No evidence polar bears survived Eemian warmth because they were not yet fully ice-dependent

From Polar Bear Science

Is evolution primarily fast or slow? Does it take hundreds of thousands of years or a few generations to produce a new species? Ignoring vast evidence to the contrary, most geneticists insist that evolutionary change is imperceptibly slow and one of them is using this misconception to support the human-caused climate change narrative.

For polar bears, the question is this: could brown bears (aka grizzlies) have survived for hundreds of thousands of years living in a completely different habitat–the perpetually-frozen world of Arctic sea ice–before significant biological changes took place? I contend the answer is no. Moreover, if I am correct that polar bears arose ca. 140,000 thousand years ago (140kya) during the height of an extreme glacial period, the fossil evidence concurs. Analysis of fossil remains show that by about 115-130kya at the latest (after perhaps 10k years), polar bears were primarily eating seals as their modern counterparts do and their bones had lost the distinctive features of their grizzly ancestors.

But that’s the maximum time frame: research on other animals indicate that such critical changes almost certainly took place long before that, within the first few generations of life on the sea ice. If coordinated changes had not taken place very quickly, within ecological time, brown bears would simply not have survived the harsh life on Arctic sea ice.

An essay published earlier this month by Ned Rozell (1 June 2023), ‘Polar bears of the past survived warmth,’ included an interview with experienced polar bear geneticist Sandra Talbot (e.g. Heaton et al. 1996; Talbot and Shields 1996a, 1996b). She essentially told Rozell that the reason polar bears survived the thousands of years of summer ice-free conditions during the Eemian Interglacial (ca. 115-130kya) was because they were still grizzly-like and therefore able to spend large amounts of time on land eating terrestrial foods.  

“The warm period of the Eemian might have come at a time when the polar bear wasn’t such an ice specialist, Talbot said.”

This is an extraordinary statement given that Talbot was a co-author of one of the papers that provides evidence to the contrary (Ingolfsson and Wiig 2009; Lindqvist et al. 2010). Isotope analysis of the Eemian-aged fossil mandible (jawbone) found on Svalbard (see image below) confirmed that this animal ate a similar diet to modern polar bears. Another paper describing the fossil states explicitly that the overall size and shape of the bone, as well as the conformation of the cheek tooth sockets indicate an animal closely resembling a modern male polar bear.

“...our results clearly demonstrate that the jaw is from an individual that had a feeding ecology similar to present-day polar bears, at the top of the Arctic marine food chain.” [Lindqvist et al. 2010:5055]

Morphological analyses of the mandible suggest that it comes from a fully grown male that was similar in size to extant male polar bears.” [Ingolfsson and Wiig 2009:455]

Upper: polar bear male left mandible ca. 12.9-12.4ky old from Asdal, Denmark, Geert Brovad photo, Natural History Museum of Denmark. Lower: polar bear male right mandible (mirror image) from Svalbard ca. 130-115ky old, Karsten Sund photo, Natural History Museum, University of Oslo. Middle: grizzly left mandible sketch isolated from larger drawing, Canadian Museum of Nature.

And as the drawings below show, it’s not just the mandible that differs between grizzly and polar bear. There are major differences in the skull as well, which means that all of these changes likely happened at the same time. Not shown are changes in the rest of the skeleton, from the vertebrae to the foot bones.

By her statement Sandra Talbot, is telling readers that it must take hundreds of thousands of years to produce a new species because she assumes that the process is driven by the accumulation of many random genetic mutations. She is like most geneticists and many evolutionary biologists in holding this view.

However, there is a huge body of evidence that this time frame is incorrect and that a species can transform into a new distinct form within 10 generations or less. It is a little-know fact that modern biologists cannot explain precisely how a distinct species, like a grizzly, could have transformed into a unique entity (the polar bear) via randomly accumulated mutations in genes. This is known within the field of evolutionary biology as “The Species Problem” (Crockford 2004, 2023).

However, I have developed a plausible, testable theory that explains it well (Crockford 2003, 2004, 2023a, 2023b). My new book lays out the concept in detail because understanding how a polar bear arose rapidly in response to their colonization of the extremely harsh new environment of the mobile sea ice explains how most other speciation events probably happened as well.

