Genetic Fact Vs. Fiction And Everything In Between With Janina Jeff : Short Wave Geneticist Janina Jeff is back on the show to talk with host Emily Kwong about season 2 of her podcast In Those Genes. They talk about rhythm, aging and navigating what can be ascribed to our genes and what is determined by society.

Check out more of Janina's work on In Those Genes:
Episodes referenced in today's Short Wave include:
- R&B: Rhythm & Blackness
- Black Don't Crack
And listen to our last episode with Janina:

Email the show at

Genetic Fact Vs. Fiction And Everything In Between With Janina Jeff

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EDDIE MURPHY: White people can't dance. And y'all be trying. Y'all be - really? Do y'all hear - do y'all listen to the words or the beat?

KWONG: This is Eddie Murphy in his 1987 stand-up, "Raw," making comedy out of a trope that's been kicking around for a long time - that certain people are better at catching the beat, better at rhythm. It's a mainstream idea, but is it true? Where does the social construct of race and the genetics of us humans meet? Crossroads like these are exactly where the podcast "In Those Genes" sits in its new season - out now. The show is hosted by geneticist Janina Jeff.


UNIDENTIFIED PERSON #1: Self-proclaimed audiophile. Wife of Andre 3000. Manager of J Dilla "Donuts." Glorified hip-hop head.

JANINA JEFF: Yo. That's yours truly.

KWONG: Yup. Janina came on our show last year to talk about DNA tests and genetic ancestry. We'll drop a link to that episode in our notes. Science is Janina's passion, and music is, too.

JEFF: I've always thought of music and dance as something that's being, like, ingrained in my DNA, you know? And being the lightest one in the family, like, everyone was looking at me like, oh, we hope she can dance. You know, like, hope she got rhythm, you know? And I'll be - I'll confess and say I'm not - like, I'm not dancing like my aunts, but I am not dancing off beat (laughter).

KWONG: OK. OK. But what does it mean to be off beat? Well, Janina has a clapping experiment for you.

You start the episode with this kind of brilliant audio experiment. I want to add some SHORT WAVErs to your dataset. So, yeah, set it up. What were you trying to do here?

JEFF: So here, we open the episode with describing what rhythm is. And we define rhythm as being able to clap along to a beat. So the idea is you hear a beat, and then after a few seconds, you can now clap along in the same cadence at that beat. And so we give two different cadences - one that is on the twos and the fours, and one that is on the ones and the threes.

KWONG: OK, wait. I'm ready. I'm ready. I'm ready.


JEFF: We're going to play a song and ask you to clap along to the beat.


UNIDENTIFIED PERSON #2: Three, two, one. Begin your claps.


CHUBBY CHECKER: (Singing) Come on, baby. Let's do the twist.


JEFF: I heard you clapping. Do you know which one you clapped on?

KWONG: I got so nervous that I just started clapping when it felt right.

JEFF: (Laughter) I heard a lot of claps. I was like, I think she's just clapping. I don't know if she can hear.


KWONG: OK. So - OK, so if I clapped on the twos and the fours, that would mean I'm on beat, right?

JEFF: So this is by cultural standards. So cultural standards is saying, you're being able to clap along to the beat. And we're saying, if you can clap along to the beat, by cultural standards, that means you have rhythm. But when we really think about rhythm, it is about having any type of cadence at all.

KWONG: And genetically speaking, like, what is your final statement on this stereotype that certain people have better rhythm than others?

JEFF: (Laughter) You're probably not going to like this answer, but the answer is that it's very complicated and we don't know.

KWONG: On the contrary. We on SHORT WAVE love a we don't know. We find it humble and real.

JEFF: OK (laughter). We don't know. I think that we have insights though. You know, I learned a lot about how we receive music and how our bodies respond to music and rhythm and learning kind of the different integral parts that play into this entire process. And I think it's safe to say that scientists really don't know the answer to the question. But I feel like a lot of the evidence and research point strongly to there's likely not a huge population difference that could be explained by genetics.

KWONG: So that is Janina's genetic finding when it comes to rhythm. But what about aging? And how does a geneticist like her navigate what can be traced to our genes and what is determined by society? You're about to find out, because today on the show, we welcome back our science podcast cousin Janina Jeff.


KWONG: OK. Before we get into this conversation with Janina, we had a few technical issues recording her, so you may notice a little difference in the audio. Such is the life of a pandemic podcast-maker, am I right? All right, enjoy.


KWONG: We're going to link all of Season 2 of "In Those Genes" in our episode notes. Like, you can't fully understand this show until you just listen to it, including this episode we just talked about, which is "R&B: Rhythm & Blackness."

Now I want to talk about this incredible piece you did about age and perception of age. It was called "Black Don't Crack." Tell me about that phrase and what you were trying to figure out with it about aging.

JEFF: Yeah. So Black don't crack comes from this idea that Black people age slower compared to other populations. And it's something that has become so mainstream that I don't even think it's just something that Black people say. Now, I wanted to talk about it because a lot of people who talk about this say it's genetic. But we first wanted to kind of talk about, what are the things that people think about when they say Black don't crack, and what is aging, really? And so similar to the rhythm episode, there are somewhat kind of two different definitions for that. You know, when we say Black don't crack, we're talking about wrinkles in your skin. We're talking about how fast you go gray. We're talking about your ability to memorize things and your memory. And ultimately, we lead the listeners down a very, very fun adventure - very "Magic School Bus"-esque (ph) adventure - where our cells kind of have a personality of their own, and we talk really deep about the cellular biology of aging.


JEFF: Hey, we need some more keratinocytes. Commence cellular division.





JEFF: Typo alert?

KWONG: That is the sound of a body getting tired. Scientifically, what's going on there?

