Posted onJune 21, 2023|Comments Off on Claims of interspecies hanky-panky have unfairly sullied polar bear & Neanderthal reputations
One big question I asked before writing my book on polar bear evolution was this: did interbreeding with grizzlies, aka brown bears, profoundly impact polar bear history, as geneticists insist? Or is something else going on?
Virtually all genetic studies done in recent years, which I review in my book, conclude that hybridization with grizzlies has happened to various degrees over the course of polar bear history (e.g. Cahill et al. 2013, 2018; Cronin et al. 1991; Edwards et al. 2011; Hailer 2015; Kumar et al. 2017; Miller et al. 2012). Two of the most recent studies claim the most complicated hybrid ancestry for polar bears yet, invoking tales of “extensive” past hybridization events between the two species (Lan et al. 2022; Wang et al. 2022).
But does their interpretation of the genetic data represent reality or does it simply fit the authors’ preferred but false narrative that climate change is to blame for recent hybridization events and therefore likely to happen more often in a warmer world? And if, as I argue in my book, grizzly hybridization isn’t needed to explain polar bear evolutionary history, what does that say about similar claims that there has been a significant amount of Neanderthal interbreeding with humans in our past? Put another way, are geneticists everywhere going overboard with claims of interspecies hanky-panky?
Posted onMay 8, 2014|Comments Off on Ancestor of the polar bear by any name: grizzly vs. brown bear monikers explained
Apparently, all media outlets (exceptFox News) so confused the distinction between the two common names used for the ancestor of polar bears, Ursus arctos, that they got the point of a recent news story totally wrong. An Alaskan journalist explains.
Coastal brown bears from Admiralty Island, southeast Alaska (courtesy Jim Baichtal, US Forest Service, Alaska). See previous post here.
Tundra grizzly bear from the Yukon (courtesy Government of Yukon Territory). These bears also occur across the north slope of Alaska and are the bears that occasionally hybridize with polar bears this time of year, as explained here.
Posted onMarch 27, 2013|Comments Off on Polar bears cavorting with ABC brown bears not supported by geological and fossil evidence
The authors of a new paper out in PLoS Genetics (Cahill et al. 2013, entitled “Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution”) propose to explain how and why the brown bears (aka grizzlies) of the ABC islands of southeast Alaska (Admiralty, Baranof, and Chicagof – see previous post here), got to be so genetically distinct from brown bears on the Alaska mainland and so surprisingly similar (genetically) to polar bears. The authors determined (using a model) that this genetic pattern could be explained by an ancient hybridization event resulting from female polar bears cavorting with male brown bears in SE Alaska.
I had some issues with the way the paper was promoted by some of the co-authors, which I dealt with separately here. More importantly, I found the scenario these geneticists offered to explain how hybridization might have occurred to be patently implausible. Geological and fossil evidence from SE Alaska largely refutes their scenario, although another explanation may be more tenable. It is not impossible, in my opinion, that hybridization occurred in SE Alaska during the last Ice Age, but if it did, it almost certainly did not happen the way Cahill and colleagues suggest.
Posted onMarch 24, 2013|Comments Off on Polar bear spin reaches new heights as geneticists promote their work
A new paper out in the journal PLoS Genetics proposes that a hybridization event between female polar bears and male brown bears (aka grizzlies) occurred in Southeast Alaska at the end of the last ice age. I’ll get to a discussion of the paper itself (coming in a day or two) but first I have a few things to say about the global warming hyperbole generated by the people promoting the paper. I found it simply mind-boggling.
While the paper itself (Cahill et al. 2013: “Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution”) contains only one short phrase that could possibly be interpreted as linking the results to future scenarios of catastrophic global warming, some of the co-authors have made statements (for the press release and in media interviews) that spin the global warming mantra right over the top. Continue reading
Comments Off on Polar bear spin reaches new heights as geneticists promote their work
Posted onAugust 19, 2012|Comments Off on Is it plausible that Polar bears are 4-5 million years old? Part 1
A new genetic study (Miller et al. 2012, now in print) suggests that Polar bears arose between 4-5 million years ago and thus survived the more than 50 glacial/interglacial cycles of the 2.5 million year Pleistocene epoch. Here I’ll begin to explore some of the claims of that paper on the emergence of Arctic bears, suggesting why we might want to take them with a grain of salt.
See my introduction to this topic, which contains information on the so-called ‘ABC’ bears of Southeast Alaska (as well as some notes on my adventures in ABC bear territory a few years ago). It’s worth taking a look at Doug Hoffman’s excellent Aug. 5 summary of the original paper here. The NIPCC also has a summary here.
Here are some of the points regarding this new paper by Miller and colleagues that I think deserve a critical look. In this post, I’ll elaborate on Claim #1. Continue reading
Comments Off on Is it plausible that Polar bears are 4-5 million years old? Part 1
Posted onAugust 8, 2012|Comments Off on ABC bears and polar bear evolution – and an adventure
A new genetic study (Miller et al. 2012, in press) suggests that polar bears arose between 4-5 million years ago and thus survived the more than 50 glacial/interglacial cycles of the 2.5 million year Pleistocene epoch. I will explore some of the claims of that paper later, suggesting why we might want to take them with a grain of salt.
But first, a bit of background and my personal caving adventure in ABC brown bear country.
Update: see new ABC bear photos added, courtesy Jim Baichtal, US Forest Service, Alaska (“real” ABC bears, he says)