Can Dolphins Really ‘Hear’ Human Tumors?

Can dolphins detect cancer in people? To some scientists, it’s not even a legitimate hypothesis; and to many animal-rights activists, “swim-with-the-dolphin” cancer diagnostic centers would be no less objectionable than any other form of captivity.

“Thank God to this little dolphin, Keppler. He saved my life,” Stoops says.

But what if the rather far-fetched idea were true? What if we tested dolphins and discovered they can detect tiny tumors and abnormal growths in humans, perhaps even those missed by state-of-the-art technology? Instead of x-rays, MRIs and CAT scans, will patients one day be clamoring for cetacean-grams?

Probably not. But I, for one, believe the hypothesis is plausible. Others are positively convinced it is fact, including Patricia Stoops of Panama City, Florida, who claims that a captive dolphin named Keppler saved her life after a chance meeting at a swim-with program in the Caribbean.



Stoops was on a Carnival cruise in the British Virgin Islands when she eagerly signed up for the “dolphin excursion” on the island of Tortola. 

She and about 15 others entered the water as a group of captive dolphins approached them and began interacting as normal. But one dolphin, Keppler, took a keen interest in Stoops and refused to leave her alone.

“He did a flip in front of me,” she told WJHG-TV news in Panama City. “He kept running into me and I explained to the trainer that the dolphin had hit me. He said, ‘Oh, that's unusual.’ The dolphin trainer said the dolphin detected something wrong with me.”

Stoops was taken aback by what the trainer’s said next: He asked if her trip was sponsored by the Make-A-Wish Foundation, to fulfill a final wish of swimming with dolphins.

“He asked if I'd ever had cancer. I said, ‘no way!’” she said. In fact, she had never been healthier in her life. But, she would soon discover, that was not true.

A week after returning home, Stoops noticed some pain in her chest. Thinking it had something to do with the dolphin encounter, she went to the doctor, who discovered a spot on her lung and diagnosed her with lung cancer. Now cancer free, she hopes to visit the animal in the fall.

“Thank God to this little dolphin, Keppler. He saved my life,” Stoops says.

Of course, the chain-of-events are likely coincidental, even though eerily similar, unverified accounts are posted online. Michael T. Hyson, PhD, research director at the Hawaii-based Sirius Institute, which advocates captive dolphins as therapy for people with autism and other disorders, writes about a dolphin named Dreamer possessed with seemingly miraculous abilities to heal and diagnose humans.

“A woman swimming with Dreamer thought she had been rammed,” Hyson writes. “The woman was taken to hospital for examination. The woman had a large bruise. X-ray revealed that under the ribs, near the center of the bruised area, there was a small tumor.  It is my feeling that Dreamer likely "zapped" the tumor with a powerful sound pulse, perhaps to heal it, and the high intensity sound left bruising from hydrostatic shock. At the least, the bruising called medical attention to the tumor.”

Meanwhile, “Dolphins have been known to detect certain types of cancer and pregnancy in some people,” WJHG reports, “But experts say there is no clinical research to back up those behaviors.

There has been no research in this regard, though it would be fairly simple. Dolphins could be put in the water with people with various stages of cancer and healthy controls. You could have, say, 15 controls and one patient. If a dolphin displayed unusual behaviors around that person, it’s possible the animal detects something.

Most experts I asked didn’t really know how to answer the question, “Is this possible?”

Michael Miller, spokesman at the National Cancer Institute, tells TakePart that NCI “has never conducted research of this type and I don’t know of anyone we could point you to for more information.” A search of the published literature turns up nothing.

Neuroscientist and dolphin expert Dr. Lori Marino of Emory University and The Kimmela Center for Animal Advocacy, rules out the idea.

“This is all a coincidence and nothing more,” says Marino, an outspoken opponent of dolphinariums and other forms of captivity. “Despite the mythology, there is no evidence that dolphins can detect cancers and other diseases in the human body,” she says. “Why was the dolphin ramming the woman and getting excited? It could be for a number of reasons—agitation, play, but none of them show the dolphin detected the cancer.”

There is evidence to suggest that dogs, and cats, can be trained to detect certain forms of cancer in the breath or urine of people, though the science on that is slim. “We are not aware of any convincing evidence to show that dogs can detect cancer in patients,” says Andrew Becker, director of media relations at the American Cancer Society.

There are few published studies on dogs, cancer and diagnosis. A literature review published last year in an “effort to determine whether dogs have a role to play in modern health care as an alert tool or screening system for ill health,” especially cancer, seizures and hypoglycemia, highlighted “weaknesses in the work” and proposed “directions for future studies,” hardly a decisive conclusion.

As for low blood sugar (hypoglycemia), in one study of 138 diabetes patients with dogs, 65.1% of respondents said their pet “had shown a behavioral reaction to at least one of their hypoglycemic episodes, with 31.9% of animals reacting to 11 or more events.” 

