The bulk of human history has been that of a culture of hunter gathers or foragers. They did not plant crops or modify ecosystem dynamics in any significant manner as they were passively dependent on what the local environment had to offer. They did however domesticate dogs as early as 100,000 BCE (Vila et al. 1997); these animals were useful as hunting aids, guardians, and occasionally as food during times of scarcity. Hunter gatherers maintained social organization and interdependence, and prevented the loss of food to spoilage by sharing the harvest among community members. These people lived in harmony with their supporting ecosystems and their ability to unsustainably stress and damage their environment was limited by the fact that if their numbers exceeded the carrying capacity of the complex, self-managing, species diverse, resilient terrestrial and aquatic ecosystems from which they gained their sustenance, then hunger and lower fertility exercised negative feedback controls on further expansion.