Her only concern was a primitive instinct to continue breathing.

And, like its predecessors, it flew in the face of a primitive human instinct.

"Is it because they're different in grain, or educated out of some primitive instinct?"

Some primitive instinct brought his head up with a jerk.

The primitive instincts of the hunted were suddenly working inside his brain.

Some of his most primitive instincts had gone to red-alert status.

Although man needs civilization, it is important that he also be aware of his more primitive instincts.

The dark well where primitive instincts mix with human intelligence.

With the primitive instinct of the hunted, she knew it was too late.

All people have a primitive instinct to flee or fight in the face of danger.