Wild Speculation on Climate and Polar Bears

English: A road sign just outside Longyearbyen...

A road sign just outside Longyearbyen, Spitzbergen, Norway, warning of danger of meeting polar bears. “Gjelder hele Svalbard” means that the warning goes for the entire island of Svalbard. (Photo credit: Wikipedia)

By Dr. Pat Michaels at World Climate Report, reposted with permission.

Here is another big one from PNAS.

For those who don’t know, PNAS stands for the Proceedings of the National Academy of Sciences and it has gained the unfortunate reputation for publishing scientific research articles that regularly get knocked out of the park within hours of their release. The lack of rigor stems from its rather unique “peer-review” process in which National Academy members can submit articles for publication that the authors themselves have had “peer-reviewed”—that is, they passed the article by a couple of friends of theirs for comments. It’s more like “pal review.”

It is hard to imagine many papers being rejected under this system, although it can happen. For example, a contributed article by National Academy member Dr. Richard Lindzen that argued that the climate sensitivity to anthropogenic greenhouse gas emissions isn’t as large as commonly thought was rejected by the PNAS editor in change, overruling the recommendations of the reviewers chosen by Lindzen. But such occurrences are quite rare.

Instead, papers with rather speculative conclusions can be regularly found in the pages of PNAS as we have documented on several occasions (see here and here for example).

A new paper has just appeared which should be added to this list in the form of a contribution by National Academy foreign associate and molecular biologist Dr. Luis Herrera-Estrella on the subject of polar bears, evolution, and climate influences.

While the paper employs cutting edge genetic analysis to try to better establish the evolutionary tree of the polar bear species, when it comes to tying climate changes to the branches of that tree the analysis reverts to visual association (and a selective one at that).

Genetically speaking, the research team compared the DNA make-up of today’s polar bears with those of brown bears and black bears, with that of a single polar bear from ~120,000 years ago. The differences among these genetic codes are clues to the when these animals diverged into separate color morphs*. Additionally, the authors were able to extract some information as to the size of the population of each “species” over time.

The main gist of the findings is that polar bears became a separate “species” some 4- 5 million years ago, although some interbreeding with brown bears occurred on and off throughout the period (see our footnote on the nature of separate species).

This result lends further evidence (which we have highlighted previously, here for example) that polar bears as a species have survived many interglacial warm periods and thus are less “fragile” to climate warming than the more “concerned” among us would have us believe.

But, curiously, the authors of the new PNAS paper arrive at a somewhat different conclusion based upon what we consider to be a less than thorough analysis of the climate data. Here is how they describe their take on the situation:

[T]he marked increase in [effective polar bear population] between 800 and 600 kya [Figure 2(top)], possibly facilitated by Middle Pleistocene [the era of ice ages] cooling, is approximately bounded by Marine Isotope Stage 11 (420–360 kya), the longest and possibly warmest interglacial interval of the past 500,000 y and a potential analogue for the current and future climate. Although [polar bear effective population] remains low thereafter, a small recovery roughly coincident with the [brown] bear–[polar bear] maternal split could be associated with post-Eemian cooling, although this could also indicate an increase in population structure. The very recent, slight increase in [effective population] during the Holocene [the current interglacial] might reflect cooling during the Last Glacial Maximum, although genomic signatures of such recent events are known to have less power. Overall, this analysis strongly suggests that although [polar bear effective population] might have been considerably larger in the past, it appears to have experienced a prolonged and drastic decline for the past 500,000 y, being significantly smaller than brown bear [effective population], and perhaps explaining the observed lower genetic diversity in [polar bears] compared with brown bears. Taken together, our results strongly indicate that key climatic events have played a significant formative role in bear effective population size. [emphasis added –eds.]

And further:

If modern [polar bear] populations result from Holocene range expansions from a few
small, contracted populations in Middle-Late Pleistocene refugia, this may explain the observed low genetic diversity in [polar bears] today, and possibly leave modern [polar bear] populations even more vulnerable to future climatic and other environmental disturbances. [emphasis added –eds.]

Basically, the authors contend that even though polar bears have been a separate “species “ for some 4 to 5 million years and have survived repeated interglacial warm periods, it is vulnerable to warming. It survived during a a period of 2 million years (from 3 million to 5 million years ago) with an average temperature about was as warm as today. Somehow this evolutionary history has made polar bears of today “even more vulnerable to future climatic…disturbances.”

Right. PNAS yet again has fallen victim to it’s “pal review” process.

That is certainly some creative interpretation of the data at hand!

Here is why.

Consider the temporal population data for the bear species derived by the authors compared with the relatively-well established general climate history of the earth. Figure 1 shows the full 5 million year record and Figure 2 shows just the last million years.


Figure 1 (top): Estimates of the effective population size over the past 5 million years of the different bear species studied; BLK—black bears, GRZ—brown bears, ABC1—a different kind of brown bear, PB7—polar bears (source: Miller et al., 2012). Figure 1 (bottom): General climate history of the earth for the past 5 million years as derived from a collection of ocean sediments (source: Lisiecki and Raymo, 2005).

Figure 2 (top): Estimates of the effective population size over the past 1 million years of the different bear species studied (as in Figure 1). The larger gray-shaded area on the right refers to the Early Pleistocene, and the other gray areas (from right to left) refer to the interglacial Marine Isotope Stages (MIS) 15, 13, and 11, and the Eemian, respectively. The arrows point to major events in bear population history discussed by the authors . H, Holocene epoch. (source: Miller et al., 2012). Figure 2 (bottom): General climate history of the earth for the past 1 million years as derived from a collection of ocean core sediments. The numbers are the various MIS (source: Lisiecki and Raymo, 2005).

While there is some bit of character to the population data, largely it is varies rather slowly considering the timescales involved. The character of the climate record is vastly different. The climate record is dominated by the repeated pulse of interglacial warm periods within ice age conditions. About a million years ago, the variance increased and the time between warm periods increased to about 100,000 years (from ~ 41,000 years characteristic of the previous 4 million+ years). During the past million years, there have been 11ish warm events during which time the temperature approached the average temperature of the period from about 3 to 5 million years ago. However, during the majority of the past million years, the temperatures were much colder than those experienced in the period spanning 3 to 5 million years ago.

Now, perhaps you could make a case that as the temperature variance increased about a million years ago and most notably the coldest periods got colder that this had a general negative impact on brown bear (ABC1 and GRZ in Figure 1) populations.

