Why we love this episode:
In this second episode of The Period Podcast, Dr Clancy speaks to Dr Elizabeth Rower, about why we have periods. It’s a fascinating conversation that will leave you feeling empowered periods and their purpose! You’ll also learn some pretty cool anecdotes to share are your next dinner party - WHO KNEW that they’ve trained rhesus macaques to use tampons?! Okay, so maybe not dinner party, but the next time someone is talking about how hard they find it to use a tampon, throw this fact in their face! Well, or just be nice.
Anyway, from evolution to where we are today, this episode covers it all. So hit play, or go and listen to it on your favourite podcast app. You won’t regret it! As always, we’ve transcribed it for you if you’re one of those people who likes to read and listen, or just prefers reading!
Listen & Learn:
I'm just still reacting to the fact that someone actually trained rhesus macaques, to use tampons.
This is period podcast, episode two. My name is Kate Clancy and I'm a professor researching periods, how they affect our life and how our life affects them. Today we're going to learn what a period is biologically, what it's made of, why we have it, and what it means. I've interviewed Dr Elizabeth Rowe, biological anthropologist. She studies menstruation, the uterus and genetics. Welcome Dr. Rowe. With, let's sort of start at the beginning. What actually drew you to the field of anthropology and why did you become an anthropologist?
So my answer to that question's, I wasn't interested in anthropology initially. I was interested in science. My dad's a chemist. I grew up in a house where science was okay. I always knew I wanted to be a scientist. Since the time I was a really small child and I was always also interested in human evolution. I remember having little picture books with Lucy and Australopithecines and just ancient humans. Because, I grew up in a household that really supported science. So I've always been interested in that human evolution particular, and I've always been interested in how the science of human evolution can be used to explain how humans are the way they are. It's what kind of drew me to the study of human evolution. So I kind of got into anthropology through the focus that one of the branches of anthropology has on human evolution.
And of course that's biological anthropology because that's the area of anthropology that uses evolution to answer questions about what it means to be human. So I was drawn to anthropology because of that, but I went to grad school in anthropology and I've been working as an anthropology professor for the past couple of years and I found it enormously enriching actually to be an anthropologist to learn about other branches of anthropology aside from biological anthropology. I've just really found it enormously enriching to be exposed to archaeology, linguistics, and all of that kind of stuff. So it's been an interesting journey. I can, I can definitely say that. Yeah.
Is there anything in particular you knew, when you would talk about this way in which it's been enriching to work with and learn about other sub-fields? Can you give an example of that?
Yeah. Well I guess what comes to mind is Sapir Whorf, it's a scholar from linguistics and kind of the central idea is really kind of turns the way most people think about language on his head. So a lot of people think that we use language to communicate ideas.
That's kind of a basic idea that most people have. And so some people kind of find it frustrating when other people talk and they don't seem to be communicating information.
But one of the things that Sapir Whorf was actually two different scholars, but the kind of ideas that they proposed were rather than the idea that language is just used to communicate ideas that actually language changes how we think about the world.
So one of the kind of classic examples of that I think is related to colour. So I think for example, in Japanese they don't have a colour that distinguishes blue and green or something like that. And so that affects how they talk about streetlights. Basically the idea that how we think, how we talk about things, can actually influence how we think. So it's just one example.
Well Nazis seems especially pertinent to the kinds of work that you do. Actually I'm seeing as you study periods in menstruation and endometrial function.
But why don't we start by figuring out how you got, particularly on that path, what drew you to the study of periods and menstruation?
Well, I think I have even this is a kind of a dry scholarly interview in some ways. I mean we're talking about science and things like that. I do actually have a serious sense of humour. And I think one of the things that drew me to the study of menstruation, is that menstruation is not something that's ever seen as serious. It's not worthy of study unless we're talking about in the realm of women's health and gynaecology and something's going wrong. It's just gross shouldn't be talked about or it's shameful or it's just silly. It's just not something that serious science should be used to study. And so I think I liked that kind of, I'm going to use science, serious stuff to study something that most people are embarrassed to talk about or think is kind of silly.
