What if spammers come up with an artificial intelligence before Google does? 

An early warning signal has been detected. The Washington Post reports that spammers may have control of computers that can decypher those letter puzzles on websites called CAPTCHAs. CAPTCHAs are designed to be solved only by humans, since — at least until now — only humans could unravel distorted, distressed lettering. The problem with making CAPTCHAs more difficult is that humans have trouble solving them.

The computer scientists can’t tell yet whether spammer bots or spammer-paid humans are solving the CAPTCHAs. That is the definition of passing the Turing test — if humans can’t tell.