When someone feigns sadness they “cry crocodile
tears,” a phrase that comes from an old myth that the
animals cry while eating.
Now, a University of Florida researcher has
concluded that crocodiles really do bawl while
banqueting – but for physiological reasons rather than
rascally reptilian remorse.
UF zoologist Kent Vliet observed and videotaped
four captive caimans and three alligators, both close
relatives of the crocodile, while eating on a spit of
dry land at Florida’s St. Augustine Alligator Farm
Zoological Park.
He found that five of the seven animals teared up
as they tore into their food, with some of their eyes
even frothing and bubbling.
“There are a lot of references in general
literature to crocodiles feeding and crying, but it’s
almost entirely anecdotal,” Vliet said. “And from the
biological perspective there is quite a bit of
confusion on the subject in the scientific literature,
so we decided to take a closer look.”
A paper about the research appears in the latest
edition of the journal BioScience.
Vliet said he began the project after a call from
D. Malcolm Shaner, a consultant in neurology at Kaiser
Permanente, West Los Angeles, and an associate
clinical professor of neurology at the University of
California, Los Angeles.
Shaner, who co-authored the paper, was
investigating a relatively rare syndrome associated
with human facial palsy that causes sufferers to cry
while eating. For a presentation he planned to give at
a conference of clinical neurologists, he wanted to
know if physicians’ general term for the syndrome,
crocodile tears, had any basis in biological fact.
Shaner and Vliet uncovered numerous references to
crocodile tears in books published from hundreds of
years ago to the present.
The term may have gained wide popularity as a
result of a passage in one book, “The Voyage and
Travel of Sir John Mandeville,” first published in
1400 and read widely, they write.
Says the passage, “In that country be a general
plenty of crocodiles …These serpents slay men and they
eat them weeping.”
Shaner and Vliet also found reference to crocodiles
crying in scientific literature, but it was
contradictory or confusing, to say the least.
One scientist, working early last century, decided
to try to determine if the myth was true by rubbing
onion and salt into crocodiles’ eyes. Shaner said.
When they didn’t tear up, he wrongly concluded it was
false. As Shaner said, “The problem with those
experiments was that he did not examine them when they
were eating. He just put onion and salt on their
eyes.”
As a result, Vliet decided to do his own
observations.
In the myth, crocodiles often cry while eating
humans. However, deadpanned Shaner, “we were not able
to feed a person to the crocodiles.”
Instead, Vliet had to settle for the dog
biscuit-like alligator food that is the staple at the
St. Augustine alligator farm. He decided to observe
alligators and caimans, rather than crocodiles,
because they are trained at the farm to feed on dry
land. That’s critical to seeing the tearing because in
water the animals’ eyes would be wet anyway.
The farm’s keepers don’t train the crocodiles to
feed on land because they are so agile and aggressive,
Vliet said. But he said he feels sure they would have
the same reaction as alligators and caimans, because
all are closely related crocodilians.
What causes the tears remains a bit of a mystery.
Vliet said he believes they may occur as a result
of the animals hissing and huffing, a behavior that
often accompanies feeding. Air forced through the
sinuses may mix with tears in the crocodiles’ lacrimal,
or tear, glands emptying into the eye.
But one thing is sure: faux grief is not a factor.
“In my experience,” Vliet said, “when crocodiles take
something into their mouth, they mean it.”
.
Source:- University of Florida
Published on the 11th October 2007
