When/Where/Why did humans start eating not fully cooked meat? I am aware that certain cultures were eating raw meat and still do but I am interested specifically in how it became popular in the Western world. Any sources that discuss this are welcome.
Obviously, humans have eaten raw meat since we first showed up on the planet. But even after we learned how to grill our mammoth burgers, some people preferred the taste of uncooked flesh. This is especially true in Asian countries (not just fish, but beef, horse, and pork as well; collectively known as Hoe in Korea). A common practice has always been "cooking" the meat in citric acid first, to reduce the risk of infection. Of course we didn't always know that eating raw meat was bad for you. In fact, many cultures believe that raw meat is beneficial to the body.
Around the late 19th century, some doctors began prescribing "raw food" as a medical treatment. Carpaccio (Italian dish of raw fish or veal pounded thin) was invented in 1950 by Giuseppe Cipriani, after learning that the doctors of countess Amalia Nani Mocenigo recommended that she avoid cooked meat (for reasons I'm unsure of)
Of course the science doesn't really support this theory, but raw meat can be relatively safe in small amounts if prepared carefully. Otherwise, I'm pretty sure the entire Japanese archipelago would keel over from food poisoning. Personally, I prefer my parasites cooked.