The twin primes conjecture says there are infinitely many primes p such that p+2 is also prime.
A new proof by a mathematician who isn't one of the known experts in the field, has made a big contribution towards proving the conjecture.
Apparently he was very dogged in his pursuit of the proof.
It reminds me of myself - I've proved things and noticed things in math that other people don't because I get my teeth into a math problem and don't let go. <end of dog metaphors>