A (2:35)

I use a phrase, sorry to say. I'm a king golfer. Oh. Are you okay?

B (2:39)

My name's Dr. Anna Machen and I'm based at the Department of Experimental Psychology in Oxford. I'm an evolutionary anthropologist and my interest looks at the evolution psychology and neuroscience of close human relationships.

A (2:52)

What happens when you see someone you find attractive?

B (2:56)

Okay. When you see someone you find attractive in your brain, a chemical called oxytocin is released. And oxytocin works by inhibiting your usual social worries about walking across a bar and saying hello to someone. So it acts a little bit like alcohol, actually. It makes you less scared about being forward.

A (3:14)

Men, I guess, go on that kind of chemical reaction thing that they don't hang around to find out the faults. They just believe that what they see and hear is, wow, this is it.

B (3:26)

So you get a release of oxytocin that makes you walk across the bar. When you start talking to the person, you also get a release of dopamine, which is one of the brain's reward chemicals, and that makes you enjoy your interaction with the person. So those are the two key chemicals that are released in the brain. And that's the same for men and women.

A (3:43)

I like your hair, by the way. Oh, thank you very much. Thank you. Big hair, big hair.

B (3:46)

I'm all about the big hair.

A (3:48)

The way you do it is very cool. Thank you very much. So you were born in London? No, actually I was born in Tanzania. And what senses are we using when we decide whether someone is attractive or not?

B (3:59)

In the very first instance, it's visual. You know, we have a very large visual cortex in our brain and we take a lot of information in through that particular medium. So first of all, what you will do is both men and women give a good scan of the person's face and body. There is a certain involvement of smell, but you do have to get pretty close to the person for that to actually happen. And particularly, you probably actually have to kiss them to actually taste and smell particular chemicals, both in their breath and in their saliva.

A (4:33)

A bar in the city of London. On the ground floor, about a hundred people are relaxing at the end of the working day. Groups of friends, couples too. But in the basement bar, things are a little more tense. Hello, ladies and gentlemen. Hope you're all right. Thank you very much for coming down today. I'm just going to explain how the speed data. There are 12 women, nine men, all strangers to each other, and they've come here for this speed dating event. The women are in booths around the outside of the room, and the men rotate around them four minutes with each woman. If you could just write your contact details. So whether that be your phone number or your email, we'll come back to them later to see if anyone's feeling that spark of attraction. I saw a beautiful young woman. I could see straight away, though. She's not only good to look at, but she had a profound sense of style. Can I just be very frank? She was wearing a Bieber dress. Which had a diaphanous quality to it. So I could see her more or less underneath. So, gosh, that was it.

B (5:32)

Our ideas of beauty, that's a label we've given it culturally. They're all linked to indicators that we have on our bodies that actually show off what value we have as a mate. Ultimately, what evolution wants you to do, whether you like it or not, is have children. And so when we say someone is beautiful, what we're actually saying is they have a high mate value. They're a good person to get together with and have some children with.

A (5:56)

What are you looking for? Me, I'm looking for the one like everybody in life. Do you have a type that you are attracted to physically? Yes, I've got a type like everybody's got one. You want to know the type? I like brunette, I like petit, I like smiley and I like somebody I can have fun with. Yes. And feminine. Yes. I think it's pretty important.

B (6:19)

What a man looks for when he's looking for a mate is he needs a woman who is fertile and he needs a woman who is healthy. And the reason for that is he needs that person to conceive and then carry that baby to full term and then look after it, particularly in a short term relationship, because he's not intending to stick around. Okay. So he's going to look at signs for fertility and what we call fecundity and good health. And the major indicator of that in women is the waist hip ratio. And the waist hip ratio, the absolute ideal, what men find most attractive, regardless of culture, this has been tested in many different cultures around the world, is 0.7. And that's really your classic hourglass figure. And the reason why that universally is attractive is because it's tied to the health of that individual. There's a very strong relationship between someone circulating estrogen and testosterone. Obviously we want the estrogen to be high, the testosterone to be low, for a woman to be fertile and also her General Health. So 0.7 is linked to lower risk of heart disease, lower risk of diabetes and certain sorts of cancers. I remember going to lunch at his mother's house and I saw Christie sit down and play blues piano and he picked his six year old niece Sasha up and sat her on his lap and straight away, you know, that endeared him to me. Women always like men with children. If you see women in a park and they see a single dad with children, you automatically, you think, oh, you know, what a nice guy. It endears them to you straight away. When a Woman is looking for a partner, particularly for a long term relationship. She's trying to find somebody who can protect and provide. Because actually, if we look back at the environment of evolution where all these different behaviors evolved, women were basically, I suppose, tied to the homestead because of the fact they were either pregnant or, or breastfeeding or had several toddlers hanging off their legs. So they weren't able to go out and hunt and they weren't able to protect all those children themselves, so they needed a male to do that. So a woman is looking for physical things like nice broad shoulders, narrow waist, that's known as the shoulder waist ratio. And the ideal is 1.6. But she's also looking for other indicators that this man has good resources. So in the modern era, that's looking at what he's wearing, what's his watch like, can we get onto a conversation about what car he owns, all that sort of thing? Because these are all indicators of resources. So men and women do look for very different things because women very much are the ones who have to produce the children. And generally in the past, it was the men who then had to protect and provide.

