Evolutionary Genetics of Superficial Traits

Undergraduate student Hannah Marchok interviews Dr. Mark Shriver about his work tracking down what he calls "superficial" physical traits that distinguish people from one another - and about his life as a research scientist.

Host:
Hannah Marchok, Penn State Biobehavioral Health major, minoring in Global Health

Guest:
Dr. Mark Shriver, Professor of Biological Anthropology, Penn State University
Co-director of the Center for Human Evolution and Diversity  

Transcript

Mark Shriver: 

From Penn State’s Center for Human Evolution and Diversity, this is Tracking Traits

Nina: 

Hello and welcome to the second episode of the Tracking Traits podcast. I’m Nina Jablonski , co-director of CHED – the Center for Human Evolution and Diversity at Penn State University. 

Mark:

And I’m Mark Shriver, the other co-director of CHED. Welcome to the podcast.  

Nina:

For today’s episode, Mark here was interviewed about his research on the evolution of what he calls “superficial traits” by Hannah Marchok, a Penn State undergraduate student majoring in Biobehavioral Health, with a minor in Global Health. How was that interview for you, Mark?

Mark:

It was great, Nina. Hannah did a really excellent job preparing a lot of thoughtful questions and it turned out to be a really wide-ranging conversation that I thoroughly enjoyed. Hannah works with me in my lab on the hair team with Tina Lasisi, and has a strong interest in all the kinds of things we do. 

Nina:

Such as?

Mark:

Such as the evolution of human phenotypic variation among populations, the social perceptions of race and ancestry, and the history of scientific racism.

Nina:

Oh wow, great! So you talked about these things in the interview?

Mark:

Yes, all those things and more. Hannah asked me about my own personal journey. Where and when I got into science, who some of my mentors have been, what I think it takes to do good, solid and creativeresearch that’s innovative…we even touched on how some discoveries have come to me in my dreams.

Nina:

Cool stuff!

Mark:

Yeah, very cool. We talked about new technologies and international collaborations and other positive developments in our field– but also the frustrations and struggles of being a scientist. From the social dimensions to the practical, to the analytical. Yeah, Hannah really asked a lot of great questions.

Nina:

Well, that sounds fantastic Mark. I think our listeners are really going to enjoy hearing this conversation. So why don’t we get into it?

 Mark:

Sounds good. Let’s do it.

Nina:

OK listeners, here is Penn State undergraduate Hannah Marchok interviewing our very own Mark Shriver about the “evolutionary genetics of superficial traits.”

MUSICAL INTERLUDE

Hannah Marchok:

Thank you so much, Mark, for joining us today to discuss some of your research with us. I'm really excited to hear what you have to talk about today and to introduce our audience to some cool new research that's being done right now. 

Mark Shriver:

Great, Hannah. Thanks. It's my pleasure to be here.

Hannah Marchok:

So for our first question, in two sentences, could you please introduce a bit of your research to our audience?

Mark Shriver:

So, I've always been interested in the diversity that we see when we look at different individuals, different populations. And that's kind of driven my research from the start 25 years ago. And I've been curious about the evolution and using genetics to explore the evolutionary history of these sorts of traits. So, skin color, hair form, facial features, body size differences and things like that are the sorts of traits that I'm talking about. I call them superficial because they're on the surface of us. And they're also sort of immaterial. What you look like doesn't affect your essential humanity or your worth, or your interactions with others.

Hannah Marchok:

Absolutely. So, in terms of what the broader impacts of your research could be, what impact do you potentially see on your field, which is evolutionary biology and anthropology, and on the scientific field as a whole?

Mark Shriver:

Probably the biggest, broader impact is just to help give people something to reconsider in terms of how they think about diversity. And I mean, there are folk conceptions of race that connect physiological and psychological conditions or issues, traits. And I think we're embedded in this very racialized and thus racist society. And any work on diversity I think, is going to help overcome that, because these apparent differences and the diversity that you think is there, is a lot less than actually there is.

