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- [00:02]
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- [00:33]
Mike Carruthers
Today. On Something you should know when you get interviewed for a job can have a big impact on if you get the job, then how did you turn out the way you did? Was it because of your parents? Your environment? Your siblings?
- [00:48]
Susan Dominus
The way I often talk about it is parenting effects are probably overestimated by the general population and sibling effects are probably underestimated because there's just shockingly little research about how siblings affect each other.
- [01:01]
Mike Carruthers
Also, why trying to appear younger than you are usually fails and how your DNA works and the amazing advances in that field.
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Lawrence Hurst
So when the human genome was first sequenced, all that DNA it cost $3 billion. It took about 15 years. We can now do exactly the same for around a hundred dollars. And it takes an afternoon. This is a revolution in medicine.
- [01:26]
Mike Carruthers
All this today on something you should know. I am hardly what you would call a trendy clothes shopper. I know what I like. I buy things that last and that I will wear for a long time. And so now I shop almost exclusively@quince.com and I've come to discover that a lot of people, men and women, shop there too because they have quality, well made clothes for summer that you are going to love. Like organic cotton silk polos. I've got a couple of those European linen beach shorts, comfortable pants that work for everything from backyard parties to nice summer dinners out. Here's the best part about quints. Everything with quince is half the cost of similar brands and how they do that is they work directly with top artisans. They cut out the middlemen so you get luxury clothes without the big markups. And Quince only works with factories that use safe, ethical and responsible manufacturing practices with premium fabrics and finishes. Quince is all about really great clothes at a very reasonable price. If you saw my closet, what you would see are the quince clothes hanging right in the center and my other clothes, they keep getting pushed to the sides and the same thing will happen to your closet. Oh, and you're going to love their website. Stick to the staples that last with elevated essentials from quints go to quince.comsysk for free shipping on your order and 365 day returns. That's quince.comsysk to get free shipping and 365 day returns. Quince.comsysk something you should Know Fascinating intel, the world's top experts and practical advice you can use in your life today. Something you Should Know with Mike Carruthers if you're looking for a job or the next time you are looking for a job, I have some information that you might find very useful. Hi and welcome to this episode of Something YOU should Know. When a company is interviewing people for a job on any given day, the fourth person interviewed that day is more likely to get the job. Researchers from Old Dominion University in Virginia analyzed more than 630 minute job interviews at a university career center. They found that the fourth person being interviewed got the most attention from hiring managers. While it's become popular belief that employers often make snap judgments about a potential candidate within the first few seconds of the interview, this study found that decision makers take closer to 5 minutes for the first interviewee and reaches closer to 8 minutes by the fourth applicant after this. However, the time hiring managers take to reach a decision begins to decrease with each additional interview. And that is something you should know. Have you ever sat back and thought to yourself, how did I turn out the way I did? Or how did my kids turn out the way they did? Often people lean on the idea that you turn out the way you do because of how you were parented or or because of the family you grew up in. And then you hear things about birth order that you are more likely to be a certain way if you're the oldest or if you're the youngest or if you're somewhere in the middle? What about all of this and what about that idea, and we've all noticed this, that multiple kids grow up in the same house with the same parents, yet they all turn out so differently. Well, Susan Dominus has looked at the research on this and uncovered a lot of really interesting findings. Susan is a writer who has been with the New York Times for several years, and she is author of a book called the Family A Journey into the Mystery of Sibling Success. Hey Susan. Hi. Welcome to Something youg Should Know.
- [05:42]
Susan Dominus
Thank you so much, Mike. It's a pleasure to be here.
- [05:45]
Mike Carruthers
So what about all these theories about how people turn out the way they do, how kids turn out the way they do? You know, you'll often hear people say, well, oh, that's because he's the oldest, or oh, he's a middle child. So that's why that happens.
- [06:00]
Susan Dominus
There are a lot of misconceptions about why kids turn out the way that they do. And some of that are. Some of those misconceptions are about parenting effects. Some of those are about birth order effects. Families are really messy and complicated things. And it's almost a mythology or an astrology that we impose on our own families to explain why things happen the way that they do when there are many other factors involved that people, I think, underestimate.
- [06:27]
Mike Carruthers
Well, so we hear things like, for example, you know, firstborns are likely to do this and younger siblings are likely to do that. And is that science or is that just not?
- [06:41]
Susan Dominus
Yeah, so it's true. You often hear people saying things like as if it was just a given fact. They'll say, oh, well, she's, you know, the spoiled one because she's the youngest, or she is the most conscientious because she's an oldest sibling. What turns out to be true is, is probably not that. The best research that has been done on birth order, the biggest studies, the best constructed studies, basically find surprisingly little correlation or no correlation between birth order and personality. So, for example, we tend to think of the oldest child as being the most conscientious in the family. What we underestimate is the role of developmental psychology and why it feels that way. So let's say there's a 17 year old in the family. That 17 year old may well be the most conscientious person in the family, but the 14 year old little sister, when she gets to be 17 years old, might even be more conscientious than the 17 year old. When you're older, you're going to be more responsible. It's just a kind of developmental quality. So the other thing is that the person who's the most conscientious in their own family might not even be that conscientious relative to the general population.