And I think also like this juxtaposition of something that is so feminine or so often thought of as being feminine. Menstruation is something that so many people think of as being classically masculine. So like natural sciences or what some people call the hard sciences. I don't like to use that term, but I like that juxtaposition because I think there's some baloney in this notion that hard science or natural sciences is inherently masculine. Of course it's not. And I don't even think that there's really anything to say about menstruation or leaving inherently feminine. Yes, women menstruate. But there's more to it than that. It's not just something that women do. So yeah.
Yeah. I think it's funny. So we've known each other for what I think 11, was it 2005 that we met? We've known each other 11 years now, I think.
Something like that.
Cause I think it was the HBA APAs in 2005 and.
what's interesting is I feel like your origin story is kind of similar to mine. I like leaned towards anytime, I was talking to a colleague and they started going, Oh gross. I was like, oh clearly that's the direction I have to go in. Like I had an explicit conversation with my undergrad advisor, and I was talking about how fascinated I was. There was this whole aspect of my undergrad project, my undergrad honours thesis where I was like, oh I really want to study this stuff with periods and I want to talk about menstrual blood. And he wrinkled up his nose he just went, ew and I was like, Oh, okay. Now I have an idea of what I want to be doing.
Definitely. Yeah, yeah. I think that's kind of the same thing.
Well I mean my advisor was at least in graduate school because I was in chemistry and undergrad and so I didn't do much anthropology as an undergrad, but my advisor was pretty supportive of it. She was at least with my interest in the evolution of menstruation though, she was always focused on like, well how do you study that?
Come up with a hypothesis. So she was very much like this is science and how can you do it? But yeah, so I guess we're really on the same page with like, Oh it's gross. Well if it's gross, first of all, I mean I think it's worth even discussing is it really gross?
If it's something that's part of your, not everyday life but you know pretty frequently a part of your life is it gross. Does that make you gross? Cause I mean, right.
So, I mean, again, to some extent it seems like you sort of moved in the direction of, and again it is just so delicious this moment where you get to say to these people who have this very masculine idea of science. I'm going to take something that you think is really feminine and in fact really gross, and I'm going to use your methods to study it.
I'm going to use male science methods to study all this lady stuff.
Do you feel like there are any life experiences earlier in your life that you talk about coming from a sciencey household? Yeah.
Anything that can made you head in this direction?
Well, I wouldn't say it made me head in this direction, but there's one story from growing up. I mean it's a period story, so of course it's got like weird embarrassment stuff associated with it.
So I'm the oldest in my family. I have three younger siblings and my mom was out of town for some reason and I was kind of helping out with the household tours and think I must have been in like late high school, early college age. And I noticed that my youngest sister had got some blood on her bedsheets, and at dinner time I said something to her along the lines of, Hey, don't forget to change your sheets, which was maybe more busy body than I needed to be. That kind of thing. All right. I don't remember her response to that at all. Maybe I embarrassed her.
I am sorry if she hears those to her, sorry Rebecca. But later on my dad came to me and said, your brother was really upset that you mentioned that. And again, all I said was, Hey, can you change your sheets? Not like you have disgusting menstrual blood all over them.
Right. And I didn't know that my brother had any idea about that and my dad and I ended up getting in this big fight, okay. About it. And it felt like really unfair and ridiculous. And I felt like if my mom was there cause she was out of town, if she'd been there, she would probably said something. So like definitely my dad's like this natural scientist and he was like telling me that it really upset my brother that I dare, not even really mentioned menstrual bleeding at the dinner table.
That really made me feel like, okay this is for some reason not something that my dad is okay talking about.
