Thread: Planning an investigation into human ejaculation

I'm not a professional biologist, but I do take an interest in science, and occasionally take up an experiment as a hobby. I've recently become fascinated by one aspect of human biology: the strength of a man's ejaculation. Essentially, I want to undertake an inquiry into the distance a man is able to ejaculate semen. Being as humans are not all identical, and I imagine, or rather I suspect from prior observation, that even an individual varies in ejaculatory performance, this will need to be approached statistically.

I must confess that statistics was never my strong point, and mostly in amateur investigations into physics or chemistry, you don't really need it, beyond the ability to calculate a mean average. So I am turning to this community, being the preeminent community for scientific discussion on the internet (well, you came up first in a Google search), to help me plan the specifics of this experiment. I hope you don't mind, I am fully intending on sharing my results with you afterward.

My idea of the basic procedure is thus:

1 ) Lay out a table at genital-height
2 ) Mark off centimeters (and possibly millimeters) in permanent ink on said table
3 ) Bring in test subject, sans clothes
4 ) Position test subject at end of table, facing forward, and bring him to erection
5 ) Maneuver test subject so that tip of penis is just over beginning of table
6 ) Position erection at 45 degrees, and begin stimulating
7 ) Once subject has ejaculated, note position of farthest semen droplet on table
8 ) Clean table

This seems to me to be a good basic procedure for getting the distance measurement. However I'm not an expert biologist, so I'd like to know if there are any methodological errors here, maybe it needs to be controlled in some way?

Now, getting the measurement is the easy part, I need to first find willing test subjects (I assume craigslist will be of help, let me know if you have a better idea/want to volunteer). But more importantly, I need to analyze the data.

I will keep a spreadsheet document detailing the measurement, the length and girth of the penis, the circumference of the scrotum, the age of the subject, his height, and the time of day. I think that is all the data that could reasonably affect the measurement, but do let me know if there are more.

Now, I gather there are ways of making fancy graphs to find not only the average ejaculatory distance, but also if it is correlated with age, height, etc. I would appreciate if one of you fine biologists could let me know how this is done, or point me in the direction of the correct page on Wikipedia.

The correlation I am most interested in is with age; I am almost sure that my younger lovers ejaculated much more forcefully than the older ones, but I feel a need to confirm (or refute) this with science. I suppose that the youngest subject i would be allowed to test this on would be eighteen? Not that it makes too much difference, from what I understand, boys generally start ejaculating at fifteen or so.

I am also interested in whether the "blue balls" syndrome is true; i.e. whether the time since a man last ejaculated increases the force of his next ejaculation. But I cannot think of a rigorous way of doing this that would not involve isolating the subject for a day, or fitting him with some kind of male chastity device.

Thanks in advance for all your help! xxx

Maybe this belongs in physics, muzzle velocity's correlation with gun barrel lengths. I was just thinking, if this proposed research is legitimate then funding is probably available.

Originally Posted by BorgFoem

I'd like to know if there are any methodological errors here, maybe it needs to be controlled in some way?

The force of the ejaculation is largely dependent upon the level of excitement. Having a cum with a chic who doesn't turn me on or with whom I've already had sex hundreds of times is unlikely to do much more than just have me dribble down the edge of the table.... Having the ejaculate coupled with a fantasy of some sort or being do to having sex with a chic whom I've been craving for months will lead to a much more intense and forceful velocity and volume (and there are good biological / evolutionary reasons for this).

This is anecdotal. I've read studies supporting same, but it's been a while.


Methodological error? You cannot control for what is happening in the mind of the person doing the ejaculation, and their mental state is a key variable when it comes to the force of the event.

I think this experiment is a little shaky.
Many variables like hormonal levels/length of the ducts all come into play, no?

But yeah, this is more towards physics besides those biological variables.. Maybe a model might be more appropriate as an estimate so you can control the volume of semen/biological aspects..

