I've just made a world-shaking, probably Nobel prize-winning, jaw-dropping discovery.
We are descended from walnuts.
Proof? Below is the incontrovertible visual proof.
Once upon a time there was a much more advanced civilization inhabited by beings with brains shaped exactly like walnuts. Our current brains are a de-volved, deteriorated version of the much more interesting and effective original. We can still glimpse its splendid earlier form by observing a walnut.
As you see in the photo I've just taken and placed next to a standard brain diagram, there's no split between the two halves in the wondrous walnutbrain: left and right are tenderly, harmoniously joined. Simple really.
I will now eat the proof and go to bed. Amazing what revelations can occur at 4 am.