Dolphins may detect pregnant women's growing fetuses
Using echolocation, dolphins might be
able to detect a pregnant woman's
developing fetus, some experts say.
Dolphins emit sounds in their
environment and listen to the echoes that
return — a process that helps them
identify the shapes and locations of
objects. Doctors use a similar technique
to image a developing human baby .
Both involve ultrasound — high-pitched
pulses of sound above the range of
human hearing.
"I think it's extremely plausible [dolphins]
would be able to detect a fetus," said Lori
Marino, a neuroscientist at Emory
University in Atlanta who studies cetacean
intelligence. However, "you'd have to
really do a well-controlled study to make
a definitive statement," she cautioned.
Fetal buzz-ogram
Anecdotal reports suggest dolphins take a
special interest in pregnant women. The
animals supposedly swim up to the
expecting women and make buzzing
sounds near the women's tummies.
"Buzzing" is a form of very
concentrated echolocation . When the
dolphins want to hone in on something or
stimulate another dolphin, they put their
snout against the skin and buzz, Marino
said, adding, "It sounds like a squeaky
door." [The 10 Strangest Pregnancies in
the Animal Kingdom ]
Malcolm Nicolson, a history of medicine
professor at the University of Glasgow in
Scotland, agreed that dolphins may be
able to detect a human woman's
pregnancy. For instance, a dolphin that
swims with a female trainer before and
after she becomes pregnant "might well
be able to detect a difference in her echo
profile," or the pattern of sounds
returned by echolocation, Nicolson said.
Dolphins might even have the ability to
detect a fetal heartbeat in a woman they
have never bumped up against before, he
added. But Nicolson, who wrote a book
on the development of obstetric
ultrasound , noted that this was only
speculation.
At least one study has found that dolphins
can perceive shapes through an opaque
barrier, such as a box. "It would seem
logical that they would have the potential
to discriminate between different
humans" who are pregnant or not, said
Mike Walsh, an aquatic animal
veterinarian at the University of Florida.
After all, water is the perfect medium for
ultrasound, Walsh said. Still, the dolphins
may not know that what they're seeing
inside the pregnant woman is a person,
he said.
Marino said she thinks dolphins probably
see some sort of image of the baby. "We
know from other studies that they are
very good at going from a visual image to
an acoustic image," and vice versa,
Marino said. Just as sonograms give
people a visual image of their babies,
echolocation might give dolphins a mental
image of them.
By extension, it's quite possible that
dolphins can detect pregnancies in other
dolphins, Marino said. Indeed, the animals
have been seen buzzing on other pregnant
dolphins. Dolphins use echolocation for
many different purposes, from
communicating in a group to disciplining
their offspring, Marino said, adding,
"They're always buzzing!"
Dolphin abilities
Dolphins probably aren't born with their
echolocation ability, but develop it over
time. Baby dolphins, for instance, babble
before they learn to make more complex
sounds, Marino said. She suspects their
echolocation must be learned as well.
Even though dolphins might be able to
detect a pregnancy, giving birth near
dolphins may be a bad idea, as the
meat-eating marine mammals are known
to sometimes be aggressive, scientists say.
Some people claim dolphins also have the
ability to diagnose or treat human
ailments , but these claims are much
less credible, Marino said. For example,
people have reported dolphins acting
strangely in the presence of someone with
a cancerous tumor. However, there's no
evidence to substantiate this claim,
Marino said, and no evidence that
dolphins can heal people using
echolocation.
