In this segment of the Sexual Energy Series, Emily Willingham, Ph.D., and a co‑host explore the question of whether penis size matters for sexual satisfaction and reproductive success. They note that in humans, preferences for length and girth exist but are not decisive for overall sexual fulfillment. The conversation then shifts to the animal kingdom, contrasting absolute size (e.g., the blue whale’s massive penis) with proportional size (e.g., a microscopic barnacle whose penis is many times its body length), highlighting that size rarely determines reproductive success except in niche cases such as subterranean moles where visual cues are absent. The hosts discuss historical Taoist practices that matched male and female genital dimensions, labeling this as a human‑centric obsession. They also revisit the outdated “lock‑and‑key” hypothesis for penile adornments, explaining that while species‑specific morphology can help avoid inter‑species mating, it is not the primary evolutionary driver. Overall, the dialogue balances scientific evidence, comparative anatomy, and cultural anecdotes to assess the relevance of penis size across contexts.
Chapters
Bulletproof radio. A state of high performance.
You have a whole chapter about size.
I do.
Does size matter?
It's a funny. It's an interesting question in humans, actually. Not really. You can ask people who engage sexually with penises about what their preferences are. There's kind of a tie between a certain width and a certain length, but it's not the crucial be all and end all of sexual satisfaction for a lot of partners. When you get to other animals, though, gets kind of interesting. I sort of set up the size chapter as a competition and I awarded a gold medal, I think. But the way you determine size, you can do it in lots of different ways. Absolute size. In which case the blue whale is just going to be the big winner, right? Because it's a gigantic animal and it has this gigantic penis to go with it. But if you're looking proportionally, there's this almost microscopic barnacle that has a penis as many, many, many times its body size. So it' that sense by far the big winner. It doesn't matter so much in terms of reproductive success generally. Although there are some specific examples where there might be a mole, there's an underground, you know, lives underground, can't see. And there might be some effect of penis size in with whom the female will mate because she can't see. So there's something. Since maybe at work I bumped into something. I don't know what that is.
In some forms of ancient Chinese practices around Taoism, they go to great lengths when they're matching partners to match the male penis size and shape to the female size so that they don't have reproductive problems where one is too big or too small for the other. That's the only kind of example of that that I am aware of in human practice. Is there anything there around it just doesn't fit in other animals or is that just because they're being a little bit obsessive about it?
I think that sounds a little obsessive on the human side. Yeah. We used to teach that animals had these kind of very interesting adornments on their penises because it was kind of a lock and key test to make sure you hit the right species. Because lots of animals make mistake. They just try to copulate with completely wrong species, which is, you know, it's an evolutionary dead end to do that. But now we found that it's not necessarily that so much. That's not what's driving it. It's not always a lock and key. So that actually doesn't matter as much. It does matter to get the right the right species, though, so I guess they get selected out if they do that too often.
