Human

Summary
The human race is an Early-Development spacefaring civilization whose homeworld is Earth, the third planet of the Sol System. Throughout their existence, they have developed their civilization by engaging in food production on a larger scale, developed language, developed religion and political philosophies along with better technology. After succeeding in space colonization, the human race was able to terraform and inhabit other planets besides Earth, but the human race is under pressure due to the discovery of the caste-driven Covenant after several centuries of space travel. At time of the Halo series of games and novels, there are approximately 60 billion members of the species living in parts of the Milky Way Galaxy.

Early development on Earth
The Homo sapien sapien was believed to have appeared in Earth's fossil record approximately 200,000 years ago (there was another subspecies of Homo sapien, the Homo sapien idaltu, is extinct, but was believed to have lived as long as 160,000 years previous). The current human race is not the only humanoid species known to live on Earth, but the Homo sapien sapien is believed to have displaced all predecessors, including the Neanderthal and the Homo sapien idaltu. The Homo sapien sapien usually stands several feet tall, though this varies depending on nutrition, genetics and other factors and is bipedal.

The development of human civilization as humans recognize it today started from the ability to grow food in a systemic fashion, referred to as the Neolithic Revolution; this took place over 10,000 years ago. The stability that came from systemic agriculture allowed for more permanent settlements and the development of tools to benefit the members of the species. Basic toolmaking, domestication of other species on Earth and trade and communication helped develop societies further, leading to the formation of genuine nation-states over 6,000 years ago. The first such states are believed to have formed in Southwest Asia and spread elsewhere over time. Economic, political and religious advancement continued to come as this species was able to automate many tasks in the Industrial Revolution and its associated scientific breakthroughs at the end of the second millennium. Larger urban centers and tools for civilian and military uses were able to develop, as were more modern economic and political systems. As these systems developed further, the species was able to enjoy longer lives and procreated more easily, eventually leading to billions of humans on Earth.

Space colonization and war
The species was able to explore space near their home planet in the 20th century, as the population continued to increase into the billions. The subsequent conflicts over resources, economics, religion and politics on Earth put great pressure on the species in the beginning of the third millennium, and the transnational organization that became the United Nations Space Command engaged in more frequent space colonization and sought to represent the entire species, even though no one state ever previously ruled the entire human race. The development of slipspace travel in 2291 helped the UNSC engage in spreading the human race beyond their home solar system, releasing the serious pressure on the homeworld. After several centuries spreading through many solar systems and inhabiting hundreds of wars, they discovered the violent, theocratic Covenant and were forced into the war covered by the Halo games.