Against my better judgement I decided he should climb the tree to help and my villager fell and hurt himself. His health bar dropped to about one-fifth full, He was "weakened" but not "sick". However, his parenting skills went up past adept level.

I left the game a little later and reopened it after an hour or so. I noticed he was missing, and found him in the mausoleum. He'd died because of a "work accident".

To make things worse, he was the only runner in the tribe; I had big plans for him.