An average human, utterly unremarkable in every way, can 
perceive a million different colors. Vermilion, puce, cerulean, periwinkle, chartreuse—we have thousands of words for them, but mere language can never capture our extraordinary range of hues. Our powers of color vision derive from cells in our eyes called cones, three types in all, each triggered by different wavelengths of light. Every moment our eyes are open, those three flavors of cone fire off messages to the brain. The brain then combines the signals to produce the sensation we call color.

Vision is complex, but the calculus of color is strangely simple: Each cone confers the ability to distinguish around a hundred shades, so the total number of combinations is at least 100³, or a million. Take one cone away—go from being what scientists call a trichromat to a dichromat—and the number of possible combinations drops a factor of 100, to 10,000. Almost all other mammals, including dogs and New World monkeys, are dichromats. The richness of the world we see is rivaled only by that of birds and some insects, which also perceive the ultraviolet part of the spectrum.

Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.

X, whom society’s most mild command,

For instance evening dress, infuriates,

In art is seen confusingly to stand

For disciplined conformity, with Yeats.

Taxed to explain what this resentment is

He feels for small proprieties, it comes,

He likes to think, from old enormities

And keeps the faith with famous martyrdoms.

Yet it is likely, if indeed the crimes

His fathers suffered rankle in his blood,

That he find least excusable the times

When they acceded, not when they withstood.

How else explain this bloody-minded bent

To kick against the prickings of the norm;

When to conform is easy, to dissent;

And when it is most difficult, conform?

Religion. Sports. War. Biologist E.O. Wilson says our drive to join a group—and to fight for it—is what makes us human.

National Geographic Photo Contest 2011

What’s it like to be a human
the bird asked

I myself don’t know
it’s being held prisoner by your skin
while reaching infinity
being a captive of your scrap of time
while touching eternity
being hopelessly uncertain
and helplessly hopeful
being a needle of frost
and a handful of heat
breathing in the air
and choking wordlessly
it’s being on fire
with a nest made of ashes
eating bread
while filling up on hunger
it’s dying without love
it’s loving through death

That’s funny said the bird
and flew effortlessly up into the air

by Anna Kamienska; trans. Stanislaw Baranczak and Claire Cavanagh