evolution

if we evolved to the point we are at today, will there be another major event some time in the future (in the way an asteroid took out the dino's) that causes humans to adapt to their environment in a whole new way and therefore evolve into a somewhat new form???

what kind of event could even cause something like that?? how long would it be before there were noticeable differences in the average human body mentally or physically???

this keeps me up at night