Why Bret Weinstein is dangerous

Because misinformation kills

Yuri Deigin
12 min readSep 7, 2021

His name was Leslie Lawrenson. He seemed to have bought into Bret’s misinformation:

He then got Covid and died:

I ask two favorite Russian questions: Who is to blame? What should be done?

As some pundits have already pointed out, we are living in two pandemics: the Covid pandemic and the misinformation pandemic. The second one makes the first one deadlier than it has to be.

Besides Leslie Lawrenson, there have been other highly publicized cases of Covid killing people who bought into various Covid misinformation. Here are just a few recent ones:

Between May and September 2021 Bret Weinstein has publicized dozens of false or unsubstantiated biomedical claims on his podcasts, collectively heard by millions of people. In fact, a project started by Bret’s superfan Alexandros Marinos, which was dedicated to examining Bret’s claims in just four podcasts, has collected 44 such potential claims, 36 of which were graded as false or unsupported by the only referee in that project with relevant biomedical experience.

The goal of this essay is to provide further, detailed evidence that Bret does not possess requisite competence to make biomedical claims.

A bit of context

Bret has been a friend ever since he invited me on his podcast to talk about my Medium article on the lab leak hypothesis (1, 2). We were communicating a lot in the second half of 2020 but then as Bret’s attention switched to his Unity 2020 idea, our communication gradually subsided. I would still catch some of Bret’s tweets once in a while but nothing really piqued my interest until he put out a podcast on vaccines with Geert Vanden Bossche.

That podcast surprised me because what Geert was saying should have raised a whole lot of red flags to anyone with a solid grasp on biomedicine. So that was a canary in the coalmine moment for me that something is not right with Bret’s biomedical understanding. I tried to push back on some of the claims right away:

At about the same time, I also challenged Bret’s claims about ivermectin but he just kept dodging my inquiries:

I should say that I was fighting antivaxxer misinformation even before Bret has turned into one. My May 2021 Medium article addressed some of the most popular antivaxx claims of the day:

Thus I was quite shocked to then see Bret go full antivaxxer just weeks after my article in his “How to save the world” podcast with Malone and Kirsch:

As a friend should, at first I tried to challenge Bret’s increasingly vocal antivaxx messaging privately, but to no avail. So we then published a written critique of Bret’s misinformation with Claire Berlinski, but it only prompted Bret and Heather to double down on their dangerous views on Dark Horse podcast #87:

I addressed Bret and Heather’s erroneous responses to our Quillette article first on Twitter and then on Rebel Wisdom’s podcast, where I also went over 18 of Bret’s key falsehoods:

In a nutshell, my 3 key points are as follows:

  • Vaccines are safe and effective
  • Ivermectin is ineffective and dangerous
  • Bret Weinstein is unqualified to make biomedical claims

I have addressed the first two points on numerous occasions. If you are interested in detailed rebuttals of Bret’s antivaxx or IVM misinformation, the following spreadsheet links to individual Twitter threads containing evidence for each of the 44 false or unsupported claims submitted to BetterSkeptics:

Now, let me expand on my third point above.

Why Bret is Unqualified

A great example illustrating Bret’s lack of biomedical understanding is his claim that approved drugs are unsafe because they have been tested in lab mice, which, as Bret claims to have “happened upon” in his PhD work, have telomeres that are longer than wild mice. Here is the quote from Dark Horse podcast #87 in which Bret explains that because of his 2002 hypothesis, their household is highly skeptical of pills:

[00:11:10] Bret: In our family, we actually have a kind of concern about pharmaceuticals very generally and this arises from the fact that in my graduate work … I happened on to what I believe is a flaw in the drug safety system. I published this flaw. And the flaw basically amounts to the mice that are often used for things like drug safety testing and other experiments having been accidentally evolutionarily modified by the breeding protocol that is used to produce them so that their telomeres which are these repetitive sequences at the ends of chromosomes have been elongated tremendously and [this] has potentially very large impacts. Effectively, these animals have a capacity to repair their tissues so that if you poison them, but you don’t outright kill them, they actually have an extremely good capacity to fix themselves whereas we have a limited capacity, so they’re bad models.

Now, that has caused us over the many years [since] that work was published in 2002 [to] have a kind of uneasy relationship when we opened the medicine cabinet because we know that virtually every drug in there was tested against mice that are very, very capable of dealing with toxicity, and so we don’t know. And there are lots of instances which drugs have shown themselves to be toxic after they were proven- or proven safe in safety testing. So, Vioxx, Fen-Phen, Gleevec, Seldane, erythromycin, all of the NSAIDs, all of these drugs have been shown to be hazardous at one level or another. So, ordinarily, in this household, we are very pro-vaccine and we are a bit skeptical of pills.

