Why Men’s Testosterone Levels Are Plummeting - Dr Shanna Swan

1. 0:00 – 3:40

   What’s Happening to Men’s Testosterone Levels?

   1. CWChris Williamson0:00

      What's happening to testosterone levels in men?

   2. SSDr. Shanna Swan0:04

      So that's a great question, and actually I work with a research group and have been for quite a long time now, since, um, you know, 10 years, uh, looking at trends. And, and the trend we're looking at right now is testosterone. And it's difficult. Uh, we haven't finished it. We're in the midst of it. Maybe I'll come back and talk to you when we get the results. Um, but there are a number of papers published that we think are pretty authoritative that talk about declining testosterone. But the, the other thing that we can look at, which is different from doing a literature review, you can say, "Well, how is it clinically?" And there's a lot of data, uh, showing that the use of testosterone, particularly by young men, has been climbing, um, alarmingly actually. Um, so from a lot of measures, we have hints that testosterone is declining. That's a long way from saying what we said with sperm count, you know, worldwide we see a decline. And we'll come back to that, I'm sure. We can't say that about testosterone at this point, but we can say there are a lot of signals suggesting that testosterone is in trouble.

   3. CWChris Williamson1:22

      Yeah, obviously one of the challenges we have here is, are young men taking testosterone because they're suffering with the effects of low T, uh, erectile dysfunction, low energy, low mood, et cetera, et cetera? Or is it because of increases in body dysmorphia or unrealistic representations of, of men in media and they feel like they need to use testosterone as a performance enhancer to become more masculine or to become more muscular and stuff? Uh, why is it the case that you have more verifiable data around sperm count than you do around testosterone levels? I would have thought that testosterone levels would have been more widely available. Uh, I know more guys that know their testosterone count than know their sperm count.

   4. SSDr. Shanna Swan2:05

      That's a good, good point. That's today and probably in the US. Um, but, um, sperm count has been under study for, uh, 65 years. So th- there's a, there's a long history of studying sperm count, and there's been very little on testosterone. Um, so I can't tell you why that is. I mean, men give a sperm sample for a number of reasons, not just research, right? They give it for pre-vasectomy. They give it, um, because they wanna be tested for possible infertility. They give it for a lot of reasons, and I think it's much more common. Uh, giving a testosterone, a blood sample, which you have to give for testosterone, is, um, I think less... I know it's less widespread 'cause there's much less literature on it. And it, when scientists-

   5. CWChris Williamson3:08

      Oh, interesting.

   6. SSDr. Shanna Swan3:09

      Yeah.

   7. CWChris Williamson3:12

      It's so interesting to me. You know, a- a- again, uh, maybe aga- you're, you're probably right. This is my not only weird bias, but also my Austin podcast bro, biohacker world bias coming into play, where all of my friends know that they're at 755 nanogr- nanograms per deciliter and, and they're gonna try and get up to 900 because blah, blah, blah. Uh, and I don't know who knows their sperm count. Um, just before we get onto sperm count,

2. 3:40 – 9:45

   How Important is Testosterone?

   1. CWChris Williamson3:40

      tell me, from the testosterone, i- it seems there are some, uh, sort of, I guess, uh, rough-hewn signals that indicate the testosterone is going down. Um, how important is testosterone? You know, there is a, uh, uh, somewhat in the media of a demonization in some ways of, uh, uh, of testosterone in men or, or some of the activities, I suppose, of, you know, high testosterone men. Um, how important is testosterone to function for men, for longevity, for health, for reproduction? What does it do-

   2. SSDr. Shanna Swan4:13

      I would say it's-

   3. CWChris Williamson4:13

      ... in your world?

   4. SSDr. Shanna Swan4:14

      ... a- absolutely, absolutely critical for many, many things, and I would start with the testosterone in the developing fetus. So the first time that testosterone matters a lot is in the first part of the first trimester. That's how early it is. And, and it turns out that... Okay, so l- let me back off. Okay. At the beginning of pregnancy, as soon as you can measure anything or see anything, you will see a genital ridge in males and females. That's the genital track, but it... Not different in males and females. It's just this ridge, right? And then, at the right time, and we're not sure exactly of that time. We know it in rodents. In rodents, it's day 18 to 21. But in humans, not so much. We know that it's in early first trimester. Uh, at that time, genetically programmed, if it's a genetic male, uh, programming will, um, start the production of testosterone by the testes, formation of the testes, then testosterone gets produced. And that testosterone is what kicks off the genetic male differentiating himself from the genetic female. Up until that point, it's all the same. And in fact, if the testosterone is not there at the right time or at the right amount, then that male will not proceed on the path to a male-typical genital. He will, he might have smaller testicles, a smaller penis, small, less descended testicles, and then my favorite is the anogenital distance, which we should talk about for sure. But-

   5. CWChris Williamson6:01

      I'm so glad that that's... I'm so glad that's your favorite. I was waiting for you to bring it up.

   6. SSDr. Shanna Swan6:07

      (laughs) ... well, the reason it's my favorite is because until I started looking at it, it had only been looked at in animals. Nobody thought anything about AGD, anogenital distance. It was not considered interesting for humans. And then I showed it was, yes, extremely interesting for humans (laughs) . And, and you know, so the, the first thing, talk about this differentiation, when you start out, everybody has the same AGD, lengthwise. And then as the testosterone comes in, the AGD in the male gets longer, longer, until it's about, you know, twice as long as the female or something like that. It's, it's markedly longer. If that doesn't happen, then it's still a male, but he's a incompletely masculinized male. So, so this measure is, you know, really, really critical. Um, so and other things happen. The testes don't descend into the scrotum, and the penis is actually s- smaller, which a lot of people get upset about, and other things like that (laughs) .

   7. CWChris Williamson7:20

      Ha, ha.

   8. SSDr. Shanna Swan7:22

      So, so that, you know, fulfilling that potential of a male typical genital requires... You said, "Is it important?" I would say most men would say, "That's pretty important."

   9. CWChris Williamson7:34

      Yes. Okay, roll me forward 'cause, uh, what we're talking about there presumably is, um, endocrine disruption in the mother which impacts the growing fetus natally.

   10. SSDr. Shanna Swan7:49

       Yes.

   11. CWChris Williamson7:49

       What about when, uh, mother and son are no longer attached? What, uh, what... How important is testosterone for development as we move, uh, into adulthood?

   12. SSDr. Shanna Swan8:00

       Yeah, yeah. So the... Testosterone is important at many stages. It's important for, um, puberty. It's important for other markers of male development. Um, and one of the things that's really key is it's important for libido. Um, so, um... And by the way, it's not just the male. I just wanna put in a little word for the female here. So we'll talk about chemicals that influence testosterone, and I'll just say that the class that I've studied is the class of chemicals that make plastic soft. That's the phthalates. Now when the mother or just a woman, she doesn't have to be a mother, is, um, exposed to less... well, actually more phthalates, then she is less satisfied sexually. So we found that out by asking women. We said, um, "How satisfied are you with your sex life? How often do you have sex?" That was in our study. We asked them that. And we got their urine, and in the urine, we measured their phthalates. And it turned out that when the woman had low phthalates, she was less satisfied, and she had sex less often.

   13. CWChris Williamson9:17

       L- what does low phthalates relate to from a testosterone and female perspective?

   14. SSDr. Shanna Swan9:22

       Yes. In both males and females, phthalates lower testosterone. Okay?

   15. CWChris Williamson9:28

       Hang on, but you said low phthalates mean low testosterone. Would it not be high phthalates would mean low testosterone?

   16. SSDr. Shanna Swan9:33

       I, I, I meant to say low phthalates (laughs) , low, low testosterone. Right. Phthalates come in, testosterone goes down.

   17. CWChris Williamson9:39

       Understood.

   18. SSDr. Shanna Swan9:40

       That's-

   19. CWChris Williamson9:40

       High phthalates-

   20. SSDr. Shanna Swan9:41

       ... a part... Sorry about that. Yeah.

   21. CWChris Williamson9:41

       ... low testosterone in both men and women. Okay.

   22. SSDr. Shanna Swan9:44

       Right.

   23. CWChris Williamson9:44

       Presumably,

3. 9:45 – 17:03

   Why This Negatively Affects Both Partners

   1. CWChris Williamson9:45

      this is a double-edged sword if women who are high in phthalates, lower in testosterone, sexual, sex- uh, less sexual satisfaction, and also the men who are lower in testosterone have lower libido, probably lower, um, like erection quality, and, and stuff like that.

   2. SSDr. Shanna Swan10:05

      Right, right.

   3. CWChris Williamson10:05

      So you have a, a, an environment, an endocrine environment here which is reducing sexual satisfaction for both partners and their ability to satisfy each other as well.

