Based on this idea, the length of a male proboscis monkey’s nose could be a representation of a higher efficiency in using energy. For a proboscis monkey’s nose to reach a longer length, they could have to maxed out the efficiency of energy in other aspects of their life. Another phenomenon observed is that the older the proboscis monkey is, the longer his nose can get. This could mean that the nose could be a sign of a longer lifespan. A female can be choosing to mate with a male with a longer nose because it shows they have a genetic makeup that can lead to a longer lifespan for their offsprings. A trait proboscis monkeys have is their uniquely high pitched vocalizations. A study done analyzing their high-pitched vocalizations speculated
