Research also suggests that fur color may be influenced by heat; black absorbs and retains heat more efficiently than does brown or blonde. Thus, black is more predominant in colder climates, while lighter shades are more prevalent in warmer and drier climates. Melanin is the pigment that causes the "blackness" of bear fur, and there is also evidence to suggest that the more melanin in the coat, the more abrasion-resistant it is. Thus, bears living in more dense cover benefit from more melanin-rich (black) fur.