Pecking Pigeons Detect Breast Cancer

Through food reinforcement training, the birds had a "remarkable ability" to distinguish malignant and benign tissue.

Pigeons are no bird brains.

These animals could help scientists make big advances in the world of breast cancer research, according to a peer-reviewed research article published this week in PLOS One titled "Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images."

Study leaders trained 16 birds to review digitized renderings from mammograms and biopsy slides, rewarding them with food for correct answers.

The researchers taught the pigeons to peck colored buttons to differentiate between benign and malignant slides and mammograms, and the birds learned through trial and error, Smithsonian Magazine reports.

To avoid the Clever Hans effect, which refers to a horse that was once believed to be able to do arithmetic but was in actuality simply responding to his human audience, the pigeons did all their learning in a box with no humans visible, according to Science.

University of Iowa

With food reinforcement training, the pigeons had a "remarkable ability" to distinguish between malignant and benign tissue, and were able to generalize their knowledge and apply it to images they'd never seen before, according to the study.

“Pigeons may not be able to write poetry, but they’ve had millions of years to develop the abilities that they need to navigate a very complicated and dangerous world,” study leader Richard Levenson, a professor in the department of pathology and laboratory medicine at the University of California, Davis, told Smithsonian. “So it doesn’t surprise me that they can do pathology!"

Pathologists and radiologists work for years to refine their visual skills in order to identify problems, but based on the rapid speed at which pigeons were able to learn to tell the difference between the malignant and benign images, it seems they could potentially serve as surrogate observers of medical images in the future.

The researchers found that the pigeons improved their ability to tell the difference between malignant and benign breast tissue from 50 percent at the start of the study to 85 percent by day 15. By day 25, they were correct 90 percent of the time.

However, the birds' pecks aren't a fail-safe way to tell if a person has cancer. Color and image quality both affected the bird's selections.

When it came to radiology, the pigeons were also able to detect cancer-relevant microcalcifications -- calcium deposits that could be indicative of breast cancer. But they had a harder time identifying certain tissue densities that were indicative of breast cancer.

Humans often encounter the same problem, as spotting suspicious densities in mammogram images is notoriously difficult.

Pigeons share many visual systems properties with humans, the paper says, which inspired the study. The findings suggest pigeons can help evaluate new imaging technologies.

"Pigeons' sensitivity to diagnostically salient features in medical images suggest that they can provide reliable feedback on many variables at play in the production, manipulation, and viewing of these diagnostically crucial tools, and can assist researchers and engineers as they continue to innovate," Levenson said in a statement from University of Iowa.

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