But what's interesting about the whole thing is, okay, so I did this whole dissertation project, totally about periods and unstrung bleeding and stuff like that. Who was there at my dissertation defence, my dad, and my mom and some of my dear friends. So they were there and I remember looking at my dad as I was talking and he clearly understood what I my project was about and he clearly seemed to approve of like, yes, that's the right method. You did the right thing there. Your results are accurate. There was none of this like squeamishness cause it was 100% in science.
Right. So I don't know, it was an interesting experience with my dad and with period.
I do actually have some sciencey kind of questions for you since you are. Sure.
I would say the resident minstrel expert of this episode. Can you tell me why we menstruate?
Sure. So there's a couple of ideas out there that try to explain from an evolutionary perspective why humans menstruate. There's some crazy ones out there like that we meant straight basically to get rid of any germs that might get into the reproductive tract, that are born by sperm, that we get exposed to through intercourse. If that was true, we would menstruate every time we had intercourse. Clearly that's not how it works.
So I like to mention, I always bring that one up is kind of a straw man because it's not, a really great argument. And the scholarship has really moved far away from that. What I think is going on is actually a combination of at least two factors, and they're related to features of pregnancy in humans and other animals that Menstruate. So first of all, that's something that's important to understand.
It's not just humans that menstruate, its other animals, predominantly other primates. So monkeys and apes. But there's like elephant shrews and some species of bats. It's kind of weird, some people think dogs menstruate.
That's not true menstrual breeding cause it happens at a different point in their ovulatory cycle so to speak and their reproductive cycle. But anyways, so let me tell you what I think is going on. In all of the mammals that happened to menstruate straight, and again that's mostly primates with few exceptions, but not all primates importantly. In all those animals that do menstruate, there is a pretty intimate connection between the mother and the foetus during pregnancy in terms of access to mom's blood supply. So the foetus really has this really great access to mom's blood supply. What happens in order for that to occur, that intimate connection, the foetus basically digs really deeply into mom's uterus to get out her blood supply and that happens at during the early stages of the development of the placenta during early pregnancy.
And so in animals that don't menstruate, you don't see that intimate connection. You don't see the foetus really digging so deeply into mom's uterus. The important thing to realize is that while it's great for a foetus to have that kind of access to mom's blood supply, it's great for developing foetus because you can get those nutrients and the oxygen and so forth. It's actually potentially dangerous for moms. A foetus that is a really aggressive digger so to speak, could really harm mom's body. So one of the things that moms do and species that have used aggressive digging foetuses is they basically put up a special tissue that acts as a shield against the foetus.
What's interesting though is that some species that put up a shield actually before pregnancy even occurs, it's sort of pre-emptive. And that basically protects mom. That's mom protecting her body from an aggressive foetus before one's even there. Okay. So you have this aggressive digging and you have a shield. So you have these two things and it's shields put up pre-emptively.
It's a pre-emptive shield, I call it sometimes pre-gaming for pregnancy. So what's interesting though is that, that shield is lost if pregnancy doesn't occur. It's lost actually after pregnancy but it's lost if pregnancy doesn't occur and that tissue is lost as part of menstruation, as part of menses.
I like your metaphor. I've never really heard it as like a dig deep kind of, I really like that. So if I'm understanding it correctly. Cool.
Women are, at least of the species that are menstruating, and in particular among women where we need to create this shield to protect ourselves from this really invasive embryo and foetus. We have to pregame and actually have this shield ahead of time. And that's sort of the consequence of that is since plenty of these cycles aren't conceptive, is that you end up having some shield basically to shed at the end.
Does that make sense or is that representing what you were saying? Yes, that's correct.
So what is the shield made of? Cause I feel like this is the thing that when I talk to women, this is the thing that I feel like they are really curious about but don't necessarily know like what is menses?
Well so menses is a combination of a couple of different things. That shield is just tissue. That's what we call just an endometrial stromal tissue. It's just sort of a part of the lining of the uterus that has regenerated every month. Its purpose is to basically act as that shield and so it's then lost. So it's just specialized tissue that exists for that purpose. And on top of that, of course there's blood as anybody who's ever menstruated knows, there's definitely blood. That's part of it as well.
