Did nomadic Clovis humans hunt megafauna to extinction?

The middle of the ongoing debate:

Mammoths didn’t go out with a bang

Study suggests Beringia’s shaggy behemoths went extinct after a slow and gradual decline.

Why are there no more woolly mammoths? The last isolated island populations of these huge beasts disappeared about 4,000 years ago — well after the Pleistocene extinction that wiped out much of the world’s megafauna — but what triggered their demise remains a frustrating mystery. According to the latest study to contribute to the ongoing debate, the last mammoths disappeared after a long, slow decline in numbers rather than because of a single cause…

No single cause

“No one event can be blamed for the extinction,” MacDonald explains. Climate change drastically altered the mammoths’ habitats, causing their populations to shrink. Prehistoric humans who were moving through Beringia at the time might also have played a part by hunting the remaining mammoths. That suggestion is backed up by a previous study showing that human predators could have hastened the extinction of slow-breeding mammoths that were already weakened by environmental change2.

… the mammoths’ slow decline could be a preview of what is to come for modern species. “The issues the mammoths faced of climate change, huge habitat change and human pressure,” MacDonald notes, “are exactly what species are facing in the twenty-first century.” The major difference, he says, “is that all these things are happening at a greatly accelerated rate compared to what the mammoths faced”.




But the controversy rages onward:

Shift in weaning age supports hunting-induced extinction of Siberian woolly mammoths

Chemical clues about weaning age embedded in the tusks of juvenile Siberian woolly mammoths suggest that hunting, rather than climate change, was the primary cause of the elephant-like animal’s extinction.

Woolly mammoths disappeared from Siberia and North America about 10,000 years ago, along with other giant mammals that went extinct at the end of the last glacial period. Current competing hypotheses for the mammoth’s extinction point to human hunting or climate change, possibly combining in a deadly one-two punch.

Despite decades of study, the issue remains unresolved and hotly debated. But two University of Michigan paleontologists may have found an ingenious way around the logjam.

U-M doctoral student Michael Cherney and his adviser, Museum of Paleontology Director Daniel Fisher, say an isotopic signature in 15 tusks from juvenile Siberian woolly mammoths suggests that the weaning age, which is the time when a calf stops nursing, decreased by about three years over a span of roughly 30,000 years leading up to the woolly mammoth’s extinction.

Climate-related nutritional stress is associated with delayed weaning in modern elephants, while hunting pressure is known to accelerate maturation in animals and would likely result in earlier weaning, according to Cherney and Fisher.

“This shift to earlier weaning age in the time leading up to woolly mammoth extinction provides compelling evidence of hunting pressure and adds to a growing body of life-history data that are inconsistent with the idea that climate changes drove the extinctions of many large ice-age mammals,” said Cherney, who is conducting the work for his doctoral dissertation in the U-M Department of Earth and Environmental Sciences.

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a crow funeral

by ria
big maple sprawling in leafless branches
o’er her body lifeless
unrecognizable, crushed
still they intuit it is her
arriving one by one
lit into reverent perch above her
all heads bow toward her
final shared moment with her
pervasive mourning flowing
brooding treed flock
in an instinctive moment
or perhaps on mystic cue
all clear the tree flush
lifting the loss skyward
in unifying silent  flight
bound in lingering sorrow
she’s gone

Corvid Research

About me

I’m Kaeli Swift, a PhD student at the School of Environmental and Forest Sciences at the University of Washington.  My research interests are studying cooperative behaviors and relationship dynamics in crows and other social corvids.  Currently, I’m working to understand the function of widely observed crow “funerals.”

Crows, like a number of other animals that includes some primates, elephants, dolphins and other corvids, appear to perform ritualistic funeral behaviors once they discover a dead member of their own species.  These behaviors can include: touching, communal gathering, vocalizing or decreased play.  For people who live or work closely with animals it’s tempting to anthropomorphize these behaviors based on our opinions of how smart or emotional the animals we care about are.  But as a scientist my job is to separate my personal feelings about animals, and use research techniques that allow me to objectively ask questions about animal behavior.  By conducting field experiments and employing brain scanning techniques developed by our team, I hope to gain insight into the purpose of crow funerals.  Perhaps they play a utilitarian purpose of learning about danger or social opportunities, or perhaps they are akin to the grieving process we experience as humans.  The brain scanning technique we use will allow use to peer into the brain of a living, thinking crow, without ever having to euthanize the animal.

Studies that provide bridges from humans to other animals are critical to fostering a culture that respects and protects the natural world, and this is one of the reasons I most enjoy working with crows.   No matter their feelings for them, nearly everyone has a story about crows, even those people who otherwise feel quite separated from nature.  The fact that they are conspicuous and thrive in all kinds of human dominated environments, means that crows are a uniquely accessible animal, and offer a wealth of opportunities to connect people of all interests and backgrounds to science.  It’s my hope that our research will provide a more compassionate lens with which to understand crows, and contribute to a growing movement of corvid enthusiasts…