But it is hard to know what to make of the polar bear population (PB7 in Figure 1) trace. It basically bears no resemblance at all to the climate signal—a strong indication that the environmental pressures on the polar bear populations arose from a non-climate origin.

To us, the authors conclusion that climate variation played a strong role in the evolutionary history of the polar bear over the past 5 (or even 1) million years derives from a reasoning (described in the block quote above) that just doesn’t jive with the climatological record. Assuming that the paleoclimate record and the paleo-polar bear population record are fair representations of what actually transpired over the past million years (and there is some questions about the reliability of the latter), to us it seems that the polar bear populations fluctuated over time largely independently of the climate variations.

If, as the authors assert, that interglacial warm periods were warm enough to reduce the polar bear population down to only a few bears in climate refugia thus setting the stage for enhanced vulnerability to climate change as a result of low genetic diversity, then any of the past 3-4 interglacial warm periods could have pushed them to extinction. Clearly they did not. And, further, it seems rather than extinction, what a warmer climate leads to is an increase in interbreeding with brown bears—something which apparently took place with some regularity over the bears’ history, even more so in warmer times. So perhaps in extended warm periods, the polar bear becomes a bit browner—and takes on characteristics which are better suited for a warmer climate, only to re-emerge as the great white bear of the north when glacial conditions return.

Certainly this is just speculation on our part, and perhaps is incompatible with the genetic data. But the genetic methodologies applied in the paper are very young and the sampling of bears analyzed is pretty sparse. Consequently, these first results are liable to be much less than robust as are any conclusions derived from them—especially those related to the specific details of the climate.

But one thing that is undeniable is that the polar bears have survived a score or more climate swings over the past 5 million years, including extended periods as warm as today. If climate were the only stressor on polar bear populations, these new findings should bode well. But as it is not, polar bears will almost certainly face a challenging future. But in discussing and planning their future, focusing on climate change would be off the mark—a story that is told through the findings of the PNAS paper, but not so much by the authors.

*Note that the brown bear and the polar bear are not separate species, at least in the classic sense. Mate the two and you get viable cubs that are reproductively competent. That’s the definition of what comprises a species.

References:

Lisiecki, L., and M. Raymo, 2005. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography, 20, PA1003, do:10.1029/2004PA001071.

Miller, w., et al., 2012. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change. Proceedings of the National Academy of Sciences, http://www.pnas.org/cgi/doi/10.1073/pnas.1210506109

104 thoughts on “Wild Speculation on Climate and Polar Bears

  1. A guest post, I know, but I suggest “with an average temperature about was as warm as today” (in the middle of the article) should read either “with an average temperature about as warm as today” or “with an average temperature which was about as warm as today”.

    All the best.

  2. Why do I get the image of an oddly-angled treehouse with a clumsily-scrawled sign that says “No skeptics allowed” on it?

  3. This “Pal Review” system is very close to the system that I have personally pioneered.

    Known as the “Beer Review” system, I get a couple of pals down at ‘The Dog and Duck’ to give my papers a quick once-over and hey presto, I’m published in next to no time – often in prestigious publications like ‘Hello’ magazine or ‘Exchange and Mart’.

    However, I always feed my raw data, methodology and computer codes to the dog – you never know who might want to get their hands on them!

  4. Here is a short list of peer reviewed evidence of an ice-free Arctic Ocean during the Holocene (around the last 11 thousand years).
    Here, here, here, here

    Here are some possible reasons why they survived.

    George M. Durner et al. 2011
    Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km.

    http://www.springerlink.com/content/032201r34q534455

    and

    We describe an observation of a polar bear cub on its mother’s back while the mother was swimming among ice floes in Svalbard, Norwegian Arctic. Similar observations are to our knowledge not earlier described in the scientific literature.

    and

    Estimating the Energetic Contribution of Polar Bear (Ursus maritimus) Summer Diets to the Total Energy Budget
    The analysis indicated that it is possible for polar bears to maintain their body mass while on shore by feeding on arctic charr and seal blubber. Polar bears of body masses up to 280 kg could gain sufficient energy from blueberries to match the daily energy loss.

    http://www.asmjournals.org/doi/abs/10.1644/08-MAMM-A-103R2.1

    I wonder how polar bears survived in the Arctic during the last ice age? ;-)

    It is considered unlikely that vertebrates could survive in Greenland during the peak of the last glaciation, but many species had probably already immigrated in the Early Holocene.

    http://www.sciencedirect.com/science/article/pii/S0277379197000024

  5. [Moderator’s Warning: Vukcevic, you have been posting off-topic comments like this recently. It is happening to often to be simple error. Cut it out. -REP]

  6. I am sorry to say this in case I offend polar bear lovers, but does it really matter whether a species survives? History abounds with species extinctions but the world keeps turning. Other species thrive for a period and then decline due to all sorts of influences, climate being just one of them.

    The nature of evolution is that the best adapted succeed and the less well adapted fail. The implication is that something better will turn up sooner or later.

    There is one certainty – things will change in the future, and if you don’t believe that you are in denial.

  7. Brilliant, the evidence points to no problem, but the conlusion is a problem for Polar bears!

    Reminds me rathe back a ways on the BBC’s Radio 2 Jeremy Vine show (braodcast between 12 noon & 2pm weekdays) during which some twit from Greenpeace was droning on about the veracity of manmade global warming inserting the occasional snidey remark to his opponent, about how terrible it all was for the Polar bears that the indiginous peoples whose home was melting beneath them! I recall the opponent pointed out that the Polar bear population had suffered over many years primarily through hunting, by those said indiginous people whose home was in fact not melting beneath them because they do not live permanently on said ice, to which the Greenpeace oppo scoffed! Never let facts get in the way of a good story, hey?

  8. Based on 2008 study of bear mitochondrial DNA it was +/- 700 k/y ago when polar bears diverged from brown bears ( see http://w09.biomedcentral.com/1471-2148/8/220). Yet according to certain fossils it was only +/-130 k/y ago polar bears physically assumed what is now their contemporary morphology (2010 http://www.pnas.org/content/107/11/5053.full). The detail is when polar bears so specialized as carnivores their molars could spare to lose significant grinding capacity (as compared to omnivore bears) & their skull changed to support less shear bite force (in trade off for Polar skull becoming more narrow to poke into places for prey).

