Steve Mirsky:    Welcome to Scientific American’s Science Talk, posted on September 26, 2016.  I’m Steve Mirsky.  On this episode—

Carin Bondar:    If you can imagine, these scenes from old westerns where there’s two guys standing apart from each other, and they pull out their guns.  And the first one to shoot is the winner.  Well it’s kind of like that for sex in flatworms, except instead of guns, it’s penises.

Mirsky:               That’s Carin Bondar, she’s a biologist, a TV presenter, and fortunately, a writer with a particular interest in sex.  Her new book is called Wild Sex, which was also the title of her popular web series.  Wild Sex in this case does not mean the end tables are getting knocked over.  She’s talking about sex out in the wild among animals who are not just boring human beings.  Bondar was in New York recently on a book tour.  We spoke at Scientific American.  Carin, another book I cannot read on the subway just because of the big title and cover picture.

Bondar:              It’s a bad plane read.

Mirsky:               Plane read, train read.  This is a book to read in the privacy of your home, maybe in the bathtub with some candles.  No.  Wild Sex, as you point out in the book—human sex is really boring compared to what goes on out there.

Bondar:              It is so boring and it is so easy.  It’s remarkably straightforward.

Mirsky:               Straightforward in that all the equipment sort of just easily goes with each other and—

Bondar:              Part A fits into slot B, and it generally does so without too much commotion.  Yeah, when you think about how sex occurs in the animal kingdom, things are just so much more than that, and I like to consider sex as not being just the act, although the act tends to be pretty—unfortunately violent for most animals.  Again, we’re lucky.

Mirsky:               And just the act, even stuff you’ve probably seen in nature documentaries is—you see apes or bears or antelopes or lions.  You recognize it as being basically the same.  There are definitely some important differences.  I think of lions and the antics they’re up to, but it’s recognizable.  But when you get out into some of the other creatures, especially when you leave mammalia, then things get really wild.

Bondar:              Things get very wild, and we know when we get into the invertebrate world, anything goes really.  And here is where we don’t necessarily see something we would consider to look like a penis or a vagina, and we see weapons really a lot of times other than what we consider to be genitals, though they’re genitals.  They’re getting ripped off, they’re getting stabbed in, ripped apart, stuck together, nibbled off.  There’s just so many ways that procreation can happen, and I love thinking about the processes of evolution that have occurred to make these things a valid option at hand.

Mirsky:               When you say ripped off, you don’t mean stolen from.  You mean ripped clean off.

Bondar:              I mean both, because there’s a couple instances where male bees, for example, will collect certain pollens to create a potpourri of beautiful scents for potential female mates as a certain species of bee.  And other males who aren’t as apt or lucky or clever at making this beautiful perfume will kill the male who made it, rip his legs off, and use them to court females of their own.

Mirsky:               Because the legs are where that stuff has been stored on the original collector.

Bondar:              Exactly, yes.

Mirsky:               So they just—basically, they steal—they murder the guy, steal his wallet, and buy some nice perfume and dinner for the lady.

Bondar:              That’s exactly what it is, and I love thinking about it in terms like that.

Mirsky:               So the book is divided into three big parts.  Before, during, and after basically.

Bondar:              Exactly.  People kind of get the idea that all I ever talk about is that one act of copulation, but the process of sex is so much bigger than that, and that’s why sex is involved in why and how you and I are sitting together today.  Sex has played a role in that.  People don’t often realize just how much sex plays a part in our lives.  Everything from becoming sexually mature and then looking for, finding, and courting that mate, actually engaging in successful sex with that mate, and then of course dealing with the aftermath of your sexual practices.  That is dealing with your offspring, and many different species have high levels of parental care.  Others not so much.

                           But again, there’s a whole gamut of how to make your offspring reproductively successful.  Because after all, what we want is to increase our biological fitness or the amount of our own genetic blueprints in future generations.

Mirsky:               And it’s even more than that because you also go into topics like homosexuality throughout animals, masturbation throughout animals.  The horse masturbation story was something I wasn’t aware of.

