The origin lies in the third question posed but goes back even further. The Etruscans, an Italian civilization contemporary to the Romans that would eventually be absorbed by the Roman empire, are thought to be the progenitors of the tradition. They believed in something called alectryomancy, or rooster divination, a form of prophecy which involved using the movements of a rooster to determine future events.
The process was simple—an Etruscan alphabet would be drawn on the ground, then bits of food would be scattered in each letter’s vector. People would note the bird’s movements throughout the letters and then use those notes to figure out quandaries of the day or figure out what was ahead for society. When the chicken oracle died, the wishbone would be dried out and preserved, as it was viewed as being the center of the bird’s predictive prowess. The reason why this bone, in particular, was chosen over other marrow-filled options is unclear.
As the Etruscan culture was absorbed by the Romans, the valuation of the wishbone remained, but with a twist. While the Etruscans would frequently hold and pet the bone to have their wishes granted, the Romans began the tradition of breaking it. The idea behind breaking it was based on the fact that it would allow two people to wish upon the bone, due to a lack of enough birds for everyone, according to Mental Floss. The breaking aspect certainly was a bit more gratifying, with a more definitive outcome for the bigger half-haver.
As the Roman Empire continued to expand, it carried with it the wishbone tradition. By the way, here’s the history behind another quirky Thanksgiving tradition, the presidential turkey pardon.
If you’re planning on continuing this tradition from antiquity, be sure to remove the wishbone before cooking your bird, for optimal results—here are some other turkey preparation tips you should know before Thanksgiving day.