What's interesting though is as menses itself has other components as well. So it's got an immune components.
In part because that tissue and blood that is shed would be a great place if you're a microorganism to live. So there's stuff that kind of prevents microbial growth. But I would also say that there's the stuff related to the rebuilding of tissue because that tissue is getting regenerated in the uterus. So there's some of those immune factors that are involved in that are shed as part of menstrual bleeding.
So you did start to mention your own research a little bit. Can you.
Can you tell me what your broad research goals are, the kinds of stuff that you're interested in and maybe a little bit about the stuff that you've published so far.
Well, so my research thus far has really been focused on understanding two different things. One is how menstruation evolves. I'm getting at that question of why do we menstruate? And also looking at what contributes to variation between women who menstruate in terms of their menstrual periods. So we were talking earlier about what I think is going on and in terms of explaining why it is that humans, menstruate, and I mentioned that many primates menstruate, monkeys and apes, but not all primates menstruate. So one of the things I was able to do, I was actually given a really cool dataset on menstrual bleeding in nonhuman primates. So monkeys, apes and actually animals like lemurs and lorises and things like that. That are captive primates at zoos across the United States. I actually not, not only got data from zookeepers on whether these animals were bleeding or not, but how much they seem to be bleeding, the relative copiousness of it.
So that's been a really exciting dataset to work with. I was basically able to confirm that indeed you do have to have kind of both a kind of pre-emptive shield. You have to pregame for pregnancy and you have to have this kind of especially intimate connection between the foetus and mom. You have to have both of those things going on in order to observe menstruation in primate species that menstruate.
In primate species that were no menstruation is observed, those are species that don't have that intimate connection between mom and foetus. But it's so pretty interesting. There are some species of primates where there was no data, where they didn't observe any of the members of that species of monkey for example, menstruating and in some of those species. We do know that yes they have both of those things going on.
They have both the pre-emptive shield and they do they pregame for pregnancy and they have that intimate connection between mom and the foetus. I want to investigate that further with that particular data set. So I'm going to look at things like maybe body size contributes to it cause generally speaking, one might think the bigger mom's body, the thicker the lining of her uterus is going to be, the more likely it is that if she loses menstrual blood it's going to be visible externally. Right. I mean they were just watching these primates go around in the zoo. They weren't taking samples from them or anything like that and so it's possible these species could be menstruating, but it's just resorbed internally and we don't happen to see it.
The other thing of course to think about is whether or no, is the size of the brain in the foetus and these species or the overall size of the brain in this species, especially relative to the body size because the whole idea about the intimate connection between mom and the foetus who the blood supply. Is that you have in most primate species, they tend to have pretty large brains, a foetus tends to have a large brain and large brains need lots of oxygen and they also need lots of nutrients and I wanted to see if there was kind of a contribution from brain size there as well. So I began looking at those kinds of questions to get out with this dataset. As I said, I think it's at least two things. It's quite possible that there may maybe some other things.
And if you look at the amount of menstrual bleeding, menstrual fluid that humans lose over the course of a menstrual period, even if you consider differences in body size, compared to other animals that we do have good data on. We have good data on rhesus macaques for example. They don't lose anywhere near as much menstrual fluid as we do. They've actually trained rhesus macaques to use tampons and captivities. We have a good idea of how much kind of a volume they lose and it's just not that much. So you know what's going on is it's not just the body size. Right?
Is it our big brains? Even though we're larger animals than they are, we have very large brains compared to our body size, compared to them.
I'm just still reacting to the fact that someone actually trained rhesus macaques to use tampons.
Do you remember off hand how many mils did they lose in a cycle?
I think something like six mils in a cycle.
Which for human, nothing.
And I think we're only like three or four times larger than them. So we're talking about 10 times at least as much menstrual blood loss.
But we're not that much bigger than them.
So what I remember back from when I first started looking at this stuff, which is 15 years ago now, what I'm recalling from some of those papers is what they posited was the average amount of blood loss per cycle was around 30 mils for a woman.
