In the two million years it is believed that humans have populated the Earth, they have displayed the remarkable ability to adapt to any environment. Archaeological evidence has proven that the earliest humans were able to occupy and control every terrestrial ecosystem on the planet. Human impact on the environment has increased progressively through time from the earliest hominid hunters to modern city-dwellers. A fundamental expression of early humanities ability to control the environment occurred during the birth of agriculture. While the ecological impact from this feat has allowed humanity increased control over its environment, the earliest hominids were able to survive nearly two million years without this invention. Although the interaction between humans and their habitat before the rise of agriculture may be subtle, this era beginning at the inception of the human race is no less important to the history of human environmental impact.

It is believed that the most primitive ancestor of modern humans were Homo erectus. "The distinguishing characteristic of Homo erectus is a large brain size of about 1,000cc (about three-quarters of modern human capacity).1 "With the beginning of this species may well have come the limb proportions (short arms, long legs) that characterized modern humans."2 Scientists have concluded that Homo erectus originated during the early Pleistocene era (representing the last two million years) and were the only hominid species to survive this period of time. Eventually Homo erectus evolved into Homo sapiens, and finally into modern humans (Homo sapiens sapiens). These early humans originally lived in small groups that were spread throughout a myriad of habitats in Africa.

These early hominids sustained themselves through the oldest and simplest human mode of production, hunting and gathering. They mainly "gathered nuts, seeds and plants, which they would have supplemented by scavenging dead animals killed by other predators and perhaps the hunting of a few small mammals."3 A wide variety of food was available and provided a sufficiently nutritional diet. This form of economy was often far from meager and likely represents the original affluent society since scientists speculate that a large amount of leisure time was available. Hunting and gathering provided a very stable and long lasting livelihood described as simple and communal.

An important trait to the development and spread of human societies as well as their ability to interact with their surroundings was "the adoption of technological means to overcome difficulties imposed by hostile environments."4 Stone tools, wooden spears, bolas stones, wood, skins, and fire allowed these groups to adopted a mobile existence and move into harsher ecosystems. Technology was particularly important in increasing humans' ability to hunt. Specifically, the bow and arrow along with snares, traps, and nets made hunting less time consuming and more effective. Inevitably, hunting and gathering "groups had, over hundreds of thousands of years, adapted to every possible environment in the world from the semi-tropical areas of Africa to ice-age Europe, from the Arctic to the deserts of south-west Africa."5

Throughout their travels, these groups continually effected the environment around them. Often these hunter-gatherers interfered with wild vegetation for the purpose of promoting the growth of a particular plant by sowing its seeds. They also uprooted and destroyed flora deemed undesirable. These types of environmental modification were frequently aided by the use of fire. Aside from the ability to clear large areas of land, fire was favored because of its ability to increase nutrient cycles in the soil.

However, the major impact humans had on the environment came through hunting. With their technological advancements, hunter-gatherers were able to over-hunt many species. Many of these groups concentrated their hunting to a particular species that often lead to its extinction. Humans were responsible for the disappearance of many large flightless birds and other megafaunal animals on every continent. Even in areas that were unaffected by the constantly shifting climates such as Australia over the last 100,000 years, "destroying habitats or killing the smaller herbivores on which the carnivores depended could easily lead to extinction."6 The destruction of these animals resulted in many long-lasting effects.

Early humans were the only species on the planet that was able to inhabit and dominate every type of environment they populated. Relying on a mobile hunter-gatherer existence, they managed to cause significant alterations to their habitat. Even subtle modifications to the environment lead to considerable repercussions. Even though humanities relationship with nature was undeniably changed by the adoption of agriculture, early humans still found numerous methods to affect their ecosystems during the two million years before they learned to domesticate plants.