Doug

“You have a mismatched pair of genetic characteristics. Either alone would have been useful, would have aided the survival of your species. But the two together are lethal. It was only a matter of time before they destroyed you."

[...]

Jdahya made a rustling noise that could have been a sigh, but that did not seem to comer from his mouth or throat. "You are intelligent," he said. "That's the newer of the two characteristics, and the one you might have put to work to save yourselves. You are potentially one of the most intelligent species we've found, though your focus is different from ours. Still, you had a good start in the life sciences, and even in genetics."

"What's the second characteristic?"

"You are hierarchical. That's the older and more entrenched characteristic. We saw it in your closest animal relatives and in your most distant ones. It's a terrestrial characteristic. When human intelligence served it instead of guiding it, when human intelligence did not even acknowledge it as problem, but took pride in it or din not notice it at all..." The rattling sounded again.”
― Octavia E. Butler, Dawn