Genus Australopithecus

When the Genus Australopithecus was still alive, their brains were not very well developed. They where hunter gathers who moved with the seasons and changed to better fit their environment. As their species grew their brains grew they were replaced with the Homo erectus. This new species had a larger brains better fit for survival, they created more sophisticated tools for hunting and created fire. They also created a functional language for them to communicate. While the new species gained intelligence about their world they evolved into the species we have today known as Homo Sapiens. The frontal cortex of the brain grew allowing more room for conscious thinking. This allowed more ideas for changing the land around them and have more free flow of ideas for what they can do or how they can go farther exploring. They were the first to cross the land bridge and cross oceans onto islands to live there.
Even though they had capacity to choose what they wanted to do, the new species still had to respond to the climate and geography to live. When the ice age happened, the herds of animals that lived in Asia moved to try and find warmer areas, when the water turned to ice, it created the land bridge crossing from todays Russia and Alaska. For the same reasons as the animals, Homo sapiens migrated across the land bridge into North America. The top of North America was completely frozen over so they moved South towards Central America. The Homo sapiens spread out to different areas better suited for their needs, the groups that fished spread to coasts. The ones that hunted animals like buffalo and bison stayed in the planes. Any others that wanted their own spaces moved downs through Central and South America. This was the start of the world as we know it today.