Wednesday, 19 June 2019

Bear Facts Refute Creationism

Polar bear, Ursus maritimus
Evolved by losing information.
News: How eating meat shifted polar bears’ DNA | College of Natural Sciences (CNS) | UMass Amherst

How did new information create polar bears?

According to creationists, it can't have done because, so the dogma says, no new information can arise due to mutations, and since evolution requires mutations on which selection can work, it should follow that evolution can't include new information. A corollary to this dogma is that loss of information is invariably detrimental.

The problem with that dogma is that real world biology keeps finding examples that shouldn't be there. The latest is the finding that polar bears evolved from a common ancestor with brown bears by adaptations that required changes in the number of certain key genes. This was discovered by researchers from the University of Massachusetts Amherst College of Natural Science.

Sadly their findings, which were published a few days ago in PNAS, sits behind a paywall.

According to the University's press release, the researchers chose the polar bear (Ursus maritimus) and brown bear (Ursus arctos) specifically to look at how gene copy-number variation (CNV) had contributed to the divergence of the two closely related species.

The two species only diverged about 500,000 years ago and are still close enough to produce fertile hybrids, yet they occupy very different ecologies and have very different diets. Brown bears are omnivorous and eat a wide variety of plants and berries whereas polar bears are entirely carnivorous, eating seals and other animals which are themselves carnivorous so providing little or no plant matter even from their digestive tract.

Evolution acts on different types of genetic variants to do the same thing. Now that we have the technology to detect CNVs, the consensus is that this type of mutation should be examined, along with the traditional methods for detecting parts of the genome that are shaped by natural selection.

John G. Gibbons, co-author
Using new technology that makes this sort of analysis possible, the team analysed the genome of seventeen polar bears, nine brown bears and two black bears (Ursus americanus) they identified an average of 318 genes per individual that showed evidence of CNV. Nearly 200 genes displayed species-specific CN differences between polar bear and brown bear species, with most of the difference being a lower CNV than for brown bears.

40% of these differences were in genes that related to olfactory functions and 88% of those difference involved a lower CNV in polar bears. Polar bears do not need to be able to find anything like the range of foods that brown bears need to find but need to be much more focussed on specific prey species. Basically, polar bears only need to be good at finding seals and mates. Far from being detrimental, this loss of information was adaptive to the polar bear's environment. In other words, this loss of information was advantageous to the diversifying polar bear.

A similar loss of CNV was found in the gene that codes for enzyme amylase - a component of saliva that initiates digestion of starch - absent from the polar bear diet but an important ingredient in the diet of brown bears. Similar adaptations are found in different human populations in which starch plays a greater of lesser part in the diet.

According to creationist organisations, if evidence contradicts the Bible, the evidence doesn't count, so this probably won't worry them, but this is a very clear, real world example of something happening that, according to creationist dogma, doesn't happen.

Not only does creationism fail to have any predictive power but even its basic doctrine is refuted by the facts.







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