- [07:53]
Mike Carruthers
So does birth order determine anything or is that just one of those pop psychology things that seems like birth order should matter and it doesn't? Or does it tell us anything?
- [08:05]
Susan Dominus
There's one finding about birth order that is remarkably consistent. The oldest child in a family tends to have a cognitive edge. This is on average, you know, I am the youngest of three, so I need to point out that this is on average and these effects are not huge, but it's really consistent. And the reasons for that are pretty interesting and maybe even a little bit intuitive.
- [08:29]
Mike Carruthers
And when you say they have a cognitive advantage, you mean what that they're smarter or that they do better in school or academically has a little bit.
- [08:38]
Susan Dominus
Of an academic advantage.
- [08:40]
Mike Carruthers
Okay, so go ahead with, tell me about the cognitive edge that an oldest child has.
- [08:46]
Susan Dominus
The first child is the only child in a family of siblings, whoever gets to be the sole focus of their parents attention, and they get that sole focus at a time that's really developmentally crucial. So they're getting all of the enrichment, all of the attention, all of the eye contact at a time when their synapses are firing like crazy and forming like crazy. And so, you know, parents might love all their children equally, but the second child is always going to have less of their parents attention than the older child did during that time when that child was an only child. So that's one reason why researchers think that oldest children have this cognitive edge. And by the way, they see this cognitive edge even when that child is only a year old. They do better on tests that, you know, they give to babies than their younger siblings do when they reach the age of one. So it's really remarkable. And it starts really early. However, it increases over time, this gap. And the thinking is that when kids get older, older siblings do a lot of instructing of younger siblings, and that there's something that is consolidating of knowledge or is instructive or salient and healthy somehow for cognition in just doing a little bit of that teaching.
- [10:05]
Mike Carruthers
So when we talk about, as we started talking about how a kid turns out, how a person becomes who they are, what can you attribute to that? What does affect how a kid turns out?
- [10:20]
Susan Dominus
When researchers look at twins, let's say they look at fraternal twins and they try to figure out, okay, well, how much does having a shared environment, being raised in the same home make them more similar than two people who are raised in different homes? The answer generally is not that much. And as a mother of fraternal twins, I can speak to that. My fraternal twins came out incredibly different. They remained incredibly different. What does matter about being raised in the same home is whether or not you're going to go to college. That's something that kids raised in the family, the same family, tend to have in common. And that's hugely consequential for your income. And your income affects so much of who you're likely to be and how you're, you know, how you're likely to fare. But in terms of whether you're going to be equally conscientious, whether your kids are going to be equally creative, you know, Parents can expose their kids to those things, but whatever they do in the household seems to have much less of effect of an effect than, than parents really imagine.
- [11:21]
Mike Carruthers
Well, what about things like morality? I mean, that is something that seems to get passed from parent to child. The values you grow up with seem to stick.
- [11:32]
Susan Dominus
Yeah, I think that value certainly can be passed down from parents. I think that what's a little harder to measure are things like personality traits, like how much does parenting make somebody outgoing or introverted? Can parents. These are the kinds of things that we associate, for example, with success. Right. Like conscientiousness. Can parents, quote unquote, make their kids more conscientious? It's unclear and many researchers would say probably not. You know, that's not to say that kids come into the world and how conscientious they're going to be is 100% determined by like their genetics. No, how, how you're going to be, you know, how you're going to turn out is a combination of the sort of genetic nudges that you get from the get go and the environmental effects that are part of your life. Now when we talk about nature and nurture, we think about nature, genetics and nurture, parenting, but really it's genes and environment that we're talking about. And parenting is just a small part of the whole picture of the environment. The environment is the school you go to, it's the neighborhood that you grow up in. It's the, the, you know, who's your best friend? It's what nature documentary did you watch when you were in fourth grade? It's, did you break your leg when you were in second grade? Was your bedroom sunnier than your brother's? The environment is vast. It involves huge amounts of chance. And it's sort of like you come into the world a certain way, you ex. You interact with the environment and all of the random haphazard things that happen to you, that changes you a little bit. Now there's a new version of you interacting with every other random element that you come across. Parenting is part of that for sure. It's just a smaller part of it than most people appreciate.
- [13:23]
Mike Carruthers
What about major traumatic events that happen to a child? Do those have a disproportionately large influence on a child's development?