Hannah Marchok:

Right. Absolutely. And coming at it from a point of understanding rather than judging or qualifying.

Mark Shriver:

Yeah, exactly. Looking into the history, exploring it. And then also, talking to people who are working on the other side and who are concerned more with the social aspects and policy issues. And this includes racism and sexism, and those are deeply baked in our societies. And maybe some aspects of those are in our genetics too. I mean, like I started out, we've survived because we've been aggressive and defensive, at least in part. We're also very good at working together and do that to a really nice extent.

Hannah Marchok:

You often will receive questions similar to, “do you really think that you can explain all of that through genetics?”  S ort of a genetic determinism sort of perspective on things?” So, how do you personally deal with staying away from concluding that genetics are the answer to all about humanity? Or do you keep a 30,000-foot view on the fact that your work is one aspect of it?

Mark Shriver:

I'm often surprised when people come with this sort of question because being in the field and being in the pilot's seat, I'm extremely critical and I deny most genetic effects and really want to see good, strong evidence that that effect is there before engaging in that. So I mean, to me, the world is nature via nurture. There's no split between culture and biology. Really, culture has driven much of what we see biologically. And really, trying to find out how that has happened, how culture has shaped our biology and vice versa, I think really engages the question directly. I'm not that interested in things that are just physical, physiological and not influenced by our experiences or our behavior. But I think addressing these things upfront and having a conversation about genetic determinism, and really flushing out too what's happened in the past. Phrenology, for example, the idea that somebody's appearance affects their behavior, and you can see a criminal face and a non-criminal face, these kinds of ideas, and all the racism that's built on that. Much of which is really a societal problem and not that individual scientists were themselves racist outside of their society. They were sometimes acting in very uninformed ways about it, and really not engaging critically with the society in those cases. So, I think those are easy problems to have, and they're going to happen again and again. But we need to recognize and really discuss with people what's really happening. And it's always going to be a social and a biological thing. We can't get away from that. We are biological beings, so everything we do is biological. But we're biological beings that are extremely social, and we're not individual from the rest of society.

Hannah Marchok:

One thing that I have heard multiple times through a variety of conversations related to the lab is it being made very clear to take a careful and conscious view of the work that we're doing, because we are in fact, identifying physical traits on people and sort of doing science that in the past, has been manipulated by the views as they're explained of their time. So, just to emphasize what I've noticed as a student working in your lab, is you really do have to keep that wide view. And also understanding the history of past scientists like you previously mentioned, who have used this but then been affected through their time and had their good science twisted in a way that perpetuates stereotypes or racist stereotypes, things of that nature.

Mark Shriver:

Yeah. Thanks for that. Absolutely. I think even just using words like Caucasian. I don't know if you've heard me, but if anybody says that in lab meeting or in my presence, I'm going to talk to them about it, because that's just perpetuating, like you say, the racialized society we have. And we can and need to speak up against that.

Hannah Marchok:

It seems like your research really extends out into quite a few branches of what would be considered scientific fields. So, could you just speak a little bit about what part of your research excites you the most? Is it the potential impact that it has? Is it getting to work with all the cool technology? What is it that you wake up in the morning and you're excited to go do your work?

Mark Shriver:

I really like brainstorming and being creative about the science. I don't know, that just seems to come naturally to me. I'm more of an intuitive person as well. So, sometimes managing large projects and just the day-to-day work is less my forte than trying to come up with ideas, and make things happen. You know,  contacting people, learning about new things. And the learning, I think, is really one of the things that drives me. Anthropology and science today, it’s a great time to be alive because there's so much happening. So much new technology with computer technology and biotechnology. And I think we're in a position to really discover some fascinating things and you know maybe develop technologies that can help people.

