Would the human
race go extinct if our sense of smell were blocked? I don’t think so. But that
may be how the last woolly mammoths disappeared from the face of the Earth,
suggests a group of researchers in a recent paper. "One possible mechanism
for the extinction of animals during climate change could be a disruption of
the sense of smell due to the development of allergies when the flora
changes," wrote Gleb Gilberstein, from SpringStyle Tech Design, Israel,
and lead author of the study, in an email.
Odors strongly
affect and direct animals during the breeding season, and elephants have the
most sensitive sense of smell. “The development of allergies from plant pollen,
changes in pollen's allergic toxicity, an increase in the release period of
pollen, or the emergence of a large number of flowering plants during climate
change could lead to decreases in sensitivity to odors in animals during the
breeding season,” added Zilberstein.
The climax of the
recent ice age gave way to the emergence of plants in massive numbers, likely
releasing a plethora of pollen into the atmosphere. The allergic atmosphere may
have rendered the woolly mammoths unable to smell out potential mates, thus decreasing
the rates of sexual intercourse, explained Zilberstein. He noted that disturbed
odor recognition in animals disables their ability to recognize each other,
disrupts navigation along natural migration routes, and hinders their chances
of finding a mating partner. He suspects that “these changes in allergic
responses of mammoths during a period of climate change led to a decrease in
the mammoth population and, as a result, to their disappearance.”
The multinational team of researchers from Israel, Russia, and Italy studied the remains of a mammoth, horse, and rhinoceros, scanning for immunoglobulins, all recovered from the permafrost. Immunoglobulins are biochemical markers for allergies in mammals, meaning mammal bodies produce immunoglobulins in response to allergic reactions. “We are the first to find immunoglobulins in permafrost mammoths and other permafrost animals,” said Dr. Zilberstein. “We are the first to propose chemical communication disruption between animals as one of the possible mechanisms of animal (mammoth) extinction.”
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| Woolly Mammoth - Horniman Museum, London (via Flickr: CC BY 2.0) |
Woolly mammoths
walked the Earth from about 2 million years ago until about 10,000 years ago
when their last surviving cohort moved to Wrangel Island, a remote island off
northeastern Russia. Among the multiple reasons that have been proposed to
explain the extinction of woolly mammoths—such as human hunting pressure,
inbreeding among the mammoths, temperature fluctuations, and a reduction in
available food due to climate change—this new hypothesis by Zilberstein and
colleagues introduces a possible factor that may have compelled the woolly
giants to die off: allergens.
But not everyone
agrees with this new theory explaining the mammoth's die-off. Vincent Lynch, an
evolutionary biologist at the University at Buffalo, New York, doubts that
allergies played a part in the extinction of mammoths. In response to LiveScience, Lynch said this idea is “pretty far out there” and questions
whether it could ever be proven.
In contrast,
Zilberstein believes that they “have proposed a mechanism that is universal for
other animals.” He hopes that this research will help solve the problems
associated with “preserving species such as Asian elephants, tigers, pandas,
and other rare animals.”