He urgently needed his father's obsessive and brutal instinct for survival.

This is an expression of 'cruel, brutal and destructive instincts, which lie dormant in individuals as relics of a primitive epoch'.

Was it the sudden upcropping of some lower stratum in my nature--a brutal primitive instinct suddenly asserting itself?

Were I an atheist- a man devoid of conscience- a wretch with coarse and brutal instincts- I might have found peace, long ere now.

The wilderness has him under its spell, and something inside him--"the awakening of forgotten and brutal instincts, the memory of gratified and monstrous passions"--is pulling him back.

It was brutal, simple instinct, the reaction of the monkey to the slinking panther.

In its relentlessly biological mind, what we think of as civilization is portrayed as a fragile membrane that barely prevents us from acting on our most brutal instincts.

Chendi wrote of Macedonski being "the caricature of a man", having "a feverish mind" and being motivated by "the brutal instinct of revenge".

There were those who claimed the Dreamers descended from a group of Trader geniuses morally opposed to their own brutal instincts.

Any race which can't rise above its own brutal instincts will wipe itself out long before it learns to bridge the interstellar gulf.