Why evolution still can't explain this human body part

There's one part of the human body, found in no other mammal, that scientists still don't have an explanation for.

When it comes to the human body, there are a lot of unanswered questions. Why do we dream, how are our memories stored, what causes mental illnesses biologically? The list could go on and on.

But scientists are constantly making breakthroughs, whether it be finding cures to previously incurable illnesses, or surgeons being able to operate on patients from a different country thanks to robotic advances.

And while we know that the human body is extremely complex, thanks to thousands of years of scientific research, we now know more than ever before.

But there is one body part in particular that experts, still to this day, just can't work out.

Many questions about the human body remain unanswered. (Getty stock)

And interestingly, we're the only mammal in the history of time to possess one; not even our closest cousins, the Neanderthals, had it. Scientists do, however, have numerous theories that could offer a possible explanation.

The angular, forward-projecting part of the face still poses many a question that experts have been struggling for some years to answer - and it is of course, the chin.

The human chin has been at the centre of scientific debate for a long time, and there are numerous plausible ideas to explain its evolution. Some experts have suggested that the chin evolved to strengthen the jaw of a battling caveman about 2.5 million years ago, as per BBC Future.

The human chin remains unexplained. (Getty images)

Other less convincing arguments claim that the chin evolved to exaggerate the magnificence of a man's beard.

Scientists have also questioned whether it may be a by-product of cooking, and the softer food the skill has produced over time. This theory suggests that the human chin is an evolutionary leftover, that appeared accidentally as our jaws changed.

But the most annoying part of all? We have no way of testing these possible explanations.

While the rich array of explanations could hold the key to the truth about chins, experts have have no sensible way of testing them.

Students at the University of Otago in New Zealand, however, also posed an interesting theory, as per the National Library of Medicine. They proposed in 2007, that the chin evolved in response to speech, perhaps protecting our jaw against the stress produced by contracting certain muscles in the tongue.

Maybe one day we'll really get to the bottom of it!