Let me illustrate this heuristic by the following conversation one of professors at UC Davis had with a friend of hers.
comments powered by DisqusI know there are no raccoons in Davis, but I saw one so they must be increasing in population.
No, there have always been racoons here.
There weren’t. I haven’t seen one ever before and I live here 10 years.
I mean, I study that, so I know there have always been racoons here. When did you see it?
I saw it at 2am when the baby woke me up and I went outside to chill for a bit.
Ah, you have a baby?
Yeah, she is a month old.
Congratulations. Racoon always there. Baby new.