Hannah Marchok:

Absolutely. So, it sounds you really enjoy being creative with all of these things. One other thing that I'm interested in is, just in reading over some of your articles I've noticed that your work has often left you interacting and working with people from different countries or different areas of our own country. So, I would love to know how you think your work with people internationally has shaped your views of the importance of your work and maybe help to expand your perspectives on certain aspects of your work.

Mark Shriver: 

Science is very international today, and probably has been for a long time. That's one thing that really helps with the generation of new ideas and travel and also knowing people from different cultures, really living abroad, I think is fundamental to developing a broader perspective. And I was lucky enough to be taken to Denmark when I was in the first and second grade by my parents and we lived there…

Hannah Marchok:

That's so cool.

Mark Shriver:

I have vivid memories, yeah, of just the impressions that that makes, how things are done in one place versus another place. And even just seeing the cultural differences in two populations that are genetically very close, European-Americans and Danish. But you know, just seeing the diversity of norms and behaviors really help you reflect and then say, "Oh, those are things I believe." And maybe things that are just common to me are common sense or have been normalized. So, I think travel is an amazing way to get beyond that and to get over your local programming, which does include things like racism. Even if it's not overt racism, for example, there’s this phenomenon called the own race bias. It's also called the other race effect, and people are much better at individuating knowing that that's a person I saw already when they're working within a population they're familiar with.

Mark Shriver:

So this is one strong piece of evidence that much of our tendencies to not see people for who they are as individuals, or even just focus on the superficial difference between their population and your population or the populations you're familiar with, is shown through this phenomenon. It's also interesting that you can, through experience with others, gain the ability to individuate them. And so you can get over your own race bias by getting to know different people, seeing different populations.

Hannah Marchok:

Absolutely. So, as for some of your research specifically with facial features, I would love to know what implications your research could have in relation to how these traits evolved or were selected for over time. So, for example, things about certain facial features may make it more adaptive to live in a certain area, or could it be that culturally, these were deemed to be more attractive, or is it a bit of both?

Mark Shriver:

So, I think both the environment and the social interactions people have, have shaped the face. It's very reasonable to presume this. One reason is the sex difference. You know, sex differences don't evolve without sexual selection acting, either sexual selection or niche specialization where the males of a population could be more specialized for one kind of activity and the females more specialized for another activity. So, those are observed forces that can cause a sex difference. And we have a sex difference in a number of aspects, more so than most other living apes. So, humans have either niche specialized, probably there's some of that, but have also selected for the sex differences that are present. So, we've had contest competition, again getting to the aggression and violence and dominating situations like mates, mate selection.

Mark Shriver:

So, most people think about that as sexual selection, so a personal preference for an appearance of some type. But really that's just one aspect of how these sorts of sex differences can evolve. What we found looking at different populations, and Tomas Gonzalez from my lab, he did his PhD dissertation on this, how sex differences appear in the face across populations. He found that the sex differences seem to be constrained. So, males and females are a certain amount different, and that certain amount seems to be similar across populations. But the direction of that, the facial change, so which parts of the face were more different in one population versus another? Probably some necessity to recognize the sex of somebody. And another point that secures that is that we as humans are much better at recognizing a male face as male, than recognizing a female face as female.

Mark Shriver:

Now there's probably some layers of behavior and expectation that are due to our society and the consistent patriarchy that we live in, is a small part of that. But I think too, that we're probably this way because it's safer. If you don't know the sex of a person, they're at a distance, you're walking toward them, you're putting yourself at a greater danger engaging males when you could avoid them. So, recognizing a male face as male, I think, gives you an advantage and is a safer route.

Hannah Marchok:

Interesting. So, it seems your research has implications in a lot of other areas, but could you speak a bit more about what aspects of your research are interdisciplinary? So, for example, do you do all of the coding and all of the technology yourself for some of your research projects, or do you have opportunities to work with other people? And also speaking a bit about what you feel they're able to add to the end product of your research.