Understanding that polar bears must have arisen very quickly from a grizzly ancestor also refutes Talbot’s suggestion that polar bears may have survived thousands of years of ice-free summers during the Eemian because they were not yet truly ‘polar bears.’

Bizarrely, the Rozell piece ends with Talbot implying that polar bears may not be irreversibly locked into a sea ice lifestyle and could face extinction because a return to land (presumably due to lack of sea ice caused by global warming) is now blocked by the presence of humans determined to kill them.

““We can’t predict whether the polar bear is too far out (in its evolution towards a life on ice),” she said. “It’s interesting that there are a few examples of hybridization (between polar bears and brown bears). That’s something worth watching.”

Maybe polar bears have been trying to adapt to life on land, but one species has blocked that avenue of evolution. Polar bears that wander onto land, especially near a human settlement, tend to get shot. And humans — who didn’t wander out of Africa until about 45,000 years ago — weren’t present on the edge of the sea ice when polar bears first made it their home.

“We weren’t impacting them then the way we are now,” Talbot said.”

These are very irresponsible, misleading statements. The notion that polar bears may not be thoroughly adapted to a life on sea ice is not one I have ever encountered before from a polar bear biologist. And there is absolutely no evidence that recent hybridization events represent polar bears “trying to adapt to life on land.”

Furthermore, the fact that on a few rare occasions, a polar bear has been able to interbreed with a grizzly and produce fertile offspring does not negate the unique species status of the polar bear, as many people insist. This belief is based on an incorrect, over-simplified definition of a species that fails to take into account the large number of genetic, morphological, physiological, behavioural, and life-history differences between the polar bear and brown bear (Cronin and MacNeil 2012).

“These genetic data…support recognition of polar bears and brown bears as different species under the biological species, genetic species, and phylogenetic species concepts.” [Cronin and MacNeil 2012:879]

Bottom line: Geneticists often have a limited grasp of the literature on evolution outside their specialty and some of them are making misleading statements to the public about polar bear evolution in an effort to prop up the human-caused global warming narrative. There is no evidence that polar bears survived Eemian warmth because they weren’t yet fully ice-dependent or that polar bears in the future could live on land like grizzlies if Arctic sea ice disappeared completely, in every season of the year. Fortunately, no climate model predicts that rising CO2 levels could cause that scenario to occur.


Crockford, S.J. 2003. Thyroid hormone rhythms and hominid evolution: A new paradigm implicates pulsatile thyroid hormone secretion in speciation and adaptation changes. International Journal of Comparative Biochemistry and Physiology Part A 135, 105–129.

Crockford, S.J. 2004. Animal Domestication and Vertebrate Speciation: A Paradigm for the Origin of Species. Ph.D. dissertation. University of Victoria, Canada.

Crockford, S. J. 2022. Polar bear fossil and archaeological records from the Pleistocene and Holocene in relation to sea ice extent and open water polynyas. Open Quaternary 8(7): 1-26.

Crockford, S.J. 2023. Polar Bear Evolution: A Model for How New Species Arise. Amazon Digital Services, Victoria.

Cronin, M. A. and MacNeil, M. D. 2012. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus). Journal of Heredity 103 (6): 873-881. doi: 10.1093/jhered/ess090

Lindqvist, C., Schuster, S.C., Sun, Y., Talbot, S.L., et al. 2010. Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear. Proceedings of the National Academy of Sciences USA 107:5053-5057. Open access

Heaton T.H., Talbot S.L. and Shields G.F. 1996. An ice age refugium for large mammals in the Alexander Archipelago, southeastern Alaska. Quaternary Research 46:189–192.

Ingolfsson, Ó and Wiig, Ø. 2009. Late Pleistocene fossil find in Svalbard: the oldest remains of a polar bear (Ursus maritiumus Phipps, 1744) ever discovered. Polar Research 28(3):455-462.

Talbot, S.L. and Shields, G.F. 1996a. A phylogeny of the bears (Ursidae) inferred from complete sequences of three mitochondrial DNA genes. Molecular Phylogeny and Evolution 5:567-575.

Talbot, S.L. and Shields, G.F., 1996b. Phylogeography of brown bears (Ursus arctos) of Alaska and paraphyly within the Ursidae. Molecular Phylogenetics and Evolution 5:477-494.