   4. SSDr. Shanna Swan10:17

      Correct. And, and I do not have evidence, firm evidence of this. However, you probably know that fertility rates worldwide are down and in particular in East Asia. They are absolutely at the bottom. And one of the things that's happening is that people are not having sex. They are not marrying. They're not coupling. They're not having sex. Okay? And the government is trying to pay people (laughs) to turn this around. Uh, it's, it's really serious. Now no one has linked that specifically to an endocrine-disrupting chemical, but I cannot believe giv- given what we know about the action of these chemicals, that it is not playing a role. In, in Japan-

   5. CWChris Williamson11:06

      So I've got a lot of...

   6. SSDr. Shanna Swan11:07

      Yeah?

   7. CWChris Williamson11:09

      Go ahead. In Japan...

   8. SSDr. Shanna Swan11:09

      I was just gonna say that in Japan, there is, uh, two phenomena I wanna mention. One is called rent-a-family, where if you have an... (laughs) Uh, yeah, you can rent... That's, you can sign on to rent-a-family to get a child for a party or a spouse for a party.

   9. CWChris Williamson11:28

      (laughs) Oh, my god.

   10. SSDr. Shanna Swan11:29

       Um, right? And the other one is the phenomena of Japanese women marrying themselves, and that is the weirdest thing to me. That... And you can go online and look for that. There are women who have ceremonies at which they marry themselves. So to me, this is one of the clearest indications of a lack (laughs) of libido. Uh, uh, very strange, yes. Are you looking it up?

   11. CWChris Williamson11:58

       Solo weddings. S- Japan, solo weddings for single women. Self-marriage has become increasingly popular in the 21st century, especially among affluent women. As of 2014, a travel agency in Kyoto is offering self-marriage packages for women, with some customers being wives who were dissatisfied (laughs) with their original wedding. Wow, I mean, that's even worse than being left for the guy next door, being left-... for yourself is, is a, a, a, a, a real tough pill to swallow. So yeah, I mean, look, I've had a lot of conversations on the show about declining birth rates. It's something I'm increasingly concerned about. We had D- uh, Dr. Steven Shore on the show, who I think is probably the best population demographer when it comes to birth rates at the moment. He did an amazing documentary called Birthgap. And I agree, uh, me and my evolution-pilled buddies, a lot of the time we're talking about the mating crisis, we're talking about issues with women finding a man that they're attracted to, hypergamy, uh, more distractions from screens, you know, just more life options that people have, delayed adolescence, pushing people's lives a little bit further. All of these... And, and they're all, you know, social psychology/evolutionary explanations that come into attraction. But if we just straight up say libido is lower, like if we just have that, just this one factor, libido gets reduced. We don't know by how much. Maybe it's by 10%. Maybe it's by 50%. We don't know. But people are just less bothered about being sexually active with-

   12. SSDr. Shanna Swan13:26

       Right.

   13. CWChris Williamson13:27

       ... with, uh... And, like, just that on its own, that is fundamentally the driver. And people can reverse engineer. You... I'm sure that you'll be familiar with the difference between proximate and ultimate explanations for behavior. So the proximate explanation for, for having sex is sex feels good. The ultimate explanation for having sex is that it makes babies. Now, what we're looking at a good bit of the time, I think, in my world, and this is something that's maybe an area that I need to bring up with the guys, we're looking at the ultimate explanation a lot of the time. We're thinking, well, people kind of reasoning themselves... It's a very cerebral, cognitive kind of, um, like, right brain approach to... People are reasoning themselves into having kids or reasoning themselves out of having kids. They've got other things to do. But if you just look way closer to home, sex is just less of a driver, potentially, due to reduced libido, reduced testosterone in both, uh, men and women. Uh, and that means that people are just not so fussed about getting into bed with each other. You know, I remember-

   14. SSDr. Shanna Swan14:27

       Yeah.

   15. CWChris Williamson14:27

       ... when I was at univ- when I was at university, uh, 15 years ago, uh, started at university, oh God, 18 years ago now. And when I went there, it was still this sort of very driven, lairy, lout sort of British culture and, you know, all of... Whereas now, uh, I think 50% of men aged 18 to 30 aren't looking for long-term or casual relationships. To me, a man who went through that period of my life, you know, the reality distorting power of the male sex drive in that age bracket is, is a sight to behold, you know. It's very powerful. Um, so yes, absolutely, I think that that, that base rate should be factored in, how can testosterone just impact our desire to have sex. And then down- downstream from that, the babies, the marriage, the... all the rest of the stuff. Like, if you're the sort of person that wants to have sex once a year or the sort of person that wants to have sex once a week, your desire, your, um, motivation to go out and get a partner is gonna be really different.

   16. SSDr. Shanna Swan15:24

       Yeah. Yeah. I wanted to mention, you, you mentioned briefly, uh, the effect of testosterone over your lifespan. And, and I do wanna say that there is now, and there was just a new study out about this, um, we have increasing evidence that men with low sperm count, men and women who are infertile have a shorter lifespan. It's really pretty... And now it's been shown enough times, you know, in Denmark by Mike Eisenberg in Stanford, um, there, I think there's probably a half a dozen papers on this. And it's really a lot. And w- I mean, first of all, men and women who have i- impaired, I would say hormone systems, uh, are more likely to have other medical problems. Uh, for example, heart disease is increased. Um, diabetes is increased. Reproductive cancers are increased. What this adds up to is you die earlier. So here's something that you're exposed to preatally, and then again in adult life of course, or in adolescence, we can talk about when the exposures are important, but throughout your lifespan, particularly early in life, you're setting up, you're setting up your health for the rest of your life. Exposures during pregnancy are most important for your whole life's health.

   17. CWChris Williamson17:00

       Mm-hmm.

   18. SSDr. Shanna Swan17:00

       'Cause everything's developing then, right?

4. 17:03 – 19:04

   Link Between Testosterone & Sperm Count

   1. SSDr. Shanna Swan17:03

   2. CWChris Williamson17:03

      What is the relationship between testosterone and sperm count for men?

   3. SSDr. Shanna Swan17:09

      Ah, well, if you don't... It's complicated. Men who, who use testosterone supplementation do not produce sperm. Again, do you know that?

   4. CWChris Williamson17:21

      Of course.

   5. SSDr. Shanna Swan17:22

      (laughs) Yeah, you do.

   6. CWChris Williamson17:23

      But I, I mean, I, uh, I say of course, like everyone does, but I think a lot of people think that going on TRT will somehow increase your sperm quality or increase fertility, but it doesn't.

   7. SSDr. Shanna Swan17:34

      The opposite. The opposite. However, um, for the maintenance of the system, you need adequate testosterone. So on an ongoing basis, um, for the system to work properly, and it's not just directly testosterone and sperm, it's you, you need adequate testosterone. So interfering with that, um, is going to mess up your brain and mess up y- you know, the production of sperm, mess up whatever, the whole, the whole gamut.

   8. CWChris Williamson18:05

      Presumably low... So am I right in thinking there must be a U-shaped curve to testosterone and sperm quality, that too low testosterone in men... Or i- or is it just a linear line? The lower the testosterone, the more sperm? Because obviously too much, which is the exogenous stuff, that decreases, uh, sperm count.

   9. SSDr. Shanna Swan18:24

      No, you-

   10. CWChris Williamson18:24

       But what about too little?

   11. SSDr. Shanna Swan18:26

       Yeah. So the, when you're taking testosterone, your body gets the me- e- the, everything... All of these hormones work on feedback, feedback loops. And so if you give the message, "Wait, I got enough of this stuff. You don't need to make this," y- your own testosterone production will be cut down and your production of sperm will be cut down. So it's, it's complicated. And I'm not an andrologist, so I can't really speak knowledgeably about this. But I can tell you what we observe, that, you know, that when men go... As you know, men go on testosterone, they stop producing sperm. Yeah.

   12. CWChris Williamson19:01

       All right. So moving on to the big one,

5. 19:04 – 24:09

   Statistics on Sperm Count Over Time

   1. CWChris Williamson19:04

      sperm count. What is, what are the statistics, uh, the trajectory of sperm count over the last 65 years?

   2. SSDr. Shanna Swan19:14

      Right. So until... So many people have looked at this, and we looked at this, I would say, arguably better than anyone because we used techniques that were not available in the past. And we, we used something called a meta-analysis, and, um, we did a very deep dive, um, on the whole world's literature looking at sperm count. Um, and I'll tell you the conclusion, and then we can talk about what went into that. The conclusion was that sperm counts are going down at about 1% per year, and they're not stopping. It's consistent. It's now we know from up, recent studies that we've done is actually worldwide. And, um, and it's increasing, in fact, that the, the... In our most recent study, the rate of decline was 2% per year after 2000. 2% per year, which is huge. Okay? So we published that in 2022, so after 2000. If you go all the way back till 1973 and look at the whole spread, it's over 1% a year. So that's, tells you that things are not getting better. (sighs)

   3. CWChris Williamson20:32

      They're getting worse. It's, it's-

   4. SSDr. Shanna Swan20:33

      They're getting worse.

   5. CWChris Williamson20:33

      ... increasingly decreasing.

   6. SSDr. Shanna Swan20:36

      That's right, increasingly decreasing.

