The mess came about soon after the 2006 publication of a paper by Arctic researcher Stephen Amstrup. He and his coworkers were clearly alarmed by three incidents of cannibalism by polar bears in the southern Beaufort Sea, which occurred during a two-and-a-half-month period. Two of the incidents involved the death and partial consumption of adult female bears. In one, the female’s body was found inside a maternity den that collapsed during an attack by a predatory male bear. In the second case, the female polar bear was killed on the sea ice, presumably not long after emerging from its den with a cub. In the third case, a one-year-old male was killed and partially consumed by an adult male. According to Amstrup and his colleagues, these attacks were unique because they had taken place in areas not generally frequented by male polar bears. Each year, once the Arctic sea ice melts and polar bears are forced onto the land, males are usually found near the coast while females and their cubs venture farther inland, and away from the males.
In the cases documented by Amstrup, the researchers concluded that “the underlying causes for our cannibalism observations are not known.” They suggested that the incidents could have been “chance observations of previously unobserved rare events, or even a single rogue bear that adopted a [hunting] strategy including cannibalism.”
What got the media machine cranking, though, was the researchers’ hypothesis that these attacks and subsequent cannibalism might have resulted from male polar bears being “the first population segment to show adverse effects of the large ice retreats of recent years. . . . We hypothesize that nutritional stresses related to the longer ice-free seasons that have occurred in the Beaufort Sea in recent years may have led to the cannibalism incidents we observed in 2004.”
The problem was not in the presentation of Amstrup’s hypothesis, but the fact that many of the media reports that followed neglected to mention that cannibalism in polar bears was already known to be a naturally occurring event, with the first published report surfacing in 1897. By leaving out this vital fact, those working to publicize the effects of global climate change suddenly found themselves on the wrong end of some serious butt-kicking from climate change deniers. These zealots were quick to point out that cannibalism was quite common in polar bears and that the attempt to link polar bear cannibalism to what they referred to as the “Global Warming Hoax” was just another instance in which scientists were flat-out lying to the public. In reality, modern researchers have been reporting on non-climate-change-related infanticide and cannibalism in polar bears for decades, a point Amstrup and his coauthors also discussed their paper, and a point neglected in most of the media coverage.
Ultimately, though, the authors of the sensationalized headlines ignored that information. Instead they cobbled together their stories from non-scientific sources, including a short article by another non-scientist. This one warned of “GRAPHIC PHOTOS” and opened with the line, “Cannibalism is not part of the polar bears’ M.O.” As a result, a valid scientific hypothesis—Global climate change has led to a reduction in Arctic sea ice, and this may be causing increased incidences of cannibalism in polar bears—now takes a back seat to a distorted take on the subject as well as a deceptive but well executed argument by climate change deniers.
This would be my first experience with cannibalism-related sensationalism, but it would definitely not be the last.
6: Dinosaur Cannibals?
Personally, I suspect that a whole pack of full-grown T. rex would have a very hard time finding enough to eat.
— Paleontologist Nicholas Longrich, Discovery News, October 15, 2010
While we’re on the topic of large, meat-eating animals embroiled in cannibalism-related controversies, I thought this would be the perfect time to bring up the topic of cannibalism in dinosaurs—or the lack thereof.
Coelophysis bauri was one of the earliest dinosaurs—a carnivorous and remarkably birdlike biped that lived approximately 200 million years ago across what is now the southwestern United States. A fast runner, it stood about a meter tall at the hips and had an overall length of about three meters from snout to tail. Equipped with a mouthful of recurved and bladelike teeth, Coelophysis was thought to feed on smaller animals like lizards.
In 1947, a team from the American Museum of Natural History (AMNH) working at Ghost Ranch in New Mexico unearthed a huge bone bed composed of hundreds of Coelophysis skeletons. After examining the fossils, famed AMNH paleontologist Edwin Colbert claimed that the abdominal cavities of some of the specimens contained the bones of smaller individuals of the same species. Thus was born the “cannibal-Coelophysis hypothesis” and the subsequent portrayal of Coelophysis and other dinosaurs as cannibals. Reminiscent of the misconceptions concerning male-munching black widow spiders, the depiction of dinosaurs as cannibals remained unchallenged for decades.
In 2005, another group of researchers from the AMNH set out to determine whether or not claims of dinosaur cannibalism could be supported. Led by paleontologists Sterling Nesbitt and Mark Norell, they performed detailed morphological and histological analyses of the bones (something Colbert did not do). Soon enough, the scientists uncovered a slight problem—not only were the bones in question not from juvenile specimens of Coelophysis, they weren’t even dinosaur bones. Instead, the fragments recovered from the abdominal cavities of the two relevant Coelophysis specimens belonged to crocodylomorphs, a group that includes crocodiles and their extinct relatives—but not dinosaurs.