It is also possible that human behavior and shark behavior just don't match. In the 1980s, John McCasker proposed the Bite and Spit hypothesis. McCasker said that a shark will attack dangerous prey like an elephant seal by biting it once and then letting go. The shark then swims away to wait for the prey to bleed to death before going back to eat its body. But when a shark bites a human once, the human's friends come and help them out of the water. Maybe the shark would finish eating the human, but it does not get the chance. But sharks usually attack seal-sized (or human-sized) prey in one strong bite from underneath, so people are not sure if McCasker's idea is right.