   7. CWChris Williamson20:38

      (laughs)

   8. SSDr. Shanna Swan20:39

      That was kind of weird, but there it is. Yeah. Um, (clears throat) the other thing we found in our update was (clears throat) it actually does seem to be worldwide. (clears throat) In our initial analysis, (clears throat) we had to take the data, we always have to take the data that's available, can't make it up, right? And, and, and the publications in the non-Western countries were very few. So there was not very much data from Asia and Africa and South America. But in our 2022 paper, there was much more. And I think what happened was when our paper came out in 2017, which was kind of a big thing, a lot of people started saying, "Wait, wait, about, what about us?" And started looking in these other countries and tossed that in, and then we saw that it was worldwide. So our conclusion of that 2022 paper was sperm count is declining worldwide, and the rate of the decline is increasing.

   9. CWChris Williamson21:34

      Have you got any idea what countries are having this decrease at a slower rate? Are there any, uh, blue zone equivalents for sperm?

   10. SSDr. Shanna Swan21:48

       (laughs) That's a great question. Um, I don't think w- we know enough to generalize, but I will say that in Denmark, the rate of decline has s- seems to have leveled off. That's one of the best studied countries because a lot of the work was done there. Originally, the first sperm decline paper came out of there, and a lot of work... They're excellent. And, and, um, they've been following military recruits, men, you know, young men coming into the military, and asking them if they'd give a semen sample. They've been doing that for a long time. And what they're seeing now is that it doesn't seem to be getting worse. So I would say, if we had to find one place that seems to be doing better, I would say it's Denmark. They're still not doing great. They still have a lot of men with very low sperm count. Nevertheless... Now Finland, on the other hand, which, um, you know, used to be much better than Denmark, is now going down to, to meet Denmark. So that's confusing because they're very similar popul- you know, they're, demographically, they're not that different. Their exposures are probably not that different. So that's a conundrum that we have to, to deal with.

   11. CWChris Williamson23:01

       I'm fascinated by, uh, trying to map this, because obviously if you could look at, uh, fertility rates, marriage rates, if you could do some, um, self-report studies of how much do you desire sex? How often do you want to have sex? How often do you have sex? You know, uh, you could, I guess, do surveys as well about people's beliefs, uh, and desires, uh, to get into relationships and stuff like that. I would love to map a- and then, and then look at what is, uh, very prevalent in the water, what are the sort of packagings that are used, what's the type of consumption, et cetera. Uh, I would be fascinated to see how much of this Asian downturn in birth rates can be seen as, um... There is a particular, uh, brand of plastic that is exclusively used to package all meats and, and vegetables, and it only exists in Finland. Uh, recently got introduced to Finland, and it has been in fucking South Korea or whatever for ages.

   12. SSDr. Shanna Swan24:00

       Yeah, yeah, yeah. I, I share that wish with you, but, um, I don't think we're gonna find that. (clears throat) Uh, let me... Let's just talk about

6. 24:09 – 33:58

   The Social Impact of Lower Fertility

   1. SSDr. Shanna Swan24:09

      social factors since you kind of brought those up. Um, so... Oh, uh, and we haven't, I haven't said, but I'm sure you know, you've had a fertility expert on, a demographer on, um, excellent person. So you know that the fertility rate, which is the number of children that a couple can expect to have in their lifetime, that fertility rate-... which should be 2.1 to maintain the species, is now going down almost all over the world and I'll give you the exception, but almost all over the world. Um, it's including African countries which had a very high fertility rate. Okay. Um, in East Asia... So we wanna aim for 2.1, okay? 2.1 maintains the status quo. In South Korea, at last look, it was 0.8, right? It's also, like, I think 0.9 in Japan, it's... Those East Asian countries are very, very low.

   2. CWChris Williamson25:14

      Germany-

   3. SSDr. Shanna Swan25:15

      Lo-

   4. CWChris Williamson25:15

      ... also not, not good at all.

   5. SSDr. Shanna Swan25:17

      Not good at all (laughs) . If you want to maintain the population and, and the governments are trying a lot economically to, to pay couples, to get married, to have children, to get your, you know, you get a tax credit for the child, you get a partner-

   6. CWChris Williamson25:33

      Hungary did that thing where the, the, a woman got, I think, for three kids, didn't pay tax for the rest of her life.

   7. SSDr. Shanna Swan25:40

      Yeah. Right. So, but it's not working. It's not turning that around. And, and so there's something else going on here (laughs) , you see? And, and, and so that's what we as a s- a society have to, to think about if we wanna maintain our existence. I mean...

   8. CWChris Williamson26:03

      (laughs) .

   9. SSDr. Shanna Swan26:04

      There are endangered species and, and, and the, and humans do fulfill-

   10. CWChris Williamson26:08

       We are one of them.

   11. SSDr. Shanna Swan26:09

       Yeah. So (laughs) , so, um, but let me say I'm not saying it's all chemicals. Okay? I wanna make that clear. I think the chemicals that affect our body's hormones are extremely important in this story, but they're not the whole story. So, so here's a couple of things that lower sperm count that you can control. Good to know, right? You can con- your diet, you mentioned the blue zones. Uh, be interesting to see the fertility in the blue zones and the sperm count and so on. I, I don't think that, uh, Dan has done that, Dan Buettner, but, um, the, um... We did a study with Harvard on, um, a di- uh, the man's diet and we showed that men who were eating the Mediterranean diet had better sperm count than men who were eating the Western diet. So that's one thing that's pretty clear. We know that smoking, smoking is a huge risk factor for low sperm count. So smoking, there's another one, that's not... You could say that is chemical, but I'm putting it under lifestyle, so... In some sense, everything is chemical, but (laughs) ... Um, then there's obesity and exercise, and the usual, you know, if you're obese, your sperm count is lower, your fertility is lower if you don't exercise, same. Um, stress is really important and we, we asked, um, men who gave us sperm samples in our studies, uh, about their stressors in their lives, th- in their daily lives. You know, typical stressors are moving and change of job and change of partner and death of a loved one and divorce and, you know. And if you look at those, you see that the more stressors a man has, the lower his sperm count. That's not surprising, but there's another factor. So we're talking about a lot of lifestyle factors. Alcohol is important too, particularly binge drinking, um, you know, Saturday night, five drinks, six drink- bad, bad for your sperm count. So, um, and we can find more, but the, but the point is here that it's not just these chemicals that are hormone disruptors that are- I'm caring about or that other people care about. They're also the lifestyle factors. Now in terms of fertility, there are sort of different factors and they're also important, and they particularly have to do with the female side, I think. Um, by the way, those factors also affect female fertility. Obesity, smoking, all those things, stress, all that. But, um, the availability of contraception, which primarily has an impact on females I think, um, drives down the fertility rate. So if you have contraception available, you're gonna have fewer children. Okay? Um, if you have women educated, you're gonna have fewer children. If you have women in the workforce, you're gonna have fewer children. Right? So women's place in society is very important for the fertility rate. So that's a very different kind of factor, but it's not a chemical. Right? So if you put all those aside, I would say what you're left with is the chemical and we can talk about that, but (laughs) , but I just wanted... I didn't want to give the impression that I'm all about chemicals all my life.

   12. CWChris Williamson29:31

       No. I mean, we've, we've covered... You're the first person that I've spoken to about, uh, endocrine disruptors and what's happening, uh, I guess, um, physiologically inside of the body, uh, beyond diet, diet and sedentariness and, and stuff like that. Uh, I'm gonna guess that, uh, sleep, poor sleep, um, which we are increasingly, uh, subject to screens at night, distraction, blah, blah, blah. I'm gonna guess that makes a difference. Can I give you my, uh, bro science theory, uh, about why testosterone levels are socially mediated by contraception? So, uh, as I'm sure that you're aware, men who are around guns see an increase in testosterone. If I was here and I just had weapons strewn around the table, my testosterone would be a bit higher. Probably if I was wielding a sword as well, it would be a little bit higher. But the same thing is also true for men who are around women that are fertile.

   13. SSDr. Shanna Swan30:24

       Yeah.

   14. CWChris Williamson30:24

       So if you give men the, the T-shirts of women who are ovulating and you get them to smell it, they are able to pick those women. Um, you can show men the silhouettes of women walking-... and the women who are ovulating, men are able, they, they prefer that. There is something, uh, uh, in their gait design that changes based on their st- their stage of their ovulatory cycle. So I think, here, it's bro science time. I think that the artificial suppression of women in men's local environment, their, their fertility, through hormonal birth control, the coil, et cetera, et cetera, is causing that. Because that's another huge mediator. If you were, if it was me and a bunch of, uh, grandmas or three-year-old girls, I'm surrounded by females, but I wouldn't be surrounded by fertile females. That would have an impact on my testosterone level and presumably on my sperm count. So it's my belief that you've got everything that you've spoken about plus this evolutionarily mediated testosterone and sperm mechanism which occurs by men just being around fertile women, and because there are fewer fertile women because of contraception, that's also causing a problem.