    Canadian study of ice free spells of Hudson Bay is nice 1990 science of sun tourism … ” A southward shift in the population was evident early into the ice-free period and was followed by a return movement northward during Oct./Nov. …” (http://www.nrcresearchpress.com/doi/abs/10.1139/z90-208).
    ? So how did those Canukistani Polar bears survive off the ice ? Well inconvenient data from 1986 – 1992 reported in “Terrestrial Foraging by Polar Bears During the Ice-Free Period in W. Hudson Bay” shows they actually did get into eating vegetation after all ( http://arctic.synergiesprairies.ca/arctic/index.php/arctic/article/viewFile/1350/1375)

  9. how do these guys know how many bears…..brown,white or black….there were over the years…when all we have are a few scattered fossils

  10. We have come far far away from the science practiced by Einstein and Bohr which, although they held totally opposing views, sought the opinion of one another because they held the truth higher than their careers. On the day that Bohr took his last breath he drew on his blackboard one of the last and hardest of Einsteins thought experiments. To his death, Bohr held the challenge of his opponent close to his heart. Obviously, not everything has improved with time. In comparison, climate science has become a criminal holding the truth to ransom.

  11. Since climate is changing all the time then it would have a small impact on the evolution of the bear. Colour is not the only difference, Polar bears are carnivores and Grizzly/Black bears are omnivores. Their teeth tell us this difference.

  12. ‘a warmer climate ..leads to an increase in interbreeding with brown bears’
    This means that both groups of bears benefit from climate change as climate forcing allows different breeding groups within a wide population to share genes for survival.It then follows that climate change over the past millions of years has maintained and supported the brown and polar bear populations.Climate change therefore is good for bears.

  13. Sometimes it seems like the only claim that hasn’t [yet] been made about polar bears, is that they are really just brown bears spray-painted white by big oil corporations.

  14. Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.

  15. Is not the polar bear more or less at the top of the food chain (in its domain). I conclude therefore that this kind of speculative research would need to be done on all the other links in the chain for it to have any meaning , well, speculative meaning anyway.

  16. The error bars on their estimates of the prehistoric populations are missing. They have to be magnificently large.

  17. BillD says:
    July 27, 2012 at 3:49 am

    Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.

    Now, you have to ask yourself how on Earth the polar bears survived an ice-free Arctic Ocean. See these:

    Estimating the Energetic Contribution of Polar Bear (Ursus maritimus) Summer Diets to the Total Energy Budget
    The analysis indicated that it is possible for polar bears to maintain their body mass while on shore by feeding on arctic charr and seal blubber. Polar bears of body masses up to 280 kg could gain sufficient energy from blueberries to match the daily energy loss.

    http://www.asmjournals.org/doi/abs/10.1644/08-MAMM-A-103R2.1

    and these:

    http://www.springerlink.com/content/5g5756162w677hl4/

    http://www.springerlink.com/content/58k3g6543521tu85/

    http://www.jstor.org/discover/10.2307/40512811?uid=3738096&uid=2&uid=4&sid=21101117727067

  18. The polar bears around Churchill Falls, Manitoba are in trouble. I suggest that the authors and their reviewers get there and hand feed the bears raw bacon to sustain their viability.

  19. BillD says:
    July 27, 2012 at 3:49 am
    Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.

    Assuming they weren’t in the mood to swim out to the pack ice, they’d eat (depending on the season) Arctic char, salmon, musk ox or caribou carcasses, garbage, and the occasional human.

    You don’t get to be an apex predator if you’re picky about food.

  20. Since Polar bears are carnivores and Grizzly/Black bears are omnivores. You would think the polar bear due to increased specialization would have a smaller niche and would be less viable long term. Just don’t say that to the polar bear’s face, you might get eaten.

    I keep thinking of the Koala bears (marsupials) that feed exclusively on eucalyptus leaves. They are considered one of nature’s most fussy eaters. If something ever wipes out the variety of eucalyptus they feed on (Think Dutch Elm Disease) they are set for extinction if the adults will not adapt. What is rather interesting is the brain has become drastically reduced in the present species. In the ancestors of the modern koala the brain once filled the whole cranial cavity.
    Flannery, T.F. (1994). The Future Eaters: An ecological History of the Australasian Lands and People. Sydney: Reed New Holland. page 86

    The smaller the brain and the less adaptable the lower a species chance of long term viability. Polar bears are a heck of a lot smarter and more adaptable then the Koalas so I doubt they are in any real danger as long as hunting is controlled.

  21. I like how the article uses scare quotes around “species”. If the same rigor in differentiating bear species were used with humans then blondes, brunettes, and redheads would be separate species.

  22. I will presume that seals existed during repeated interglacials. How is this possible if there wasn’t any ice? As is well known if you live in Atlantic Canada, the seals will move onto offshore islands and onshore beaches to whelp. At that point the seals would simply be a buffet waiting for the taking by polar bears.

  23. NFN (and suspending disbelief as I suspect the error bars are, as Carl suggests, perhaps bigger than the populations themselves), if you were going to ask somebody what jumps out at them about bear populations from these graphs, it is the the other three ‘species’ have a dramatic decline beginning with the arrival of man, or man like hunters on the scene. Being that we’re in the omnivore’s food chain (and vice versa) this whole thing reads a little bit more like a tale of competition for the spot as top predator. The only cautionary tale is why we would want man eatting predators to make a serious rebound into habitat we occupy. Our sudden burst of nostalgia starts to look less pre-Columbian, and more Emeian.

    brian

  24. vukcevic says:
    July 27, 2012 at 1:48 am

    Piers Corbyn got it right
    Piers rain warning from 42 days ahead for the Olympics opening.

    I have very little patience for people who post off-topic comments in the latest WUWT post in order to get people to see the latest in their pet project.

    I have absolutely no patience when there is a perfectly good open post available over at http://wattsupwiththat.com/2012/07/15/willis-on-why-piers-corbyn-claims-such-a-high-success-rate/#comment-1045320 and putting your comment there will be a heck of a lot more useful to people months from now.

    Don’t say you couldn’t find that post readily – I found it by by going to my Guide to WUWT and searching for Piers. Took me ten seconds.

    If you want to reply, do so on that post…. Unless there’s a connection between PBs and the Olympics. E.g. if Piers is featured on British Coca-Cola commercials targeted for the seal eating competition.

