It was referred to as a “Category 6 Existence Failure”, and not further elaborated upon. Mancove had disappeared right in front of everyone’s eyes.
He had been having an exceptionally bad day, no energy, no modivation, and nothing ahead of him but another bleak 15 years working in the same drab laboratory doing the same mind-numbing experiments. He was reflecting on his own doom, was just coming to some realization about what it meant, when he simply ceased to be there.
Simmons fainted. Clarke gaped, tripped, and spilled chemicals all over the floor. Someone set of the alarm.
Mancove had simply vanished.

Mancove stood on the moon. He hadn’t specifically wished to be here, but he had wanted to be off the Earth. And here he was, breathing too. He watched the blue ball turning in the sky, and all the little ape descendants scrambling about, trying to amass more than the next ape descendant. He watched for a very long time before he was ready to go back. When he finally did, he was the only ape descendant left.