   15. SSDr. Shanna Swan31:38

       And Chris, I wanna use a word here which I'm sure you know, but it's really relevant, and that's pheromones. Yes? So the pheromones that are produced, and that's, that's what the T-shirt you were saying, that if you give a man a T-shirt from a fertile woman, those are pheromones. Um, and the, the, the influence of those pheromones on men's hormones and sperm count, I don't know a study specifically where, you know, you looked at sperm count in relation to ... but I, I suspect it's there. The, the other thing is, we do know that when the woman, you have a couple, the woman is pregnant, his testosterone goes down 'cause he's not, he's gonna be staying at home and not playing around for a while.

   16. CWChris Williamson32:21

       Oh, yes, of course. Men's testosterone goes down when they get into a relationship, when they get married, and then when they have children, w- we know f- less risky behavior. Um, that wouldn't ... So I, I, uh, that mechanism works. Okay, so we, we understand that the mechanism of a, being around an unfertile female mediates it. What we don't know is how much is this happening en masse? How much ... Here's another one that I haven't even thought about until now. How much of the, uh, increasing social isolation of men, you know, just spending time in their house, maybe they work remote, maybe they've got a job that allows them to work from home, maybe they spend a lot of time on screens, as opposed to mixing, going to church, going to bars, going out dancing, uh, uh, playing sports, doing things that would have allowed them to interact with women, fertile women, in the environment. Uh, so yeah, we just have... It's this huge cocktail of social, hormonal, psychological, physical, environmental, lifestyle impacts that are all coalescing to, like, neuter the human race, both men and women.

   17. SSDr. Shanna Swan33:28

       Yeah, I don't wanna go so far as to say neuter, but certainly alter the hormones, um, (laughs) but it-

   18. CWChris Williamson33:35

       Yeah. You're the-

   19. SSDr. Shanna Swan33:36

       ... but for s-

   20. CWChris Williamson33:36

       You're the scientist. I'm the one that can use the explosive language just fine.

   21. SSDr. Shanna Swan33:39

       Yeah, you can do that. You can do that. (laughs) But, um, I, and I think all of that is extremely important. However, I don't wanna lose sight of the ability of chemicals to also alter our body's hormones. And-

   22. CWChris Williamson33:56

       Let's get into the, let's get

7. 33:58 – 42:35

   Using Chemicals to Alter Hormones

   1. CWChris Williamson33:58

      into the chemicals. Tell us, tell us what we need to know.

   2. SSDr. Shanna Swan34:03

      Okay. So can we go back to the unborn fetus? And, and I'll tell you the story. So, um, I'm flying to Japan with a colleague named John Brock, who's a chemist, wonderful chemist, and he works for CDC. And CDC, Centers for Disease Control, they have just figured out how to measure a whole lot of chemicals in a lot of people for not a lot of money. So this actually changed the whole research field, 'cause until then, we didn't know how to look. If I wanna know your levels of things in your body, chemicals in your body, I can't, I can ask you, I can ask you how much you smoke, I can ask you how much drugs you took, blah, blah, blah, blah. I can't ask you how much bisphenol A is in your body, BPA. Right? I can't ask you. So the only way I can know that is to look inside your body. And it turns out that a lot of these chemicals are water soluble, and so they're in the urine, and that makes it very easy. Okay, the ones that aren't water soluble are usually fat soluble, and they're in the serum, and so that's another way you can do it. But that's a little more difficult 'cause you have to draw blood and stuff. But urine is really easy. So, when CDC could measure tons of chemicals in, in urine, it changed our research field entirely, forever. Okay, so here I am on the plane with John, and we're having a long flight to Japan, and he says, "Shauna, you should study phthalates, okay?" And I said, as you might, if you didn't know better, "What's phthalates?" Right? And, because I had never heard of them. And, um, by the way, my background is in mathematics, and, you know, I'm not a chemist, so, you know, (laughs) this is like, "Phthalates or it's not?" (laughs) Um, so, uh, he told me, and he told me something about where they're found, which I can tell you in a minute, and, but he also said they're in everybody. So that's fact one. Phthalates are measurable in everybody's urine in the United States, in the sample, representative sample they looked at. And then he told me the kicker, which is that at the National Toxicology Program, scientists had fed these same phthalates that we have in our bodies to rats, pregnant rats, early in pregnancy, and what they found was, what I've already told you, that the male offspring are incompletely masculinized. They are born with genitals that haven't made the full transition from neutral to masculine-... okay? That is huge. I mean, really, this was a first time that, that anybody thought that th- this could happen on this physiological level in utero from these chemicals, okay? So I was like, "Wow." And then I thought, naturally being a epidemiologist, (laughs) at that time, I asked, "What about humans?" 'Cause he told me about rats, right? So I said, "Well, okay, so then if we want to ask that question of humans, what do we need?" So we have to know how much phthalate is 'cause in the lab for the rats, you gave the measure, you could know how much 'cause you gave it to them. But we can't give that to people, it's, y- unethical. You're not allowed to feed test chemicals to subjects, except for very rare circumstances. Um, and so we'd have to know how much they accidentally got in their bodies. And that's when we realized you could do that in urine, because John had measured it in urine, right? So, okay, so all I need to do is get the urine of pregnant women, and I got half the equation. And fortunately, I had a study in which I had saved the urine of pregnant women. It's always good to save urine 'cause it's cheap and it's easy to get and, (laughs) so I always tell my students, "Save the urine, save the urine if you can because j- it's gonna come out useful." And here it was being extremely useful. So we got out these urine samples from the freezer, sent them to the Centers for Disease Control, and asked them to measure the phthalates in the urine. And we found them, tons of them. Okay, so then to finish this, I had to do the second half, which was look at the offspring, right? So to do that, I had to contact the mother and say, "Could you bring your baby in so we can measure its genitals?" Kinda weird, right? But, (laughs) but we did that, and women did bring them in, and what we found was that humans, like rats, had this condition which is called the phthalate syndrome. So, I mean, this was so important because this is a, aside from one other syndrome, which is alcohol, fetal alcohol, I'm sure you've heard of that, um, there are no syndromes named after chemicals of this kind. No prenatal exposure produces this cluster of adverse outcomes in, you know, named after a chemical. So here's the phthalate syndrome, and it was just the same as in the rats. By the way, in the rats, the researchers had been measuring these things for, for about 50 years. They had been using AGD, anogenital distance, and these other measures as measures of what they call reproductive toxicity. That's part of their protocols, part of the NTP protocol, but no one had done it in humans. So what we had to do was say, "Well, what does that look like in humans? What does it... how do you translate that exam in a rat to that exam in a female, or, uh, uh, an offspring of a female human?" So designing that protocol, that exam, was, you know, diffi- uh, okay, it was difficult, but we did that. And then we had to show it was repeatable and reliable and two people got the same measure and, you know, if you did it a week later, you got the same result, and all this kind of thing you have to do there. So we did that and published, and it was a, it was a groundbreaker. It was huge. Um, and, and it w- led to legislation to keep phthalates, you know, out of certain things, not quite the right things. They kind o' took 'em out of children's toys, which is not, (laughs) related to mothers' exposure, but anyway, they were on the right track. Limit phthalate exposure. And, um, and then other people started seeing that there were other chemicals that could do this. So it's not just phthalates that lower testosterone. There are other... And the class of chemicals that lower testosterone are called antiandrogens, okay? And then, at the same time, a researcher in Washington State discovered that there was an estrogen-influencing chemical, um, and that was bisphenol A. So, you know, bis- bisphenol A makes plastic water bottles hard, and so gradually, people started saying, "Oh, and what else can go wrong? And what can influence thyroid, and what can influence this hormone and this harm..." And that class of chemicals are called endocrine disrupting chemicals 'cause as a class, they disrupt the endocrine system. So there's 80 hormones in the body, so a lot of room, (laughs) a lot of room to differ disruption. And there's, like, maybe 100,000 chemicals out there in commerce, so there's a lot of room f- for chemicals to affect them. And so this is a huge job saying, "How can this huge class of chemicals in commerce affect these very large number of hormones which govern our entire function?" Our entire function and health is governed hormonally. So it's extremely important, and it plays a big role in the sperm story and in the fertility story and, and what we're talking about today. So that's my rant on chemicals.

   3. CWChris Williamson42:34

      And

8. 42:35 – 48:28

   How a Mother’s Food Impacts Her Baby

   1. CWChris Williamson42:35

      what you're talking about here specifically is, or at least so far, natally, what does presumably a mother's consumption do to impact the development of a baby in utero? But then that baby is going to grow up-... and start consuming things that are encased in BPA water bottles and that have got phthalates, that may be in drinking water and ma- or whatever, whatever. Um, when it comes to the culprits of environmental and lifestyle, uh, absorption, consumption, wha- what are the... what are the big movers? What is it that people are exposed to, objects and things, uh, that a- are causing these to go into our bodies? Whether you're a mother or a, a, a five-year-old child?