- [13:34]
Susan Dominus
So there's something known as an adverse childhood event. You know, those are things like abuse or exposure to violence at a very young age or trauma. And we do know that that actually does really change the br. So if you want to talk about parenting Effects, it's probably most profound at the extremes. So like, you know, sort of what people call good enough parenting, you know, parenting that's basically healthy and sane, that's not going to have a huge impact one way or the other on whether your kid is super conscientious or not. If parents are abusive, they can really do serious damage to their children and then they can really affect their children's lives at the other end. I'm not saying that the opposite of abusive is overly involved with your kids extracurriculars, but if you look at somebody like a Richard Williams, right, Like Richard Williams, the father of Serena and Venus Williams is kind of the other end of the extreme. Like, it's not that he's the world's best parent, but in terms of, you know, getting achievement out of his kids. He was a very unusual parent. He devoted his entire life to making tennis stars out of them. They were very talented to begin with, and if they hadn't been, he wouldn't have been able to do what he did. But most kids, there are probably tons of other young women out there who have the talent that Venus and Serena had. But their parents weren't like these extremes. Their parents weren't willing to chuck everything and devote their lives to tennis round the clock.
- [14:58]
Mike Carruthers
Well, I bet a lot of parents who just heard you say about what you said about good enough parenting is like a big relief, you know, it's like, oh God, thank God, you know, because you always think you could have done better and. But you're saying that that's not having as big an influence on your kid as you think it is.
- [15:18]
Susan Dominus
I think if there's one takeaway, it's that you are not having, as most parents are not having, as big of an influence as they think they are. You know, we agonize over these decisions. Should we have a chore chart? Should we co sleep? You know, should we let them cry it out? Should we be strict? And you know, it's at the end of the day, like it's just, it's not as make or break as we think it is. Now what does matter, I would argue, is how your kid feels in the day to day moment in your home. You know, do they feel that you care about them? Do they feel that you are setting appropriate limits? Do they feel safe? Do they feel that you're consistent? You know, so it's not that like the parenting decisions that you make are inconsequential for your child's life. Of course they are. It's just that you don't have to feel responsible for whether your kid is valedictorian or not. I would say relieve yourself of little bit of that pressure.
- [16:13]
Mike Carruthers
We're talking about how kids, how people turn out the way they do. Susan Dominus is my guest. She's author of the book the Family Dynamic A Journey into the Mystery of Sibling Success.
- [16:27]
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- [16:59]
Mike Carruthers
We have a new sponsor and I'm really glad the timing is critical. Rocket Money I use Rocket Money because, well, look, everything's getting expensive and well, you know, as I do that, a lot of money, I mean, you're not really sure where it went, but it's gone now. And this is what's so great about Rocket Money. Rocket Money is a personal finance app that helps find and cancel your unwanted subscriptions. It monitors your spending and it helps you lower your bills so you can grow your savings. And you might say, well, how can they lower my bills? Well, when I first signed up, Rocket Money sent me this notification that they, not me, they could see if they could get me a better deal on car insurance. And for the bills you have, will they automatically scan your bills to find opportunities to save? Then you can ask them to go negotiate for you. They'll deal with customer service so you don't have to. If there's a subscription you don't want anymore, they'll cancel it so you don't have to. That's worth it right there for me because I hate dealing with customer service. Rocket Money has over 5 million users and has saved a total of $500 million in canceled subscriptions, saving members up to $740 a year when they use all of the app's premium features. Cancel your unwanted subscriptions and reach your financial goals faster with Rocket Money. Go to RocketMoney.com something today. That's RocketMoney.com something RocketMoney.com something so, Susan, I'm curious about the effect siblings have on each other, and I'm sure it depends a lot on how close they are. And a lot of siblings are far apart in age or don't get along well, so maybe they don't have. So there's probably a lot of variability. But I'm. I'm curious because I suspect siblings can have quite an impact.
- [19:00]
Susan Dominus
The way I often talk about it is to say that parenting effects are probably overestimated by the general population because we think it's the be all and end all. And sibling effects are probably underestimated because there's just really not that much. There's just shockingly little research about how siblings affect each other in general. Now, part of that is that siblings are hard to study. There's half siblings, there's step siblings, there's different age gaps among them. There's different gender configurations. So it has been very challenging to study it effectively. But researchers are starting to find interesting ways to figure out, you know, how much do siblings affect each other and how much is just, you know, to the extent that they are similar, how much of that is because of maybe a genetic overlap or because they are being parented the same way. And so there's this one study that I find really fascinating because it gets around those confounds. What this researcher did was look at school start dates. We know that kids who go to school a little bit old for their grade, just by virtue of when their birthday falls, those kids, especially, I should say, in disadvantaged communities, do better academically than kids who are younger. It's just if you're older for your grade, you're going to be a little bit more developmentally advanced. That means you're a little bit easier in the classroom. The teacher likes to you a little bit better. Things just go a little bit better for you, and then you have a positive feeling about school. You're more cognitively mature. So we know that kids who are old for their grade do better. And that's kind of a random element, right? Like, did you happen to be born at the right time for that to be possible? When you look at the younger siblings of those kids, they also do better than would necessarily be anticipated. And that's true regardless of when their birthday is. So that's how you know that it's having a sibling who had this lucky break that makes the difference for the other sibling who is just, you know, not necessarily old for the grade. It's a. It's a sibling. It's a true sibling spillover effect. It's not parenting that's making it happen. And it's not. It's not the genetics. It's just this one random element of did you happen to, you know, Have a birthday that made the older sibling a little bit older than his or her peers in the classroom.
