let's say, as they would by biting a fish.

So generally, they will release us and swim away.

These incidents were totally different.

The shark came in, attacked the victim, and came back

and attacked again and again and again,

and stayed with the victims until they

were removed from the water.

That's a very determined animal.

NARRATOR: So what could cause sharks to display

such brazen determination?

For Collier, there can be only one explanation.

In my opinion, these animals were not investigating.

These were all predatory attacks.

These sharks were attempting to feed on the victim.

NARRATOR: Sharks trying to feed on humans.

It's a terrifying and virtually unprecedented revelation.

It's extremely unique and very, very rare.

And we had to find out why.

NARRATOR: So what could cause Egypt

sharks to suddenly start attempting

to actually eat beachgoers?

For Dr. Dan Huber, such unnatural behavior

suggests that something equally unnatural

must be occurring in the predator's environment.

In fact, it could point to some kind of human intervention.

Animals can be trained to exhibit certain behaviors

in response to a stimulus.

And the reason why this works is because the stimulus

is associated with a reward.

NARRATOR: This concept is known as conditioning.

One of the primary ways that this happens

is if a shark gets hand fed over and over

and over again, it's learning to associate people

with a food reward.

Which means that it's going to exhibit feeding

behaviors around people, even if that food reward isn't present.