Damn I hate having to get up early. Thought I'd check in on this thread before going through my morning routine, it cheered me up to see there's already been such a response!

I understand that it's physics-based as well, but it's mostly examining the semen-ejaculating ability of the human body, so I guess it's biophysics? Anyway, thanks for your comments, I'd look into getting funding, but I'm not a professional, as I said.

Now, I'm a bit tired, but you seem to be saying that excitement levels have a good deal to do with it, which makes sense, and that I should hire a model to keep them excited? It's an interesting idea. I'm thinking that to save money, I could be the model, I would just have to be naked while I'm bringing to subject to ejaculation. Maybe I should ask them to rate me 1-10 attractiveness-wise before the experiment, and see if there is any correlation with that?

Oh, and maybe I could investigate whether different methods of stimulation cause different strengths of ejaculation? Like, hand versus mouth? Of course, that might be reflecting more on how skilled I am at either. But I'd only be able to do that if I got a lot of volunteers; as I understand it, the more variables you want to examine, the more subjects you need?

Anyway, it's already ten past seven, I need to have a shower and get dressed, head off to work. Maybe I'll be able to sneakily log into the forum while I'm there! xxx

Have you read any of the prior research on the topic? A lot of what you're describing seems to be coming from first principles. Surely if you're serious, which I'm not sure you are, you should already have some idea of the most common methods, apparatus etc. used to address the questions you're asking. You ought to have some vague idea of what questions have already been answered by research and where there is still uncertainty. So perhaps you could give us an outline with some references?

This is a valid research topic, and valuable, but to say I'm skeptical about the motive of this thread would be an understatement. I will be watching closely.

Originally Posted by TheBiologista

to say I'm skeptical about the motive of this thread would be an understatement. I will be watching closely.

I could be the model, I would just have to be naked while I'm bringing to subject to ejaculation. Maybe I should ask them to rate me 1-10 attractiveness-wise before the experiment, and see if there is any correlation with that?

After reading that, I am no longer skeptical, I'm convinced that this is a bunch of bullshit. For all you little hopeful sperm out there, rest easy, you're safe for now and you still might get your big chance someday.

Originally Posted by TheBiologista

This is a valid research topic, and valuable,

Valuable. Really? I don't see it myself.

Kinda related and something which would actually be valuable to sportsmen is whether ejaculation before sports adversely affects performance. I've heard of individual studies with mixed results but is their any meta-analyses?

Originally Posted by Prometheus

Originally Posted by TheBiologista

This is a valid research topic, and valuable,

Valuable. Really? I don't see it myself.

Kinda related and something which would actually be valuable to sportsmen is whether ejaculation before sports adversely affects performance. I've heard of individual studies with mixed results but is their any meta-analyses?

Sexual function is a major concern in quality of life studies relating to a huge array of medical interventions. To my mind that matters a lot more than performance in sports, at the very least because it affects a broader population.

Perhaps you should try ejaculating your test subjects onto a pressure sensitive pad. This should eliminate some of the static in your data from the varying levels of vigor involved in performing the test.

Sorry guys, couldn't sneak any forum time at work today!

Anyway, it's nice to see that you're all being so nice and responsive (except zinjanthropos, but there's always one). As to reading other investigations in the matter, as I said, I'm an amateur. I don't have a subscription to any biology journals, but if there are copies of the studies online, I'd be glad to read through them, and see what has and has not been focused on before (there's always something new to investigate in a topic!)

As for the pressure sensitive pad, I'm not sure what you mean? Like make the table pressure sensitive to get a more accurate measurement?

Originally Posted by TheBiologista

Sexual function is a major concern in quality of life studies relating to a huge array of medical interventions. To my mind that matters a lot more than performance in sports, at the very least because it affects a broader population.

This assumes the distance a man is able to ejaculate is correlated to sexual function. If it is then fair enough, but is it?