Bondar:              I wasn’t either, and this was something I found shocking.  And it speaks to humans, how we even in this day and age—sex is still a taboo topic.  We don’t like to consider ourselves sexual beings, despite the fact that our closest primate relatives, the pygmy chimpanzees or bonobos, are incredibly sexual organisms.  So horses are quite sexually active.  Males experience erection and undergo masturbation by rubbing themselves on things several times per day.  But of course in the equestrian industry where it’s all very prim and proper, this is very much frowned upon.

                           There’s just an unbelievable selection of anti-masturbatory gadgets and things you can buy to prevent your horse, your stallion, which is just ironic that it’s called a stallion, from masturbating, and this is politically correct to do so.  But interestingly, male stallion horses, the ones that win most of the shows, are totally sexually messed up because they’re—they have been sort of discouraged from engaging in what comes naturally to them sexually.  So that really sets the scenes for stallions not being interested in sex in sort of conventional ways.

Mirsky:               So they’re psychologically very disturbed.

Bondar:              Yeah.  As you mentioned earlier in the podcast, I love to do things you said, which is compare this to human terms.  What would it be like if it was in a human?  It’s crazy that sex is so taboo that these prize winning stallions are unable to do it.  What would that look like in a human world?

Mirsky:               Let’s talk about some of the—let me put it to you this way.  What did you learn when you were writing the book that just shocked you about what goes on out there?

Bondar:              I think that what I liked most about my journey in researching and writing this book was I discovered a couple themes that humbled even me as somebody with a very open mind and biology background.  How often homosexuality occurs, why it occurs in different contexts.  I have yet to find a species that doesn’t engage in some level of homosexual behavior.  The very well founded scientific theories for why this occurs are quite interesting and something we can learn a lot about.  And again, we don’t need to necessarily question these kinds of things in our own species because we, like every other species out there, is doing it.

                           Another one I found to be very interesting is the whole monogamy scenario, and I recently developed this term I lovingly called the perfectly perfect person hypothesis, and this is something humans do where we like to find a person, one person, who is our socially monogamous partner and our sexually monogamous partner.  Humans are 100 percent exclusive in the animal kingdom in terms of doing that.  This perfectly perfect partner does not exist anywhere else, and this is something I find tremendously interesting about our species.

Mirsky:               Yeah, even species that were long time thought to be monogamous, when they got studied really closely, true monogamy is really rare.  It does exist, but it’s really rare.

Bondar:              That’s right, and where you will see it is species of birds that have a high degree of shared parental care, and this makes sense because a female can extrude those fertilized eggs very quickly after they’re fertilized, and then mom and dad can go ahead and take turns looking after the eggs, incubating the eggs.  The same thing doesn’t happen in a lot of invertebrates, and never happens in mammals.

                           And so yeah, you don’t expect monogamy, but yeah, a lot of these species we’d considered to be the good family models for us to look towards, things like penguins or some of these other family dwelling animals.  With the advent of genetic sequencing where biologists were actually able to go in and say, “Okay, whose children belong to whom?”  We found out that sexual monogamy is an absolute no go.  Not in any of the species, even if they are socially monogamous.  A lot of species have a socially monogamous partner that they may share a nest or borough together.  They certainly may have sexual activities together, but those sexual activities are almost never exclusive. 

                           Males go off in search of other female partners, and of course they leave their female partners at home only to be discovered by a different male partner who is out searching for additional female partners.

Mirsky:               Right, one of the birds goes on a business trip for the weekend, and all hell breaks loose, but then they come back and reestablish their socially monogamous lives together.

Bondar:              Correct, yeah, because a lot of times, especially in difficult climate years where resources are harder to come by, it is important for both mom and dad to be contributing resources to a nest.  And sure, in a lot of cases, males may actually be contributing effort in terms of resources to offspring that don’t belong to him genetically.  But chances are, there’s another guy out there who is doing the exact same thing to some of his own offspring.  So in the end, it kind of works itself out.