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June 30, 2023 6:17 pm

New species can arise in a single generation, moreso in plants than animals, but it still happens in our kingdom. Usually rapid evolution is thanks to polyploidy or total genome doubling. This was not the case in polar bears, but there was for sure strong selective pressure in favor of seal hunting adaptations.

Dr. Crockford is correct that at least paleoprotopolies had evolved by the maximum of the Riss glaciation, before the Eemian interglacial. There may well have been seal specialist populations earlier.

Richard Page
Reply to  Milo
July 1, 2023 5:16 am

The controversial DNA studies that pushed the evolution of the Polar bear back to 600k years ago could be of an early Brown Bear offshoot that became a seal specialist and, eventually, may have evolved into a Polar Bear. Certainly the earliest Polar Bear fossil records indicate an evolution around 150k years ago and Dr. Crockfords theories definitely support this later date. Interesting stuff.

Reply to  Milo
July 1, 2023 9:49 am

Not in a single generation; it takes multiple generations to produce a gene pool capable of reproducing itself as a distinct species as opposed to a one-off mutation.

The theory that Dr. Crockford disagrees with based upon the evidence is that the evolution of distinct species as a result of environmental changes requires thousands of generations. But Dr. Crockford shows that evolutionary change can be evident in as little as 10 generations, and is not a result of very long term random gene mutations. Evolution resulting from environmental change rather quickly deselects individuals not capable of surviving in the changed conditions, because they die before reproducing .. whereas evolution selects individuals who are more adaptable to the changing conditions.

In other words, evolution not about random gene changes, but forced changes. Same thing occurs with domesticated animals which can be bred in just a few generations into a stable, self reproducing new variety, if not new species.

Since geologic timeframes are such that, during glaciation/interglacial cycles last roughly 100 thousand years, a 10 generation timeframe is not all that long (50 years?) by comparison, probably much shorter than the timeframe in which the planet switches from glacial to interglacial conditions which occurs over hundreds if not thousands of years. Thus polar bears ought to be able to evolve right along with the climate – exactly as polar bears, and all other bears, have been doing for hundreds of thousands to millions of years.

Reply to  Duane
July 1, 2023 10:25 am

Alteration of a single developmental regulatory gene can produce multiple morphological changes all at once. If these changes are advantageous, they can be fixed in a population in a few dozen generations.

Reply to  Fran
July 3, 2023 6:00 am

No geneticist agrees with your single gene theory. Nobody really knows how many genes much change to create a new species, but all of the science to date suggests that speciation requires multiple, even many gene changes.

For example, with polar bears, it is not just the shape of their skull that differs from brown bears, it is also the shape of their body and the color of their fur and how their digestive system functions to live on a diet of fur seals instead of fish or berries. None of that range of genetic change is based upon a single gene.

Reply to  Duane
July 3, 2023 11:56 am

Polar bears are still omnivores and their seal diet tends to be during a short annual period when seals can be caught.

June 30, 2023 6:24 pm

PBs hunt mostly at the edge of the ice.

If the Arctic is 100% sea ice in autumn/summer/spring, hunting becomes very difficult.

The drop in sea ice extent from the extreme highs of the LIA and 1979 has been great news for PBs hunting seal.

Reply to  bnice2000
June 30, 2023 10:10 pm

What is essential to PBs is land fast ice in the spring, where female ringed seals make their snow lairs for giving birth to pups. No amount of global warming will end spring shore ice. After sow bears fatten on seal pups, summer and fall feeding doesn’t really matter. They can do that on sea ice or on land.

Tom Halla
June 30, 2023 6:26 pm

My dilettante view is to favor Steven Jay Gould, and believe in fairly rapid speciation. Susan Crockford notes there was the emergence in the record of a group of traits that can be called consistent with being a separate species, and that emergence was fairly rapid.
What polar bears seem to be dependent on is seals, not ice. Predating whelping seals looks like their specialization, so where the seals can whelp is their habitat.
What seals do is important as well. Just how dependent are seals on broken spring ice? This is a system, not a single element.