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Mike Carruthers
Is there any research that would show that siblings who are close influence each other more than siblings who are less close? Is the relationship of siblings impactful?
- [21:36]
Susan Dominus
So what I would say we know is that in disadvantaged families, the sibling effects tend to be stronger. And one reason for that, it doesn't necessarily speak to whether the siblings are more emotionally close, but they tend to spend more time together because maybe their parents are working long hours or they don't invest as much in extracurricular. So it's not like one kid is out, you know, rock climbing, you know, all afternoon, while the other one is practicing oboe. You know, the kids are kind of hanging around the house a little bit more when there are fewer resources to spend on extracurriculars. So those kids do have more of a. Of a sibling. Sibling spillover effect. I think when siblings are close and they collaborate, they can have this incredible network effect that allows them all to do better than they would if they were operating independently. But I will also say that sometimes you can see siblings in whom there is this rivalry and that, you know, people think that everyone's trying to please their parents, and it might have nothing to do with the parents sometimes having a sibling who you want to best, perhaps because there is tension, there can be extremely motivating. I mean, this is anecdotal, but in. In my book, I do write about this family, the Groffs. And Lauren Groff is this tremendous novelist, best selling, award winning. She has an older brother who she felt always patronized her a little bit, and it created this fury in her to show her worth and show him up, I think, basically. And she told me at one point, and by this. And she was by then like a mother and a accomplished author. And she said that 90% of what motivated her was this sort of feeling she had towards her brother. I mean, quite an extraordinary thing to say. So I think sibling dynamics are complicated. They are messy. They can work in all kinds of different directions. And we're just trying to understand what some of the consistent patterns are.
- [23:30]
Mike Carruthers
You've talked about how the oldest child often has a cognitive advantage, an academic advantage over the other children. But. But is there any research that shows that younger children have an advantage somewhere else?
- [23:44]
Susan Dominus
There is good research that finds that younger siblings are overrepresented in elite sports and that they also, you look at all the entering freshmen in a class who played varsity sports in high school, More of those kids are younger siblings. As well, and the idea is that the oldest kid does well academically and the younger kid says, all right, I'm going to pick a different lane, I know I can excel in this.
- [24:09]
Mike Carruthers
Where does the only child fit in this discussion?
- [24:13]
Susan Dominus
I'm not aware of any research to suggest that it's like damaging to be an only child. You know, it's true that they lack the kind of network effect that strong sibling groups have with each other, but they have something else, which is they have all of the attention. You know, if you think about the oldest child having this academic edge because their parents poured all this enrichment to them, even just for a couple of years, think about how much that's going to do for an only child over the course of an entire life. Right? Like, and it's not just that they have all the parents attention and enrichment efforts being focused on them. They also have all of the parents financial resources. And so much of what affects our quality of life frankly is, you know, what economic opportunities do we have?
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Mike Carruthers
After looking at all this research, what other conclusions can you come to?
- [25:08]
Susan Dominus
I mean, I think that consistently I found that when parents know their kids well and they treat them like individuals, you're going to get better results. So it's about setting expectations for your child that are consistent with who your child is. You can't just say, I had one mother say to me, I don't understand. I set really high expectations for both of my children and only one lived up to them. Maybe your second child is not destined to be the valedictorian in the class. Not everybody is. And so when parents set expectations that are inappropriately high for a given child, not only can it be demotivating for that kid, but we also know that it can be linked to, linked to high rates of anxiety and depression.
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Mike Carruthers
What about the idea that parents today are just too involved with their kids and that's not doing them any good?
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Susan Dominus
When I look at these high achieving families, I do see the parents really encouraging their kids to believe that they're tough, to believe they can do it. They let them take risks even when it was scary. I mean, Marilyn Holifield, who went on to become the first black female partner at a law firm, a major law firm in Florida, she ran an influential boycott. She's just this extraordinary woman. She was the one who told her parents when she was 15 that she wanted to be one of the first kids to desegregate a high school in, in Tallahassee. And I'm sure her parents knew it would be awful, but she was hell bent on doing it because it was the best high school in Tallahassee and she wanted access to the best high school and they let her do it. And they never tried to twist her arm into quitting, even when things got really, really tough. I think there's language that a cognitive psychologist once used with my family when we were helping one of our kids who was struggling with something. And she said that we just needed to say to him when he didn't want to do something because it made him anxious, hey, you're tougher than you think. You can handle this and you know you're tougher than you think is very much an implied message that I saw in a lot of the families. And that really became extremely useful language for us.
