Think of it as a biological and political necessity.

Junk is a biological necessity when you have a habit, an invisible mouth.

Speaking of biological necessities, there's something else I need to take care of before we eat.

It's almost a biological necessity for us to compete.

"And who only sticks out her tongue for biological necessity!"

But this change is dictated by absolute biological necessity.

That the Northwest Union should eventually fight the rest of the world was a biological necessity.

Eating was not enough; it was a biological necessity to eat well.

I think a family is a biological necessity, a good higher organism for people.

"I teach out of intellectual and biological necessity," he says.