JEFF: Yeah. So we're talking about the process of cellular division - right? - and what happens when certain things happen in the body, right? So I think the big takeaway that we want listeners to get from the entire episode is that aging is very complex, but it's mostly cellular. You know, even when we talk about wrinkles, when we talk to Tina - who also has been on SHORT WAVE - in this episode, we talk about hair and we talk about melanin - right? - and your melanocytes. And so all of these are tied to our cellular health. And so we just try to emphasize to everyone that cellular health is a major part, if not the biggest part of aging, right? It's kind of where the process of aging starts and ends, you know?

KWONG: I mean, taken altogether, what would you say is true and not true about the idea of Black don't crack? What did you end up finding?

JEFF: Well, we did find - and this is one of the rare episodes where we see some really strong genetic correlations - with genes that are involved in melanin production, there are certain parts of aging that we can ascribe to having more melanin, thus, you know, being darker. I'm talking particularly, you know, in our skin and the melanin in our hair. Aging is super complex, and we don't have enough to give out a prescription of this is what you should do, and this is what you should not do. But I think this is a start to understanding aging. And I think it's a start to understanding how complex some of the things we casually say and culturally say are not as easy as we say them, right?

KWONG: As the episode goes on and you're pulling back the layers of aging and health, you start to talk really candidly about disproportionate impacts for African-descended people when it comes to certain diseases and lack of access to health care and lack of access to social support. And I'm wondering, you know, when you were reporting this out, how did you separate in your mind all these things, like, what was genetically determined by what was socially and environmentally made to be?

JEFF: Yeah. So, you know, the hardest thing is going through the literature and trying to distinguish the racial and bias implications in medical research from the actual thing we're talking about. African-descent people are not living longer compared to their other counterparts. And that's because when we think about some of the major causes of death - heart disease and cancer - a lot of them are dependent on having access to health care. A lot of them are dependent on having access to medication and clean water. And it was really disheartening, actually, to think about - we can't even really answer the question if Black people live longer because there is so much systemic racism and capitalism that is embedded in the health care network. We can't actually control all those factors and then ask the question, is it purely genetic or not, you know?

KWONG: Yeah.

JEFF: And that's the thing I'm the most passionate about.

KWONG: Yeah. At one point you say in this kind of frustrated way - you're like, is genetics the thing we should be chasing? And I'm wondering how working on this season - how you feel about some of the things you've discovered and how it makes you look at your own profession now.

JEFF: The one thing that this podcast, even in Season 1...

KWONG: Yeah.

JEFF: ...Had, like, definitely taught me is to be critical of the science and the scientists, right?

KWONG: Yeah.

JEFF: ...'Cause I think if you're not in the field, it's very easy to take with someone who has a Ph.D. or an M.D. what they say and say, oh, that must be true. But a lot of the things that I've realized is that there is so much bias in the research itself. In some ways, it has been somewhat traumatic - right? - to be trained in a field - and even myself - the way I think about a lot of the questions are all kind of centered in some of the bias that already exists in academia. And how do I disentangle that? I will say I have noticed that there has been a shift. And I think that shift has come from a lot of the younger-generation scientists really being at the forefront in understanding how important social constructs are.

KWONG: Yeah. I think - what you're pointing to reminds me of something that our producer Eva Tesfaye said when we all listened to the season - is you are so embracing of the fact that there's multiple ways of knowing, some of which are outside the realm of science. And one of the most beautiful things you do in this episode is you are weaving in and out of this conversation with Irma Shaw, this 94 year old who grew up in Guyana, and you're talking to her about aging. And she kind of levels up the conversation at the end. She goes beyond science and said, you know, Janina, like, the spirit never ages.


IRMA SHAW: The spirit doesn't die. The spirit lives on.






KWONG: And you have all this audio of the Black Lives Matter protests and resistance.




KWONG: And I'm wondering, how did it feel when she said that to you about, like, this other idea of aging having to do with spirit, as a geneticist?

JEFF: Yeah. I, as I have gotten older, have become more appreciative of ancestrial (ph) religion and practice. And in ancestrial - you know, for all and purpose sake (ph) - a lot of Indigenous religious practices on the continent of Africa - they have always believed that the spirit lives on. The spirit lives in you. The spirit is in your DNA - and that, you know, from a genetic standpoint, I think about, yeah, I am - my ancestors are embedded in my DNA, you know? And their spirit does live within me. And their spirit does continue on. And if you were privileged enough to have spent time with your ancestors while they were here before they transitioned, that spirit lives on through you, right?

And so that oral history and telling that story is so important and a part of how we age - right? - because it doesn't even have to be things like our ancestors said - drink more water, or, you know - but just being in the very presence of them and looking at the things they've done and the things that they practice - naturally, you're going to gravitate to those things and learn those things as well. So I wholeheartedly believe that all of this plays a part and a role in how we age and how we commune. And I think...

KWONG: Yeah.

JEFF: ...When she said that, it just - it spoke volumes to - you know, to me specifically, and I hope it spoke volumes to others.


KWONG: Yeah. Oh, you're giving me chills. Thank you so much. It's been so awesome to have you back on the show.

JEFF: Oh. Well, thank you guys so much.


KWONG: The new season of "In Those Genes" is out now. Check out our episode notes to learn more about this podcast, which is independent and run by Black women.

Today's episode was produced by Eva Tesfaye, edited by Gisele Grayson, who is our senior supervising editor, and fact-checked by Katherine Sypher. The audio engineers for this episode were Natasha Branch and Josh Newell. Neal Carruth is our senior director of on-demand news programming. And Anya Grundmann is our senior vice president of programming.

I'm Emily Kwong, and thank you for listening to SHORT WAVE, the daily science podcast from NPR.

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