    Have a nice day.

    [REPLY: Sorry. Punched in a little late, but I got to it. Commenters are asked to be courteous and post their comments to the appropriate threads. OT comments will be deleted. -REP]

  25. “a strong indication that the environmental pressures on the polar bear populations arose from a non-climate origin”
    Or the polar bear just evolved in the last ice age and not earlier. Most evolutionary biologists agree that climate is a very important factor in the evolutionary history of species.
    But here we go again: In the lab these issues seem to be of no importance at all. The importance of the genetical material seems to get the upper hand at the moment.

    “Genetically speaking, the research team compared the DNA make-up of today’s polar bears with those of brown bears and black bears, with that of a single polar bear from ~120,000 years ago.” If the researchers did not obtain genetic material from older polar bears this research as Dr. Michaels puts it is just mere speculation. He is right.

    There are still huge gaps to be resolved between genetical and fossil evidence in the evolutionary history of species. Let the researchers find fossil evidence of polar bears that is at least 10 times older.

    http://www.ecologia.unam.mx/laboratorios/evolucionmolecular/viejo/talleresycursos/arts/Ho-Larson_2006.pdf

  26. Gail Combs says:
    July 27, 2012 at 5:02 am
    The smaller the brain and the less adaptable the lower a species chance of long term viability. Polar bears are a heck of a lot smarter and more adaptable then the Koalas so I doubt they are in any real danger as long as hunting is controlled.

    From an outfitter with a hunting camp 100 miles north of Churchill, Manitoba: “Our clients have seen anywhere from 5-10 bears a day with some of our clients seeing 100 bears in 10 days of hunting.” So, the bears are doing fine, even though one per hunter gets culled every 10 days during the hunting season.

    BTW, Churchill has a 24-hour hotline for notifying the authorities that a bear has wandered into town and could pose a threat to people — with a 6-cell holding pen to secure the interlopers until they can be returned to the suburbs…

  27. “Philip Finck on July 27, 2012 at 5:19 am
    I will presume that seals existed during repeated interglacials. How is this possible if there wasn’t any ice? As is well known if you live in Atlantic Canada, the seals will move onto offshore islands and onshore beaches to whelp. At that point the seals would simply be a buffet waiting for the taking by polar bears.”

    Philip, you beat me to it; seems blindingly obvious to me. Why so many people seem to hold the view that “nature” is incredibly fragile and permanently teetering on the brink of collapse is beyond me (the word adaptation springs to mind).

    Cheers

    Mark

  28. John Doe – the “subspecies” term, in conjunction with a paucity of specimens at or beyond a species’ natural habitat can be used as a powerful tool to stop human activity within many miles of a “conveniently found” stray. Don’t get me going on albino bears, which are now enshrined as part of a culture.

  29. ****
    BillD says:
    July 27, 2012 at 3:49 am

    Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.
    ****

    I’d think they’d do whatever needed to track the seals. Seals in ice-free areas have to breed on islands & shores. Polar bears would track them there, or anticipate their arrival.

  30. The study proves that Polar Bears are not endangered due to predicted sea ice melt.

    They have made it through thousands of other times in history when sea ice was far less than today or predicted to occur.

  31. gopal panicker says:
    July 27, 2012 at 2:01 am

    how do these guys know how many bears…..brown,white or black….there were over the years…when all we have are a few scattered fossils

    They’re not using fossil counts to estimate numbers, they’re using genetic analysis- they must have taken genetically samples from that ancient polar bear.. Most of our, and polar bear genes are “garbage- turned off genes”, which have no effect on our appearance or behavior. Mutations in genes affecting our physiology will affect us , and bears, immediately- theyr’e usually disadvantageous. Mutations in “garbage” genes have no immediate effect and accumulate with time. Counting the number of distinctive mutations in
    “garbage” genes gives an estimate of how long a species has been in existence,, how long ago two species split.

    There’s also variance in the “on” genes – blood types, length of canines, or whatever. Evolutionary pressures, and random luck, act directly on the “on” genes, limiting variability..
    When there is a sudden drop in population, as in polar bears at the end of the pleistocene or humans about 70,000 years ago, there is a drastic drop in genetic variability in active, “on” genes. For more, do a web search on “population bottleneck”

  32. gopal panicker says:
    July 27, 2012 at 2:01 am

    “how do these guys know how many bears…..brown,white or black….there were over the years…when all we have are a few scattered fossils”

    I am making a bit of an assumption here, but this will be based on the variations in DNA markers between and within populations, taken together with estimates of the rate at with new variations occur. If both of these estimates are correct, then you can calculate population sizes pretty accurately. However, this would get really screwed up if there was even a small amount of interbreeding with other species (brown bears, for example) as it would appear as an increase in the effective population size.

    As to definitions of species, this is one of those nice hard and fast rules that have had to have been softened quite a bit with more data. It has always been very iffy with plants (which have very relaxed issues over fertility of hybrid offspring) but even with animals, we are finding it harder to be quite so dogmatic. The question is not whether offspring of inter-species crosses survive, but how fertile the hybrid offspring are. It seems that polar bears and brown bears have pretty fertile offspring (at least, this is what has been reported), despite very noticeable differences in morphology and behaviour. It may be that they could (or should) be re-classified on this basis, but I suspect that there is little political will for that. However, it it likely to seriously screw-up the population estimates based on genetic variability referred to in this paper.

  33. If the main gist of the paper was that Polar Bears became a separate species 4-5 mya, what (in an ice-free climate, warmer rhan today (http://en.m.wikipedia.org/wiki/Pliocene)) was the ‘driver’ on the specific white coat adaptation? I would have thought that the species would have differentiated itself from its family while its new niche was actually present…?

    I guess I better read the paper.

  34. I would be very surprised that any meaningful error bars could be constructed for the population size graphs shown above.

    The estimates are based on a statistical “house of cards” model which examines genome segments and infers the size of the population through a complicated mathematical process with lots of assumptions along with some researcher choices.

    The paper and supplementary information were found here.

  35. I have watched these animals hunt fish along the shore of Hudsons Bay, they eat fish like it is their favourite thing in the world. These bears are absolute top level predators, to watch them operate in the wild is truly humbling. To go anywhere close to them without a reliable firearm and a means of rapid escape is insanity, they move like ghosts and they fear nothing except larger bears. If you live anywhere close to these animals, they are of concern every time you step outside.
    A few degrees C either way will not harm them, of course if we want to be sure, we could send unarmed AGW alarmist’s out to monitor and “raise awareness” of their plight, that way the polar bears will never starve.