Reply to  Tom Halla
June 30, 2023 6:36 pm

Gould tried to squeeze biology into his Marxist belief system. The fact is that evolution occurs both quickly and slowly. Gould was a Commie just one cut above Lysenko. Ignore his entire body of work, ie lies.

Tom Halla
Reply to  Milo
June 30, 2023 6:41 pm

Trashing someone for their politics is pure Lysenko. What substantive objections do you have to Punctuated Equilibrium?

Reply to  Tom Halla
June 30, 2023 8:29 pm

I already gave them. Puncuated equilibrium is utter rubbish. As I said, evolution occurs both gradually and in a single generation.

Gould and his unindicted co-conspirator admitted that their hare-brained scheme was inspired by Marxism.

Human evolution alone shows the garbage false. H. erectus grade humans gradually evolved into H. sapiens by small, steady increase in brain size over more than a million years, but the initial increase from H. habilis was due to two discrete mutations.

Sometimes there is long stasis in species, when environmetal conditions don’t change, but often there is rapid change in response to altered conditions or adaptive selection. Or just random genetic drift from reproductive isolation.

Nobody today credits Gould’s Marxist fantasy. There is zero evidence in support of his ideological delusion and all the evidence in the world against it. Even in Marxist-friendly academia of the last century, it was rightly ridiculed by real biologists, not popularizing polemicists like Gould.

Pointing out his ideological “science” is the opposite of Lysenkoism. It’s science.

Reply to  Milo
June 30, 2023 9:07 pm

Even in his own time, 50 years ago, Gould was eviscerated by real evolutionary biologists like Dawkins, Dennett and Trivers. Only his writing skill made it possible for him to peddle his Commie trash to an uneducated public.

Please trot out an evolutionary biologist today who embraces Gould and Eldridge’s garbage. Eldridge (born 1943) is still alive. He was a young post grad (Columbia Latin and geology undergrad) on the make when Gould recruited him into his conspiracy in 1972. I don’t know if he still supports the scam or not. He claimed not to be a Commie, but then he wasn’t really much of a scientist either.

Reply to  Milo
June 30, 2023 9:56 pm

Not trashing, just the facts. I enjoyed reading some of his science history essays, even though I knew he was a New York Commie enemy of truth, justice, the American way and the scientific method.

Reply to  Tom Halla
June 30, 2023 10:14 pm

Let’s hear your argument in favor of the blatantly Marxist ideology of “punctuated equilibria”.

Izaak Walton
Reply to  Milo
June 30, 2023 11:57 pm

And I would like to hear how Marx’s theory of how history can be explained using the idea of class struggle between different classes with different modes of production can be used to explain how random mutations in genes leads to evolution. The two are completely unrelated. Steven J Gould may have been a Marxist but his theory is completely seperate from his political views.

Reply to  Izaak Walton
July 1, 2023 2:53 pm

No, they were not separate to Gould, which fact he admitted.

Reply to  Milo
June 30, 2023 7:28 pm

Ah, yes, Evolution– the theory that explains why all hirsute primates are in the Arctic.

Reply to  hiskorr
June 30, 2023 8:30 pm

Before humans, there were no Arctic primates. What’s your point?

Reply to  Milo
July 1, 2023 8:09 am


Richard Page
Reply to  hiskorr
July 2, 2023 4:04 am

Ah yes, hiskorr – your comment might make sense if the only purpose of hair was for thermal insulation. The thing is, it’s a rather complicated issue – hair also works in hot climates to prevent exposure to high levels of solar radiation and, with sweating, to thermoregulate heat as well. It’s known that hair and feathers give animals and birds an evolutionary advantage to flourish in a wide range of temperatures without more evolutionary changes – much more adaptable, d’you see?

old cocky
Reply to  Milo
June 30, 2023 10:40 pm

It might just have been one of those “it seemed like a good idea at the time conjectures”. With a scant fossil record, intermediate forms would have been few and far between.
As I understand it, many genetic changes aren’t expressed in body shape. Based on fossils alone, it may have appeared that there were long periods of no change, then some sudden changes..

