In the course of a discussion on Twitter regarding what makes a good (more usually a bad) sex scene, someone mentioned that people should try reading a book of comparative reproductive systems, and that even amongst mammals things got a bit strange. To which someone else responded, “One word: ducks”.
This got me curious, so I looked up duck reproductive systems and found a university site that gave a brief overview of duck reproductive organs and included the following gem of information:
So now I’m wondering, what could have prompted the domesticating humans to say:
Bird with penis: let’s domesticate that sucker!
Bird without penis: naw, we don’t want that in our farmyard.
Yes, I know that not all species of duck, goose, or turkey are domesticated, but when you look at farm fowl, you see almost exclusively duck, goose, turkey, and chicken. (Secondary question: is there such a thing as wild (not feral, wild) chickens?) And I know that other bird species such as quail and pheasant and emu are now farmed, but I think that’s a comparatively recent development.
Link to university site. Spoiler tagged because it shows photographs of duck reproductive organs as well as duck innards, and some people may find that gross. (I sure did. I did *not *expect to be looking at a dissection or surgery or whatever that was. Ugh.)
I suspect this is correlation ≠ causation. This doesn’t sound like something that would be a conscious choice on the part of those domesticating animals.
Humans domesticated (for food) any bird that is large enough (which means it has to grow fast) that can reproduce in captivity and doesn’t have other marks (such as being vicious, like many large flightless birds).
I doubt the phallus has much of an impact on their mating behavior, so no impact on their ability to mate in captivity. Humans did domesticate other birds, but many of them were not domesticated for food (parrots, songbirds, etc). People did raise pigeons (in dovecotes) for food, and I think at one time people regularly ate starlings, neither of which have such external genitalia on their males.
Yeah, I didn’t think that the penis played any part in choosing which birds to domesticate, it just seems weird that the ones picked to be domesticated for food animals were the only ones that had penises.
I suspect that all of the species you mention are related to each other, and because they’re related, they share a number of features in common. One of those features happens to be their genitalia, but other features were doubtless the reason for their domestication.
They seem to be calling it a penis to make a point. It’s just a vestigial homolog of a true penis. It’s like saying that humans have a tail because we possess a coccyx. I wouldn’t refer to it as a penis myself.
As mentioned above, functional penises are found in ducks and geese but not chickens or turkeys. Ducks have dicks, but cocks are cockless.
As mentioned, the groups of birds that have penises are:
Ratites, including ostriches, rheas, emus, and cassowaries (but not kiwis)
Guans and curassows, a family of chicken-like birds that appear to have regained them after other members of their group lost them.
Ducks and other waterfowls.
Besides these, males of two species of Buffalo Weavers possess a pseudo-penis or phalloid organ which is not erectile and does not transmit sperm, but apparently is used in sexual stimulation.
Why aren’t pet birds–parrot, canary, cockatoo, pigeon, falcon–included in your definition of “domesticated”? I have no idea whether any of these have penises. If you just mean birds that are raised for humans to eat, it seems to me that a lot of other birds used to find their way to our tables, though they were hunted or trapped, not raised. Also, I wonder if “true penises” might not be a result of being farm-bred and -raised, not the reason for it? Farmed salmon have different characteristics than wild ones, though probably not that one.
