Mammoths, Gray whales ... and Polar bears.

9 Jul 2011

Beneath an alpine meadow in the Colorado Rockies a huge fossil bed has been foudn - exactly how and when it was laid down is yet to be worked out. It is some 35 feet deep and is choc a bloc with Ice Age mammals (see www.nytimes.com/2011/07/05/science/05dig.html ). What is now a meadow environment was formerly a lake and previous to that, a glacier - but where do the animals come from?

Weird story of the week - Polar bears have an Irish ancestry (see www.sciencenews.org/view/generic/id/332192/title/DNA_hints_at_polar_bear... or www.physorg.com/print229261177.html). This may sound a bit like the American obsession of tracing their roots - very often back to Ireland, but the use of DNA ancient and modern within polar bears, combined with DNA extracted from a fossilised bear found in a cave in Ireland, does appear to show a link - but that might just reflect on genetic research. Who knows. The cave bear happened to be available as a DNA source so therefore the link with Ireland might be accidental - on the basis that cave bears elsewhere in Europe and the Americas might have produced the same result. This particular animal dates back to between 20,000 and 50,000 years ago, a modest margin on a geological scale but must presumably reflect a warm period in Europe preceding the Late Glacial Maximum. The paper was published in Current Biology July 7th and quite what this might say about the origin of polar bears, that evolved much earlier than the cave bear lived, is yet to be assessed. In addition, the paper has the compulsory AGW add-on, in this context, polar bears are on the verge of extinction - they will turn back into brown bears (or grizzlies, or cave bears, or ... may stay white and attached to snow bound landscapes).

Meanwhile, at www.physorg.com/print229192389.html we learn that the Gray whale feeds on bottom dwelling organisms yet they survived through a succession of Ice Ages and warm interludes so they must have adapted their diet. The Gray whale we may note has a migration route down the Pacific coast of North America, from Alaska to way beyond California, and as we all know it was very cold in this part of the world during the last Glacial period (100,000 years) - or was it? Funny thing the Gray whale has adapted to nosing into the bottom sediments of the seafloor in search of food, rooting out and filtering the worms and crustaceans, and ignoring anything else. Now, in this new research, evolutionary biologists suggest Gray whales may once have had a more varied diet - in order to survive climate changes they are assumed to have experienced. 

It seems that during the Late Pleistocene, and especially between 50,000 and 10,000 years ago, although there was an extensive amount of land extinctions in some parts of the world there was none of note within the marine environment. Gray whales, for example, can feed even in icy waters of the North Pacific. In this bit of research, a computer simulation we may note, the focus was primarily on the last 120,000 years. It began by assuming a huge amount of water was locked up as ice in the northern hemisphere during the last Ice Age (or 100,000 year intervals). This resulted in lower sea levels - especially in the North Pacific - the Bering land bridge was above sea level so it is assumed sea levels globally had fallen. Alternative ideas are of course not part of the computer simulation input. They are ignored. Movement at the axis of rotation could equally cause sea levels to fall - in some regions. Sea levels would rise in other parts of the world as a result of a differing shape of the geoid. That is a basic nitty gritty of catastrophism - the global geoid is not necessarily static. However, by jumping to the conclusion the geoid is moreorless the same over long periods of time the only answer the computer could produce was that lower sea levels meant a reduced amount of food in the North Pacific for Gray whales to take advantage of - so the researchers then assume from this that the Gray whales must have been eating a different diet to that which evolution had predisposed them to partake. If they had insisted on a benthic diet, as nowadays, there would have been a drastic drop in population - but apparently they could find no evidence for a genetic bottleneck. However, instead of eating something other than a benthic diet Gray whales may have had plenty of ocean available for them to cruise - as a result of a different shape of the geoid.