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Mike Carruthers
I love that. You're tougher than you think.
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Susan Dominus
You're tougher than you think. Yes. And you say it in a very Mary Poppins like, cheerful and assertive tone without overdoing it. And kids are tougher than they think. Lisa d' Amore is a really well respected child psychologist who's written several best selling books. She believes that parents are too afraid of their children's anxiety and that makes the kids afraid of anxiety, nervousness, anxiousness. These are normal, healthy responses. Before you head into a game with a team that you know is going to kick your butt. It is normal to go into a solo, you know, at a concert feeling nervous. That's okay. It's not something that means you have to then avoid altogether so that you don't have that uncomfortable feeling. No, that's a healthy feeling and you're gonna survive it. And you know what? If you screw up the solo, you're gonna survive that too. It's okay. You're tougher than you think.
- [28:16]
Mike Carruthers
Well, this is a topic that I think everyone thinks about, either about themselves, how did I turn out the way I did? Or my kids or my siblings, how did we come to be who we are? It's great to get some insight into it. I've been speaking with Susan Dominus. She is a writer who's been at the New York Times for several years and she is author of a Called the Family A Journey into the Mystery of Sibling Success. There's a link to her book at Amazon in the show notes. Susan, thank you for being here.
- [28:47]
Susan Dominus
Mike, thank you so much. I've really enjoyed talking to you.
- [28:51]
Mike Carruthers
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- [30:29]
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- [30:47]
Lawrence Hurst
You can Venmo this or you can Venmo that. You can Venmo.
- [30:53]
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- [31:03]
Mike Carruthers
Humans are not perfect. I'm not talking about not perfect in the sense that we make mistakes or make bad choices. I'm talking about biology. So humans have been around for a long time. So one might think that by now, over that time, evolution, survival of the fittest, and all that would have weeded out the flaws, the diseases, the genetic imperfections by now. But we have a fairly high rate of genetic diseases compared to other species. So why aren't we closer to genetic perfection than we are? And will we ever get there? That's what Lawrence Hurst is here to talk about. Lawrence is a professor of evolutionary genetics in the Milner center for Evolution at the University of Bath. He's author of the book the Evolution of the science of why we aren't and can't be perfect. Hi Lawrence, welcome. Glad to have you on something you should know.
- [32:01]
Lawrence Hurst
Lovely to be here.
- [32:03]
Mike Carruthers
So let's begin with an example of what you mean by we're not perfect genetically.
- [32:09]
Lawrence Hurst
One of the things that has been discovered over the last few years, for example, is that about half of all fertilized eggs, so the very earliest embryos, half of those will die in humans. In humans. But if we do exactly the same experiment in fish, for example, the answer is none. They're all fine. So it's a funny human thing. And again, if we look at human pregnancy, about 5% of human pregnancies will end in a condition called preeclampsia where population the mother's blood pressure goes sky high. And this can kill the mother and the baby. So it turns out it's one of the great killers of mothers and babies globally. And the odd thing about this particular condition is it's only seen in humans. So it's a human specific but lethal condition of pregnancy. And there are many other sort of similar genetical issues where they just leave you scratching your head going, why are we so bad? Did you know for example, that we've got one of the highest mutation rates? So when parents get together to make kids, usually the kid's DNA is simply a copy of the parents DNA, but they we all have new mutations, a little error somewhere in the DNA and we've got one of the highest rates of all species in these errors. And one of the consequences of this is that we have a very high rate of so called genetic diseases or rare genetic diseases. So a rare genetic disease is one that affects less than 1 in 2000 of us. But about 5% of us have a rare genetic disease. They're not that rare. And that's because humans are odd. We've got a very high mutation rate.
- [33:51]
Mike Carruthers
What are some examples of these rare diseases you talk about?
- [33:55]
Lawrence Hurst
Oh, there's loads of them. Some of the haemophilias, for example, these bleeding conditions, these are quite commonly due to a new mutation in part of the system that makes sure that when you cut yourself you don't bleed. For example, haemophilia A, haemophilia B would be some of the more common ones. So that's the sort of thing that we're talking about. They're not common, but you may well have heard of some of them. But they are particularly common in humans.
- [34:23]
Mike Carruthers
So when you say mutations you mean that when two people get together and Have a baby, they create this baby. And rather than the baby being just a copy of the genetics from the parents, something changes.
