or not something works, or is true. The recently popular cultural trope that truth is malleable, and that each person can choose their own “facts,” is dangerous. When it comes to scientific facts, that’s just wrong.

Parachutes work, and not using them would be exceedingly risky. Vaccines aren’t quite as guaranteed as parachutes, but they come pretty close.