I'm wondering now this again, so that my reading of that was 15 years ago and a lot of those papers that did the preliminary work were from the 60-70's. And that was sort of in contrast to, they were trying to determine like what is considered a pathological amount of menstrual blood loss.
So where should the cut-off for menorrhagia be? Should it be at like at 60 or 80 or 120 mils? Yeah.
So what do you think the normal averages in 2016, I'm guessing it's higher than 30.
Well, yeah. In my studies, the research I did something different than what they were doing. You're talking about the, I think of them as a Scandinavian tampon squeezers.
Like the 1960s mostly, people from Scandinavia doing this research where they were squeezing tampons and pads. I mean I was doing pictorial stuff, so I was having women just kind of mark on a chart how much training they saw in their pads and tampons. I was seeing on average in my study, 70 mils per cycle.
It was pretty close to menorrhagia. They're cut off for menorrhagia, which is 80 mils.
And I think there were a number of actual individuals in my study who would have met their criteria for having menorrhagia, too mentioned on menstrual bleeding. So, I don't think we have a good handle on it.
It's just not one of those sayings that gets a lot of attention. It's not something that's studied in biomedicine unless they're studying pathology.
But even then, I don't think there's a whole lot of interest in getting to the root of the pathology of excessive menstrual bleeding however you might want to define that. I think a lot of it is what happens from talking to so many people who want to talk to me about their horrendous periods.
I get the impression that a lot of it is, okay, well you have horrible periods, well. We'll put you on the pill and if that doesn't work, we're going to do maybe endometrial ablation or something like that and some of them can actually do get relief from that kind of stuff. So it's not like that's effective or anything like that. It's just that we don't know.
We know very little about what contributes to what might be considered pathological menstrual bleeding. We know even less about what contributes to a normal variation in menstrual bleeding.
We don't know very much about the breadth of that variation. I mean in my study, most of the people in it were in the average age was something like 20.
Cause they were mostly college students. So for that small population that was average. But you know in terms of looking across the United States or globally, I don't think we know. I mean the average length of time over which the women in my study had their periods with something like five and a half days.
Per cycle over three cycles, consecutive cycles. I've heard other averages in other countries being something like three days, predominantly in developing countries. So I don't know if there's something going on with that like related to nutrition or something like that.
What's interesting too. I mean just the fact that what was normal for your sample.
Was borderline considered pathological.
And again there I do remember reading a paper some years back that was like his 80 really right or would it be 120 and are we capturing too many people or classifying too many people.
As like menorrhagic with this lower value.
Cause certainly from, I know you have just one year's is just one dataset but still it makes me think maybe it's normal to bleed at least in industrial, you know American or sort of developed countries.
It's normal to bleed a whole lot more than 30 mils.
As opposed to, no that classifies you as abnormal does. How much or when we menstruate tell us anything about our health. I mean cause you are making that nutrition point earlier. What can we sort of help our listeners understand about that link?
It's very difficult to say. I think in an individual circumstance what might be going on unless you know more about underlying hormones and usually you're not going to get any information about that unless you go see a physician. But even then they don't often collect daily cycles. They just check like daily samples of your hormones. They're just taking one blood sample to see are you way out of range or are you in the normal range for hormones?
Some women do have really erratic cycles where they don't have a period for maybe months or they have like a period every few weeks or something like that. That whenever I hear something like that. To me that sounds a lot like polycystic ovarian syndrome, which is an endocrine disorder.
So when women have that, that's something definitely to get checked out by a physician because that's a hormonal disorder and obviously you can have other problems alongside of that. But that's an issue, in terms of how much menstrual blood's lost.
