 Damn thing. That sounds sexy. Here I go. Here I go. Here I go. Again, girls, what's my weakness? Okay, then chillin', chillin', monin' my business. Your soul's a-looked around and I couldn't believe this. Welcome to NerdNight. This is a great and gigantic crowd. Thank you for coming. So we have one big thing we have to do before we even start NerdNight. It is co-executive president, et cetera, et cetera. Rick's birthday today. So I found this out like 30 seconds before, so I got you a cake to blow out, Rick. That'd be great if you could just come down here and blow it out, make a wish, chill out, mom. I borrowed it. I don't smoke. It's totally fine. Don't worry about it. So our first talk is gonna be Benji Kessler. And Benji Kessler's entire extended family is in the audience, apparently, which is very exciting. So this talk could be a little challenging for some people in the audience, and so I've tried to figure out how to, like, get you ready for this talk, okay? So there's this thing called exposure therapy. So, like, if you're afraid of the dark, they put you in the dark room, you freak out, and then you freak out a little less, and you freak out a little less, and, ta-da, you're not afraid of the dark anymore. Or you're afraid of flying. This is for all the people that are my age. You're afraid of flying, and so they push you up in an airplane, and they wait for the ding thing, and is when you hear the ding, you know, the pilot thinks the plane isn't gonna crash, okay? So you put on a plane, you're not afraid of flying. Or you're afraid of snakes. And so they just, they're throwing a big fucking pit of snakes, well, they don't do that actually in real life, but you get exposed to a lot of snakes, and you're no longer afraid of snakes, okay? Or the famous farsight cartoon, where you're afraid of lots of things like fear of heights and snakes in the dark, and they get them all done all at once, which is good. So we're sort of gonna do that. So Benji Kessler's talk, The Dong of Man, perhaps you've figured out has a lot of dicks in it. Like a lot, I know y'all have the internet, so you think you've seen a lot of dicks. This has a lot of dicks in it, all right? So I'm getting you ready. So sometime between the 23rd and 25th day of embryonic development, the mesoderm that makes up the urogenital sinus, due to some chemical injury or physical injury or some homeobox domain, incorrect programming. So that tissue can occasionally, one in 5.5 million births, bifurcate. Do we know what bifurcate means? Yeah, bifurcate means what you think it means. You can end up with two dicks. Okay, so now we've seen two dicks. You're about to see a whole bunch more dicks. Please welcome Benji Kessler to the stage. Hey, hello everybody, happy birthday Rick. Okay, so glad you're all warmed up. So since the beginning of time, one question has plagued the human mind. Specifically, what's up with penises? So I present you the dong of man. And today I'm gonna talk to you about the evolution of the human penis. How the human penis became the way that it is today. So throughout the animal kingdom, there are some very weird, very diverse penises. You can see the red and blue penises of the verbed monkey, the two penises, which is normal for a steak. Same thing with sharks, and then you've got your pokey seed beetle penis. You've got your, you know, you've got your harvest man daddy long legs penis, your spider with his two face penises, duck with a corkscrew, walrus, it's big. So penises can be super weird, basically. Why are they so weird? What's up with that? As evolutionary biologists, we think the evolution of penis morphology usually has to do with three top things. And that's a female choice, so female animals picking, which penises they like best, sperm competition. So if multiple males are mating with one female, whosoever sperm could actually fertilize the eggs, that penises could evolve to be better at that, or co-evolution, so the penises can evolve, the penis morphology could evolve alongside the vaginal morphology. So now back to human penises. Just so you know, I found this picture by googling lots of penises. At work. Which was not by far the worst thing I googled while researching for this. So human penises, it turns out, are weird too. And the question is, where do humus penises fit in? In evolution. So, in terms of evolution. So, what are some weird things about the human penis? I mean, it's shaped, if you look at it, shaped differently than the other ones I showed you on that diversity slide. It's got to start at its own shape, it's smooth. So I'm going to now talk about how we compare to other apes. And the reason that we want to do that, see here, there's some human penises. The reason we want to do this is because penises don't fossilize in humans well, and so we don't have a fossil record. So what we have to go on is comparing ourselves to our closest living relatives, which are the great apes. So if, especially our closest living relative, the chimpanzee, so if we look how we compare to our other relatives, penises, we could see