- [34:40]
Lawrence Hurst
Yep, absolutely. You can think of it as a bit like you've got a, a data file on your computer and you're transferring it over to, I don't know, you're making a copy of it and you're transferring it over to a USB stick. This is a bit like parents copying their DNA, giving it to the kids. What's happening in the process is occasionally mistakes are made. So just as occasionally, that file can end up having not quite the right instructions, or rather not the original instructions, you might say so too. When Mum and dad make copies of their DNA to give to their kids, there are differences made because of that copying process. So we're all born with about 50 or so of these new mutations. Changes to the DNA. More if your father is old, less if your father is young.
- [35:32]
Mike Carruthers
Do we know why that happens in humans and why it happens less in other species?
- [35:38]
Lawrence Hurst
Well, we do indeed. And so this is one of the themes of a body of theory that I think is not particularly well known. It's called the nearly neutral theory. And what it says is that this classical process of natural selection, survival of the fittest, that is not so efficient when populations are small. And typically what we think natural selection should do is keep the mutation rate really low. Now, why is that? Well, it's because organisms are actually well functioning things. And if I were to give you my lovely watch, for example, and you were just a tinker with it, you're more likely to break my watch, watch and get me very angry. Likewise, if you go to a really well functioning engine of a car and you just randomly change something, then you're more likely to break the engine of the car. And the same is true of DNA and mutations. So mutations are like random tinkering of the engine or the Swiss watch, you're more likely to break it. So then the question is, why do we have a rate of mutation that's three orders of magnitude higher than some other thing? And that's where this other theory comes in. It says actually that selection to keep the mutation rate down is inefficient if populations are small. So our problem in having a high mutation rate is because we evolved when we didn't have a very large number of us. We think there were about 8 to 10,000 of us. And evolutionarily speaking, that's very, very small population.
- [37:09]
Mike Carruthers
Are there a lot of mutations that get passed down that are fairly benign? And what I mean, by that is, as I understand it, some time ago there was a mutation and somebody, for the very first time was born with blue eyes. And then that person had children who had children who had children who also had blue eyes. But blue eyes, although it's something that's very obvious, you see it, but it doesn't really have much effect. In other words, being born with blue eyes doesn't change your life a whole lot. Doesn't ruin your life, doesn't kill you. It's a mutation, but with no real consequence.
- [37:52]
Lawrence Hurst
So there are some sort of. Yeah, obvious ones that may well be largely irrelevant in terms of your ability to survive and reproduce and leave kids and so on and so forth. But the great majority of mutations probably have absolutely no effect whatsoever, or almost no effect whatsoever. They almost all will have some tiny, tiny, tiny effect, but not one that you can physically see. That's because most of our DNA appears to be relatively pointless. There's this sort of magical 10%, which is not pointless, that if you have an effect in there, you will see some deleterious effect. Probably most of it. Yeah. You change it and it has no effect.
- [38:33]
Mike Carruthers
Do the mutations. So when my parents had me and there were mutations.
- [38:39]
Lawrence Hurst
Yep. About between 10 and 100 or so. Yep. You are unique. We're all unique.
- [38:43]
Mike Carruthers
Okay, so when I have children, is it possible for those mutations to stop with me or will I automatically pass them on to my children?
- [38:52]
Lawrence Hurst
You will not necessarily pass them on. So there's two processes we have to think about here. One is what we call purifying selection. So imagine there was a mutation and it killed you. Yes. Before you got to reproduce. That is good old, what we call purifying selection. That mutation came into the population, it killed you, it's gone out again. You will not be transmitting to any kids because you will not have any kids. So that's selection. There's another process which is just simply chance. So you got two copies of the. Of your DNA, but the mutation will only have been in one of them. Typically, the DNA you get from your dad, we get many more mutations from dad than we do from mum. But it's quite possible that when you transmit your DNA to your kids, they got your version that you got from your mum and not the version that you got from your dad. So there you are giving, on the unmutated version, just simply the version that you got from mum, not the mutated version that you got from dad. You do get a few mutations, mutations from mum, just not, not as many. So, yes, it is possible that you have mutations, you simply don't transmit them, not because they're bad mutations, but simply because, in effect, they're unlucky mutations. Your kids only have half your DNA, and so you flip a coin, as it were, and half the time you flip the coin and they don't get the mutation. Half the time they will get the mutation.
- [40:17]
Mike Carruthers
Is what you said about large populations and small populations, the reason why other animals, flies, mosquitoes, where there's zillions of them, Is that why they don't have these problems?
- [40:32]
Lawrence Hurst
Absolutely. That's why we think this is the case. In the last 10 or so years, we've been able to work out what the mutation rate is for lots and lots of different organisms. And we can do this because we can basically work out the DNA of Mum, we can work out the DNA of Dad, we can work out the DNA of the kids, and then it's a spot, the difference competition. Yeah. So you go, where is the kid's DNA different from mom or Dad's DNA? And we go, okay, you must have got a new mutation. And so we can work out what's the rate at which that's going on? And the answer is that if you're in a population of mosquitoes, the rate at which that is going on per unit of DNA is about an order of magnitude lower than the rate at which it's going on in us. But, yeah, they've got a lower rate. And it turns out that the mutation rate very nicely scales that we now know with how many individuals are there in the population. Lots of individuals in the population and the mutation rate is low. Few individuals in the population and the mutation rate is high.