   2. SSDr. Shanna Swan43:26

      Food I would say is the primary, is number one, um, 'cause there's so many opportunities, and we can talk about what those are. Um, (clears throat) there are also, um, the chemicals we put on our body, like skincare products, makeup, because they're absorbed. So when, when you, when you use a chemical, it will influence you to the extent that it enters you. If it doesn't enter you, you don't worry about it, right? You have to think about-

   3. CWChris Williamson43:57

      It's still e- it's, it's over... it's over the other side of the room still.

   4. SSDr. Shanna Swan44:00

      Right, right. They're not gonna hurt you. Um, but... unless it's in your air duct or something (laughs) but f- so the, the three ways you get the stuff in your body is, you eat it or drink it, that's ingestion, you breathe it, respiration, or it's dermally exposed through your skin. And it turns out that several of these chemicals are designed to increase absorption. They're put into products, phthalates particularly are put into products, so they'll go into your skin. That's what, quarter of your body.

   5. CWChris Williamson44:28

      Wow, so the thing, the, the, the thing we don't want in us makes stuff that we do want in us more likely to carry the thing we don't want in us into us.

   6. SSDr. Shanna Swan44:36

      Exactly, (laughs) into us. Right, right, right. (laughs)

   7. CWChris Williamson44:38

      Right. Fantastic. All right, um, when it comes to, when it comes to foods, uh, what do you mean when you say foods? Is it the content of foods? Is it the packaging of foods? How so? How can we avoid it?

   8. SSDr. Shanna Swan44:48

      All of... all of the above. So, um, the, um... go back to the, the growth of the, of the, of the food. So (clears throat) there's the question of organic and inorganic, which is another thing we can talk about. But I just wanna add that some chemicals are added, like phthalates, to increase the absorption of the pesticide into the plant, so even, you know, y- the pesticide will be harmful on its own and it will also be harmful because phthalates are entering that lettuce or that s- asparagus and, and... because they're put in deliberately to increase absorption. So- so in the growth process, you have the concern about endocrine disruption, and then in the packaging, from the farm to the factory to the grocery store to your house, all along the way you have the option of introducing these chemicals. Um, l- milk is a great example. So a- and I went... I was at a farmer's market, I talked to the farmer and he's very proud of his milk. He said, "I'm... this is organic, uh, our, you know, er, food for the cows i- is organic," and so on and so forth. And I said, "Great, and how do you milk them?" You see it, right? I can see you're smiling (laughs) . You g- you got it. (clears throat) So m- milk that's hand-milked has no phthalates and other chemicals in it, if the far- if the farm was organic. Milk that's collected through a milking machine which has lots of tubes, you've seen those pictures of the milking machines with all the tubes, those are conveying the phthalate that's in the tubing, which is put there to make that tubing soft. And it turns out that the chemical is not bound to the matrix that it's in. It's very easy to come out of the matrix and enter, particularly if the... if it's a warm product. So the milk is warm, the phthalate goes into the milk, it goes into the (laughs) bucket, it goes into the bottle, it goes into us.

   9. CWChris Williamson46:54

      Fantastic.

   10. SSDr. Shanna Swan46:54

       And you can think of this for lots and lots of food, making spaghetti sauce and making... any product that's gonna be processed is going to go through some contact with some plastic. There's... it's unavoidable. So it, it's, it's in the growing, it's in the shipping because the shipping containers contain plastic, it's in the processing, and then there's concern of how we store it in our f- fridge and how we heat it. And, uh, I'm sure you've heard, you never should microwave in plastic, right? I mean, no, no, no, that is like the biggest no. And, and, um, yeah. So I, I actually w- want to do a little study called Farm to Fork where you take this little tomato or this, you know, bottle of milk at the farm and just track it and see what the s- levels are of these chemicals all along the way. But no one's given me the money to do that. (laughs)

   11. CWChris Williamson47:53

       Presum- p- uh, maybe, maybe someone will after this. Presumably as well, um, the increasing shelf life that we have of produce, uh, gives them more time to be wrapped in, uh, plastic to sit on a shelf, to accumulate in that wha- wha- whatever preservative. Or maybe something's been pasteurized, and because it's been pasteurized, it's able to sit without accumulating bacteria and going off. All of this is just more opportunity for these endocrine disrupting chemicals to just leak into the food and then for us to absorb them into our body. Um,

9. 48:28 – 57:15

   Lifestyle Changes to Avoid Toxicity

   1. CWChris Williamson48:28

      just to kind of round out that from a lifestyle perspective, what are the principles that you try to follow yourself or what are the biggest movers people can do to try and avoid, uh, this stuff? Presumably eating organic, trying to get the... I mean, is there someone that wraps their tomatoes in a paper bag? Like, what, what, what are the... what are the things people can do beyond, "Do not microwave your food in plastic?"

   2. SSDr. Shanna Swan48:52

      You could. Yeah.

   3. CWChris Williamson48:52

      This podcast should be called Do Not Microwave Your Food in Plastic. Beyond that, what are the other lifestyle changes and things people can do, either when shopping, storing, et cetera, to, to maximize this?

   4. SSDr. Shanna Swan49:02

      Yeah. So I've- I've had some ex- experience going around the supermarket with people who are concerned, and- and actually we filmed that and that's another story. But- but, um, it's- it's really interesting to- to do that and pay close attention to, you know, how things... how much plastic there is in our supermarket and how unavoidable it is. It's not completely unavoidable. If you go to the vegetable area, the produce area, you can see, in some supermarkets, packaged lettuces and in some su- you know, some places, just open heads of lettuce. And it's so refreshing to see that and- and, um, I did a little experiment with some friends I was going round with and I said, "Oh, let's weigh these." And it turned out that the unpackaged ones actually were a lot cheaper than the packaged ones. That's a little aside, but- (laughs) but they're also, um, you know... And that's true of- of fish that's already been fileted or meat that's already been, you know, cut up or whatever. There- there's always gonna be more exposure and more cost. So it's really to people's advantage not to... you know, to get as simply as possible. And my ideal is, if you have a farmer's market near you, which not everyone has the good fortune to have, you go to that farmer's market and you buy it in the simplest, most primitive form possible. Out of the ground if possible. Take it home, wash it and then don't put it in plastic. There are other kinds of bags you can buy. You can buy beeswax bags, you can buy... I- that- this area's kind of under-served, I would say, by (clears throat) industry, but I think it's growing, there's getting more and more options. There are bags that are safer, yeah.

   5. CWChris Williamson50:56

      From my perspective, one of the biggest changes I made, uh, less long ago than I would like to have known, but as soon as I kind of found out, um, there's a number... Pyrex do quite a few of glass, uh, Tupperware containers.

   6. SSDr. Shanna Swan51:10

      Absolutely.

   7. CWChris Williamson51:10

      Now, I'm yet to f- I'm yet to find one that has a glass lid. Uh, most of them t- tend to have plastic lid, plastic seals, but I'm going to guess-

   8. SSDr. Shanna Swan51:20

      Or some of them don't.

   9. CWChris Williamson51:20

      Yeah. I'm gonna guess that the food is- that the food is actually touching the glass part, which is the bottom- the main bottom bit. You can go on Amazon and get these. Uh, typically I think you want to get a two liter or above. One liter sounds like a ton of food, but when you actually look at the size of a piece of Tupperware that's only a liter, it's not actually that big. So go two liters or above. And, you know, just replace y- right now, get rid of the Tupperware, get rid of whatever you- you're doing and Pyrex or s- some other company will make some really great glass bowl. I'm gonna guess you're okay with glass? Glass is all right?

   10. SSDr. Shanna Swan51:50

       Absolutely, the best.

   11. CWChris Williamson51:52

       Okay.

   12. SSDr. Shanna Swan51:53

       I love them, yeah.

   13. CWChris Williamson51:54

       Are there any types of plastic that are worse or better for us? Let say that somebody can't avoid, uh, e- either due to they don't have a farmer's market near them, uh, they are, uh, battling against budget restrictions or- or- or whatever it might be. Um, is there something that we can look for when we're looking at the- the plastics of the foods and- and the drinks and stuff? Is there better and worse and how do we work that out?

   14. SSDr. Shanna Swan52:18

       So, um, silicon products are- resemble plastic and they are safer. They are not... I understand from my packaging p- friends, they are not ideal but they're certainly better than... They are not gonna contain phthalates, they're not gonna contain the bisphenols. We didn't talk much about bisphenols, but the bisphenols, BPA, BPF, BPFS, BPFS, there's now more and more of them, because, by the way, when people said, "Oh, I don't want BPA," then the manufacturer said, "Okay. We're taking it out, but we're not gonna tell you that we've put in BPF and BPFS," which do the same thing, by the way. Um, so that's- that's how... (laughs) that's- that's been going on for quite a while, um, this thing we call Whac-A-Mole, which is, you know, just swapping out, you know, things people don't want with things that are just as bad, but have a different name.

   15. CWChris Williamson53:12

       They don't know about.