  36. Rob Potter, Northern Europeans have up to 7% Neanderthal DNA and it appears that some Asian population have about 3% of a Devonian DNA.
    Genetic bottle necks are mostly a problem because they denude the population of immunological depth; modern Cheetahs may have had a 1 female, 2-3 male bottle neck very recently.
    If Polar Bears interbreed with other bear species this is not going to be a problem.

  37. Population estimates? Good grief. You mean like those pengion population estimates for today ?

    And the first satellite count showed that the population was TWICE the estimate ?

    That implys that the error bar on penguin population estimate should be….wait for it….100%.

    Are the error bars on those bear population estimates millions of years back in time also 100% ?

    It would’nt surprise me one bit. So it isn’t science. It is guesswork. All of it.

  38. I sometimes think that the obsession with polar bears signals either teddy-bear deprivation, or perhaps over-attachment, in its adherents. Or is it because they are big? It is like focusing on elephants, or whales, as a metaphor for … oh, wait.

    Seriously, the points about the definition of species variation are very relevant. If polar bears can produce fertile offspring when they breed with other bears (and it seems that they can), then they are just a sub-species. Meh.

    Once upon a time, people used to get excited about lions that way, hence the term ‘lionisation’, which means, among other things, elevating something or someone way beyond its/their actual importance. All this anthropomorphic BS gets very tiresome. If I see one more wildlife documentary about the allegedly noble and self-sacrificing behaviour of animals raising their young, I will puke.

  39. Gail Combs @ July 27, 2012 at 5:02 am

    Although commonly known as Koala Bears, Koalas are not Bears at all. In fact they are a closer relation to the pig than a Bear.
    A warning though, If you’re ever walking in the Australian Bush, it’s Drop Bears you have to watch out for.

    As for Tim Flannery…he’s a lot in to flying pigs.

  40. Gail Combs says:
    July 27, 2012 at 5:02 am
    …. I doubt they are in any real danger as long as hunting is controlled….
    Bill Tuttle says:
    July 27, 2012 at 5:59 am
    …..” So, the bears are doing fine, even though one per hunter gets culled every 10 days during the hunting season.…
    _______________________
    Bill, I am well aware that hunters were the first conservationists. I was just pointing out that humans are their predator and climate means diddly compared to that.

  41. It seems whatever subject the AGW crowd approaches is pure propaganda. More melting ice bricks thrown into the pile to expand the pile. As long as the subject here is genetics,(remembering my fruit fly days) it seems that history may show their (AGW gene pool) gene pool emerges when times are ripe with plenty of leisure time. I have always maintain that there is a genetic link to the mind set of those who follow blindly in the path of similar zealotry; like maggots, they will be blind to the shrinking food supply. And when the food is gone, the maggot is gone. Their behavior does not allow for expressing anything but deceit. They use their intelligence in pursuit of pure selfish gain, blinding any sense of enlightenment.

    Polar bears don’t have much leisure time, they will be here long after maggots among us vanish.

    Sound harsh, but so is the life of a polar bear.

  42. C.M. Carmichael says:
    July 27, 2012 at 7:03 am

    …… if we want to be sure, we could send unarmed AGW alarmist’s out to monitor and “raise awareness” of their plight, that way the polar bears will never starve.
    _____________________________–
    I volunteer Al Gore, Mikey Mann, Jimmy Hansen, Phil Jones, Billy Connolley, and Pete Gleick as the first course team to monitor the poley bears. You can make your favorite picks from this smorasbord menu list of Climate Scientists.

  43. Must point out that U. arctos excluding U. maritimus does NOT forma clade, does if U. maritimus is included. The closes relative is U.a. middendorffi.

  44. It’s a kind of reverse Goldilocks story: current temperatures are supposedly too warm for polar bears but previous temperatures, which were even warmer, were supposedly too cold for them … or something like that.

  45. Who Else says:
    July 27, 2012 at 7:38 am

    Gail Combs @ July 27, 2012 at 5:02 am

    …Although commonly known as Koala Bears, Koalas are not Bears at all. …
    ________________________________
    That is why I put in (marsupial) they do not even make it near anything in the North American continent except for opposums our only marsupia. Marsupials and placental mammals split well before the period in this study so I doubt they have any close relation to pigs. (Pigs are a member of the infraclass Eutheria, not Marsupialia.)

    As for Tim Flannery, he was the only reference I could find on the internet about the brain shrinkage. I would really like to see the paper on that information.

  46. Gail Combs says:
    July 27, 2012 at 7:46 am
    Bill, I am well aware that hunters were the first conservationists. I was just pointing out that humans are their predator and climate means diddly compared to that.

    I knew that. Honest.

  47. “I sometimes think that the obsession with polar bears signals either teddy-bear deprivation, or perhaps over-attachment, in its adherents. Or is it because they are big? It is like focusing on elephants, or whales, as a metaphor for … oh, wait.”

    ….allow me to assist: There is a specific size envy underlying. However, to disguise that envy, they occasionally throw in a frog attachment or adherence. The same creature that will voluntarily cook themselves. Maybe we have something here…. ;)

  48. What intrigued me in the original report was the drop in genetic diversity of the polar bear population over time. This is consistent with the hypothesis that polar bears went through genetic bottlenecks as warmer conditions at the peak of interglacials forced them into refuge areas in high Northern latitudes. There small populations could survive until conditions became more suitable across the rest of the Arctic.

    http://evolution.berkeley.edu/evosite/evo101/IIID3Bottlenecks.shtml

  49. DocMartyn says:
    July 27, 2012 at 7:12 am
    Rob Potter, Northern Europeans have up to 7% Neanderthal DNA and it appears that some Asian population have about 3% of a Devonian DNA.

    I think you meant “Denisovan” DNA.

    Denisovans were to Neanderthals as polar bears are to the brown bears on the Alexander Archipelago.

  50. I notice that they “studied” ‘BLK—black bears, GRZ—brown bears, ABC1—a different kind of brown bear, PB7—polar bears.’

    Is ABC1 the Shrot Faced Bear? (Arctodus simus and Arctodus pristinus) This long legged critter could likely have run down a horse if it wanted to.