Yeah, so we've been talking about the issue of menorrhagia, which is what's basically means pathological menstrual bleeding or too much menstrual bleeding. There's a clinical criteria for that. That was, as we were talking, all kind of decided in the 1960s and it's related to this cut-off that they kind of came up with based off of the statistical analysis and its association with iron deficiency anaemia. One of the things I found really interesting just talking to women anecdotally about their periods is that, some women have found that they lose just incredible amounts of menstrual blood. In ways that really cause not just inconvenience but, pretty serious suffering for them.
So one woman for example mentioned to me after a talk I gave about the evolution of menstruation, she said, I can't make it across an airport terminal without going to every single bathroom when I have my period.
It's pretty breathtaking because nobody should have to live like that. That just sounds like a lot of suffering to me. And she mentioned that she had kind of a low grade bleeding disorder and then somebody else I knew said, yeah, I've always had these really heavy crazy periods. They last for a long period of time and I just had some minor surgery and when I woke up they told me that they had to me extra clotting factors or whatever because my blood wouldn't clot.
So one of the things I'm really interested in is just this connection between between low grade but pretty common bleeding disorders where maybe you're not producing enough of a clotting factor or something like that.
And what we might consider to be excessive menstrual bleeding. I think we really need to get on the whole menstrual cup trend and use those to our advantage and research because you can really answer those kinds of questions with that stuff.
Yeah, I think I've only seen one paper that's sort of a proof of concept paper using menstrual cups for research.
You have a woman wear them for I think either two or four hours and then you collect the menstrual fluid and you can do all sorts of Eliza's which are just again, for our listeners that are not nerding out to the extent that we are, these are just enzyme immuno assays.
Basically it's like glorified recipe following in the lab to help you measure hormones and biomarkers and all sorts of different fluids and so there are ways that you can do that. We've done that in our lab and I'm sure your work, Elizabeth with, Pee, fecal matters, saliva, blood, blood spots, but it turns out menstrual blood, you can also collect the same information, sometimes cooler information cause it's direct from the endometrium. Well Elizabeth, thank you so much for doing this. This has been really interesting. I feel like I got, what I really enjoyed was getting to learn a couple of things about your work that I didn't actually know or that you know, wait a minute I know I've read these papers, how did I not hear about these extra things. So that was really, really fun. Thank you so much.
Oh well you're welcome. It's been a real pleasure.
You know, I never intended this podcast to issue career advice but I can't help but advocate for the jobs of monkey tampon trainer and Scandinavian tampon squeezer. If you ever see these pop up on monster.com or Craigslist, I'd go for them. Same goes for any other tampon related careers to be honest. I kind of think tampons are cool. Anyway, emits the interesting menstrual methodologies and career choices. We did learn that there is a biological reason for periods. Periods come from having invasive foetuses who want to null more glucose and oxygen. If we were to let them null at will, it would be harmful for us and limit future reproductive capabilities. So the way we control their feeding habits and not overshare our own resources is that we create a nutrient rich barrier that both feeds them in the first trimester and protects us. This endometrial lining is necessarily thick, so thick that we can't just resorb it into the body when it's time to start a new cycle.
Humans are especially copious menstruaters and what can't be resorbed must be excreted, that's excretion is what we call menstrual blood. I'd like to thank Dr. Rowe for her great interview and tampon related expertise. She's just started using that expertise and her skills as a grant writer to support the menstrual hygiene initiatives of a non-profit agency called Childbirth Survival International. Go find her on Twitter @ElizabethJRow.
Excerpt: Kate interviews menstrual researcher Dr. Elizabeth Rowe about why we have periods.
Summary: In my first full episode, I interview Dr. Elizabeth Rowe, a PhD in biological anthropology and grantwriter at Purdue University, about her research on menstruation, and why we have periods. Dr. Rowe shares broad evolutionary insights about why people menstruate, as well as quirky tidbits about how researchers have studied periods over the years. Learn how scientists discovered how much monkeys menstruate, and which region of Europe seems to enjoy wringing out sanitary products.
Next week, I’ll interview Dr. Alma Gottlieb, a cultural anthropologist who also studies periods, to look at the other side of the menstrual pad on matters periodic.
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