Think about it this way, Prometheus. The more forceful the ejaculate, the further up the fallopian channel the sperm will go without needing to start swimming. They'll be much closer to the egg just as a result of entering, whereas less forceful ejaculate mean the sperm start farther away from the egg and need to spend much more energy swimming... There is a huge increased risk in never making it to the egg at all.


BorgF - Pressure sensitive plates measure force of an impact very precisely. Also, type scholar.google.com into your browser, enter your search terms (like ejaculatory force or something like average ejaculate distance) and you can get quite a fair amount of data through online journals for free. For those articles which are pay-walled, but seem to touch on your subject of interest, you can write down the citation and often find many in the libraries at your local university.

Ahhh, so I'd get them to ejaculate straight into the pad, and calculate the distance it would have gone from that? Not as fun to watch, but I am trying to do this as a rigorous scientific experiment, and it would eliminate uncertainty around firing angle, etc.

And that Google Scholar thing is really useful, I can't believe I've never seen it before! I'm trying searches right now, but so far there does not seem to be much on human ejaculatory performance, just cheetahs, rhesus monkeys, etc.

There must be something there though, so I'll keep looking.

Thanks for the advice! xxx

Originally Posted by inow

Think about it this way, Prometheus. The more forceful the ejaculate, the further up the fallopian channel the sperm will go without needing to start swimming. They'll be much closer to the egg just as a result of entering, whereas less forceful ejaculate mean the sperm start farther away from the egg and need to spend much more energy swimming... There is a huge increased risk in never making it to the egg at all.

The cervix would get in the way of any ejaculate making this the furthest it could go via expulsion.

Originally Posted by Prometheus

Originally Posted by TheBiologista

Sexual function is a major concern in quality of life studies relating to a huge array of medical interventions. To my mind that matters a lot more than performance in sports, at the very least because it affects a broader population.

This assumes the distance a man is able to ejaculate is correlated to sexual function. If it is then fair enough, but is it?

It's a metric of sexual function, so the question is not whether it correlates. That'd be like looking for a correlation between rainfall and "weather". The bigger question is whether it's a relevant metric within that set of metrics. I have no idea whether it is or not, but in principle it's worth investigating, assuming it hasn't already been done.

It's worth noting that in QOL studies, the subjective value of metrics to the patient is the main consideration, so we can't discount the impact on things like weak ejaculation force, low volume etc on the patient's happiness.

Originally Posted by BorgFoem

And that Google Scholar thing is really useful, I can't believe I've never seen it before! I'm trying searches right now, but so far there does not seem to be much on human ejaculatory performance, just cheetahs, rhesus monkeys, etc.

Right... so what you're saying is that you're planning to embark on a sexual biology study using human subjects and yet you've never so much as heard of one of the worlds biggest primary literature search engines and you don't understand the relevance of animal models to human studies?

Either you're just taking the piss, or you're a totally unqualified layperson about to seriously consider recruiting men for a study with some pretty huge legal and ethical implications for you personally. You do realize that any without appropriate design and clearance for something like this, you're opening yourself up to sexual assault, solicitation and scientific misconduct charges, depending on where you're located and who you're claiming to be?

To be honest I'm leaning towards closing this thread in either case...

Originally Posted by Prometheus

Originally Posted by inow

Think about it this way, Prometheus. The more forceful the ejaculate, the further up the fallopian channel the sperm will go without needing to start swimming. They'll be much closer to the egg just as a result of entering, whereas less forceful ejaculate mean the sperm start farther away from the egg and need to spend much more energy swimming... There is a huge increased risk in never making it to the egg at all.

The cervix would get in the way of any ejaculate making this the furthest it could go via expulsion.

This is untrue. The cervix connects the vagina with the uterus and fallopian tubes where fertilization occurs. If, as you say, ejaculate cannot get past the cervix, then none of us would be here today.


To the study parameters, another potentially confounding variable is duration since last ejaculation. My recollection is that the more recent it's been since previous emission, the less forceful.

The external os is the opening from the cervix to the vagina. It's a small slit like opening. It dilates in some circumstances but not during coitus. Forcing semen through there in the initial ejaculate would require extreme luck i would imagine.