Reply to  old cocky
June 30, 2023 11:32 pm

Actually, there was no scientific basis for the supposed hypothesis, only Marxist ideology. All the evidence in the world was against the conjecture.

old cocky
Reply to  Milo
July 1, 2023 1:14 am

The late 1970s and early 1980s seemed to be an exciting period in popularising science, with Hawking, Penrose and Thorne coming up with new stuff on black holes, and Horner’s Bakker’s warm-blooded dinosaurs. Perhaps Gould thought he had a great insight in evolutionary biology.

As you said elsewhere, he was quite an engaging wrier. I quite enjoyed his popular science books.

Reply to  Milo
July 1, 2023 4:53 am

I lost all respect for Gould when he came out against the Data Quality Act. He objected to colleagues, with whom he was ideologically aligned, being subject to actual scrutiny. It was the ramping up of the wars over secret unvettable SCIENCE and unchallengeable EXPERTS being used to drive policy choices.

I did like his take on preadaptation. Probably mostly bullshit, but it was an appealing idea.

June 30, 2023 8:17 pm

Eemian? Come on. You made that up.

Reply to  Tony
June 30, 2023 9:24 pm

Yeah, I thought that was the name of one of the world’s foremost poets of the late 20th Century too.

June 30, 2023 9:15 pm

Evolution this evolution that, what exactly is evolution? The closest explanation I can come up with is that it is the study of differences and similarities. There are many differences between different animals as well as many similarities. We all know that. Many people spend lifetimes attempting to discover why some animals are so similar and is there a connection between them. Looking for connections tens even hundreds of thousands of years ago, sometimes more than that is a monumental undertaking. We can’t possibly know what was happening to these creatures that long ago. The most we can do is look at what remains they have left behind and point out similarities and differences. Anything more than that is pretty much pure speculation.

Reply to  Bob
June 30, 2023 9:53 pm

Evolution is the change in genetic frequencies from one generation to the next.

Reply to  Milo
June 30, 2023 10:34 pm

And what is that?

Reply to  Bob
June 30, 2023 11:30 pm

What is change in gene frequency? Alleles for one trait becoming more frequent in one generation to the next. For example, selection in favor of blue eye color, a recessive trait.

Evolution is a fact. Please deal with that scientific reality. It’s a consequence of reproduction.

Reply to  Milo
July 1, 2023 1:15 pm

Yes alleles favoring blue eyes over brown or vise versa I understand, one animal changing into another not so much.

Reply to  Bob
July 1, 2023 3:05 pm

If you studied the subject, you’d find lots of examples of such change, both in the past and now. New plant species can arise in a single generation by whole genome duplication. That rarely happens with animals, but such events do make available more genetic material with which evolution can work. Vertebrates have enjoyed three whole genome duplications in their evolutionary history, and some species more.

Reply to  Milo
July 1, 2023 3:53 pm

I have studied the subject and realize there are huge limitations to what evolution is capable of doing.

Reply to  Bob
July 1, 2023 7:28 pm

Of course. Whales don’t evolve into birds. But lobe-finned fish evolved into tetrapods, which evolved into amniotes, which evolved into reptiles (including birds) and mammals, the latter of which evolved into primates, which evolved into humans.

We no longer need to rely just on fossils, anatomy, biogeography, etc., to work out the relationships among all life on Earth. We now have biochemistry and genetics. We can see the steps that occurred right in our own and our relatives’ genomes.

And beyond genomes. Our chromosomes show our descent from other great apes. Human chromosome #2 resulted from the fusion of two smaller standard great ape chromosomes. It’s associated with upright, bipedal walking.

We can also see the two mutations which increased brain size in the hominin lineage, for instance.

You haven’t sufficiently studied the subject to have discovered these facts.

Reply to  Milo
July 1, 2023 9:07 pm

I am not convinced that because different animals share similar genomes or chromosome or what ever that that is a guarantee that one is descended from the other.

Reply to  Bob
July 1, 2023 8:16 pm

The principle of selection applies to all genes, whether for eye color in humans or wooliness, body fat, ear size, different trunk fingers and teeth in mammoths. As the Pleistocene glaciations advanced, northern populations of steppe mammoths evolved into wooly mammoths. We don’t have whole steppe mammoth carcasses, as come from the tundra permafrost for woolies, but we have their bones.

Same for evolution of polar bears from grizzlies under the same cooling conditions. Same for evolution of our ancestors from more arboreal ancestors as the unbroken African forest was replaced by savana and isolated woodlands.