[00:12:56] Heather: A lot skeptical.

[00:12:57] Bret: A lot skeptical of pills because we know that even if you know that they’re hazardous, you don’t know which pills it applies to and in what way.

There is plenty of bad science and even bad logic in that short quote. Let me address both.

Bad logic

First, I will elucidate the ‘bad logic’ part. Even if Bret’s claim that lab mice have longer telomeres was true, his inference that approved drugs are unsafe because of it is simply illogical. Drug safety is validated in several rounds of human trials before any drug is approved, so even if lab mice somehow masked some dangers of a given drug candidate for humans, those dangers would still be caught during human trials.

Or, conversely, if those dangers were so rare that they slipped even through human trials and were only caught by pharmacovigilance years after drug approval, as was the case in the examples Bret mentions, then no animal trials would have been able to catch a side-effect so rare that it only manifests itself at a rate of 1/100000 or rarer, as each animal study only consists of dozens of animals.

Also, even before a drug is allowed to be tested in humans, its safety must first be validated in several animal species, including non-rodent species. So even if lab mice were somehow more resistant to drug toxicity, other animals would not be. But then again, subsequent human testing makes the point about potential animal testing issues moot.

Bad science

Now, let me address the ‘bad science’ part. First of all, if you are really interested in all of the details of this “stolen Nobel Prize” story as it’s come to be known, watch this podcast entirely devoted to it. In a nutshell, the story from Bret’s perspective is as follows: he came up with a theoretical prediction that lab mice might have much longer telomeres than wild mice due to peculiarities of lab breeding protocols. He then told it to Carol Greider, and she “stole it” — first confirmed it in her lab, and then published this confirmation without acknowledging Bret as the source of the hypothesis.

There are several problems with Bret’s claim. First of all, “could lab mice have longer telomeres?” is not an earth-shattering insight worthy of a Nobel Prize. Carol Greider got hers for completely different reasons.

Second, Carol published the paper which Bret claims “stole” his idea in 2000. But Bret published his ‘prediction’ after, in 2002. This is already a bit of a mismatch. But the biggest mismatch is that Carol has actually published the same observation in 1995:

So there’s that.

Ironically, Bret’s original prediction and Carol’s observation have actually been disproved by Jackson Labs, the premier research animals breeding organization:

So there’s that as well.

Finally, telomeres were quite fashionable in early 2000s but have since largely proven to be a red herring. They’ve been disproved as the cause of cell senescence — there could be many other pathways to cause a cell to become senescent that just telomere shortening. They’ve also been disproved as a cause of aging. Here is a great illustration showing that:

The red box shows that for a ~10 kb specie telomere length, there are species with wildly different lifespans — from 2 to 210 years, and the blue box shows that for a maximum lifespan of 5–20 years, there are species with wildly different telomere lengths.

Oh, and lab mice don’t have “bizarrely long telomeres” as Bret has put it. In fact, some other species have them even longer (last column, in kb):

Squirrels, shrews, rabbits, and even tigers have longer telomeres than mice. Moreover, rats have telomeres about as long as mice. So there really isn’t anything special about telomeres in mice — lab or otherwise.

In light of all of the above, I can’t help but revisit something else Bret said in the “stolen Nobel Prize” podcast. In it Bret claims that after reviewing his 2002 paper Carol produced “pages and pages” of criticisms, which Bret implies were made in bad faith — as an attempt to somehow torpedo his paper (although the first time she made them was in private to Bret). However, after looking at his 2002 paper, I cannot help but wonder that maybe Carol was honestly trying to help. Because as it stands, Bret’s paper is, well, not very good. For example, their opening hypothesis is just wrong:

We hypothesize that (1) in vertebrates, a telomeric fail-safe inhibits tumor formation by limiting cellular proliferation. (2) The same system results in the progressive degradation of tissue function with age.

Even in 2002 it would have been shortsighted to assume that age-related tissue-degradation is driven by telomere shortening. We have over 200 different tissue types, each with its own aging dynamic. Neurons don’t divide after birth and survive for hundreds of years (in whales), while hematopoietic stem cells divide constantly and actually have active telomerase to elongate telomeres on demand.

Also, the following quote alone is enough to conclude the authors are not well-versed in the highly variable lifespans between different species, even between mammals where some rats live for less than a year and whales live for over 200:

If a simple modification of telomere-system parameters would extend life without significant costs, it should already have spread due to selection.

