India, Dec. 2 -- image credit- freepik

Immunologists spent the better part of eighty years puzzling over something odd. We each carry an enormous variety of antibodies and T-cell receptors, and plenty of these could, at least in theory, turn on our own tissues. The strange part is they mostly don't.

It comes down to a classification problem. Under uncertainty, how does the body figure out what's friendly versus hostile? And having made that call, how aggressively should it respond? These aren't easy questions.

You see the classification problem everywhere now. Email filters trying to catch scams without losing legitimate messages. Smoke detectors that need to ignore burnt toast. Airport scanners, fraud detection at banks, autonomous ve...