Down the centuries biologists have wondered why every face has this particular feature.
It's this bit here - the groove underneath your nose.
It's called the Philtrum.
I've got quite a prominent one, his is less prominent, but we've all got one.
What we now know is it is the place where the puzzle that is the human face finally all comes together.
We've taken data from scans of a developing embryo
so we are able to show you, for the very first time, how our faces don't just grow
but fit together like a puzzle.
The three main sections of the puzzle meet in the middle of your top lip
creating the groove that is your philtrum.
This whole amazing process,
the bits coming together to produce a recognizable human face,
happens in the womb between 2 and 3 months.
If it doesn't happen, then it never will.