A (8:54)

But the choice of a partner is about more than just worldly resources, it's about biological resources too. Genetic strength. And that we can actually smell.

B (9:04)

What you want your offspring to have is the broadest immunity to the diseases that are out there. So you don't want to mate with someone who's got genes similar to you, you want to mate with someone who's got very different ones. So they have lots and lots of defences against possible illness. So what we're doing, when we smell someone, we say, I like the smell of you, I don't like the smell of you, is we're actually reading their genes. Certainly when you kiss somebody, one of the things you're tasting in the saliva is also the mhc.

A (9:30)

Mhc, Major Histocompatibility Complex, a group of proteins which controls our immune responses. So when you smell or kiss a potential partner, you're actually sampling these proteins and that tells you something, the genes that produce them. If the other person's immune system is dissimilar to your own, they smell good. And any offspring stands a better chance of fighting off disease. Smell matters, but to begin with, at least, it's the look that matters most. Michael, have you done this before? No, first time. Were you nervous? Yeah, very nervous. Very nervous. Physically, what do you look for in a person? I'm sporty, athletic, so I'm looking for someone who's similar I paid attention to the things that they like to do, but that was only sparked by the attraction, the physical attraction. So you don't get a tick from Michael unless you're pretty? Yes. For me, attraction is also personality. Yeah, but looks first, huh? I wouldn't say looks first. Looks provides a key to the door. How's it going? Have you found anybody that you're attracted to?

B (10:52)

There's actually one person that had a little kind of, you know, we took in nicely, and it seemed that there was a little bit of a spark. So that's quite nice. I didn't expect it.

A (11:00)

And what was it that you found attractive about?

B (11:03)

He was really friendly.

A (11:03)

He seemed to just really, like, be comfortable in his own skin. And what about physically?

B (11:08)

Yeah, physically he's attractive, too.

A (11:10)

What made him attractive?

B (11:12)

There's no one specific thing. I think he just had a nice smile. I kept looking at his smile, and.

A (11:16)

I thought, okay, he's a nice smile.

B (11:17)

He has really nice eyes, very friendly eyes. When the bell rang, we just carried on talking. He didn't want to go.

A (11:25)

So what do we look for in someone's face? David Perrett is from the School of Psychology and Neuroscience at St. Andrews University in Scotland. Well, there's a whole plethora. We can start with mobile cues. I mean, how much you smile and how tired your eyes look count for a lot. There's the structural cues, the bones that give away whether you're more masculine or more feminine. And then there's the covering with adipose tissue or fat tissue that can make you look lean or plump. All of these change as well with age. The skin obviously becomes more wrinkled. So all of these contribute to our judgments. These are the shape cues, and then there's a whole string of color cues. And the skin tone, whether it's a healthy glow or kind of a dull, listless color.

B (12:16)

Both men and women do. This is you do look at the person's face. And the reason why you look at the person's face is because it's a very good indicator of genetic strength. All relationships are to do with producing children. What you want your children to have is the strongest possible set of genes. So both men and women look at the face because the symmetry of the face is a very good indicator of how strong those genes are. And the reason for that is our genes are programmed to make us bilaterally symmetrical. Okay, so two arms, two legs, two ears. However, when we're developing in the womb, the foetus undergoes a lot of what we call chemical, environmental challenges. So it Might be that the mother is very stressed. It might be that you're in an environment where a lot of pollution is being breathed in, for example, and that knocks those genes off that course. So nobody is completely symmetrical. However, people who have a high degree of symmetry, who we universally find attractive, what that's saying is their genes went through all those challenges, but they still managed to do a pretty good job of making that person as symmetrical as possible, which suggests they're very strong. And that's why universally and animals find symmetry very attractive. It's why we find symmetry attractive, because it's saying this person has strong genes. You want to mate with them.