Mark Shriver:

I could do a lot of science by myself, but I wouldn't have time for working with others and working with students and postdocs and things. So you know really, you have to take on a management role at some point if you're going to run a lab that's more than just yourself. You got to have that. So that's part of it. So that's working with other people, and working across disciplines is really natural in this area. I mean, I actually never took an anthropology class until I started teaching them here at Penn State. I was trained as a human geneticist and human population genetics, more specifically. So, a big part of anthropology today is genetics. So, I'm interdisciplinary being in this department.

Mark Shriver:

Likewise, really a lot of good science today is synthetic, drawing from multiple fields, you know. And that's how many breakthroughs are made, bringing different fields together. And again, with the technology advancing as it has, there's lots of different tools you could apply to the kinds of questions that we're interested in. So yeah, keeping an eye on the technology and also the mathematical and statistical technology, the field work, the clinical work, you know each of these is a lifetime career, and you can't expect to be able to do them all. But you really need to be able to talk to people who do other subjects. So you know being widely and just generally educated in science is a really good start to that, so that you can communicate with statisticians or clinicians, or just people in the breadth of science.

Hannah Marchok:

Absolutely. So much of what Penn State these days is emphasizing in different majors I know is interdisciplinary work for the exact reason you’ve  just stated, is even though it may not be your career, if you want to be able to relate effectively with those careers, you have to have a strong basis of it. 

MUSICAL INTERLUDE

Hannah Marchok:

 Could you speak for potential budding researchers about what some of your biggest frustrations are that you experienced during your research process?

Mark Shriver:

Yeah. You know, at different stages in my career I’ve had different kinds of frustrations, but I think a lot of them revolve around time and effort, and really managing your time, making your home life something that's nice enough you don't think about it when you're at work, and vice versa, really getting your work done so you can have a peaceful home life. So, I think managing your time and really being realistic about what you can get done, setting good goals on a daily basis and weekly basis, and own up, those are fundamental to really having the effort and the time to find the money to work with other people and read the papers, make sense of things you don't understand yet as you're learning. All of those things can take some effort. And you have to build the time into your life for a career like this.

Mark Shriver:

I mean, in some ways, it's really very different from many other professions where you know you have work and then you have home. With science, I don't think you can get away from it. I've had some of my best ideas in my dreams, actually. You know, so it's constantly turning in there and you're working toward figuring that out. And that's really a lot of the fun parts. Some of the frustrations too, are having to deal with bureaucracies like granting agencies, universities and the IRBs and the material transfer offices, and just everything else that's part of doing science today. And I think some of the institutes could do better at supporting those kind of distracting activities that have to be done. But by calling on each PI, each professor to focus on each of those themselves, it's not always efficient. So, you face the typical kinds of struggles working inside large organizations. I think those are my main frustrations.

Hannah Marchok:

To whom do you go to help you resolve these frustrations? Is it a fellow researcher, a grad student, your family?

Mark Shriver:

Yeah. The administration. It's good to speak out, and I don't think I've had any problem doing that. So, contacting the person in charge directly to state what it is that's happened and what you think could improve it. But then also, you know having a solid social life with friends and with family and mentors too, who you become friends with. They often are older because they've gone through more of this process.

Hannah Marchok:

So speaking of your mentors, I've been very interested to know who some of your inspirations were in science.

Mark Shriver:

The advisors that I worked with are at the core of that. And it's a process of both you finding them and them finding you and that communication. So that's not something that's given, it's something you have to work toward. Find somebody you can communicate with, and then you have to be on the right wavelength. And yeah, so my advisors, Ronajit. Chakaborti, Eric Boerwinkle, or my two PhD advisors, and they are fundamental in shaping a lot of my thinking around these questions. They're both very active and well-known, and had some major breakthroughs themselves which inspired me. Ronajit  was a big part of this transition from population genetics as only looking at populations, to looking at individuals.