   16. SSDr. Shanna Swan53:13

       Yeah, they don't yet know about them. So anyway, um, yeah, if you can... Uh, silicon is- is preferable. Glass, like I said, is perfect. Um, so, uh, china. You know, any- anything that's, um, you know, pottery, uh, i- not lead (laughs) no. Pottery without lead. Um, and I- I buy a lot of things in glass and then I wash out the jars and I just save them. And I have couple of drawers full of glass jars and I just use those, uh, to the extent that I can.

   17. CWChris Williamson53:46

       I've- I've heard you talking- I've heard you talking before about the number in the triangle on-

   18. SSDr. Shanna Swan53:51

       Yeah.

   19. CWChris Williamson53:52

       ... the- the recycling thing. What- what is that?

   20. SSDr. Shanna Swan53:56

       I think that's a moving target, Chris. I don't actually, um, ascribe to that anymore myself. I don't. Um, I- I believe that recycling is, um, not gonna solve the problem for us and- and w- the purpose of those numbers is to get you to recycle, to buy recyclable and- and- and, you know, to increase recycling. But the problem is that, um, if you have a chemical that's harmful to start with, and when you recycle it, it's still harmful. So I'm not- I'm not s- I... You know, I'm- I'm- I've- I've moved my emphasis from recycling to trying to get these things out at- to- at the beginning, you know?

   21. CWChris Williamson54:44

       Okay.

   22. SSDr. Shanna Swan54:44

       So that we don't have to keep exposing ourselves, yeah.

   23. CWChris Williamson54:47

       All right. So, uh, tin. I'm just thinking about some of the other places that people might consume stuff from. Presumably, uh, plastic bottles of water, not good? Much better to get bottled water- bottled water from glass.

   24. SSDr. Shanna Swan55:02

       Not good.

   25. CWChris Williamson55:02

       Uh, what about those, you know, the very large cooler, like water cooler in the office type things? I'm... Is that the same?

   26. SSDr. Shanna Swan55:09

       Many of them are plastic.

   27. CWChris Williamson55:11

       Right. Yeah, uh, y- but any plastic. So there's basically, there's- if it's plastic, assume that it's bad.

   28. SSDr. Shanna Swan55:17

       Right. That would be my assumption.

   29. CWChris Williamson55:18

       Right, okay.

   30. SSDr. Shanna Swan55:19

       Until proven other wise.
10. 57:15 – 1:00:19

    Effectiveness of Reverse Osmosis Filters

    1. CWChris Williamson57:15

       my, uh, you can tell me whether or not my solution actually works for this. For years, for over a decade, uh, I would only drink water from a, a Brita filter. You know, like a classic desktop-style filter. I then kind of got red-pilled about that doesn't, it may get rid of something, but it's not getting rid of really any of the things you want it to get rid of. I'm now using a four-stage reverse osmosis filtration system. In your experience, if it's of high quality, how good is that at getting rid of what we need to?

    2. SSDr. Shanna Swan57:44

       Yeah. I would say, I would look at what it's made of, what its, uh, the components are made of, and where is there plastic in that device. Um, because obviously you'd prefer not to pass the water through plastic. Um, I want to mention an alternative, which is what I happen to use, which is a desktop or a tabletop distiller. So we actually distill the, our water. It's very simple. It's free. (laughs) You don't have to change any filters. You don't have to, you know, you just put the water, it boils it, and steam, you know, the steam comes up, and then it condenses, and it comes down into a glass container, and that's it. So there are alternatives. RO is good. Distillation is good. Filtration is complicated, um, in part because of the filters, w- what's in the filters, and you have to change them, and you have to pay for them. So...

    3. CWChris Williamson58:37

       Yup.

    4. SSDr. Shanna Swan58:38

       Yeah. Yeah.

    5. CWChris Williamson58:39

       Yeah, there's two, th- the brand that I use is, uh, Aqua Tru. Um, they're great. I do need to look at what pipes are internal to the system, uh, but I certainly know that the, the carafe that it fills at the front is glass.

    6. SSDr. Shanna Swan58:52

       Mm-hmm.

    7. CWChris Williamson58:53

       Um, and my solution is I have, this is a steel, steel shaker, and I just fill like five of those, and they live in the fridge of the door. So I always have...

    8. SSDr. Shanna Swan59:05

       Mm-hmm.

    9. CWChris Williamson59:05

       ... water going from, uh, four-stage. The other big one that I think, uh, sometimes is sold out, sometimes isn't, called a Berkey.

    10. SSDr. Shanna Swan59:11

        Mm-hmm.

    11. CWChris Williamson59:12

        So this is a, a charcoal filter, like a multi-level charcoal filter thing, uh, and the whole thing is made of steel. Um, so...

    12. SSDr. Shanna Swan59:20

        Wow, yeah.

    13. CWChris Williamson59:20

        Uh, so in terms of, in terms of plastic, I think it's made of steel. I really hope that the spout at the front isn't a plastic spout, um, but I can't remember, and I don't own one, but I'll, I'll, I'll ask-

    14. SSDr. Shanna Swan59:31

        Yeah.

    15. CWChris Williamson59:31

        ... my friends about that, but a bunch of my friends-

    16. SSDr. Shanna Swan59:32

        Yeah.

    17. CWChris Williamson59:32

        ... have got those. So those are the two that I know, at least from, uh, my experience and what my friends are talking about, Berkey and, uh, uh, Aqua Tru. Those are the two, um, for water. And thinking about, you know, everyone's thinking about, "How can I get more, uh, hydration? I, I know that water is really important for me, and I need to stay hydrated." But you know, there is a world in which you increase your hydration at the cost of increasing the amount of phthalates and microplastics and BPA and stuff that you're, um, uh, that you're being exposed to. One of my friends lives in Dubai, and I went into his fridge, and he's a health-conscious dude, and it was just bottles and bottles and bottles of Evian. You think, "It's high-quality water held in plastic bottles." So I'm like...

    18. SSDr. Shanna Swan1:00:12

        Right.

    19. CWChris Williamson1:00:12

        ... "Dude, I, I want, I really wanna..." I was gonna buy him one of those things, but I don't think that they ship there, so. Um, okay, uh, one thing,

11. 1:00:19 – 1:10:35

    How Bad Chemicals Impact Behaviour

    1. CWChris Williamson1:00:19

       one of the most interesting things that I learned from you is these chemicals impact behavior, so the way that children play, the, the, the way that they, uh, boys and girls learn to speak, and stuff like that. Can you explain what the effects are there?

    2. SSDr. Shanna Swan1:00:34

       Sure. Um, so just as the genitals need hormones to develop and to differentiate between males and females, they're different, that's is- also true of the brain. And, um, this is kind of a controversial topic in some political circles, that people don't like to say that the brain is sexually dimorphic, but th- it's, there's no question. You can see it on everyone's body.

    3. CWChris Williamson1:00:59

       This is a, this is a safe space for you here, Shanna.

    4. SSDr. Shanna Swan1:01:03

       Yeah, right. (laughs)

    5. CWChris Williamson1:01:05

       This is a, you know...

    6. SSDr. Shanna Swan1:01:05

       Um, and, um, so the changes, uh, in the brain are influenced by testosterone, just as the genitals are.... and not quite the same time. It's later in pre- it's also in pregnancy, but it's later in pregnancy. Okay? So, um, there's a lot of things you can see on MRIs, by the way, you know, we can see those differences between males and females in different parts of the brain. Um, I think you're referring... By the way, I th- you've read my book, right? Countdown? Is that how you know? Yes. So I wanna put in a plug for Countdown, maybe you can... (laughs)

    7. CWChris Williamson1:01:45

       Of course.

    8. SSDr. Shanna Swan1:01:45

       But, um, yes. Um, in Countdown, this is one of the things we discuss, but it's not the main focus 'cause the book is largely focused on reproductive function. But I have a, a colleague, had a colleague, um, who said, "Shauna, the brain is the biggest sex organ in the body," and, um, it's true that the brain is influenced by hor- sex hormones just as the genitals are. So, um, if you're going to mess with the estro- estrogen and testosterone, you're gonna mess with the, with the brain. And specific things that we looked at was language development and... So, yeah. So how do males and females differ? Well, one way they differ is that... And this is gonna sound very... You know, there'll be people that won't like this, again, politically, but females have better earlier language development, and they l- they know... If you have a child, you know, (laughs) you- you see, you know, how quickly they acquire words and, and, and, uh, and, um, and m- men on the other hand have better spatial ability. That's the joke about the, you know, a woman will never ask, (laughs) will never find her way out of a bo- you know, out of a box, um, I'm like that, I always lose my way, but, um, men are much better spatially. So, um, so we, we found in our study, we asked four-year-olds, um, the mothers of four-year-olds how many words the child knew or could understand. We did it in our study and also i- with a colleague in Sweden, and we found that the phthalate levels were related to the number of words the child knew or understood at age four, that, particularly in females. It wasn't much i- in males, but in females, it was pretty marked. Um, the other study that you're referring to, I think, is the play behavior, and this is even more controversial because, um, it's based on the assumption that the behavior of children in play and in their daily activities is sexually dimorphic, and that, um, you can ask a mother, "How often does your child play with guns or play with cars or play with tea sets or play dress up or play with dolls?" Well, first of all, they did this with monkeys, and they showed that the monkeys made the same choices as, as human children, that a male monkey will go for the car and vroom, vroom, vroom, vroom with the car, and the female monkey won't. And it turns out in, in our study, when we asked the mother about the play behavior of the child and ranked their answers as male and female, the sh- the male typical behavior was less male typical in men, boys who were exposed to phthalates. So that's... For what that is, it's, it's a suggestion, I would say, that exposure to these chemicals in pregnancy, during pregnancy, 'cause it all happens in pregnancy, um, are going to affect the masculinization of the brain.

