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| Various baculums from different mammalian species. This image demonstrates the variation in form and size. |
If you are partial to using the term “boner” to refer to an
erect penis then this blog post will disappoint you. A recent study by Brindle and Opie (2016) discusses
the evolutionary reason for why humans, unlike other species of primates, do
not have a bone in their penis. Today’s blog
post summarizes that study herein.
A baculum is an extra-skeletal bone that floats at the end
of the penis. Eight orders of Mammalia,
including most primates, have a baculum.
Tarsiers, some Platyrrhine species, and humans are the only primates
that do not have one. Brindle and Opie
(2016) found that the baculum developed in mammals around 145 million years ago. It remains unclear why it developed and what
its specific purpose may be.
There are three competing hypotheses to explain these. The first hypothesis claims that the baculum
may be useful in triggering ovulation in females who only release an egg upon
sexual relations. The second hypothesis
associates the baculum with the purpose in of boosting the penis’s ability to
penetrate the vagina. The last
hypothesis puts forward the notion that the baculum allowed prolonged
penetration and sexual intercourse in order to allow sperm to be released into
the vagina, thereby increasing the chances of pregnancy resulting. This latter hypothesis has the most support
as baculum size in nonhuman primates is bigger (in length and width) among
nonhuman primates that have increased competition for mates.
This may also be the reason for why humans do not have a
baculum. Our unique mating strategies do
not foster its need. Humans do not typically
copulate with more than one individual over a short period of time. We tend to mate with one male or female either
within a 24-hour period or even longer.
Orgies, which necessitate sexual relations with multiple partners within
a short period of time, are not typical despite our pop culture fascination
with the phenomenon, but such activities are more common among species that do
have a baculum. Therefore, our mating
patterns, as well as the decreased competition for mates, remove the need for
the baculum.
Humans as a species are unique in many different ways, so
the loss of the bone in the proverbial boner is because of our uniqueness. While several different human cultures practice
polygamy they typically mate with one woman at a time, which is unlike other
nonhuman primates. Therefore we lost the
need for a penis bone.
References
Brindle, M.
(2016). “Why Humans Have No Penis
Bone.” Scientific American.
Retrieved from https://www.scientificamerican.com/article/why-humans-have-no-penis-bone/
Brindle M, Opie C. (2016). Postcopulatory sexual selection influences
baculum evolution in primates and
carnivores. Proc. R. Soc. B 283: 20161736.
27 comments:
I feel like it's good that men do not have the baculum because, if men had that bone now I feel like more women would get pregnant and even spread disease (depending on how many sexual partners). The bone back then was used to procreate among primates. As we evolved we don't have the use for it and now sex can just be for fun rather than to produce children. I thought this blog was pretty interesting because I didn't know about this.
I found this very interesting, and I also wonder if at some point throughout early human history (for example homo species') males might have baculums. I also agree that it is probably better that humans don't have the bone, or we would have entirely too many people getting pregnant!
Great question, Sydney. It is possible that our earliest ancestors from the Ardipithecus genus may have had a baculum. We do not have many complete specimens from that genus. The most complete was identified as a female, so we wouldn't see that there. I know that several early Australopithecines have been found, and no baculum was found with the males. So the loss of the baculum must have occurred early in our evolution. :)
Akwila Cooks
This blog is very interesting. I have never thought of why humans don't have a penis bone and now that I read this article it has me thinking. I think the whole idea of sex would be different if the penis had a bone. I agree with one of the comments above that there would be a lot more pregnant women then there already are but in my opinion that is a good thing. I never actually heard anyone use the term boner but in movies I have.
This blog had grabbed my attention for the simple fact that I'm a dude and I wondered why do we call it a boner but I see that we are so wrong and the mammals that do have a bone in theirs it is to help the penetration but it's more of our species have evolved to a new development of a penis
I feel really disturbed knowing the baculum "floats," but I guess our kneecaps do, too, so I suppose it's not hard to compare. All and all this is absolutely new information to me, so I absolutely found it very interesting.
Before this post I was completely unaware that we're the only species without an actual bone in our boner. However, I have wondered why we didn't have one anyway? I agree that since most men usually mate with one woman at time that the need for such bone would be unnecessary. However, in today's sex culture it's actually good to last longer than the average 5-10 minutes so this bone could come in handy for a small percentage of men.
