Can Pigeons Detect Breast Cancer?

Story at-a-glance -

  • Pigeons trained to read medical images were able to accurately distinguish between digitized microscope slides and mammograms showing normal or cancerous breast tissue
  • In two experiments, the pigeons had 90 percent and 99 percent accuracy, rivaling that of radiologists with extensive medical training
  • The birds were able to accurately spot both cancer and calcifications linked to cancer

By Dr. Becker

Animals often have uncanny abilities that rival (and in some ways surpass) those of humans, and pigeons are no exception. As a wildlife rehabilitator, I've found pigeons to be smart and cooperative patients. They're certainly deserving of respect but unfortunately are often viewed as "dirty" or unintelligent.

New research published in PLOS One may help put this latter image to rest.1 The birds share many visual system properties with humans, and have impressive visual skills, so researchers reasoned the birds may be able to accurately distinguish between malignant and non-malignant medical images.

Pigeons Decipher Medical Images as Well as Radiologists

Remarkably, pigeons trained to read medical images were able to accurately distinguish between digitized microscope slides and mammograms showing normal or cancerous breast tissue.

In two experiments, the pigeons had 90 percent and 99 percent accuracy, rivaling that of radiologists with extensive medical training. You can see one pigeon in action in the video above. The birds were able to spot both cancer and calcifications linked to cancer. According to the study:2

"We found pigeons to be remarkably adept at several medical image classification tasks.

They quickly learned to distinguish benign from malignant breast cancer histopathology at all magnifications, a task that can perplex inexperienced human observers who typically require considerable training to attain mastery."

Lead author Dr. Richard Levenson, professor of pathology and laboratory medicine at UC Davis Health System, further stated in a press release:3

"With some training and selective food reinforcement, pigeons do just as well as humans in categorizing digitized slides and mammograms of benign and malignant human breast tissue …

The pigeons were able to generalize what they had learned, so that when we showed them a completely new set of normal and cancerous digitized slides, they correctly identified them.

Their accuracy, like that of humans, was modestly affected by the presence or absence of color in the images, as well as by degrees of image compression.

The pigeons also learned to correctly identify cancer-relevant micro-calcifications on mammograms, but they had a tougher time classifying suspicious masses on mammograms — a task that is extremely difficult, even for skilled human observers."

The pigeons proved to be such accurate pathologists that the researchers suggested the birds may be reliable stand-ins for humans to test new types of imagery or technology, in which large numbers of images must be viewed for refinement purposes; there are ethical considerations for this, however.

Pigeons Master Remarkable Visual Feats

Pigeons' neural pathways involved in visual processes are thought to be functionally equivalent to those in humans. So perhaps it's not entirely surprising that these birds can be "prodigious discriminators of complex visual stimuli."

Past research has shown, for instance, that pigeons can recall more than 1,800 images and can detect or discriminate:4

Foreground from background Misshapen pharmaceutical capsules
Letters of the alphabet Basic object categories such as cats, flowers, cars and chairs
Identities and emotional expressions of human faces Paintings by Monet vs. Picasso

In addition, psychologists at the University of Iowa previously concluded pigeons are "capable of making highly intelligent choices, sometimes with problem-solving skills to match."5 In a classic test of basic intelligence known as the "string task," pigeons selected the correct string (the one attached to food treats) up to 90 percent of the time.

Even more remarkable, according to the lead study author, "The pigeons proved that they could indeed learn this task with a variety of different string configurations — even those that involved crossed strings, the most difficult of all configurations to learn with real strings."

Pigeons even have the ability to learn abstract mathematical rules, a skill thought to be shared only with humans and rhesus monkeys.

Remarkable Examples of Animals Detecting Cancer

Pigeons are not the only species that has an uncanny ability to detect cancer and other diseases. Dogs can detect subtle differences in the breath, urine, skin, blood and feces of cancer patients, allowing them to detect certain cancers with up to 97 percent accuracy.

In one study, dogs were able to detect or rule out lung and breast cancer, at all stages of the disease, with about 90 percent accuracy just by sniffing breath samples. Dogs were also able to detect prostate-cancer-specific volatile organic compounds (VOCs) in the urine of prostate cancer patients with 98 percent accuracy.6

So-called medical detection dogs and medical alert assistance dogs are also being trained to detect medical crises before they happen, helping to alert patients so they can seek help. This includes:

  • Changes in blood sugar levels to help people with diabetes
  • Seizures
  • Severe allergic responses
  • Narcolepsy

Beyond dogs, Giant African pouched rats are able to detect tuberculosis,7 mice can detect Avian flu and potentially other pathogens, and even fruit flies, which have highly developed and sensitive odorant receptors, respond to cancer odors. It's time to give not only pigeons but all animal species the respect they deserve.

Ed Wasserman, PhD a University of Iowa professor who has demonstrated some of pigeons' unique intellectual abilities, said it well:8

"Most people would credit pigeons with little intelligence, but we've been studying them for 40 years and they seem to engage in highly complex visual tasks that require a considerable amount of learning. We need a dose of humility in our evaluation of other species."

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