Biologists agree that polar bears, brown bears, and black bears all descended from a prototype of the bear kind. Some researchers infer from the biblical record that bears rapidly and recently diversified from a representative bear pair on board Noah’s Ark, while those who reject the biblical record derive age information from other sources.
One group of researchers pinpointed polar bear divergence at around 150,000 years ago, beginning with mitochondrial DNA. They converted DNA base pair differences into years by assuming evolutionary time in their estimated DNA change rate. The similar date assignment paleontologists gave to the oldest polar bear fossils bolstered their confidence.
However, using nuclear DNA instead of mitochondrial DNA, another group reported in Science that polar bear’s “divergence time was estimated at 603ka [a thousand years] (median estimate), with 95% credibility intervals”—four times the earlier estimate.1 Both ages cannot be correct, and perhaps neither one is true. One or both of the research groups must have made a mistake. A closer look at the procedures that the evolutionists used to convert DNA base sequences into time sheds light on the age discrepancy.
The supplemental material attached to the Science report provided the first clue about how the researchers estimated the polar bear divergence time: “Protein-coding sequences from polar bear and giant panda were added to the alignment of 15 other Laurasiatherian mammals from Hallström et al.”2 Essentially, they hung their new DNA data into a historical scaffold from a previously published evolutionary timeframe that included many mammals….
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