Early Humans

Human species go back 195,000 years ago but depending on whom you associate most with, you can consider Australopithecus an early ancestor dating back to 4 million years ago. Since Australopithecus was the species who made the leap from walking by using both hands and feet to standing upright and walking on two feet. This made the species more mobile and able to cover more ground.

Australopithecus is considered a species of humans because of the great development of being able to walk upright. Fortunately, they managed to keep the features that allowed them to continue to climb trees so to protect themselves from predators. They soon further developed the ability to run after pray and hunt for food, rather than simply gather grains.

Homo Erectus from about 1.8 to 1.5 million years ago is a species of the human kind and is the first true hunter gather ancestor to humans. Homo Erectus is also the first to migrate out of Africa in large numbers. With the development of longer legs and shorter arms the Homo Erectus began to lose the ability to climb trees. A significant adaptation that may have helped their evolution is when they began to eat cooked meat which could be quickly converted to energy. They also learned to make tools for hunting. All of the above developments allowed them to adapt to changing environments.

It's also believed that we human species may have coexisted with other close evolutionary species such as the Neanderthals and the Denisovansin. It is very possible that evolution overlapped and depending on the region some species developed faster than others. Nonetheless, humans have been evolving since the beginning of time and will continue to do so as our environment changes.    

In terms of range and duration of their presence on the planet earth Homo Erectus and Homo Sapiens, Homo Erectus lived on earth from about 2 million years ago till about 100,000 years ago. Homo Erectus also lived in numerous locations across the world, including South Africa, Kenya, Spain, China, and Indonesia. Homo Sapiens, however, have only been around for 195,000 years and such are still in the early stages of life and development. Modern Homo Sapiens have been recorded as late as 50,000 years ago. Modern Homo Sapiens have migrated to the South Asian continent, Australia, and North America through the Bering Plain as late as 15,000 years ago.

After all of the research and understanding of Big History and the evolution of humans, one has to think if we will make it for millions of years to come, as our ancestors have, or have we become so far developed and smart that we are too dump to see our ecological disruption on earth so far. I believe only time will tell.

Website References: 
https://www.newscientist.com/article/dn9989-timeline-human-evolution/
https://www.discovermagazine.com/planet-earth/just-how-many-extinct-types-of-human-did-our-ancestors-meet
https://www.youtube.com/watch?v=Liv6QCgVie0
https://blogs.ntu.edu.sg/hss-language-evolution/wiki/categories/chapter-15/
https://cpb-us-e1.wpmucdn.com/blogs.ntu.edu.sg/dist/a/853/files/2017/03/1homo-12l0n41.png
https://www.sciencephoto.com/media/903538/view/early-human-modelshttps://humanorigins.si.edu/evidence/human-fossils/species/homo-erectushttps://www.livescience.com/41048-facts-about-homo-erectus.html
https://www2.palomar.edu/anthro/homo2/mod_homo_4.htm