If dogs can detect human cancer, they do so with their keen sense of smell. But dolphins have little or no ability to smell. Underwater, their world is informed primarily by sound and electric waves.

The ability of whales and dolphins to emit and receive high-frequency sounds, called echolocation, has long baffled and awed scientists. Even today, we do not fully understand the remarkable process, which literally lies outside our own brains’ ability to perform.

I became fascinated by echolocation when researching Death at SeaWorld, a book about killer whales, the world’s largest dolphins.

Dolphins have a sac atop their skulls called the “melon,” filled with a fine, waxy oil. They can manipulate nasal sacs behind their melon to make clicking noises, which sound like fingers running over a comb and each last from one to five milliseconds. As I wrote in the book:

Sound travels through water about four and a half times faster than air - around one mile per second. When each click pings off an object, part of the sound wave is sent back toward the dolphin, where it is received through fatty tissue located in the lower jaw. From there it is transmitted to the middle ear and the brain.

Each click is exquisitely synchronized so that outgoing sounds do not interfere with incoming ones: each echo is received before the next sound is dispatched. The amount of time that lapses between a sound and its echo tells the dolphin how far away an object is. By sending and receiving a continuous string of clicks, all dolphins can follow moving objects (like food) and home in on them.        

The visual and auditory regions of dolphin brains are highly integrated, allowing them to construct visual images based on echoes. Their accuracy is astonishing.

Dolphins can differentiate between objects with less than 10 percent difference in size, down to a few millimeters. They can do this in a noisy environment, even while vocalizing. And they can echolocate on near and distant targets simultaneously, something that boggles the imagination of human sonar experts.    Even a modern supercomputer using thousands of times more energy could never produce such an accurate visual image based merely on the echoes of pings.

For example, resident orca populations in the Pacific Northwest covet Chinook salmon, which are large and energy-rich. Thanks to echolocation, they can “distinguish a species of salmon by its size, or by echolocating inside the fish’s body to determine the dimensions of its air bladder,” I wrote in the book.

Researchers wonder how female dolphins discover they’re pregnant, and some believe other dolphins detect the fetus through echolocation and communicate that to the mother. In killer whales, such information would be crucial for mothers to prevent sexually mature daughters from mating with the bulls who sired them.

Even Marino agrees that, “There is some anecdotal evidence that dolphins may be able to detect pregnancy.” But, she adds, “in that case, it is plausible because they can use echolocation to examine a woman's anatomy and determine if there is another body inside of her moving about. That is not the case with cancer and disease.”

But maybe dolphins can “read” our electromagnetic waves, and tell if something is wrong. The new issue of Science News reports on the recently discovered ability of dolphins to sense electrical signals from other animals in the water, such as those emanating from heartbeats, muscle contractions or gills. Believed to be the only mammals capable of “electroreception,” dolphins are equipped with unusual sensory organs on their rostrums (snouts) called crypts that can detect electric impulses.

One former dolphin researcher, who asked not to be identified because it’s sensitive, “and I put it in the highly suspect category,” did admit that cancer detection by cetaceans was “possible,” albeit through intelligent observation, not echolocation or electroreception.

“If Make-a-Wish takes people down there, the dolphin could’ve figured out that some people get special treatment and attention from others, such as help in swimming, and decided to figure out what sets the special people apart,” my source said. “The dolphin may have made a game of seeing what is different about the swimmers, then pointing it out.”

The ex-researcher, and many other cetacean activists, couldn’t justify captive dolphins for detecting human illness. I have not made up my mind. If I knew my mother might be saved through early detection by a dip with some dolphins, would I try to stop her? It’s a hypothetical topic for another day.

We may never know if dolphins can “hear” our cancers. But we do know their echolocation is exquisite enough to copy. Researchers at Tel Aviv University are studying echolocation in bats, moles and dolphins to help develop sophisticated ultrasound machines for prenatal care and cancer detection.

“But,” they caution in a press release, “when it comes to more accurate sonar and ultrasound, animals' ‘biosonar’ capabilities still have the human race beat.”

Related Stories on TakePart:

• Can Dolphin Self-Healing Save Human Lives?

• Dolphin Pod Saves Woman and Her Dog From Drowning (VIDEO)

• Taiji, Notorious Dolphin-Hunting Town, Plans Dolphin Amusement Park

David Kirby, a regular contributor to the Huffington Post has been a professional journalist for 25 years and was a contracted writer for The New York Times, where he covered health and science, among other topics. He has written for national magazines and was a correspondent in Mexico and Central America from 1986-1990. His third book, “Death at SeaWorld,” was published by St. Martin’s Press. He is also an experienced writing coach and media trainer: For more info visit

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