"Why do we care differently about the past and the future? One answer to this question is immediately obvious. Horwich suggests the following explanation:

'An organism that wanted its future selfish desires to be satisfied would flourish relative to an organism that didn’t care; however there is no particular advantage in wanting past desires to have been satisfied.'

Dread, fear and anticipation are all tensed emotions that might plausibly have evolved to make us better able to avoid dangerous experiences and maximise beneficial ones. Dreading danger in ancestral environments may have caused us to work out ways of avoiding conflict or to devise safer hunting techniques. Fear leads to increased alertness as part of the ‘fight or flight’ response, which is obviously adaptive in organisms faced with dangerous predators or indeed dangerous prey. Obviously none of these emotions is adaptive if directed toward past events precisely because we lack causal influence over those events. This observation is the evolutionary equivalent of ‘there’s no point crying over spilt milk’."