Originally Posted by
Salodin
There's different theories on time travel, but the only two things I'll point out is that going so far in the past might not affect them as much in the future as say going back 100 years instead; after all unless we evolved from dinosaurs I think we're pretty safe. Second point is even if it did, some time travel theories have it that even if you change the future through your past actions, because you are now in the past and not the future it doesn't effect you at all.
But in the end trying to make sense of time travel is just stupid. Just sit back, and enjoy the show/trainwreck.