    9. CWChris Williamson1:05:12

       Could this change gender identity?

    10. SSDr. Shanna Swan1:05:16

        Oh, I knew you were gonna ask that. (laughs) That's the $64,000 question, isn't it? Yeah. Um, so there's some indication that it could, but I wouldn't say we know at all the answer to that question. But here's two things. Um, y- if you look at... So I have to tell you about twins. Okay. So if you have... I'll start with rats. They're not twins. There's, like, 10 of them in the uterus or something like that. So the, the rat gets... If it's a male rat between two females, he's slightly less masculinized at birth, and that's true of his AGD too, by the way, and the female between two males is somewhat masculinized. Okay? So what that's mean-

    11. CWChris Williamson1:06:11

        So it's like a, a, a u- u- uterus environment that, that, where they're bleeding between each other. Right. Okay, yeah.

    12. SSDr. Shanna Swan1:06:18

        Exactly. And that's called the, the, um, in utero position effect, and it's been known for a long time. What about humans? Um, well, it turns out that when, uh... If you... This study looked at twins in Finland and found that, um, f- female-female twins were more likely to get married and have more children than male-female twins. So they were s- maybe a little less feminized if they had a male co-twin. Okay, now I'm gonna turn to your question. It turns out that if you look at twins, and this is a very nice and m- m- pretty recent study, you look at twins, the twins that have a partner, co-twin of the opposite sex, are more likely to be gender dysphoric.So they're getting an influence, they're getting some influence from their co-twin, so.

    13. CWChris Williamson1:07:26

        How... Has this been done with adoptive twins in, like, a Plomin-esque style? How do you know that this isn't just sisters growing up with brothers, brothers imprinting behaviorally, uh, social roles theory type stuff, social learning theory?

    14. SSDr. Shanna Swan1:07:40

        I... Not from that study, but the, um, the brains, you can look in, in MRI at the brains of the male and female, and you see, um, that reflect there. I don't have that-

    15. CWChris Williamson1:07:57

        So less female typical-

    16. SSDr. Shanna Swan1:07:59

        Yeah. Oh. Right.

    17. CWChris Williamson1:07:59

        ... brain development in the female that has the... Right. Yeah. Understood. Und- there's a, a really gr- I, I brought this up a couple of weeks ago on a podcast. There's a really great, um, bit of data around MRI scans of 10-year-old, uh, boys and girls, and the computer can predict with 90% accuracy whether it's a male or a female just based on the brain scan. But that's almost the same (laughs) uh, level of accuracy that humans have when looking at the face of another human. So if you cut my face out and showed it to someone, it you'd... It's around about 90. It's a tiny little bit higher. Uh, so your ability to, "I know what a man or a woman is," well, so does the MRI machine, and it's around about as accurate as you are. But even in utero, you know, I, I, I've been over this. David Putz, who did a phenomenal, uh, bunch of s- uh, uh, work on this, David Geary as well who did a ton of great stuff on this, in utero brain scans of developing, uh, fetuses, they show sex differences, I think, three months old.

    18. SSDr. Shanna Swan1:09:00

        Yeah.

    19. CWChris Williamson1:09:00

        Three months, four months, five months old. You can start to see-

    20. SSDr. Shanna Swan1:09:03

        Yeah.

    21. CWChris Williamson1:09:03

        I, that's... You know, you're a minus six month-year-old. I, I, there, there, this isn't anything to do with socialization-

    22. SSDr. Shanna Swan1:09:13

        No. No.

    23. CWChris Williamson1:09:13

        Um. It-

    24. SSDr. Shanna Swan1:09:13

        That-

    25. CWChris Williamson1:09:13

        It's-

    26. SSDr. Shanna Swan1:09:13

        That, that, that's because, Chris, the, the time in your life that your cells are most rapidly dividing and forming organs is then. It's all happening then, you know-

    27. CWChris Williamson1:09:29

        Yeah.

    28. SSDr. Shanna Swan1:09:30

        ... in utero. But, uh, I mean, it, it, it changes, you know, like genitals are very early and brain is later, but it's, that's, that's the sensitive period. You asked me before about sensitive periods, and I wanna just mention (clears throat) some other. Um, so there's the in utero period, of course. We've talked about that a lot. There's a period right after birth called the mini-puberty, and it's the first six months of life. And there's been some work showing that that period is very sensitive to environmental insults as well. And then there's puberty, which is another period. W- you wanna look for the periods of rapid cell division. That's, that's-

    29. CWChris Williamson1:10:09

        Yeah. Yep. Yep. Yep.

    30. SSDr. Shanna Swan1:10:10

        ... when you'll be... Yeah. So, so puberty, um, and then for women in pregnancy, themselves when they're pregnant, and then for, uh, menopause. There's a lot of changes in menopause, so-
12. 1:10:35 – 1:13:28

    Men & Women’s Reproductive Success As They Age

    1. CWChris Williamson1:10:35

       what is happening to the relationship between female and male age and reproductive success or fertility in the modern world?

    2. SSDr. Shanna Swan1:10:50

       I... It's very hard to say because so much of it is choice now. Um, right? Um, so, uh, women, couples are postponing having children, and so they're... The, the natural default is, um, that women and men's reproductive function decreases with time, but women's much more dramatically, of course, at menopause, and men just decline very, very, very slowly un- until their, their death. So, um, if you push women, particularly, into the period of lower fertility, natural fertility, they're, you're going to have an e- (laughs) fertility, you know, either through because they're going to school or because they're in the workforce or because they wanna do something else for a while. You know, that's going to... Uh, uh, so I don't know how to separate that from the biological changes, and I can't say-

    3. CWChris Williamson1:11:52

       Yeah, I-

    4. SSDr. Shanna Swan1:11:52

       Yeah. Yeah.

    5. CWChris Williamson1:11:53

       I understand. I guess, uh, maybe one of the things that you could look at would be at what age do people start using, um, fertility treatments more sooner? Uh, you know, th- there should be a, um, volume. There should just be a, a number of people, and if there are more 30-year-olds or there are more 35-year-olds going in to use IVF or, or whatever, um, that would be an interesting place to start. But again, you know-

    6. SSDr. Shanna Swan1:12:22

       Yeah. I agree.

    7. CWChris Williamson1:12:24

       ... it, it-

    8. SSDr. Shanna Swan1:12:24

       I agree.

    9. CWChris Williamson1:12:24

       ... it's kinda circumstantial.

    10. SSDr. Shanna Swan1:12:27

        I don't know. Yeah.

    11. CWChris Williamson1:12:28

        Um. What-

    12. SSDr. Shanna Swan1:12:28

        But, but I promised you something, and I wanna come back to it because we talked about fertility decline worldwide, and I told you every country was declining. And I, now I wanna tell you the exception, um, and that's Israel. And the reason is fertility includes, um, artificial, you know, assisted reproduction, births. It's just births. It doesn't say how they got there. And in Israel, uh, people are guaranteed two children by, if they need it, by artificial, you know, art- A-R-T, artificial reproductive technology. And, and their, their fertility has not declined. Um, so, you know, that's pretty dramatic, um-

    13. CWChris Williamson1:13:14

        Yeah.

    14. SSDr. Shanna Swan1:13:14

        ... every other country. Um, and, and the other thing is that the use of assisted reproductive technologies has been increasing. I, I can't give you numbers on that right now, but it definitely has been increasing.

13. 1:13:28 – 1:22:03

    Future of Fertility in Humanity

    1. CWChris Williamson1:13:28

       I have a friend who is, within the next two years, the company is already up and running, although it's dark at the moment. I have a friend who is doing, uh, embryo selection for a variety of traits. So, you can go in with your, um, harvest of ten fertilized eggs, and they can give you a polygenic risk score for externalizing behavior, for autism, uh, for IQ, for a number of other things. Obviously, it's not a perfect science, but it's pretty predictive, according to him. Uh, and that's already happening. I mean, that- that- that just straight up is happening now. Uh, I'm sure that you've learned about IVG as well, which is sort of the next stage beyond IVF, where you don't necessarily... you're not as restricted by harvest, you're not as restricted by a lot of different things. Um, how... Well, actually, bef- even before that, let's- let's forget the- the new fertility technologies coming down the pike. What do you think the future of fertility has in store for humanity kind of generally at the moment? What- what's- what's your prediction?