Species adapt to changing conditions under selection for favorable traits out of the range of genetic variation. And that’s just one means of evolution among several.

Reply to  Milo
July 1, 2023 9:03 pm

I would think that selection would suggest traits that were already there but not expressed or expressed in a minority population. If that trait became advantageous those populations expressing the trait would become the majority.

Reply to  Bob
July 1, 2023 10:14 pm

New traits evolve all the time. That’s the variation upon which evolution works.

Please study the subject before presuming to comment upon it. Evolution is a fact, both adaptation within species and the emergence of new species throush the same mechanisms.

Or do you believe that God poofed chickens into existence in a single instant? One second, no chickens; next second, chickens.

All actual physical evidence says that birds arose among maniraptoran theropod dinosaurs, and that chickens are among quite early diverging fowl and waterfowl. The group’s ancestor might have survived the asteroid strike by being in Antarctica. Please see Vegavis, that is if you’re interested in actual science, as opposed to ancient Near Eastern myths.

Reply to  Milo
July 2, 2023 7:29 pm

You have done an admirable job trying to defend your view, in the end what you have done is describe the science of similarities and differences like what I said to begin with.

I was waiting for the Near Eastern myths, I was expecting different words but you got around to like I expected. I have had this discussion with countless professors and in the end their answer is that I am a flat earther or a creationist or any number of things they think will hurt me but it doesn’t.

I never bring up the shape of the earth or religion or even my view of how life began or how life has progressed or evolved if you choose. I don’t know how life began I wasn’t there, I don’t know how life progressed, evolved, changed or whatever, I wasn’t there. I question everything and if someone truly believes something and thinks I should believe it they better damn well be able to prove it beyond a doubt or I will keep my doubts.

It’s been fun, cheers.

Reply to  Bob
July 1, 2023 5:24 am

Evolution is where critters change over their generations to take better advantage of the environment. ie. Critters become different than their ancestors.

Fruit fly evolution is commonly studied because they live short lives and can go through many generations quickly.

Here’s a dandy article about fruit fly evolution. Apparently genetic changes can be quite rapid and several traits can change at the same time as the fruit flies adapt to a changing environment.

Reply to  commieBob
July 1, 2023 7:33 pm

Great study, but rapid evolution has long been observed. Always good to have more instances.

On the flip side, evolution will keep a well adapted organism from changing much over many generations. At least superficially, the Australian lungfish, a close relative of us tetrapods, remarkably resembles its ancestor of 10 million years ago. For it, being a fish out of water is no big deal. African lungfish are practically amphibians.

Clyde Spencer
June 30, 2023 9:25 pm

I suspect that evolution is ‘punctuated,’ with rapid evolution more likely when there is great need for survival. Otherwise, there is probably only a slow drift over time.

Reply to  Clyde Spencer
June 30, 2023 9:52 pm

Evolution proceeds under various mechanisms, some rapid, some gradual, ie stochastic and some random, some directional, ie under selection.

Reply to  Clyde Spencer
June 30, 2023 10:12 pm

Gould’s Marxist fantasy of “punctuated equilibria” is a blatant lie, which he knew so to be.

old cocky
June 30, 2023 10:50 pm

And humans — who didn’t wander out of Africa until about 45,000 years ago — weren’t present on the edge of the sea ice when polar bears first made it their home.

This seems to be out by almost a factor of 2.
Even if this means modern H. sapiens, we were apparently in Asia at least 70,000 years ago.

Reply to  old cocky
June 30, 2023 11:28 pm

Nowhere near sea ice until the oldest evidence of Arctic humans until 42 KA.

But yes, out of Africa much earlier.

Richard Page
Reply to  old cocky
July 1, 2023 5:28 am

We were across Europe and into Britain some 100k – 150k years ago, neanderthalensis before that. Inuit have been around the Arctic for about 4,000 years. The date given does appear to be oddly adrift.

