Only single individuals are real, but they can be grouped together by a human observer through their similarities.

But the human observer would never know the difference.

Nonetheless, human observers would find a large decrease in available light.

As a result, females are sometimes mistaken for males by human observers.

A human observer would have made little of these deep, angry noises.

This spring, two programs bring together whales and their human observers.

These data were measured for human observers and a 2-degree field of view.

The only human observer left to watch them now was the man named Birch.

Never did they meet the gaze of their human observers.

It became a full weather station in March 1966, with readings made by a human observer.