Mark Changizi, assistant professor of cognitive science, says that eyes facing the same direction maximise the ability of humans and some other animals to see in leafy environments like forests.
He corroborates his proposition with the fact that a person can see through a pen to the world behind it with both eyes open, though not with one eye closed.
Similarly, a person can see almost everything beyond his/her fingers when they are placed in random directions, and the subjects both eyes are open.
"Our binocular region is a kind of 'spotlight' shining through the clutter, allowing us to visually sweep out a cluttered region to recognize the objects beyond it," says Changizi, who is principal investigator on the project.
"As long as the separation between our eyes is wider than the width of the objects causing clutter - as is the case with our fingers, or would be the case with the leaves in the forest - then we can tend to see through it," he adds.
Changizi, however, feels that eyes located on either side of the head-as in fish, insects, reptiles, birds, rabbits, and horses-might be more beneficial for humans these days because the sideways-facing eyes could allow them to see in front of and behind themselves.
"In today's world, humans have more in common visually with tiny mice in a forest than with a large animal in the jungle. We aren't faced with a great deal of small clutter, and the things that do clutter our visual field - cars and skyscrapers - are much wider than the separation between our eyes, so we can't use our X-ray power to see through them," he says.
"If we froze ourselves today and woke up a million years from now, it's possible that it might be difficult for us to look the new human population in the eyes, because by then they might be facing sideways," he adds.