Chief among the influences made by these steroids is that “you repress expression of a lot of genes important for an immune response to occur,” Dr. Ashwell explained. Now why would it benefit us to have our elegant defenses repressed? The logic comes again from evolution. If your ancestor was under sudden and profound stress—say, fearing a bear or lion attack—it would be problematic for inflammation to create fatigue or fever. For most of human history, stress meant imminent threat, and imminent threat meant the body needed to be alert, fully functional, even a bit superpowered. This is where
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