The evolution of size matters

It would be more interesting if we had access to penis size information from before the time of clothing to compare to information from today.Would we find an increase in penis-size variability over time as selection pressure disappears?ABE: Are there any known clothing-less cultures that might make this research possible?Edited by Jon, : No reason given.

Of course. And if the preferred mates are statistically those with larger members, then the tendency will be for the population to evolve larger members on its men. Over time, the entire population would have statistically larger-membered men even to the point, perhaps, that no male would have a member as small as any male in the original ancestor populationdeformities aside. In what way? So-called 'minor differences' are what evolution is all about. There are other sexual characteristics in humans that are also unusually evolved; it's not just penises.JonEdited by Jon, : No reason given.

It's not about whether you reproduce or not but about how many times you reproduce.Assuming everyone's penis size is easily determined (folks are naked, for example), a man with a larger penis will mate more than a man with a smaller penis. The man with the larger penis will have more females who are interested in him (because females prefer his larger member) while the man with the smaller penis will have fewer females who are interested in him (because they mostly prefer the other guy's larger member).This difference in reproduction frequency is all it takes to create changes in the whole population, especially when the changes are really minor like the size of the penis. No, but they are getting more. Even selection pressures that are nothing more than a preference are enough to direct evolution down one path as opposed to another. Your belief on how strong those preferences have to be doesn't hold up; even a slight preference for a particular trait is enough to evolve toward possession of that trait given enough time.Jon

I'm speaking from the study linked in the OP. If women prefer larger penises, then men with larger penises will get more female attention. None, but life in 21st century civilized America is far from comparable to the societal, environmental, and cultural conditions of our earliest ancestorsthose in whom larger penis size first began being selected for.

No one has said that nothing else goes into the decision process. In fact, the page linked to in the OP clearly discusses some other physical factors that affect attractiveness.However, penis size is clearly one of the factors, likely more weighted than some other factors and likely less weighted than some others. Whatever the case, it is a factor; and this is what makes it susceptible to sexual selection.Jon

You are taking my words out of context, plain and simple.The post was directed at Prototypical, who understood the point.I can live with that.

Only in advanced societies with institutional system to support inequality do females not enjoy almost pure control over mating matches.In societies where those institutions don't exist, or exist to lesser degrees (such as most of the First World), females have more control over mating matches than males. Well, a drive to breed isn't some magical thing. The drive has to be acted on. And it is. Penises aren't that large; we aren't talking about a third leg, just a penis that is larger in proportion to the rest of the body than for other primates. Even with small selection pressures (and the study suggests that the pressures are small) it seems very conceivable that the penises of today could be produced through sexual selection.You also have to take into consideration the fact that some of these factors probably didn't exist when penis size was being selected for, or could have been being selected for at the same time as penis size. What about boobs?

Well, the thing is that penis size and mating frequency will show direct correlation. Let's say that in early populations 3" erect was smaller; 4" erect was average; and 5" erect was larger. Assuming a direct correlation, each man with a 3" penis reproduces less than each man with a 4" penis who reproduces less than a man with a 5" penis. Also, let's assume that penis size is standardly variable so there are as many men with 3" members as there are men with 5" members.Given this, the subsequent generation will consist of more offspring from fathers with 4" and 5" penises than from fathers with 3" penisesassuming 50% of the children born to each father are males; i.e., they father a proportion of males equal to their reproduction proportions. It doesn't matter. As long as it is a preference that preference will show in the evolutionary trajectory. And it will. Because not all men equally handsome have equal-sized members; not all men equally wealthy have equal-sized members; etc. Furthermore, not all females rank the importance of different elements of attractiveness the same. There will be some women for whom the choice comes down to penis size, and if their choice is always for the larger member, then we can expect the population as a whole to move in the direction of having larger members.Do you not find it odd that the very things that separate men from women physically are the things most tied to attractiveness (body size/shape, breasts, penises, face structure, etc.)? When so many members of the population possess features considered generally attractive by the opposite sex, can it be any wonder how those features evolved?Members who have those features are selected by the opposite sex to reproduce more often than members who don't.Penis size is just another one of those features. Penises are far larger than they need to be to function. Something has to account for this. Evolution just doesn't make things bigger randomly; in fact, without some other selection pressure for being larger, things are rarely evolved to be any bigger than they need to be.How do you account for unusually large penises? I guess it's time for you to lay out your alternative theory.Jon

A lot of the world was still pretty civilized 2000 years ago. You need evidence to back this up. You need to present something to support your implied position that before the advent of modern societies with their views on equality a woman mated at the whim of whatever man happened to be nearest her.This talk about women never having had any say in mate choice is quite silly. Unfortunately for your argument natural and sexual selection have absolutely nothing in common with buying a car. That's ridiculous. All of these things are measures of attractivenessit's not just physical. Even though penis size has/had to compete with the other measures in importance it is still a factor of attractiveness and thus subject to sexual selection. It would be odd to assume it developed along with general physique because it is not just that humans are bigger and so are their penises; instead, human penises are proportionally much larger than other primates'. Something specifically drove selection toward unnaturally large members. Your graph is crap. It would help. Right now the theory proposed has all that is needed to explain the evidence and is perfectly logical and reasonable. Without a better theory to replace it, there's no need to even give the situation a second thought.Seriously.Jon

Maybe; but I really don't need to. Unless you think that the evolution of larger penises occurred within the last 2000 years, the specifics of mate selection in the year 13 a.d. are completely irrelevant. Any evidence relevant to the time period during which larger penises evolved? What you say is true of many species, and yet female sexual selection is still a meaningful part of these species' evolution.Rape is not the primary means of reproduction for humans. A particular female may be at the mercy of a particular male, but that particular male is then at the mercy of that female's social group. Definitely. Do you accept that the preference can have an impact on penis size? What 'perfect size'?Jon

But society of 2000 years ago wasn't really that much different than society of today. Why not go even further back to the most relevant possible timethe time when large penis size was being selected for. But we aren't talking about history; we're talking about prehistory. No you can't; the two time periods have nothing in common. Please tell me you have more than a list of 'betchyas'. But that isn't what we are talking about. A 5" penis and a 6" penis are still within the average range. We want to know why humans don't all have 'micropenises' since, proportionally speaking, this is the size of penis that we would be expected to have given our size were there no other selective pressures acting on penis size. Of course not; but there's a range. Read the study in the OP. There is a clear preference indicated.Edited by Jon, : No reason given.

It has to be heritable. How else could it evolve into the population at large?Maybe it's heritability is half-ass, but you cannot explain the entire population evolving larger penises if the trait is not at least somewhat heritable.

It has nothing to do with ease of functionality. A small penis can release just as much sperm as a larger one. Even accounting for these factors almost every male has a penis within the attractive range. Does it matter when the larger penis evolved?Half-ass heritability is still heritability. A slight preference is still a preference.

It would had to have been for the average to increase over time. And thank God for that!But I think you are overestimating just how large a penis needs to be to penetrate through the vagina and achieve insemination. Do you know the average length of a vagina?

It doesn't matter. They were once smaller than they are now.Do you dispute this?