what changes have happened over evolutionary time to produce the penises that humans have today. So, that's what I'm going to do. And I'm going to start telling you a little bit about how human penises differ from ape penises. Right now we've got a picture of a bonobo penis, a drawing, and a picture of the common chimpanzees penis, pantroglydides, right down there. And so these two species are equally related to humans, but you could see that neither of them, neither of their penises looks quite like a human penis. So we've got, oh this didn't come out that well, we've got, the average human penis is about 5.1 inches long and it's about, it's about 4.6 inches in diameter, or no, a non-diameter in circumference, so I think they're wrapped strings around penises. They, that's how they do it. Oh, also speaking of that's how they do it. For the length, they either stretch the penis, they measure from the back of the pubic bone to the end of a stretched penis, stretched flaccid. This is Jonah Falcon, he has the largest penis of any primate, about a 13 and a half inches. So, human penises are also smoother than ape penises. Smoother, that's a weird thing to talk about with a penis, penises are smooth, not all penises are smooth, that's a weird thing about the human penis, you might not think about. Ape penises have penile spines on them, which in addition to sounding really icky and probably actually being icky, are sensory apparatus that make the penis super sensitive. So, ape sexual encounters always last less than a minute because the hairs which are related to whiskers in a way actually make the ape penis super duper sensitive. Plus, human penises don't have bones. Ape penises do have bones. Yeah, so humans are the only great apes without a penis bone. Most primates, but not all I'll get back to that, most primates do have penis bones. They are reduced in the great apes in general and completely absent in humans. This is a picture of a bunch of penis bones, they're also known as bacula, baculum, singular. A lot of mammals have them. Also fancier, you may have noticed from the chimp and bonobo penis pictures that there was no mushroom tip. Get it? All right, because it's a mushroom. I'll get back to it. Immediately sized testicles. They're just right. Human testicles are larger than gorilla testicles. Imagine that, right? Gorillas are big. Bigger than gorilla testicles and much smaller than chimpanzee testicles. If you guys have ever seen like a dead chimpanzee preserved in alcohol, you would notice that their testicles are much, much bigger. I have, I don't know if you, I didn't expect it either. It was like a real surprise. I thought I was gonna see like a fish or something. But why? Why all these differences? Why, through evolution, did our penises diverge so much from that of our closest relatives and presumably our common ancestor with those relatives? So to figure this out, we have to go back to the dawn of man, which for anyone who didn't get the pun that I was making my title from, and we have to think about how early humans live and what their mating systems must have been like and sort of what kind of evolutionary pressures were on them and what drove penis evolution. So I'm gonna give a disclaimer. This is the only really tech slide I've got in the book of the talk, but since there's no fossil record of humans boneless penises and there are so many differences between human penises of those of our closest relatives, the study of the evolution of the human penis is highly speculative enterprise. The hypotheses to come are plausible guesses at best and unfiltered bullshit at worst. And saying that, I present you all of the hypotheses. So back to the test use size, what's up with that? The best guess is that it has to do with mating system in a lot of mammals, including in chimpanzees and gorillas. There's a pretty clear correlation with relative testicle size and the mating system. Specifically, the more males a female will mate with in close succession, usually the larger relative penis size to body size, or not penis size, testicle size to body size will be in a mammal and that's presumably for sperm competition reasons. If a female's mating with just one male, there's not gonna be sperm competition. Any sperm is gonna be the one fertilizing it, but if she mates with multiple males, whichever sperm gets to the egg gets to fertilization. So bigger testicles, more sperm, better competitor. So the idea that people have speculated that humans sort of original or natural and it's always kind of weird and problematic to say what natural things are for humans, but presumably selection pressures for humans have involved at least some sperm competition or more than gorillas where they're big alpha males will monopolize a lot of females and other males won't mate with them. So that's the first little speculation. Next, we've got the mushroom tip. And the reason I called it fancier beforehand is because it's, I mean, if you looked at the chimpanzee penises, they're pretty plain, right? They're just like tubes of different