    2. SSDr. Shanna Swan1:14:38

       I would say the most... Uh, well, first, my first prediction is that we're going to rely on it more and more. Whatever form it is, we're going to rely on artificial reproduction more and more because of the decline in sperm count and fertility. I- I don't think there's any way around it. Um, but the technologies are rapidly, as you say, rapidly d- i- increasing. And the one that's so intriguing to me, and wondering what's gonna happen with this politically and otherwise, is the production of egg and sperm from stem cells. Have you heard about this?

    3. CWChris Williamson1:15:09

       I've... Uh, that's IVG.

    4. SSDr. Shanna Swan1:15:11

       Yeah. Okay. Right. Okay.

    5. CWChris Williamson1:15:13

       Yes. Yes.

    6. SSDr. Shanna Swan1:15:13

       I didn't know... Ha- I hadn't called it that.

    7. CWChris Williamson1:15:15

       Sorry. Yeah, that's IVF, IVF, and IV- IVG is the pluripotent stem cells. Um, y- yeah, I mean, this is some dystopian, i- if you want it to, uh, some dystopian future where you have basically a million test tube babies, artificial wombs, um, and you c- you just go to town. I'm- I'm pretty sure you do it for... you can even do it from skin cells and stuff like that.

    8. SSDr. Shanna Swan1:15:37

       Yeah. You can, yeah. Yeah. I actually-

    9. CWChris Williamson1:15:40

       When you think that a woman, a woman produces one egg per 28 days. Uh, how many trillion skin cells are there on my upper arm?

    10. SSDr. Shanna Swan1:15:49

        Yeah. Yeah. So, uh, there's obviously a lot of scary scenarios here and a lot of hopeful scenarios. And, um, politically, particularly now with the ruling of the Alabama Supreme Court, we have, uh... (laughs) You, you know what I'm talking about, right?

    11. CWChris Williamson1:16:07

        Yes.

    12. SSDr. Shanna Swan1:16:08

        Uh, it's- it's- it's going to be even more complicated. Um, and, um, I don't know where this is going. I mean, but this is, this is definitely what's happening right now. And- and part of the reason is, that it's getting increasingly difficult to people, for people to make kids the old-fashioned way. That's driving this desire for new technologies, right?

    13. CWChris Williamson1:16:33

        Well, don't- don't forget, there's a decreasing di- uh, desire for people to do the action that causes children to come about the old-fashioned way as well.

    14. SSDr. Shanna Swan1:16:42

        Yeah.

    15. CWChris Williamson1:16:42

        You know, we can go even further upstream than the difficulty of the mechanism, where just the desire is- is- is also being muted. Yeah, it's, um, it's fascinating. It's- it's... What a time to be alive, you know, to be studying this stuff. It's just endlessly, to me, this whole... Uh, it is apocalyptic, right? And I'm not, and I'm not saying that I'm glad that it's happening, but in some ways, it's so... it's just endlessly interesting to me. What, what's going on socially, environmentally, psychologically, physically, hormonally, uh, e- everything? Uh, how- how can we, uh, uh, you know, combat this challenge? I- I- I... It's a, uh, uh, a big problem. And if we don't fix it, i- it's not good. And, you know, for the people that say, "Well, there's too many people on the planet," and all the rest of it, I... Your wish is already going to happen. You're going to see population decline within, maybe even within our lifetimes. Uh, back end of the sort of 2000s, you're definitely going to see it start to dip, and then that... It could be precipitous. But here's the other thing, and this is, like, my, my super hardcore, uh, red pill, which is, for the antinatalist subcultures that really don't want humans to destroy the planet and- and- and, uh, w- w- you know, "There's too many people on here in any case," and so on and so forth, a lot of people's ideologies, especially their political affiliation, is heavily genetically predisposed. It's not predetermined, but it is predisposed. If you are someone that wants to make a change in the world, the change that you're talking about will be washed aside by other groups that have lots of children, because those children are likely to have lots of children. So, in 100 years time, maybe it's just, it's Mormons and it's, uh, the j- the, uh, Israelites, and it's, uh, like, whoever else is there. I don't kn- like, whoever's, whoever else is having a... blue zone people. Uh, and you go, "Well, that, you know, that's the culture." That's the culture that the future will inherit, because those are the only ones that have got positive birth rates.

    16. SSDr. Shanna Swan1:18:41

        Right.

    17. CWChris Williamson1:18:41

        And, um, yeah, another friend, th- he's the next level of the spicy red pill, which is, a friend said to me she thinks that this, uh, fertility bottleneck is good because it's basically culling stupid anti-human, antinatalist cultures through this genetic predisposition to ideology, and that coming out on the other side... Basically, it- it's the same argument, I think Thomas Sowell made it, about how, um, uh, the clergy is good because it screens fanaticism out of the gene pool, um, the people that are, uh, you know, super crazy. And I was like, "W- I mean, that's..." That wasn't me. That was just a, uh, a friend that'll-

    18. SSDr. Shanna Swan1:19:21

        Yeah, right.

    19. CWChris Williamson1:19:21

        ... remain nameless, but, um-

    20. SSDr. Shanna Swan1:19:23

        (laughs) Look, Chris. Chris, do you have children?

    21. CWChris Williamson1:19:26

        No, not yet, but I can't wait-

    22. SSDr. Shanna Swan1:19:28

        Oh.

    23. CWChris Williamson1:19:28

        ... to become a dad.

    24. SSDr. Shanna Swan1:19:28

        Good.So if there's other couples that can't wait to b- become parents, and their opportunity for achieving that is taken away, I believe that they have been deprived of a basic human right. I think that is a right of people to have a child if and when they want it. Not, I'm not saying anything about they should want it, but if they want it, when, you know, they should be able to. (coughs) And to the extent that products in, that plastics and products and, you know, pan liners and food containers are taking away this option, um, is, is terrible to me. It's, it's, it's, uh, it's unfair. It's unfair. And, and I, and I should add, by the way, that, that if you have money and education, you have a much better chance of avoiding losing that option, right? Because if you're poor and you're working two jobs and you don't live near a farmer's market or a grocery store that has fresh vegetables and, you know, and you don't know to go on the web and look for alternative, you know, alternative, safer alternatives, you, you can't do that. You can't take care of yourself that way. You're gonna be more likely not to have a, be able to have a child, and so it's, it's not an equal opportunity for everybody-

    25. CWChris Williamson1:21:07

        (laughs)

    26. SSDr. Shanna Swan1:21:07

        (laughs) ... to be deprived of having a child (laughs) , right?

    27. CWChris Williamson1:21:10

        Mm-hmm. Mm-hmm.

    28. SSDr. Shanna Swan1:21:10

        So there's this whole social issue here too. Yeah.

    29. CWChris Williamson1:21:14

        Yeah, there absolutely is. It's, uh, it, uh, like I say, just what a time to be alive and, and to be thinking about these problems and sort of grappling socially with what's going on. That's, um, one of the things I'm really gonna leave this conversation with is, just how much of this is downstream from reduced libido? It sounds like such a basic bitch solution and to, to all of the questions that we're asking, but if people just wanna have less sex, all of the things that occur after that, the, the desire for relationships, the desire to get out of the house, the desire to leave the house, to leave the screen behind 'cause I'm just, I just, well, I gotta find someone. Uh, yeah, it's, it's amazing. Look, uh, uh, your work is, is, is really fascinating, and it's the, uh, synthesis of a lot of different pet interests that I've got. Where

14. 1:22:03 – 1:23:16

    Where to Find Shanna

    1. CWChris Williamson1:22:03

       should people go? They wanna find out more, the, the book, the, wh- where should they go to check out-

    2. SSDr. Shanna Swan1:22:07

       Yeah.

    3. CWChris Williamson1:22:07

       ... more of the stuff that you do?

    4. SSDr. Shanna Swan1:22:08

       So you can go to shannaswan.com, and you can see, you know, lots of things I've said. (laughs) And then you can go to Amazon or some other dealer, book dealer, and order Countdown. Um, by the way, it's important that you put in two words, "Countdown," because countdown, one word, is something else, (laughs) another book. So Countdown, um, yeah, that's, that's w- what I recommend. And, um, if this stuff bothers you, this bombardment of our lives by these chemicals, um, I suggest you go to Environmental Health Sciences and see what you can do about it. That's a group I work with, and I think they're doing wonderful work to help turn this around.

    5. CWChris Williamson1:23:01

       Hell yeah. Dr. Shanna Swan, ladies and gentlemen. Shanna, I really appreciate you.

    6. SSDr. Shanna Swan1:23:05

       Thank you, Chris. I had a lot of fun. (upbeat music)

    7. CWChris Williamson1:23:07

       Thank you very much for tuning in. If you enjoyed that episode, there is something else you will absolutely love right here. Go on, give it a tap.

Episode duration: 1:23:16