Mirsky:               Some of the actual physical apparatus that goes into sex in some of these creatures is amazing, like the jousting matches. 

Bondar:              If you can imagine these scenes from old westerns where there’s two guys standing apart from each other, and they pull out their guns.  And the first one to shoot is the winner.  Well it’s kind of like that for sex in flatworms, instead of guns, it’s penises.

Mirsky:               We’re talking about flatworms now.

Bondar:              Yes, flatworms, and you’d definitely find these guys in the ocean.  So these are aquatic, so yeah, and also, another really important characteristic here of the flatworms is they are hermaphroditic, and that means that they’re both male and female at the same time.  And it’s in these hermaphrodites where you can essentially think they’re at war with themselves as well as at war with every other partner that they have.  This is where we see some of the really horrifying sexual practices.  So these two guys, erect penises out, standoff.  Because the first one to successfully stab, and I do mean stab—these things are razor sharp.  His penis, his her—you know, into the partner, will play the more male role in the future together with this partner.

                           Now that’s important because it’s very easy to be a male when it comes to sex.  You have sperm, you shoot it out, you fertilize the female’s eggs, and off you go.  I know, right?  It’s much more difficult and time consuming and energy consuming to be the female because first of all, eggs are expensive, and then second of all, eggs need to be gestated and dealt with and given birth to, depending on the species.  So it’s much more expensive to be a female.  So most hermaphrodites when they encounter a partner have a suite of techniques they use to manipulate the maleness, if you will, of their sexual partner so they can become the male and their partner becomes the female.

Mirsky:               Make the other one do most of the work.

Bondar:              Absolutely, yeah, and that’s how you’ll maximize your own genetic blueprints in future generations. If I’m only being the male—and that said, there’s always some femaleness going on because we have to assume these things have evolved over time, and there’s got to be advantages for being male and female, but for the most part—and these things are having sex a lot.  Several times a day.  So yeah, we want to just get that sperm out there, and also say to our potential partner, “Now stop having sex and use my sperm for all your eggs, and that will make me mostly reproductively successful.”

Mirsky:               So I was at a party recently, and the subject came up where somebody didn’t realize that all the kittens in a litter don’t necessarily have to have the same father.  So we looked it up, and it’s theoretically possible that every kitten in the litter could have a different father.  That brings me to the various techniques that you describe in the book that different animals have developed to figure out—it’s not a conscious process, but to determine which sperm they want to actually use with the females—which sperm they want to use to actually fertilize their eggs.  There are a lot of different versions of this, whole different types of animals do this.

                           Post copulatory sperm selection is wild, and let’s talk about that subject just a little bit.

Bondar:              Yeah, this is such an interesting topic because it’s something that eludes scientists to a certain extent.  It’s difficult to study how this happens, but yes, so many females—I lovingly call this chapter “Supertramps” because a lot of females have sex with a lot of males.  So it could be one female, 20, 30 males, but this does make a lot of sense if they’re able to utilize the DNA of different dads and have a very genetically diverse brood.  This can be advantageous in terms of living in very stochastic, or changing, environments, weather wise or landscape wise.  And it’s generally a really advantageous thing to do.  Just what the mechanisms are for cryptic female choice, it’s tough to elucidate, but interestingly, a lot of females have a very, very complex reproductive systems. And this has been studied a little bit more in the duck system.

                           If you know anything about ducks mating or fowl in general, it’s very violent and horrible.  I remember the first time I saw it I was at a little lake, and we were having a little picnic, and it was lovely.  These ducks came along and started—what it is basically is gang rape, and they pretty much keep the female in this water.  They almost drown her.  I was throwing rocks.  I was horrified.  I was absolutely upset by this thing, but I learned after this is exactly what ducks do.  This is unfortunately how it is in ducks.

Mirsky:               Not to mention, just take a second and talk about duck penises.

