In theory, humans can have innate predispositions to certain stimuli. These reactions would be vestiges of natural selection, in that early humans who had the most successful gut reaction would gain an evolutionary advantage.
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Researchers at McGill University asked 82 males to listen to a script reader while they sorted photos. Some of the photos were images of meat, while others had neutral images that were unlikely to provoke any particular reaction in the participants. […] Instead, the pictures of meat actually made the subjects less aggressive. That certainly suggests the subjects did have some kind of innate reaction to the meat, but not the one the researchers expected. After all, ancient humans would have associated meat with hunting and the competition for and protection of food resources.
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Kachanoff is pretty sure he knows why the experiment produced those results. He simply showed his subjects the wrong sort of meat: “We used imagery of meat that was ready to eat. In terms of behaviour, with the benefit of hindsight, it would make sense that our ancestors would be calm, as they would be surrounded by friends and family at meal time. I would like to run this experiment again, using hunting images. Perhaps Thanksgiving next year will be a great opportunity for a do-over!”

Perhaps this should become a new military tactic. During a fire fight, hold up meat so the enemy becomes tranquil and you can kill their asses. Of course, that means our troops need anti-meat goggles to keep them fierce. Hmmm… I smell government contract (ie,$$$$$) on the barbie!