Saturday Science: But We Knew That

A little break from "Earth: A Biography" this week: I have a lot of material to digest on eukaryotes, and I have a lot of other stuff on my plate right now, but I found this interesting:

The human eye is capable of detecting the presence of a single photon, the smallest measurable unit of light, in the dark, researchers said.

In a study first published in the journal Nature Communications Tuesday, scientists found that the human eye can sense individual particles, seemingly concluding the quest to test the limits of human vision.

“If you imagine this, it is remarkable: a photon, the smallest physical entity with quantum properties of which light consists, is interacting with a biological system consisting of billions of cells, all in a warm and wet environment,” Alipasha Vaziri, lead researcher from the Rockefeller University in New York, reportedly said.

For some reason, I thought that had been established. Maybe it was just a hypothesis.

Myllokunmingia; image from BBC

This actually does relate to the development of life on Earth: one of the favorite objections of the creationists/IDers to evolution is "What about something as complex as the human eye? That couldn't have happened by chance." Well, aside from the fact that evolution in not entirely -- or even mostly -- a matter of chance, it's had 500 million years to work on the human eye, maybe even longer: many, if not most single-celled organisms are sensitive to light, which means they have to have some means of detecting it, and they've been around for a couple billion years. And one of the first known chordates, Myllokunmingia, had eye spots: photoreceptors, if you will. We don't know how complex they were, because all we have are fossils, but 500 million years ago, there was already a creature with eyes.

So maybe it's not so surprising that we can detect one photon -- we've been working on it long enough.