The long and tiring digestive process of howler monkeys and the constant competition for fruit make adult-adult grooming impossible.

If fruit were not a part of the diet of howler monkeys, their social groups might be more peaceful.

For howler monkeys, digesting a meal is normally a long and tiring process.

An available source of fruit might help determine which howler monkeys are the most skilled at getting what they want.

Though fruit is a sought-after item, it cannot in general be considered a crucial part of the howler-monkey diet.