Atheists: Where does truth come from?

Humans do not determine truth. If everyone on earth thought that 2+2=5, we would all be wrong and it would still equal 4. Likewise if we all thought that the earth was flat we would all be wrong. Therefore we (humans) do not determine truth. Without a 'higher being' were does the concept of truth (let alone 'right and wrong') come from? As a Christian I think it comes from Jesus - "I am the truth", but what do you guys think?