Of course you won't think of one.

The question is an oxymoron.

When an ENTIRE tribe is mass murderers why worry about what they spawn, unless it was someone with a conscience?

Head hunters and head scalpers were doing what the ENTIRE tribe would have done, ALL spawned were mass murderers...

Huron, Chichimec , Iroquois and Muskhogean tribes all scalped their enemies.

Additionally, China, Nigeria, Nuristan, Myanmar, Borneo, Indonesia, the Philippines, Taiwan, Japan, Micronesia, Melanesia, New Zealand, and the Amazon Basin, as well as among certain tribes of the Celts and Scythians of ancient Europe, all practiced head hunting.

That's twenty, want more on other occasions, or what?