I'm still not convinced how far one can ejaculate is a measure of sexual function. Perhaps that's something Borg can investigate - how well distance of ejaculate correlates to measures of sexual satisfaction.

You could further correlate it with penile length. Obviously, those with shorter equipment would benefit more from a more forceful ejaculate than would a person more endowed.

The key point here is not (IMO) one of satisfaction, but instead how far the sperm must swim. Sperm generally die pretty fast. If they don't make it to the egg quickly, they rather likely won't make it to the egg at all. The closer the sperm is "placed" to the egg from the ejaculate event, the more likely it is to achieve insemination.

Shaft length and force of ejaculate are pretty critical in impacting these probabilities (but, so too is the shape of the woman's reproductive tract... there is no ideal length or force since different approaches work better in different women).

Okay, so, I'm going to measure height, penis length and girth, scrotum diameter, age, time since last ejaculation, how attractive they find me, perceived sexual satisfaction, and force of ejaculation as measured by pressure sensitive pad. I've drawn up the spreadsheet, and I'm looking for a place to buy a pressure sensitive pad, and stand. Any recommendations?

I'm going to put the ad up on craigslist soon, asking for volunteers. I suppose I'll need a "stratified" sample, but how do you recomend I stratify it? Obviously I'll need even numbers in each age group, but is there any other stratification I will need to do? And how many subjects will I need in each stratum?

also...

You do realize that any without appropriate design and clearance for something like this, you're opening yourself up to sexual assault, solicitation and scientific misconduct charges, depending on where you're located and who you're claiming to be?

I've got the design, I'm just going to use a pad on a stand, how do I get clearance? Is there some sort of "science police" I have to register with? I'm in SF and I'm not going to pretend to be a professional, just a woman carrying out a study into human ejaculation, and I'm not going to be assaulting anyone, I want willing volunteers...

Thanks for all your help and advice! xxx

What is craigslist? If this is some sort of specialised group then your sample will not be represenatative of the general population. Also the fact they are volunteering may mean they are in some way different to the general population (esp. in this study). The latter seems unavoidable though. Stratifying means you'd need to recruit more participants than you would otherwise need, but since you haven't done a power calculation anyway it would render results irrelevant anyway.

Any experiement involving human participants has to go through an ethical review. You'll be breaking international law if you don't (see the Helsinki Declaration). Not sure about US ethical review bodies but i'd be very suprised if you got permission. You would need to submit a scientifically valid research proposal, answer questions in front of a review board and prove you have the skills, qualifications and resources to complete the study. You also have to prove the research is worth doing. Also, these craigslist people, sound like they may be considered a vulnerable population in this particular context (i.e. their sexuality being exploited with the promise of sexual contact). I wouldn't approve it if i were sitting on the review body as it stands.

inow. We're starting to agree i think. Seems there are too many potential confounders to assess causality and even correlation - the experiment would have to be rigorously controlled or/and use logistic regression to control for them.

Originally Posted by inow

You could further correlate it with penile length. Obviously, those with shorter equipment would benefit more from a more forceful ejaculate than would a person more endowed.

The key point here is not (IMO) one of satisfaction, but instead how far the sperm must swim. Sperm generally die pretty fast. If they don't make it to the egg quickly, they rather likely won't make it to the egg at all. The closer the sperm is "placed" to the egg from the ejaculate event, the more likely it is to achieve insemination.

Shaft length and force of ejaculate are pretty critical in impacting these probabilities (but, so too is the shape of the woman's reproductive tract... there is no ideal length or force since different approaches work better in different women).

Maybe, but there's no evidence that it would be statistically significant. Numerous studies have been done on male infertility, and I have never heard of any finding links to smaller penises, or fecundity. Moreover, fertility is incredibly difficult to measure because in every case of analysis we have what is an interaction between two individuals, and there are factors like female arousal and hormonal levels that have significant effects on fertility.

