25.10.2015 16:45
The study of the international group of scientists has shown that a strong chilling cry of howler monkeys can show their reproductive weakness. This was reported by the BBC.
Biologists say that primates develop or loud voices, or large testicles, but both at the same time does not happen. Such evolutionary trade-offs may occur more frequently than previously thought. His scientific work scientists published in the journal Current Biology.
howler monkeys so named because of their inherent powerful, fearsome roar. These cries of primates are trying to scare their opponents and like inhabiting nearby females. In order to issue a strong roar of these animals have a special instrument – a bone in the throat acting as a resonator.
The vocal cords are used like monkeys stringed instruments, and hyoid bone – as the tool itself. Its size is directly related to the depth of the roar.
The head of the team of scientists Jake Dunn of Cambridge University, explains that the deeper roar, so it seems to be more attractive to partners
The bone in throat
In the process of monitoring the various types of howlers, the researchers found that the hyoid they reach very different sizes. The biggest differs from the smallest at 14 (!) Times. Scientists are very interested in such a variation in the size of the body.
Biologists held laser scanning over two hundred hyoid howler from museums in the United States and Europe. In addition to variations in the size of the bones, it found an association with another striking difference in the structure of the body of primates.
« difference in the amount of monkey testicles are also very important. The largest is 6.5 times more massive than the smallest », – says Jake Dunn.
compromise
Comparing animals, Jake Dunn and his team found that different kinds of howlers, it seems, are looking for a compromise between the development of powerful vocal tract needed to play lower and impressive music, or the development of large testicles – for more sperm.
According to him, depending on the conditions in their mating group of various primates choose which of these signs develop.
Jake Dunn explains that some animals – such as walruses, seals and sea lions – especially large sizes have smaller genitalia.
In 2012, it was even published study suggests that a man with a deep voice, have fewer sperm left.
But the results of studying howler is the first recorded example of a compromise between the vocal and sperm production of all types.
« It was a surprise – to find out that such trade-offs may be more common than previously thought », – said Jake Dunn.
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