Mark Shriver:

Each individual is a population, just a really small one. So, that really inspired me when I was a young grad student and really looking toward the kinds of questions that I was curious about. And also, my post-doc advisor was fundamental. I mean, the others too, would have fun with what they were doing, but Bob Farrell was just amazing at really enjoying his work and having fun with it and not taking it too seriously. One of his favorite quotes was, “I t's good enough for government work.”

Hannah Marchok: 

(Laughing) That's wonderful. So, in addition to the perseverance and support system required to overcome any frustrations or financial barriers in the research process, what do you feel makes a strong research project?

Mark Shriver:

Well you’ve got to have a solid foundation in the literature. You know, know something about that area. It may be an area people haven't looked at much, but you got to read about it. I mean, if it's a project that you're interested in, or you have a reason to be interested in it, you want to do the research and discover about it, and read broadly. You want to have something creative about it as well. I think, I mean it's good to do replication studies and you know day-to-day science is important. And every time I do an experiment, I have positive controls and negative controls. To  be reality checks. So, that sort of work is essential and important, but really interesting projects are those that innovate and are creative in some ways. So, that's an important piece.

Mark Shriver:

And finally, to me, having solid data that can be measured, even if there are things perceptions or feelings about something, you can still measure these things in a way that you have numbers you can respect and you can depend on. And then having a good analysis that really can bring forth statistically solid results. So, you know that's kind of my bias. Not everybody thinks about the way to interpret data and understand them in the same way, but for me, just having solid testable results is an important piece.

Hannah Marchok:

You mentioned that sometimes your best ideas have come to you in a dream, and it's all affected by your work outside and how your work in the lab influences your life and vice versa. So, could you share an example of a creative research idea that has come to you in a dream?

Mark Shriver:

Well, um sometimes it's hard for me to know if I'm dreaming or awake, I'll say that first. (Laughs) But one idea that I clearly recall coming to me early in the morning, in that waking up time, and it was the name for a molecular method that I had developed. So, a colleague and I developed this melting curve snip analysis. And it came to me that I should call it “McSnip”, after McDonald's, “McSnip.” It's a very cheap and inexpensive method too. So, that was part of my thinking. But until that occurred to me, we didn't have plans to patent the method or really try to push it further, but we ended up getting a patent and had a company working with us for a few years on that.

Hannah Marchok:

That's so interesting. The creativity just doesn’t stop with you….You are very widely published by several high profile publishers such as the New York Times and the American Journal of Human Genetics. But I'm sure this has been a long journey to establish yourself. So briefly, could you discuss how you established your career, whether it was making certain connections, finally getting that paper published, et cetera?

Mark Shriver:

I was actually born a scientist. (Laughs) From a really early age, I remember thinking critically and looking for internal consistencies, you know,  inconsistencies in belief structures. And I rejected Catholicism at like 10 years old, because I couldn't see how things could happen the way. I mean, I could understand things could be figurative definitely, but did that really happen? So yeah, I got interested in chemistry and physics in school. But then, when I started to learn about biology and really how wide open that was, lifeforms are all these different types, and really got fascinated by that. And then, learned about recombinant DNA technology that had happened in the late 1970s, early 80s, and really moved in that direction because I saw that genetics was a really powerful way to investigate and, you know a powerful record of history and the evolution of life. So I wanted to move in that direction.

Hannah Marchok:

Very cool. So you've been a scientist from birth.

Mark Shriver:

Pretty much.

Hannah Marchok:

Awesome. So, as for what is next for you and your research, where do you see your research being 5, 10 years from now? And you can answer this in terms of technologically, or in terms of impacts that may be having at a certain point.

Mark Shriver:

My studies have been really long-term, and some have been going on for 20 years. Not that we're actively collecting people, but analyzing the results of that. So yeah, I think I'm going to be continuing on this path and helping to elucidate the genes underlying traits like facial features and the hair form and other things that vary between us. And then you know, working to help interpret the genetic findings in evolutionary terms. How could that change have come about? One thing I'm really curious about, can we differentiate sexual selection from natural selection on a molecular level in population genetics? A lot of questions haven't been addressed yet because there wasn't the data to test them with. So, I am continuing and we're going to have a new building for anthropology in four or five years.