Reply to  Richard Page
July 1, 2023 3:07 pm

Anatomically modern humans were not in Europe 100 Ka. Neanderthals were, and before them other archaic Homo forms, going back 800 Ka or longer.

old cocky
Reply to  Richard Page
July 1, 2023 4:10 pm

We were across Europe and into Britain some 100k – 150k years ago,

That early? The couple of quick checks I made to avoid embarrassing myself too badly mentioned the Levant around that time frame, but not much about Europe. neanderthalensis before that

There appears to be some degree of disagreement as to whether it’s H. sap neanderthalensis or H. neanderthalensis.

I only have high school and some undergrad grounding, but it still piques my inner geek. Unfortunately, there is only limited time available to spend on interesting nerdy topics.

Reply to  old cocky
July 2, 2023 10:28 pm

Either classification, ie subspecies or species, is acceptable. H. s/n and H.s/s produced fertile offspring, yet so do polar and brown bears.

“Anatomically modern” humans, ie we, with chins, didn’t enter Europe until well after 100 Ka, and not to stay until about 43 Ka.

old cocky
Reply to  Milo
July 3, 2023 12:57 am

Thank you.

Krishna Gans
July 1, 2023 4:22 am

The best examples for fast evolution are cichlid fishes. I remember to have read about a lot of discussion, concerning these in Africa and America living fishes.

Ben Vorlich
July 1, 2023 7:25 am

What’s the life span of a polar bear in the wild, about 15 years?
So one century is about 8-10 generations? If the Arctic is ice free all year 100 years from now then the Polar Bear has 10 generations to evolve. Doesn’t seem impossible.

But what about seals, can they adapt?

old cocky
Reply to  Ben Vorlich
July 2, 2023 12:16 am

What’s the life span of a polar bear in the wild, about 15 years?

So one century is about 8-10 generations?

It’s more a matter of the age at which the first offspring become self-sufficient.
That’s a combination of sexual maturity, gestation period and time to weaning.

At a guess, that’s probably around 5 or 6, so possibly 12 – 15 generations per century.

A quick check says females first breed around 5, have an 8 month gestation period, the cubs leave home at around 4 months, but they only have a cub every 2 or 3 years.
Males are a bit slower to breed, so the 8 -10 generations in a century looks about right for males and a bit low for females.

July 1, 2023 9:04 am

“The Soviet leaders reserve unto themselves the right to commit any crime, to lie, to cheat and that the only morality they recognize is what will further their cause.”
— Ronald Reagan
It isn’t just the Soviets but all of their ideological descendants.

July 1, 2023 9:12 am

As an aside – the environmentalists tend to abhor meat eating because it is cruel and yet the Polar Bear is good. In addition, those environmentalist that go to the Arctic may go by a Russian nuclear ice breaker. Obviously there will be no complaints about the risk of a nuclear ice breaker getting into ‘difficulties’ or the fact that Russia is able to exploit the Arctic for resources any which way it likes.

Chad Jessup
July 1, 2023 10:02 am

I think some do not realize that being an isolated intrabreeding population is part of Darwin’s definition of species. Polar bears and grizzly bears belong to the same genus, Ursus, so they share substantially more morphological similarities than differences (driven by natural selection), but they still are separate species, Ursus maritimus and Ursus arctos horribilis, respectively, able to produce fertile offspring upon mating.

The Arctic Ocean began forming in the Early Cretaceous 112–140 million years ago, and since then the region has undergone profound oceanographic and paleoclimatic changes providing the polar bear with a sufficient period to evolve in a time frame consistent with Darwin’s concepts.

Robert B
July 1, 2023 5:23 pm

It doesn’t take many generations to breed an animal that would look like a different species if you were to make judgement on fossil evidence. There seems to be this idea that natural selection can not act like a human breeder because there is no intelligence in control. But that is in argument for why it’s usually a long process, not that speciation can not happen quickly at times.

July 3, 2023 11:53 am

Typo alert:

that polar bears arose ca. 140,000 thousand years ago”

140,000 thousand translates to 140 million years ago. The second thousand is redundant and confusing.

Those changes in the skulls of polar bears do not happen over night!

Don’t forget that polar bears have complex hollow fur that traps heat while grizzly bears have simple fur; not hollow or complex.

The guard hairs appear white, but are actually made up of a light-scattering translucent cylinder surrounding a chambered core. This sophisticated structure not only absorbs heat from the environment but also prevents the heat that radiates from the bear’s body from easily escaping into the air around it.”comment image

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