Maybe we evolved without a baculum because there was no need to get pregnant every time we have sex. There would be extreme over population. I wonder if there is a relationship between the woman's and male reproduction system how each system evolves. Do think this adaptation was in response to the female reproductive system? Has there been any adaptation to the female reproductive system sense then?
Excellent observations and questions, Shamari, but unfortunately as I am not an evolutionary biologist/anthropologist I do not have the answers. I encourage you to look into the answers, though, particularly in Anth 310: Physical Anthropology and Archaeology (offered in 2018-2019 school year).
This is Jalen Scuefield and in all honesty I feel that it would be very dangerous for a human to have a bone there that is probably the most sensitive spot in the body and if it was to break things would not go well for males as a whole and the way everyday life goes for a male it wouldn't be safe to do anything with a bone there
Im a little confused, is the bone attached to any tissues or is it really "floating" ? Also, are there any articles on why humans dont have this bone, especially if the bone makes it easier for penetration. This is interesting
Technically, any bone is connected by tissue, which is the case of the baculum. It's not connected by tissue to another bone but to the muscles that make up the penis.
Regarding your second inquiry you can find the original study and a summary of it in the references cited (at the end of the post).
I never knew the penis doesn't have an bone but when you think about it that is dangerous because the penis is a very sensitive part of the body.
I never knew about a bone being in the penis. I don't see how the bone would make the female ovulate. I think that the bone would be pointless in today's time because sex now is just for the enjoyment not for reproduction.
Kenneth Granger Jr.
This isn't directly related to the blog, but it make me wonder why it seems humans are one of the few mammals to have sex for pleasure and not just for mating. What makes that the case?
My uninformed opinion is that it relates to our brains and their complexity. Also, it could be how we socially and culturally view sex. At one point in several societies (including our own) sex was seen as a chore and a reproductive requirement, so many people didn't like sex based on that.
It was very interesting to learn that we lost this bone due to eveolution. I had never really thought about it, but we really don't need it. Therefore it makes sense that we no longer have it.
Amber Barnes
This seems a bit bizarre to me.Do you think the reason we have birth complications is because we are not equipped with the baculum? I know that seems like a dumb question but people tend to be pregnant less and not hae many children. It makes me wonder if that may also have something to do with it.
I don't think the loss of the baculum accounts for negative pregnancy outcomes, but as this is not my area of research I could be wrong. Based on what I do know about this subject (which is not much) the reasons we, as an American population, are birthing less children is because we are choosing to. There are definitely situations where people want to have children but are unable to, and that's because infertility is actually more common than we, the public, give credit to. It's actually less of an issue today due to fertility treatments, but that's only available to those who can afford it.
I really didn't know the penis doesn't have a bone, this is very interesting makes me want to find out more about this and why don't it have a bone.
Lindsey Wilkerson
This blog is quiet interesting and very different. Me personally I never thought about why men do not have bone in their penis. Then to find out that at one point in time they did just makes me wonder why and how has it impact not only them but the relations the make with others.
Interesting I didn't even know other species had a penis bone and it explains the term boner and why we use it today even though we don't have one. Same thing with a lot phrases like " sweating like a pig" even though pigs don't sweat. However what if the reason we don't have the bone is because human females are easier to get pregnant so we have no need to go for longer duration's and be bigger/harder to penetrate the vagina. -Malachi Brewer
I never thought about if a male had bones in their penis , but after reading this blog I think its interesting that they did have one and is it for the better. I wonder how would it be if they did have a bone in their penis in this generation.
-Tae'lor Pearson
I figured the penis didn't have a bone, so is it made up of cartilage?
- Malacia Lowe
The baculum's purpose could also be something similar to the knot of a dog. That is, to ensure a better chance at reproduction. However, it might also be an unnecessary bone altogether.
Hi my name is Avery Davis,and I think this blog is so interesting. I wondered a while back why do they call a erect penis a boner and boys don't have a bone down there? Reading this blog illustrated a image in my head about what if my life added that edition to me.
I had no idea that the penis didn't have a bone..its funny though because "boner" is used when males erect however, there isn't bone down there. How is it that they had bone back then and now they don't??? that really trips me out and the fact that back then they did ad it altered their relationships with people is crazy.
-Kyla Thomas
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