A (13:30)

Daniel, have you been attracted to anybody yet? Few times, but I don't think I found the one. But there were plenty of lovely ladies, had good conversation, it was really fun. I really recommend this experience to any.

B (13:43)

Single man or ladies.

A (13:45)

It's all about having five minutes. You don't risk anything. So have you found anybody you're attracted to yet?

B (13:52)

Not yet, no. But nice people. It's good to have a chat. You just end up saying the same.

A (13:57)

Thing again and again.

B (13:57)

But that's all right.

A (13:58)

Do you think it happens quickly? I mean, how rapidly do you know whether you're attracted to somebody?

B (14:04)

Well, I went on another speed date about six months ago and I met a guy who I went out with. I've just split up with him now, but it was instant, instant. We just, both of us knew and that was it. So, yeah, it happens very quickly with me.

A (14:14)

I think individuals grow up and they like looks in partners that simulate or reminiscent of opposite sex parents. So a girl may grow up more likely to marry a male partner who looks a little bit like her father, provided that she gets on with her father. So that's one influence. But also in life, if somebody crosses you and is mean to you, you remember that experience and it actually puts you off faces that may share a similarity with the person who's been mean. So there's all sorts of individual life experiences that influence us and our judgments of attraction. But we can change our faces, can't we? We can change our faces with exercise and surgery and makeup. The most important change we can make is one of how we interact with others. I think plastic surgery really doesn't count for much in the end. You could be with somebody who's aesthetically very beautiful, but if they don't smile and react, then that counts for much less. So we can change our faces by interacting with others and doing so in a pleasant manner. And that will Aid our attractiveness and make others interested in us. I'm told that my resting face looks rather grumpy. I think I'm told that all the time.

B (15:31)

Personality wise. I like intellectuals actually. Yeah, they have to be sparky intellectuals for me. Arthur Miller, playwright. I can totally understand why Marilyn Monroe married him. A very attractive guy. I think it's important with attraction that we go beyond the physical. And you do have those conversations with someone and you get to know them, you get to understand their values and their beliefs and their thoughts. Because actually those are a major component of what will attract you.

A (16:08)

When you stare into each other's eyes now, what do you see? I see lots of things. I see a girl I love and I see a young girl I love. And I also see an elegant, interesting woman and mother and I see a sexual partner. And again, I'm lucky Claire happens to be physiologically built that she's exactly the same she was when she was 18. Well, thank you. There we are. It's amazing. A lot of yoga, a lot of Pilates, but it's incredible actually. I'm slightly sort of droopier and drink beer and all that men's stuff.

B (16:34)

I still see that. The young man I first met at my parents house all those years ago too, particularly in Christie's eyes. I see him more like that than I see him in a day to day way. Which I think is a very good sign and good significant thing in our relationship. When you go into a longer term relationship, the thing about oxytocin is it's very short acting, it degrades very quickly. So it's not a good chemical to maintain a long term relationship. What we tend to use for a long term relationship is a chemical called beta endorphin. And beta endorphin is one of the body's opiates. And it's addictive in the same way that those external opiates such as heroin and morphine are. And so what happens when you're in a long term relationship is that particular mechanism takes over from oxytocin and it's what underlies your interactions with the person you love. So people will say, I'm addicted to the person I'm with. They are, they actually are. And when they're away from that person, they will get withdrawal symptoms. And the severest case of those are, you know, severe separation distress or anxiety. And so what we do is because we're addicted to endorphins and they're released by that person, we're constantly drawn back to that person. So in terms of deep long term love, the chemical that's key there is beta endorphin. I think the in lust bit certainly turns into love. And scientists say that too, that there's an initial intensity in the relationship where you just want sex all the time, which lasts for, I think it's a maximum of 18 months to two years.

A (18:08)

Well, it means going by which time.

B (18:11)

In our case, we'd already had twins.

A (18:13)

Twins, yes.

B (18:14)

But then the man stays around because he wants to see his children grow up and also because the relationship changes. So it changes from lust into a friendship. And then if you're lucky, you can have a friendship where the lust stays.

A (18:46)

Thanks for listening to the Y Factor. If you'd like to hear more episodes, there's a wide range of programs on our website. Among them the Pain of Loneliness, the Rise of the Robots and safe spaces. Visit bbcworldservice.com yfactor@thebc we go further so you see clearer. With a subscription to BBC.com, you get unlimited articles and videos, hundreds of ad free podcasts and the BBC News Channel. Streaming live 24. 7 from less than a dollar a week for your first year. Read, watch and listen to trusted independent journalism and storytelling. It all starts with a subscription to BBC.com find out more@BBC.com unlimited.