Molar Bears

Image of black bear (Ursus thibetanus)

Mama bears know: raising kids is like pulling teeth! 

This is Sandra Tsing Loh with the Loh Down on Science.

So, what really stands between a bear and your picnic basket? 

Wildlife management! Japanese ecologists need to manage Asian black bears, and that involves tallying up newborn cubs. How does one do that WITHOUT watching mama bears twenty-four seven?

Kahoko Tochigi at Tokyo University and colleagues have a jaw-dropping idea. Look at their TEETH! Teeth have layers just like trees — one ring, one year. Ring thickness is affected by nutrition.

The researchers lured ten female black bears into honey barrels, then sedated them — oh, Pooh bear! They took one premolar from each bear. The teeth were sliced thin, stained with cell dye, and put under a microscope.

Results? Tooth rings were THINNER in years that bears had cubs! Why? Gestating and breastfeeding use up mama bear’s nutrients.The team needs more data before predicting cub numbers from teeth alone. Still, this finding links mommy’s molars to motherhood!

And that’s not just word of mouth! Well, actually, it is.

Reference: Tochigi, K., Tamatani, H., Kozakai, C., Inagaki, A., Naganuma, T., Myojo, H., Yamazaki, K., & Koike, S. (2018). Reproductive Histories of Asian Black Bears Can be Determined by Cementum Annuli Width. Mammal Study, 43(4), 261.