    If the “study” didn’t take it into account, there might be a bit of an issue with just how believable it is. It would have been a major competitor.

  51. “polar bears, is that they are really just brown bears spray-painted white by big oil corporations.”

    I KNEW IT!!!!!!!!!!!!!!!!!

  52. “Which came first, the study or the title?”

    Actually in MSM driven Climate science (not the real stuff we so rarely see) the conclusions come first. Everything else is just noise to be lost, misplaced, hidden…

  53. Peter Plail says: “I am sorry to say this in case I offend polar bear lovers, but does it really matter whether a species survives?”

    Only Homo Sapiens. A warmer climate is 99% beneficial to our species. In their desperation to find a pretext for banning vital CO2, Warmists have spent tens of billions trying to scrape up the 1%, totally ignoring the 99%. Should we be surprised that the results are fabrications, exaggerations, and misconceptions? No. Science is dead, dead, dead and may never recover.

  54. DocMartyn says:
    July 27, 2012 at 7:12 am
    Rob Potter, Northern Europeans have up to 7% Neanderthal DNA and it appears that some Asian population have about 3% of a Devonian DNA.

    Interesting. I was curious when one graduate course elective psychopath shrink prof pronounced that humans and chimps are genetically 98% similar. Ah, so are worms, etc., so I responded with a question on the % difference between the human male Y and human female X. No answer. (3:1, female to male) All those sleeper genes just waiting for climate change.

  55. Evolution is how Mother-Nature hedges her bets to ensure life goes on. Organisms diversify and adapt to occupy every ecosystem available, and then continue to change as those ecosystems change. Biodiversity is a reflection of ecosystem diversity. The divergence of bears, wolves, dogs, foxes raccoons and pandas from a common ancestor is a perfect example.

    Extinction events usually result from extreme ecosystem changes over short periods of time. There is no credible evidence to support the claim that the Earth’s climate is changing, or could change fast enough to cause polar bears to become extinct. But even if that happened, during the next glacial interval a new subspecies of bear would move into the arctic and the evolution of a new “polar” bear would begin again. While we should be careful to ensure our activities don’t drive any species to the brink of extinction (with the exception of parasites perhaps), when extinction happens naturally, it’s just evolution.

  56. DocMartyn says:
    Northern Europeans have up to 7% Neanderthal DNA…

    And some of us here may have even more, (which Real Climatologists believe is the explanation for our unevolved, knuckle dragging, mouth-breathing attitude toward anthropogenic climate change!) (sarc)

  57. BillD says:
    July 27, 2012 at 3:49 am

    Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.
    ———————
    When there is no ice for the polar bears, there is no ice for the seals either. The seals come to shore to rest, and are caught by lurking polar bears.

    Just this morning CBC was broadcasting a story of a lady being mauled by a polar bear at a remote camp.
    CBCNunavut

    http://twitter.com/CBCNunavut

  58. Bear in mind:
    +/- 20 million years ago = Ailuropoda melanoleuca ->
    > 10 million years ago = Tremarctos ornatus ->
    +/- 5 million years ago = Ursus ursinus ; which became distinct bears as
    < 5 million years ago = Ursus americanus & U. malayanus & U. thibethanus
    as well as these
    < 1 million years ago = Ursus maritimus & U. arctis ….
    Be fair, I don't see the study authors placing polar bears in a climate past 1 million years.

  59. They have roads on Spitzbergen? Who knew? Seriously, I thought the place was no more than a coal mine and a port for shipping the coal.

  60. Entropic man, I can’t help but think you are still rehashing the drawing-of-silly-trend-lines concept that is still so badly understood by Richard Black at the BBC.

    Statistician William M. Briggs has a good blog article on how not to be confused by spurious, arbitrary “trend lines” here:

    http://wmbriggs.com/blog/?p=5107

    To summarize:
    “Again, if you want to claim that the data has gone up, down, did a swirl, or any other damn thing, just look at it!”

  61. The evidence of Founder Effect impoverishment in the polar bear population is consistent with this study showing superwarming of the Arctic during the peak Milankovich warming of previous interglacial periods.

    I always enjoy it when jigsaw pieces fit together.

  62. michael hart says:
    July 27, 2012 at 10:35 am
    “Statistician William M. Briggs has a good blog article on how not to be confused by spurious, arbitrary “trend lines” here:

    http://wmbriggs.com/blog/?p=5107

    To summarize:
    “Again, if you want to claim that the data has gone up, down, did a swirl, or any other damn thing, just look at it!” ”

    You may have missed the point of Mr. Brigg’s article. If you just look at the data you are filtering it through your own cognitive dissonance and confirmation bias.
    If you use the statistical techniques designed to show patterns in data, you get an outcome independant of observer expectations.

  63. GeoLurking says:
    July 27, 2012 at 8:52 am
    I notice that they “studied” ‘BLK—black bears, GRZ—brown bears, ABC1—a different kind of brown bear, PB7—polar bears.’
    Is ABC1 the Shrot Faced Bear? (Arctodus simus and Arctodus pristinus) This long legged critter could likely have run down a horse if it wanted to.

    ABC1 is the population on Admiralty, Baranof, and Chichagof Islands in the Alexander Archipelago. Short-Face was supposedly a vegetarian, which would make him an unlikely ancestor for Ursus maritimus, but the most probable one for Ursus teddy…

  64. Entropic man says:
    July 27, 2012 at 12:13 pm

    michael hart says:
    July 27, 2012 at 10:35 am
    “Statistician William M. Briggs has a good blog article on how not to be confused by spurious, arbitrary “trend lines” here:

    http://wmbriggs.com/blog/?p=5107

    To summarize:
    “Again, if you want to claim that the data has gone up, down, did a swirl, or any other damn thing, just look at it!” ”
    ———————————————–
    You may have missed the point of Mr. Brigg’s article. If you just look at the data you are filtering it through your own cognitive dissonance and confirmation bias.
    If you use the statistical techniques designed to show patterns in data, you get an outcome independant of observer expectations.
    ———————————————–
    Just words. What are you trying to say that I may have misunderstood?

  65. Following up my previous post; the use of the extreme El Nino year of 1998 as the starting point for describing 21st century warming is an example of choosing a starting point which distorts the outcome in the way you want, xactly as Mr Briggs describes.
    Now, back to the polar bears….