- [41:36]
Mike Carruthers
Well, what's a lot? I mean, we have several billion people on the planet.
- [41:40]
Lawrence Hurst
We have several billion now. We did not have several billion when we evolved. So, as I said, if we go back to before the modern expansion of humans, which is 20,000 years ago or so, we estimate that there were about 8,000 or so of us, which isn't many, and that's pretty normal for a primate of our sort of body size. So the other predictor of this is just how big is your body? So whales have a low rate, like us. They've got very big bodies and very small population sizes, likewise elephants and so on and so forth. So, yeah, the things with largest bodies, evolutionary speaking, comparing across all organisms, we've got a large body. So there were historically very relatively few of us. And the consequence of that is that when we were evolving, we were much More prone to chance events.
- [42:31]
Mike Carruthers
So help me understand this. Something I've never been clear on. If I got cancer, it might be, or people would say it could be hereditary, but it could also be a mutation. And a mutation doesn't necessarily bring the disease with it, it creates the disease when it mutates. Is that correct?
- [42:59]
Lawrence Hurst
Cancer is complex and in many regards, what you said is absolutely spot on. So if you look at something like breast cancer, for example, about 5% of breast cancers are highly heritable. So if your mother had breast cancer and her mother had breast cancer, we can now sequencing up your DNA and go, okay, you've got a mutation. And then you can do what Angelina Jolie did, for example, go, I likely will get breast cancer. And so there you have a key mutation that is really tilting the balance towards you getting cancer. Many other cancers are not like that. There may be weaker genetic predispositions, but many cancers go lie simply on bad luck that in your body the cells are dividing all the time, they're mutating all the time, and you could just get unlucky. You may have no predisposition genetic wise towards cancer, but because those cells are dividing all the time, they're mutating all the time, you could just be simply unlucky and develop cancer within your body. And at the moment, because people are living quite long, we estimate that about one in two people will get cancer sometime in their lifetime. But it isn't necessarily because they inherited genes for cancer. They could have inherited some weaker disposition, or they could inherit, as with these 5% of breast cancers, very strong predispositions. And those very strong predispositions are such that you only really need one other mutation and you will get cancer. For the others, you need a handful of mutations, an unlucky combination, and you will get cancer. But yes, you can inherit predispositions to getting cancer, But a lot of cancer is simply bad luck.
- [44:42]
Mike Carruthers
So how close are we to being able to find mutations and go in there and tinker and fix them?
- [44:49]
Lawrence Hurst
Great question. So this is really the most exciting age in many regards, because what we can now do is sequence DNA. So every one of us has about 3 billion base pairs of DNA. There's quite a lot in every one of our cells, actually two copies of that. And we can now work out exactly what that looks like for each, each and every one of us. And in principle, we can then go and go, okay, you've got this condition, whatever that condition may be, and go, oh, we found what the problem is. You've got this mutation in this, this gene here. And we can do that now ultra fast and ultra cheap. So let me give you some really, I think, interesting and fantastic figures. So when the human genome was first sequenced, all that DNA from one individual was sequenced. It cost $3 billion. It took about 15 years. We can now do exactly the same for around a hundred dollars and it takes an afternoon. So because of this, you can now go to your doctor and the doctor goes, I think you've got a genetic condition, sequence up the DNA, have a look at it and go, right there, we think, is the problem. So there are cases now where, for example, kid goes into hospital screaming their head off. Awful headache, very young kid. And in this case, the doctors decided the kid almost certainly had a genetic disease, sequenced the DNA, worked out what the problem is, worked out what the cure was, and that was two and a half days. So this is a revolution in medicine. In that particular case, it turns out it was a problem with importing a particular vitamin into the cells. It was a B vitamin that couldn't go into the cells, so a diet could fix it. What's particularly exciting at the moment is there's a different sort of fix to these genetic problems. And that different sort of fix is called gene therapy. So, for example, with haemophilias, but also with sickle cell anemia, which is very common in, for example, the African American community in America at the moment. But with haemophilias, for example, we know what the mutation is. So you've got a gene, it's making a protein that's not working right, and so your blood isn't clotting properly. You bang your head, you will probably die. Currently, the best we can do is give you synthetic versions or give you blood transfusions. So the idea behind gene therapy is to say, no, those are all just sticking plasters. What you really need is the right version of the gene to make the right version of the RNA to make the right version of the protein. And so we can give you the gene, and that, in a very profound sense, is a cure. But this is a gene that goes into your body to allow you to make the missing protein, that allows you to clot your blood properly. It doesn't go to your offspring because it's only going to affect the cells of your body, but not the cells of sperm or eggs. And likewise, with something like sickle cell anaemia, we can take out your bone marrow, engineer the bone marrow genetically by giving it the right gene, putting it back again. And you now can be effectively cured of sickle cell disease. It is a cure. You're taking a mutated gene and you're giving the better version of the gene, the one that most other people would have, and that then is working absolutely fine. But there are all sorts of problems with it. It's not a pleasant process to have this done. And there is mortality along the route. So the first gene therapy trials had to be stopped, for example, because it turned out that the intervention itself was causing downstream problems, was actually causing cancer. Some of the next ones had to be stopped because the way of delivering the gene, it turns out, caused a massive immune response in the poor individual concerned and they died. So it's been a very slow birth. But we think we're overcoming a lot of these technical hurdles, and most particularly safety hurdles. And so I suspect it's something that we will hear a lot more about in the not too distant future.