Mark Shriver:

And we have a human sample collection suite as part of that. So, I really want to also move toward creating better datasets. Collecting interesting traits from people and collecting them from people in such a way too, that we don't run into the IRB problems that we have now. I mean, I think they're important privacy considerations. But I think these can be overcome and can be dealt with. So, I want to really collect data for the future that will be useful maybe for generations. I think that's a critical part that's sort of difficult today and has to be dealt with.

Hannah Marchok: 

Obviously, there are so many different types and kinds of data that you can get even just on one person, let alone one trait. So, when you talk about getting a like quality data set, what does that mean to your research? And does that differ for different kinds of research, different avenues of research, or is it similar all throughout?

Mark Shriver:

So, in terms of data sets, one of the problems with the data that we've collected so far is really the informed consent and the ability of the participant to act and to have a say in what happens to their data. The studies right now, the way they're made possible through the IRB is very short term. You work to get all this great data, but then you have difficulty actually carrying out the work, not because the participant consented. You know, they've consented to the work we want to do, but you end up just hitting road stops with the bureaucracy here and everywhere. These are similar problems that people face in pretty much any institute.

Hannah Marchok:

Right. Always the bureaucracy interfering. So, to kind of conclude here, I would love know if in a perfect world with no bureaucratic restrictions, no financial limitations, do you see an end goal of your work, or is the goal of your work to continue finding and discovering for as long as you wish?

Mark Shriver:

Yeah. I don't know if there's an end goal. I can see some efforts worth working toward and trying to see how we can use the understanding we gain to help people. And one of those that I've had thoughts about is ways that we could diminish racism and sexism perhaps, by illustrating the superficial nature of these kinds of traits. And also, maybe helping people empathize with each other by experiencing what it's like to perhaps be in a different skin, be in a different face. And there are great technologies now for this, they call them deep fakes sometimes, computer learning altering images. You could do that in real time. So, there's really the possibility of giving somebody the chance to you know, be in a call like we are here, or a classroom or whatever, but have a different ancestry background.

Mark Shriver:

They could be male, or they could be female. Really, they could probably easily feel some of the differences in how they're treated by others in that case. It just seems that's the kind of experience that maybe really good fiction can bring to us, novels. But it doesn't always work. We need more and more empathy. And I think the kinds of traits that Nina and I study are really the kinds that can perhaps bring some of that. Bring us together on a different level logically, and through scientific evidence.

Hannah Marchok: 

Interesting, it’s taking  putting yourself in another person's shoes to a whole new interesting level. I love it. So finally, this is my last question for you today. What is one piece of advice that you would give to the next generation of scientists?

Mark Shriver:

So my advice for the next generation of scientists would be along the lines of enjoying yourself and having fun with what you do. Science really an important human endeavor, but it's not done best when it's done seriously.

Hannah Marchok:

I absolutely love that. And it certainly seems like that curiosity and childlike wonder has led you throughout your career very, very well. So that concludes all of my questions. So, thank you so much, Mark, for speaking with us today. We've gotten much interesting information on a variety of the aspects of what being a researcher today means. So, thank you so much for that.

Mark Shriver:

Great. It's been my pleasure, Hannah. You've had some excellent questions. It's been a fun conversation.

MUSICAL INTERLUDE

Mark Shriver:

Tracking Traits is a production of Penn State’s Center for Human Evolution and Diversity. Our producer, audio engineer and musical theme composer is Cole Hons, and our logo was designed by Michael Tribone of mtribone design. 

If you enjoyed this podcast, please subscribe through your favorite app, and help us reach more people by sharing it with others and rating us on Apple podcasts. 

You can also follow us on social media and learn more about CHED and all of our interviewers and guests at our website, ched – that’s C H E D dot L A dot P S U dot E D U.