And fortune of fortunes the WHO actually has data on total sperm level of male ejaculate.

http://humupd.oxfordjournals.org/content/16/3/231

They only looked at ejaculate volume and sperm count though, not distance traveled. Lower volume of ejaculate, and lower sperm concentration, were found amongst partnered men who had taken longer than 12 months to father a child.

I think it makes sense that the size of the ejaculate matters, as does the ability to make healthy sperm in the first place. Though I'm not sure distance would matter.

As seems obvious from the conversation, it truly is an interesting topic and would be cool if approached with appropriate rigor. However, I'm becoming more and more inclined to agree with TheBiologista and am growing skeptical that the OP is serious. The nonchalant nature of responses and lack of any a priori personal research on the topic suggests a serious study is not the end goal here, but instead to go on a site with a bunch of science-ey types and talk about getting naked and people spooing.

Why do I get the feeling we're being set up to have an established thread, with decent google analytics, ultimately point to a pr0n site?

Originally Posted by inow

As seems obvious from the conversation, it truly is an interesting topic and would be cool if approached with appropriate rigor. However, I'm becoming more and more inclined to agree with TheBiologista and am growing skeptical that the OP is serious. The nonchalant nature of responses and lack of any a priori personal research on the topic suggests a serious study is not the end goal here, but instead to go on a site with a bunch of science-ey types and talk about getting naked and people spooing.

It is an interesting topic, which is why I took an interest in it. I stated from the beginning that I was not a professional biologist, and that I was just a person who was interested in how far the average ejaculation would launch. Yes, it's true, I'm excited by ejaculation, what woman isn't, but that doesn't mean I don't want to try and construct a rigorous experiment to slake my curiosity. Of course, it seems that there are entire organisations dedicated to stopping me doing this. Apparently, giving free handjobs to men is a-OK, but giving free handjobs to men in the persuit of scientific enlightenment is severely illegal. Go figure.

And for the record, a priori refers to knowledge acquired through logic and reasoning alone, with no reference to physical observations. For example, the knowledge that 2+2=4 is a priori. You cannot have a priori scientific research, because science is by its very nature a posteriori (relating to knowledge gained through empirical observation).

A priori literally = prior to. I just meant beforehand... you do not seem to have done your homework or any research beforehand.

It's all super that you dig cum, and I applaud you for it. I've been with a number of women who feel the same way, but who lacked the scientific insight to consider setting up an experiment where they got naked and tried to find out who can spoo the farthest. I'm sure your dad is mighty proud.

Also, just to clarify, there is no science police per se, but you might look into the institutional review board, or IRB, to better understand some of the concerns being expressed in context of actual research.

http://en.wikipedia.org/wiki/Institutional_review_board

To quote Wikionary on the matter:

Adjective
a priori
(law, Latinate) Known ahead of time.
(logic) Based on hypothesis rather than experiment.
In his opening argument, the student mentioned nothing beyond his a priori knowledge.
Self-evident, intuitively obvious
Presumed without analysis
(linguistics, of a constructed language) Developed entirely from scratch, without deriving it from existing languages.

If you want to say "prior" use the word "prior", don't abuse well-established technical terms to make yourself sound smart.


Anyway, as for these IRBs, the article you linked had this to say:

These regulations implement provisions of the National Research Act of 1974, for example defining IRBs and requiring them for all research that receives support, directly or indirectly, from what was the Department of Health, Education, and Welfare at the time, and is now the Department of Health and Human Services (HHS)

So it would seem I'm free to measure "spooing" all I like, as long as I do not accept funding from the HHS. Which I was not planning to. If you have any more constructive suggestions on the design and execution of the experiment, I'd be glad to hear them.

If you want to do potentially controversial, perhaps legally dubious research without having so much as read the current literature in the field, or bothered to consider small matters such as ethics, then that's your prerogative (or not as it may unfortunately turn out). I will not enable that, however.

I think we're done here.