  66. Concerning Polar Bears and Brown Bears as species. “Species” as currently used in biology isn’t nearly as neat as the concept as advanced by Linnaeus, but neither is reality. For the purposes of biology, polar bears and brown bears are separate species, at least as separate as say dogs, coyotes and wolves, all which also hybridize occasionally, and paleonotogically speaking they diverged much more recently than brown and polar bears. Statistically they remain effectively separate because except for rare hybrids, polar bears are going to be far more closely related to other polar bears than they will be to any brown bear. Anyway, it is best not to get hung up on whether polar bears are “safe” because they are just a different race of brown bear not. They aren’t. The argument is pointless. They are safe because they have a demonstrated capacity to deal with major climatic changes over a very long period of time.

    As far as gene flow and hybridization goes, a search on “viral genes in the human genome” will reveal that we carry the genes of a number of different viruses within our own genome. That does not place us in the same species as viruses, nor does it elevate any variety of virus to the status of a hominin.

  67. DougS–I laughed out loud at the “Beer review” process! As a researcher in social sciences, alcoholism to be exact, this particularly tickles me. Thanks.

  68. Duster
    July 27, 2012 at 12:31 pm
    ###

    Some of your statements are wrong. U. maritimus is more closely related to U arctos middendorffi then either is to U. arctos arctos which means that either A) U. maritimus is not a species, but a sub species, or B) U. arctos is a set of species. Also C. latrans diverged from the lineage producing C. lupus around 4 million years ago, possibly earlier. Dogs were derived from wolves 100000 at the earliest estimated using DNA, but only evidenced to 30000 years ago based on archeological evidence ( though this might change real soon !) The authors contention that Polar bears separated from Brown bears 4 million years ago is highly suspect, as every other study has shown them diverging from middendorffi 150000 to 75000 years ago. The genus Ursus did not show up until 4.5 million years ago! As I stated before, the polyphyletic nature of U. arctos ( as currently circumscribed) could easily make this study meaningless, though its hard to tell based only on what is in the lame press release.

  69. BTW, Ursus arctos horribilis is closer to U. arctos arctos then either is to middendorffi, and
    Canis latrans is closer to Canis aureus then either is to lupus! So much for geography being an indicator of anything.

  70. michael hart says:
    July 27, 2012 at 12:21 pm
    “Just words. What are you trying to say that I may have misunderstood?”

    1) Mr. Briggs blog.
    2) My words.
    3) My point.

  71. Gail Combs says:
    July 27, 2012 at 5:02 am
    “Since Polar bears are carnivores…

    This is a common misconception, Gail. Polar bears are highly intelligent and can and do eat just about anything – eggs, vegetation (including kelp), berries, and human garbage etc. This ability to succeed in difficult times is what makes them such a long lasting species, just like us.

  72. But Duster—-The issue, I should think, is not whether semantically white (polar) and brown bears are conspecific or not. This issue is that if white bears can mate and produce fertile young with brown bears, then the genetic diversity of the brown bears is available to the white bear population if they come into contact, which apparently they do.

    Thus the thinning of genetic diversity of the white bears, leaving them at risk for climate crises, is lessened. This is especially true if the brown bear, being adapted to warmer climates, has variants that would help out the white bears if the climate naturally or anthropogenically warms.

  73. “BillD says:
    July 27, 2012 at 3:49 am
    Since the main diet of polar bears is seals hunted on the ice, it would be interesting to know what they would eat if the near-shore ice disappears.

    The gosh darn bears can swim HUNDREDS of miles. Damn .
    Polar Bears are completely unnecessary to the rest of the foodchain.

  74. Sorry. Just testing to see if WUWT “not publishing” means that comments are also shut down.

  75. WOW! I just took a break from work to look at Wikiganda just to see what the current lefty narrative is. The Polar Bear page already references this silly PNASPOS paper! Propaganda travels faster then the speed of lie!

  76. highflight56433 says:
    July 27, 2012 at 8:29 am

    “I sometimes think that the obsession with polar bears signals either teddy-bear deprivation, or perhaps over-attachment, in its adherents. Or is it because they are big? It is like focusing on elephants, or whales, as a metaphor for … oh, wait.”

    ….allow me to assist: There is a specific size envy underlying. However, to disguise that envy, they occasionally throw in a frog attachment or adherence. The same creature that will voluntarily cook themselves. Maybe we have something here…. ;)
    ——————————————————-
    Thanks, highflight. It’s interesting that green propagandists focus on large, lumbering evolutionary dead-ends (pandas come to mind also).

    Maybe the metaphor applies in ways that they don’t quite grasp.

  77. Tenuk says:
    July 27, 2012 at 3:54 pm
    Gail Combs says:
    July 27, 2012 at 5:02 am: “Since Polar bears are carnivores…
    This is a common misconception, Gail. Polar bears are highly intelligent and can and do eat just about anything – eggs, vegetation (including kelp), berries, and human garbage etc.

    It’s not a misconception, it’s a classification — their dentition defines them as carnivore.

    A short-tailed shrew’s dentition defines it as an insectivore, but a shrew will kill and eat a mouse in a heartbeat.

  78. John Marshall says:
    July 27, 2012 at 2:22 am

    Since climate is changing all the time then it would have a small impact on the evolution of the bear. Colour is not the only difference, Polar bears are carnivores and Grizzly/Black bears are omnivores. Their teeth tell us this difference.

    It’s like people who say “I’m a vegetarian but I do eat fish.” ;-)

    Polar bears are carnivores who also happen to also eat goose eggs, blueberries, kelp, garbage, etc.

  79. Carnivory is subdivided into hypo-, meso-, and hypercarnivory. This division is most appropriately applied to the order carnivora. It can be based on dentition, but also on diet. the two do not always correlate. Bears are mostly hypocarnivores. As a family they are among the least carnivorous of all the families of carnivora. The main exception is the mostly hypercarnivorous polar bear, but nothing in its dentition precludes it from eating anything that it wants. This itself is a bit of an exception because many other hypercarnivores do have dentition that makes eating non-meat items difficult. Bears are pretty much an exception to everything. They are what could be called “Hyper-generalist” just like us humans.

    Ursus arctos as a species tends to be mostly hypocarnivoruos but this is only a tendency as populations of even the same sub species can have very different diets. They will eat what ever is available and looks tasty.