That quote reminds me of the following joke:

An economist and his friend are walking down the street when the friend sees a $100 dollar bill on the sidewalk.

“Look,” he says, “a $100 dollar bill!”

“Nonsense,” says the economist. “If that was a $100 dollar bill, someone would have picked it up by now.”

Bret’s telomere hypothesis, while possibly the most illustrative, is not the only evidence why he should not make biomedical claims. There are a couple of other, more recent statements that also raise eyebrows of competent biologists.

Ivermectin and soil bacteria

In the same Dark Horse podcast #87, Bret muses that ivermectin is somehow superior because it was originally extracted from soil bacteria:

The fact that the drug in question, ivermectin, comes from soil bacteria, it’s not a completely synthetic molecule, means that that it is likely to be similar to the things that one’s ancestors have encountered before, and there’s, therefore, a good chance that the body has a reasonably elegant way of dealing with it rather than using some mechanism that’s-that’s not so great.

There is absolutely no evidence that a molecule extracted from soil bacteria has any safety of efficacy advantage. There are plenty of counterexamples of toxic molecules found in soil bacteria: anthrax, botox, Clostridium tetani (cause of tetanus), etc.

Natural, organic, non-GMO anthrax infection

Anti-GMO and anti-sunscreen

Also in podcast #87, Heather read an excerpt from their joint book which revealed that Bret and Heather espouse anti-GMO and anti-sunscreen beliefs. Heather also repeated the “if it were that easy, selection would almost certainly found a way” trope, to which I would only ask why selection hasn’t provided humans with endogenous antibiotics or vaccines, and we had to first invent science to fix selection’s many shortcomings.

Bret and Heather’s anti-sunscreen stance is quite revealing of their anti-science beliefs. Heather actually said that sunscreen “probably caused more problems that it solved”:


She then revealed that she has been withholding sunscreen from her own children:


Bret also weighed in on this topic a while back:


As usual, Bret tried to tie the scientific findings they were discussing on their podcast to his telomere work and his “lifetime capacity for repair” hypothesis. Let me just quickly dispel that hypothesis: animals do not have some sort of limited capacity for repair that they use up and thus die. If that were the case, athletes would keel over in their thirties, and mice undergoing caloric restriction would live shorter, rather than 50% longer lives. On the contrary, it seems various insults seem to prolong lifespan and/or make animals fitter — that’s the concept of hormesis.

In the clip above, Bret also seems to make a distinction between getting sunburns and getting “sun-damaged skin”, which reveals a misunderstanding of the biological process behind UV’s effect on skin. Both sunburn and suntan are skin’s responses to detecting UV-caused DNA damage. (I’ve actually dug into this topic quite deeply, albeit in Russian). And sun-damaged skin is the result of many repeated instances of such UV-caused DNA damage: when DNA damage is beyond repair, most cells become senescent (growth-arrested, and it’s not due to telomere shortening!), while a small proportion of such cells might actually turn cancerous.

Published papers

Some of Bret and Heather’s listeners hold a misconception that the two are highly credentialed scientists. They are not: they have not done any research in years, and any research they have done years earlier is minimal. In all of his academic career, Bret has published only two biology papers (in 2002 and 2005), while Heather — three (2001, 2006, 2007):


I think by now it should be abundantly clear that Bret is not competent to make biomedical claims, and should retract all of the false antivaxx and ivermectin claims he has made. He should also refrain from making further biomedical pronouncements.

Bret knows that the price for spreading Covid misinformation is measured in lost lives. He conceded as much on his podcasts. However, he felt he had a moral obligation to speak up as he thought he possessed some superior knowledge that was being suppressed. Tellingly, he didn’t seem to feel the same responsibility if his highly publicized views turned out to be wrong and responsible for people’s deaths:


Unfortunately, as in the past, Bret’s superior knowledge is simply a delusion. He is wrong. Moreover, when shown to be wrong, he is unwilling to admit it but would rather see himself as a kind of a martyr who is being suppressed by some DISC forces.

That’s not what good faith actors do. Good faith actors acknowledge their mistakes and correct any previously wrong claims they have made.

Bret, if you are truly a good faith actor, please publicly retract your erroneous claims and tell your followers to get vaccinated ASAP. I still hold out hope that deep down you are a good man.



Yuri Deigin

Longevity maximalist currently building rejuvenating gene therapies based on in vivo partial cellular reprogramming with Yamanaka factors.