December 12, 2015

The Pigeons That Can Spot Breast Cancer


To a con artist, a pigeon is a gullible person, but pigeons are actually surprisingly shrewd.

They can pick out letters of the alphabet, detect emotion in people’s faces and even tell a Picasso from a Monet. During World War II, the renowned psychologist B.F. Skinner taught pigeons to guide bombs toward a target for the US Navy, although his avian pilots were never sent into combat.

Now researchers at the University of California, Davis, the University of Iowa and Emory University have demonstrated that pigeons are surprisingly good at detecting cancer as well. Using grain as a reward, the scientists managed to train hungry pigeons to reliably spot malignancies in images of human breast cells.

The birds achieved roughly 85% accuracy, which is probably better than beginning medical students, the scientists said, although it doesn’t approach the prowess of seasoned pathologists. On the other hand, the birds’ training only involved 24 slides at four times magnification (and they graduated debt-free). What’s more, when Edward A. Wasserman and his colleagues exploited the “wisdom of flocks” by combining the “votes” of four pigeons on each slide, the birds’ accuracy shot up to an astonishing 99%.

When confronted with mammograms, by contrast, the pigeons were flummoxed. After awhile, they seemed to learn to detect cancer on these images, but when shown new ones, they couldn’t do any better than chance, which implies that they had simply memorised the right calls on the initial images during repeated viewings. By contrast, birds that learned to pick out cancer from tissue samples could carry over their skills to new images.

Why so good with images of actual tissue yet so bad with mammograms? The former consist of breast cells seen under a microscope, while the latter are murkier images of overlapping elements (such as blood vessels) within the breast. Like physicians, pigeons find it easier to make the diagnosis by looking at cells, which is why biopsies are taken.

The research is squarely in the Skinnerian tradition. The birds, kept at 85% of their normal weight, are put into what are known as Skinner boxes, allowing strict control of their environment, and shown images on a flat screen. If they spot cancer, they might be required to peck on a blue area of the screen. If there is no cancer, they might have to peck yellow. Choosing correctly yields a grain reward. If they choose wrong, they see the image again and have another chance to peck the right colour.

Dr. Wasserman, who has been working with pigeons at the University of Iowa for decades, says the research could help scientists better teach humans the complex and high-stakes task of detecting cancer visually. Insights from the pigeons could also help computers do the job someday, Dr. Wasserman says.

 A small team of pigeons in a rural area of a developing country, he says, might even be able to provide a rudimentary form of cancer screening.

“Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images,” Richard M. Levenson, Elizabeth A. Krupinski, Victor M. Navarro and Edward A. Wasserman, PLOS One (Nov. 18)

By Daniel Akst
With many thanks to The Australian