shapes. But the mushroom tip adds some complexity to it. And the reason I use this picture is because one hypothesis is that female choice for increased sexual pleasure is why the penis is more complex. And there's some evidence that in some insects, more complex penises will increase stimulation to females and that's what's led to the evolution of their morphology. So could be complexity for female pleasure or maybe it's for scooping. It has been hypothesized that the coronal ridge of the glands penis in humans is a sperm removal device. And this is backed up by the idea, by a test where they took dildos with and without mushroom tips and using a cornstarch mixture, which I'm pretty sure is just oobleck, oobleck, they saw which one scooped out more sperm. And it turns out it's like a lot more sperm get scooped out if you have the mushroom tip. So hey, so could be that. And it's not that, that outlandish because damselflies are known to do exactly this and scoop out sperm with their penises, the sperm of competitors. And this is the thing that animals do. So why not humans? All right. All right, now talking about the laculum, the lack of baculum. The boneless penis. The to prevent, might be that the bone is too big of a liability. You don't want that particular bone to break. Evidence for this hypothesis comes from the fact that as I said, most primates have penis bones, but there are a few that don't. That includes humans, gibbons, which are lesser apes, the ones that are like that. So they're always swinging through trees, like pretty upright, upright-ish kind of posture, penis breakage maybe. Same also spider monkeys, which are a little more upright and Tarsieres, I think Tarsieres. These ones don't comb me on, but I think Tarsieres, and which are all relatively upright primates and were the most upright primates by far. And so it could be just an upright primate thing that you lose your penis bone, so you don't want it to break because it's more exposed. Another idea is back to the female choice. It could be selection for flexibility of the human penis. By not having a bone, you could actually get a lot more bending action and more sex positions. This is, I don't know how clear this is, but this is a scan of two humans having sex. This is the woman and this is the man. These are the testicles and this is the penis. And you can see that it actually bends quite a bit. And with a penis bone, that's not really an option. So yeah, it could be back in the day, you know, whatever Sally Cave woman was just picking the dudes with the more flexible wings. Let's see, and the other one is, this one's sort of in a different vein, but one evolutionary biologist, I need to say that, this one. And an evolutionary biologist teamed up with a biblical scholar and wrote a paper saying that it could be that Adam's rib was actually his penis bone. And that explains why humans have an even number of rib, but don't have a penis bone anymore. So that's something to chew on. The other one is the lack of spines. Why is the human penis so smooth? And be another female choice thing. I found a great article on Cosmo about this. For you can't read it, it says lose the spines. Penis spines vibrusae will make your man finish way quicker, choose to mate with men with reduced spines to increase the duration of sexual encounters and pleasure for you and your descendants. It's really like Cosmo covers everything these days. And so yeah, as I said, penis spines really sensitize the male penis and make sexual encounters super short. So it could be just for, just selection for pleasure. Other people have put forth the idea that longer sexual encounters have led to better pair bonding, which has even downstream led to the formation of human society in general. So people put a lot of weight in this. I don't know. People always say everything is the reason for human society, but I mean, who knows? Could be this. All right, and then last but not least, hugeness. Why are human penises really big? So could be another female choice situation. It could, they did a study on modern human females asking which simulated male images they found most attractive and then penis size, larger penises had an effect of increasing attractiveness. So it could be that with the rise of upright posture, the penis became more visible and then was then subject to more picking and choosing by females. They could get a little more information when they're picking between males because they could see the penis right away. Other people have said it was another sperm competition thing that bigger penises, especially longer, could do more scoopage or would be more likely to fertilize. It also could be co-evolution, as I mentioned at the beginning, it could be that human penises just got big because human vaginas got big because humans have bigger brain sizes at birth than other apes and so that makes sense that that could drive up the evolution of, drive up the size of the human vagina and an increased size of a human vagina could cause an increased size of a human penis and there's lots of examples.