In my post concerning the Chicken or the Egg? riddle solved! story, I made a point of saying that while we can now point out the differences between a domesticated chicken and a red junglefowl, at one point it would’ve been damn hard. My ultimate point was to show that while we may view the world in an essentialist mode of thought (a chicken is always a chicken), the world-as-it-is doesn’t necessarily agree, i.e., chickens change.
I also asked, “Can [chickens and junglefowl] interbreed, I wonder?” Well, yes they can, as Neil pointed out in the comments. I was unable to access the article he cites, but I was able to find a more recent article from the same authors. I also won’t bother with the methods of their study – I just want to quote a part of their discussion:
The findings in the present study indicate that inter-species hybridizations have occurred, i.e. between [Grey JF] and [Red JF]/chicken and between [Grey JF] and [Ceylon JF]. Red junglefowls are considered to have largely contributed to the establishment of contemporary chicken, and [Grey JF] and [Ceylon JF] also are considered to have contributed to the establishment, although to a lesser extent.
Basically, the extant species of the Gallus genus (with the exception of Gallus varius can and have interbred at some point. Interestingly, not only are domesticated chickens direct descendants of red junglefowl, but they also received genetic contributions from grey and ceylon junglefowl! As the authors point out later in the discussion, this calls into question whether or not the species of Gallus are distinct species or just subspecies (although they point out more work is needed before making such a call).
These results make my point even stronger – not only could you not tell the difference between chickens and red junglefowl at one point, but the domesticated chicken is a combination of several species/subspecies. Essentialism just does not work here.
Thank you for the comment, Neil!
Nishibori M, Shimogiri T, Hayashi T, & Yasue H (2005). Molecular evidence for hybridization of species in the genus Gallus except for Gallus varius. Animal genetics, 36 (5), 367-75 PMID: 16167978