The First Humans on Earth

According to the Aganna Sutta of the Digha Nikaya, the first humans that appeared were Devas from one of the heavens of form, the Abhassara heaven. Millions of years ago, when there were no humans on Earth yet, a group of devas descended down from the Abhassara to explore this land. During this time some of them ate and developed a craving for a naturally abundant crop down here. But after having ate this earthly food their subtle bodies became coarse and heavy, such that they were no longer able to fly back to their heavenly abodes; so they had no choice but to stay on earth as humans. From this group those with stronger craving became females and those with lesser became males. With males and females, they started to reproduce and populate the Earth. Those other devas whose good karma were exhausted like them were also reborn down here as humans.

Some people are also puzzled as to why the human population keep increasing if each being had only one consciousness. They forgot that besides the human realm there are also beings from the Deva, Asura, Animal, Ghost and Hell realms. They also forget that our world (called Jambudiva) is not the only world in the universe. Humans who do enough good karma get to be reborn as a deva, but this is a small number as compared to devas who used up their good karma & be reborn as humans. Those beings in the lower realms who have exhausted their bad karma were also reborn as humans, but this is also a relatively small number compared to humans who fall into those realms. Why is that so? Simply bcos the upward climb to the higher realms is always more difficult than the downward descend into the lower realms. That's why there are much more animals than humans.

Also considering the fact that beings from other worlds who share collective karma with the beings in this world get reborn here as well, so the number of people on earth can only go up!