    Some poster referred to polar bears as a evolutionary dead end. This is silly. Nothing in the polar bears physiology prevents it from taking up what ever life style it chooses. They have changed in the past and they will change in the future. Something lost on the authors of the PNASPOS paper.

  80. Gail Combs says: @ July 27, 2012 at 5:02 am: “Since Polar bears are carnivores…
    _______________________
    Tenuk says: @ July 27, 2012 at 3:54 pm
    This is a common misconception, Gail. Polar bears are highly intelligent and can and do eat just about anything – eggs, vegetation (including kelp), berries, and human garbage etc.
    _______________________
    Bill Tuttle says: @ July 27, 2012 at 9:10 pm
    It’s not a misconception, it’s a classification — their dentition defines them as carnivore.

    A short-tailed shrew’s dentition defines it as an insectivore, but a shrew will kill and eat a mouse in a heartbeat.
    >>>>>>>>>>>>>>>>>>>>>>>>>
    Yes try telling my old golden retriever that he was a carnivore. Darn dog learned to eat the raspberries right off the canes and there went my berry patch. (at least he was not a bear)

  81. Bill Tuttle
    July 27, 2012 at 12:19 pm

    ABC1 is the population on Admiralty, Baranof, and Chichagof Islands in the Alexander Archipelago. Short-Face was supposedly a vegetarian, which would make him an unlikely ancestor for Ursus maritimus, but the most probable one for Ursus teddy…

    ###
    U. arctos sitkensis and friends, well must give the authors credit. That actually is a good choice for a study such as this, and they did use U. americanus (assuming that’s what they meant by black bear) as an out group, another good choice. Maybe the procedure is good, but its just the conclusion they drew from the results are bunk. I don’t see how they can reconcile their dates when the appearance of the genus Ursus was around 4.5 million years ago.

    I guess I am going to have to find a way to read this paper.

  82. Polar bears eat anything, high-protein foods must taste best and have the added benefit of building strength.
    Survival of the fittest.

  83. So when will these bears evolve to have white winter and brown/black summer coats, switching like snowshoe hares do?

    Oh wait, the bunnies evolved that for camouflage due to pressures from predators. Much evolution comes from adapting to predation, and the bears largely lack native predators, thus there is little “incentive” to evolve. These bears are practically evolutionary dead ends.

    So if humans would hunt bears more often, even polar bears, we’d help them to evolve into a more advanced form.

    Good. So we’ll hunt the polar bears more often, they’ll (eventually) develop brown/black summer coats, which will help them to survive in the upcoming ice-free Arctic summers, and both species will benefit. Likewise hunting more brown and black bears will yield white winter coats, which will look cute as all heck.

    Plus there’ll be the all-around reduction of bears disturbing human garbage and habitation, which will also benefit both species.

    Sounds like a plan to me!

  84. Well I just read the Web Miller paper, as much as I was able with my eyesight failing. This study is pretty intense. They authors address a lot of issues including possible problems with their results. They also make their data available! It appears that the moonbat nonsense was just the standard CAGW tie-in demanded by the Marxist brain-washed publishers so that they can write alarmist press-releases and greenies can site to advance the cause. It really has nothing to do with the rest of the paper.

    Damn Marxist are destroying science.

  85. Just because the planet has (allegedly) warmed and populations of the various
    bears have dropped at (more or less) the same time is not necessarily cause
    and effect. There is such a thing as coincidence.

    It could (and probably is) indicative of the appearance of, and contact with, a
    much nastier superior predator—man.

    We currently “enjoy” the largest ever population of our species. Many of the
    other top carnivores have been hunted if not to actual extinction, then to the
    verge of it by us. The PB is suspected to be related to the Irish brown bear.
    Ireland no longer has any bears. Around the world, the bears have been severely
    predated by us for our protection. It happens when our population expands and
    our land use impacts on the bear’s.

  86. sophocles says:
    July 29, 2012 at 2:01 am
    Just because the planet has (allegedly) warmed and populations of the various bears have dropped at (more or less) the same time is not necessarily cause and effect. There is such a thing as coincidence.

    Precisely. And the 1,000 pound gorilla in the room is that PB populations have been increasing to the point that Canada has increased the number of bear permits it issues every year.

  87. DesertYote says:
    July 28, 2012 at 2:51 pm
    U. arctos sitkensis and friends, well must give the authors credit. That actually is a good choice for a study such as this, and they did use U. americanus (assuming that’s what they meant by black bear) as an out group, another good choice. Maybe the procedure is good, but its just the conclusion they drew from the results are bunk. I don’t see how they can reconcile their dates when the appearance of the genus Ursus was around 4.5 million years ago.
    I guess I am going to have to find a way to read this paper.

    I was kind of chary about their claim of 4.5mya, too, but the paper *is* an interesting read.

    You can expand .pdfs to almost 250% — this paper’s best-read at note-taking speed.

  88. Gail Combs says:
    July 28, 2012 at 2:05 pm
    Yes try telling my old golden retriever that he was a carnivore.

    Trying to tell a goldie anything is futile unless you make a game of it. Problem is, they make up their own rules when you’re not looking…

  89. kadaka (KD Knoebel) says:
    July 28, 2012 at 3:03 pm

    So when will these bears evolve to have white winter and brown/black summer coats, switching like snowshoe hares do?…
    ____________________________________
    I notice that some of my ponies do the same as the snowshoe hares. They have light/white winter coats and dark summer coats especially the liver chestnuts but the Varnish roan appy is the most dramatic. He goes snow white in the winter. What is really interesting is nutrition has a lot to do with the coat color too. More protein/fat gives a darker shinier summer coat.

    It is interesting that wild animals do not show many coat colors but domesticated animals do. I have seen black, bay and pinto coat colors on deer over the years as well as the famous white deer in Seneca NY. But most are the typical brown.

    It would seem the genetics are there but the colors are not “optimal.” Przewalski’s horses, one of the last surviving subspecies of wild horse, are also”optimized” to mostly one color link to photos

    Genetic drift, ain’t it great?

  90. Gee, as human hunting develops, all bear populations drop. When we stopped hunting polar bears just a few years back (having developed guns of sufficient power to kill them at will) they began a poplution recovery (and have about 5 x the bear population now).

    Any reason to think “climate” enters into this at all? Looks to me like hunting explains it all.

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