Life itself is a characteristic that distinguishes objects that have self-sustaining processes (biotic) from those that do not (abiotic). Living organisms undergo metabolism, maintain homeostasis, possess a need and a capacity to grow, respond to stimuli, reproduce, and, through natural selection, adapt to their environment in successive generations. In the wild, "survival of the fittest" rings true; the organisms that are best suited for competition win out in the competiton for resources and territory. Animals who are weaker, or do not possess the tenacity or resourcefulness to compete, are gradually weeded out in the process of natural selection. Bears, for example, in an effort to protect their established territory, have been known to not only kill or ward off other predators, but also kill other bears and their offspring, viewed as competition for the available resources at-hand. "To the victor go the spoils" would be another way to put it. The organisms that are better able, that have an edge, some mechanism that puts them over the top in the race for survival against other animals, usually come out on top.