Based on Darwin's Theory of Evolution, humans have taken thousands of years to evolve from primates. However, one of the primary questions in many people's minds is why monkeys, apes, and other species with the same ancestors as humans did not develop the ability to speak?

For many years, scientists have claimed that the primary cause of monkeys' inability to speak is that they lack the basic anatomy for vocalization. However, recent studies have found that monkeys and other primates do have the anatomy for speaking.

So why can't monkeys talk?

In search for answers, scientists have stumbled upon a limitation in the apes' brains linked to the physical anatomy of vocalization.

To explore the different reasons why monkey can't talk, the University of Vienna and Princeton University used x-rays of primate vocal tracts and made comparisons among them. Their study has resulted in an unbelievable finding -- that monkeys do have vocal tracts.

This means that all primates have the same opportunity that humans have for vocalizing. However, there was a point where humans have developed a link between the brain and the vocal cord allowing the vocal organs to create sounds on the brain's cue. This particular skill has not been developed in other species of primates.

According to a report from the Economic times, it is the lack of a neuro-cognitive development of the apes' brain that prevented them from using words and language as a form of communication. Based on the physical anatomy of the apes' vocal cord, in theory, they should be  able to produce words.

A report from Phys.Org noted that there is still an interesting mystery which could not explain how humans have speech ability. It is still a big question how mankind has developed the neuro-cognitive requirements of being able to form words and languages while the rest of their primate relatives could not.