All Bears Are Brethren
The world-wide variations on bears could have come from one original type.
American black bears can vary in color from tan to black
It has been known that Alaskan brown bears can hybridize with polar bears. The resulting mixed breeds, sometimes called ‘pizzlies’ or ‘cappucino bears’, were thought to be rare. Now, in a surprising study from Senckenberg Research Institute and Natural History Museum, scientists have found that mixed breeds of bears are not as rare as they had assumed:
Senckenberg scientists have sequenced the entire genomes of four bear species, making it now possible to analyze the evolutionary history of all bears at the genome level. It shows that gene flow, or gene exchange, between species by extensive hybridization, is possible between most bear species — not only polar and brown bear.”
The breeding between different species is now seen to extend to Asian sun bears. The researchers figure that brown bears can act as a ‘vector species’ causing gene flow from different parts of the world, between polar bears and Asian sun bears, for instance.
Some bears are good tree climbers; others are not.
This realization has broader implications. Have scientists been wrong to consider the various kinds of bears separate species? If interbreeding and hybridization is possible across the globe, what does the term species mean?
The detected gene flow among bears also questions the basic biological concept of a species. The biological species definition assumes that different species cannot produce offspring in the wild or that hybrid offspring are sterile. The best-known example of this is the mule — a hybrid between a horse and a donkey. However, it has been observed that grolars, the hybrids between polar and grizzly bears, are often fertile. Janke: “We have to ask ourselves: Does the species concept still hold true, given there is evidence of gene flow not only in bears, but also in other animals? Therefore, what do we need to protect for the future — species or genomic diversity? .”
Undoubtedly the findings will also impact evolutionary theory.
Creationists often assert that the many varieties of animal families (e.g., cats, dogs, horses) could have diversified from original created kinds. Only those original parent stock would have been needed on Noah’s ark. From the breeding pairs, all the varieties could have descended in just centuries or millennia. This research goes against evolutionary expectations—the article uses the word “assumed” three times, in the sense that the findings undermine previous assumptions. Animals diversify and adapt not due to mutation and selection, but due to expression of inherent variability the Creator gave them to fit into changing environments, which would have been extreme after the Flood with ice ages and climate extremes. No doubt this also accounts for the wide variation in other families, and even in the outward appearances of ‘hominins’ that represent the one human race created in God’s image. We humans are all family brethren, and so is br’er bear.
Grizzly, by Carolyn Randall