American black bears come in varied colours from bluish grey to sandy blonde to rusty copper. Yet what intrigued scientists was the ones with cinnamon-coloured fur as per a report in smithsonianmag.com and the reason was that it made them look more like their grizzly cousins aka brown bears in appearance.
A study published in the journal Current Biology finally cracked the reason for this resemblance. It was due to a genetic variation in some black bears. Scientists pinpointed that this mutation took place in a gene called tyrosinase-related protein 1 or TYRP1, after scrutinising the DNA samples of 151 black bears living in the United States and Canada.
The modification in the gene caused alterations in the amino acid building blocks which resulted in the bear having either more reddish-yellow or more blackish brown fur.
Interestingly this change in the gene is not very old in terms of evolution as research showed that it happened 9,360 years ago and then spread through breeding.
At present, cinnamon-coloured bears are found in Idaho, Nevada and Arizona States while their presence is less likely in East Coast or areas along Great Lakes as they haven’t spread out there.
Highlighting this aspect, Emily Puckett, the study’s co-author and a biologist at the University of Memphis to Live Science, said: “Geography definitely plays a part. The bears don’t pass through the Great Plains. If they wanted to go east, they would have to go up north to Canada, across the Canadian [Prairies], around the Great Lakes and then drop back down into the eastern populations. That would take a long time.”
The spread of cinnamon coloured is possible but being a slow process, it would take time.
With expansion in the range of black bears thanks to programmes protecting them; reforestation of their habitat, stricter regulations for their hunting and their reintroduction in the wild, it is vital that people should know that black bears can be brown too.
Scientists also tried to find out the reason for this mutation. It was suggested that either it helped the creature to regulate the temperature of its body or it could be to copy the grizzly bear’s appearance.
As data doesn’t support both these theories, it was postulated that cinnamon hue helped them to blend with the habitat they reside in and avoid detection by predators. This method is called crypsis and an example of this giant panda whose black fur blends with dark tree trunks while the white portion helps them to hide in the snow.
Apart from protecting them, the blending may also provide these bears an advantage in hunting their prey.