- [48:58]
Mike Carruthers
Well, I suspect everyone has wondered, you know, why do we have cancer and other genetic illnesses and why can't we get rid of them? And I appreciate the explanation. And it sounds like anyway that there is promising future in medicine that will address this whole issue. I've been speaking with Lawrence Hurst. He is a professor of evolutionary genetics and author of the book the Evolution of the Science of why We Aren't and Can't Be Perfect. And there's a link to his book in the show notes. Thank you, Professor. I appreciate the explanation.
- [49:32]
Lawrence Hurst
Thank you very much. It's been a real pleasure.
- [49:38]
Mike Carruthers
Your kitchen has a way of attracting clutter that you probably don't even notice. So the editors@delish.com have some advice to get rid of the clutter, starting with a really easy one. The real estate agent and pizza delivery magnets on the fridge. They can go. Then there's your plastic container collection. Empty food storage containers take up a lot of space in the kitchen. The recommendation is to limit yourself to two sizes of reusable containers, five to six pieces in each size. And that way you're not fighting to find the right lid for each bowl. Coffee mugs, they just seem to multiply and pile up. Most people don't need more than six coffee mugs. The rest can go anything that came for free with your dinner. Spare chopsticks, soy sauce packets, kids meal toys. You're always going to get more the next time you order. So there is no point in stockpiling barely used cookbooks. If you've owned a cookbook for over a year and haven't made a single thing from it, it's probably time to consider selling it. Unless it's a family heirloom, in which case you could just move it to the living room. Pots, pans or skillets. There's a pretty good chance if you look where you keep your pots and pans and skillets and things, there's a few in there that you never use. I can't remember the last time you used it. So why do you keep it? Those recipes you're saving for someday, if you printed out or tore out of a magazine a recipe more than a month ago and you haven't made it yet, you're not going to make it. So you might as well just get rid of them. And that's okay. And that is something you should know. A great way to show your support for this podcast is to leave a rating and review on whatever platform you listen on. Apple, podcasts, Spotify, most all of them have a way to leave a rating and review and they help us and we appreciate it. I'm Micah Ruthers. Thanks for listening today to something you should know.
- [51:48]
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- [52:43]
Amy Nicholson
I'm Amy Nicholson, the film critic for the LA Times.
- [52:46]
Paul Scheer
And I'm Paul Scheer, an actor, writer and director. You might know me from the League, Veep, or my non eligible for Academy Award role in Twisters.
- [52:55]
Amy Nicholson
We love movies and we come at them from different perspectives.
- [52:59]
Paul Scheer
Yeah, like Amy thinks that you know Joe Pesci was miscast in Goodfellas and.
- [53:03]
Mike Carruthers
I don't he's too old.
- [53:04]
Amy Nicholson
Let's not forget that Paul thinks that Dune 2 is overrated.
- [53:08]
Mike Carruthers
It is.
- [53:09]
Amy Nicholson
Anyway, despite this, we come together to host Unspooled, a podcast where we talk about good movies, critical hits, fan favorites.
- [53:16]
Paul Scheer
Must sees, and in case you missed.
- [53:18]
Amy Nicholson
Ems, we're about Talking and Parasite, the.
- [53:19]
Paul Scheer
Home Alone from Grease to the Dark Knight.
- [53:21]
Amy Nicholson
We've done deep dives on popcorn flicks, we've talked about why Independence Day deserves a second look.
- [53:26]
Paul Scheer
And we've talked about horror movies, some that you've never even heard of, like Ganja and Hess.
- [53:30]
Amy Nicholson
So if you love movies like we do, come along on our cinematic adventure.
- [53:34]
Paul Scheer
Listen to unspooled wherever you get your.
- [53:36]
Amy Nicholson
Podcasts, and don't forget to hit the follow button.