Bondar:              The duck penises, incredible.  From completely flaccid to totally ejaculated in less than a second, this thing is a spiral.  You’ve got to look up on Google the video of this thing.  It’s incredible.  This little spiral wormy thing just bam, out it comes.  So at least it’s quick if nothing else.  The female, of course, has a spiral shaped vagina to receive this thing, but what she also has is a very complex series of tubes.  Some are blind endings.  Others are tubes that lead directly to her ovaries, and so what the female can do, among other things, is alter her postures during sex to manipulate where certain sperms will go.  Some of the sperms will go to these blind tunnels and never be used to father the offspring, and others will.

                           So that’s an example where a behavior that the female can do is actually—and you wonder is she thinking about this.  What is the level of consciousness at a female duck that she’s going, “Nope, don’t like you.  I’m going to do it this way,” because there’s also a lot of physiological mechanisms at a level that perhaps precludes consciousness on that level that females will somehow—their bodies will allow the sperm of the most suitable suitor to reach her ovaries.  More likely than any other sperm.

                           This is where it makes it extremely difficult to study because how do you study that?

Mirsky:               But you assume on a molecular level, there’s some kind of assay that the female is able to perform and who knows what it is, the level of sugar, the level of protein, something—she’s measuring something with her own molecular machinery that then triggers the decision about which sperm to keep and which to throw out.

Bondar:              That’s absolutely right, so these are incredibly complex mechanisms that biochemists and behaviorists are working on together.  Another really interesting example that’s a little more tangible is in some spiders that use these wonderful things called mating plugs, and I often sort of refer to these as being like chastity belts.  Essentially, a female gets sealed up one way or another, whether it’s with something tough and hard, like a limb or detached penis, or something a little bit more synthetic, like a plastic like substance, something really sticky.  So in a couple cases, there’s spider species where the male will secrete part of this mating plug into his female’s genitals after he’s deposited his sperm.  Then if the female likes him, she will then go ahead and secrete the second part.

                           It’s almost like a two part epoxy if you will.  If she’s pleased with the mate, she’ll then be on board with essentially being sealed up, and this precludes any other males from bugging her and trying to get on board to have sex with her.  She will be essentially closed for business.  If however she doesn’t like the male partner, she can withhold secreting part two onto the mating plug and is free to go mate with others.

Mirsky:               You talk in the book, I forget which species it is, where the sperm may be stored for a year before it gets used.  This is internally.  They’re not putting it in the freezer.

Bondar:              Yeah, that’s right, and this is something that’s actually even relevant in our own species.  Biologists and physiologists are currently looking at how humans do that, too, because even other mammals, things like marsupials can store sperm for long periods of time, several months.  So what is it about the female physiology that can keep this sperm alive?  Because certainly, we know sperm out in that airborne sperm does not last very long.

                           But there’s some kind of PH mixture, whatever it is in certain female reproductive tracts—and I mean some females have structures called spermathecas, which are evolved specifically for sperm storage.  They can be one big ginormous melting pot of all the sperm she’s collected.  They can be very carefully layered in terms of first one in is on the bottom, next one, next one, next one.  There may even be some mechanisms by which the females can actually specifically choose a layer at a time when she needs to fertilize her eggs.  Crazy.

Mirsky:               Yeah, things are nuts.  But you also talked a lot about—well not a lot, it’s not a huge part of the book, but one of the chapters is all about maybe one of the most fascinating things in nature is the females who eat their male partners, and some of them aren’t even their male partners.  They just eat other guys who happen to drift by and think they’re going to be a part of it.

Bondar:              Light snack.  Yeah.  It’s just—and people often have totally valid questions about sexual cannibalism because how on earth can you continue to maximize your biological fitness if you’re dead?  And so what we have to keep in mind with a lot of these species is that several of the males will only have one or two chances to mate in their lifetime, so they’ve got to really go for the most bang they can get for their buck, pun intended.  And so a lot of times, what that means is allowing the female to perhaps feast on his body.  Because if you’ll note, in some of those praying mantis videos that are all over the place online, the male’s decapitated body continues to have sex with the female as she is devouring his head.  But let’s think about that.

