““So what?” Travis snorted quietly. “Well, what about the foxes that’ll need those mice to survive? For want of ten mice, a fox dies. For want of ten foxes, a lion starves. For want of a lion, all manner of insects, vultures, infinite billions of life forms are thrown into chaos and destruction. Eventually it all boils down to this: Fifty-nine million years later, a cave man, one of a dozen in the entire world, goes hunting wild boar or saber-toothed tiger for food. But you, friend, have stepped on all the tigers in that region. By stepping on one single mouse. So the cave man starves. And the cave man, please note, is not just any expendable man, no! He is an entire future nation”” (Bradbury 39)
Travis, one of the leaders in the expedition, makes it very clear how even the slightest action will affect the future, and continues to carry on about it for the entire time they are in the past. Because of his constant lecturing to the others, it could be concluded that Travis is a very concerned and anxious person always thinking ahead.