The bears reach sexual maturity by the age of 3, while they continue to grow up to 10-12 years. Life expectancy in nature rarely exceeds 30 years, while in captivity it increases to 50 years. This is due to the fact that although in nature the bear has practically no enemies, strikes between the same males occur quite often. Sometimes – with a lethal outcome. Nevertheless, the life expectancy of a brown bear against the backdrop of many other animals is quite high.
The polar bear is the closest relative of the brown bear. It is believed that the division between them occurred about 500 thousand years ago. In the future, crossing of these two species occurred, hybridization took place. Scientists believe that polar bears are descendants of those same hybrids.
As in the case of the brown bear, the life expectancy of a polar bear is 25-30 years in the wild and no more than 45 years in captivity.
Another famous species of bear is the grizzly. It is a subspecies of the brown bear, which for the most part lives in Canada and Alaska. The appearance of the grizzly resembles the Siberian subspecies of the brown bear.
Grizzly in nature lives a little less – up to 25 years, and in captivity can live up to 40 years.