                           She’s busy.  She’s not out there seeking another partner.  She is busy eating his head.  She will then go on to have sex with his body, but his sperm will have a much longer period of time to reach her eggs.  If he tried to get away, chances are she would go and seek another mate before his sperm had a chance to reach her eggs.  You brought up a case of where females just actually eat males, and this happens in a lot of different cases.  In one case, there’s a praying mantis that is indigenous to New Zealand, and this one is being wiped out at a very quick rate by an invading South African praying mantis species.

                           And in this case, they’re pretty closely related, and so males are attracted to the pheromonal signals, these fake pheromonal signals if you will, of the invading female.  So these invading South African females, here they are, they’re attracting the New Zealand males.  They’re eating the New Zealand males before they have a chance to have sex with anybody.  So you can see how this is a very effective strategy for wiping out the indigenous species.  It’s crazy.  And other spider species, there’s something we call aggressive spillover.

                           And this is a suite of characteristics that are inherited altogether.  Some of the characteristics are great for biological fitness for the females.  They’re larger, they’re more _____.  They have more eggs, but they’re also very aggressive, and chances are they may just simply eat males.  Go around, snacking on males because they’re pissed off at the world.  And they’re not generally very selective over the males they have sex with.  Interestingly, the females that don’t have this suite of characteristics, the non-aggressive spillover females, the weaker ones if you will, are the ones that are actually exerting selective pressure on the males because they are choosing which males they copulate with.

                           But the aggressive females, no, they’re just out there being crazy.

Mirsky:               And here is—this scenario where the male is mating and being killed is where you—it’s really helpful to think of in terms of the selfish gene kind of outlook where all that matters is getting those genes duplicated and passed on to future generations because that’s how we’re going to be measuring fitness is in terms of the number of genes that wind up being passed along and spread out into the environment there.

Bondar:              That’s right, and that’s what we ascribe—we biologists ascribe.  So all animals out there – this is what they’re trying to do.  And interestingly, this gets into some topics that are worthy of thinking about when we talk about us, mammals, primates especially.  Because humans are so different from that.  Humans are often doing things to totally limit our biological fitness, you know.  We’re using birth control, we’re exclusively having homosexual sex.  We’re doing all sorts of things that don’t maximize our biological fitness.

                           So I love thinking about the line like where is that line where animals start going, “Huh, you know, I’m busy today.  I don’t necessarily want to spend all my time and energy maximizing my genetic blueprints in future generations.”  These are questions that aren’t answered yet, but they’re extremely fun to ask.

Mirsky:               I’m busy today, I have to wash my fur.

Bondar:              Right.  You see certain species of baboons, olive baboons in Nigeria, for example, there’s this African black plumb that flowers at a very specific time of year.  The fruits become available, and the females, even though these are totally generalist feeders, meaning they can eat pretty much anything.  But when the plumbs are available, the females go for the plumbs.  The males don’t, the females do.  Now the plumbs themselves contain high levels of progesterone, and they effectively shut down the female’s reproductive system much like the contraceptive pill does for many, many millions of human females.

                           And you know, biologists are all up in arms about this.  Well there’s got to be something, maybe in future reproductive seasons, this means females will be able to have more offspring, and so on and so forth.  But you know, maybe they just want a break.  Maybe they do, Steve.  I certainly did.

Mirsky:               You had four kids.  What are the exact words at the end of your book about that?

Bondar:              I don’t want anymore.  I’m perfectly happy with the level of biological fitness I’m contributing to future generations.  Thank you very much. 

Mirsky:               That’s it for this episode.  Get your science news at our Web site, www.scientificamerican.com, or you can follow the announcements of the Nobel prizes in the sciences on October 3rd, 4th, and 5th.  We’re planning podcast coverage of the prizes, and in the coming weeks, we’ll also talk about what fish know about training your cat, and we’ll have more audio from my July trip through the Grand Canyon.  And follow us on Twitter where you’ll get a new tweet whenever a new item hits the Web site.  Our Twitter name is @sciam.  For Scientific American Science Talk, I’m Steve Mirsky.  Thanks for clicking on us.