Can Pigeons Really Diagnose Cancer?

Paging Dr. Pigeon! A new study has found that pigeons can be trained to diagnose cancer from medical images—and they’re pretty good at it.

At an impromptu avian medical school research lab at the University of Iowa, each pigeon was placed in a small box that had a touchscreen on one wall. As microscope images of human cells popped up on the screen, the pigeon clicked a yellow button to identify one pattern (cancerous cells) and clicked a blue button for another (healthy cells). The pigeons learned by being rewarded with treats when they were correct.

From Jen Christensen at CNN:

Over 15 training days the birds were able to tell the difference, even with images they hadn't seen before. The pigeons showed "remarkable" success, getting the right answer 85 percent of the time. The birds did better with color images than black and white, but when the birds did a little "flocksourcing" and worked together to identify the images, their accuracy rose significantly—[to 99 percent, which is comparable to trained human doctors].

The birds didn't do as well classifying suspicious mammographic densities or masses. In that case birds mostly memorized and weren't as successful identifying the novel cases. Inexperienced human students may also struggle with these same images.

The pigeons don’t know that they’re looking at cancer, of course; what the study really demonstrates is their surprising ability to identify visual patterns and sort them. They can discriminate foreground from background, sort letters of the alphabet, identify human emotions and facial expressions, and even tell the difference between paintings by Monet and Picasso, write the researchers in their paper published in PLOS One earlier this week. Pigeons can also recall more than 1,800 images from memory, and the parts of their brains responsible for vision are functionally equivalent to those in humans, write the researchers.

It’s not known why pigeons developed such a fine sense of pattern and color discrimination, but we do know a few things about their vision. Because a pigeon’s life frequently ends in the jaws of a predator, they have a highly attuned sense of movement in their immediate environments. From a 2007 article in The Telegraph:

To keep alive in the wild, a pigeon needs to keep its eyes open for predators. Having eyes on the side of its head gives it a field of view of 340 degrees and, in order to fly at speed, its brain can process visual information three times faster than a human's. If a pigeon watched a feature film, 24 frames per second would appear to it like a slide presentation. They would need at least 75 frames per second to create the illusion of movement on screen. (This is why pigeons seem to leave it until the very last second to fly out of the way of an oncoming car: it appears much less fast to them.)

Of course, you’re not likely to see a pigeon in a lab coat anytime soon—but they could help make our cancer diagnostic tools better. Pigeons make errors similar to the ones diagnostic machines make, the researchers write. It’s possible that by studying pigeons, programmers could identify where the machines go wrong, and how to improve them. And that’s nothing to squawk at.