Life span is 20 years. Very thickly enameled molars are an adaptation for processing grass. This is the only primate that is primarily a grazer. The opposability of thumb and first finger aid in precise plucking of blades of grass. The large size and huge canine of males is probably due to sexual selection rather than an adaptation for defense.
Males make no effort to defend females except from takeovers by conspecifics.
Predator pressure is not heavy today, except by humans and domestic dogs. Ferdigan, Linda Marie. Eden Press, Montreal, Canada. Nowak, Ronald. 1991. Endangered and Threatened Wildlife and Plants.