circa 2,300,000 BCE — The ancestors of humanity leave the trees

The earliest known member of the genus Homo, habilis evolved on the savannah of Africa between 2.5 and 2 million years ago. They are believed to have been the earliest part of our evolutionary chain to have been fully bipedal, to have lost (almost all of) the body hair that other primates have, and to have lived entirely on the ground – although possibly still gathering fruit from and seeking shelter in trees, much as we still do.

The reasons for this evolutionary move are many, but some of the more important ones include greater access to water, increased dietary variety and increased use of tools in hunting, which also made defence against predators easier than it had been for their australopithicene ancestors.

circa 2,400,000 BCE — Genus homo evolves

The earliest species to evolve in the genus homo was Homo habilis, which is believed to have evolved in Africa from Australopithecene ancestors (although which of several species of australopithecus was the direct ancestor is not known). The genus homo would go on to become the most successful species in the entire history of the earth, until it created a global ecological catasprophe in the early to mid twenty first century, which destroyed all the members of that genus, and almost every other genus above the size of bacteria.

(By the way, if you’re reading this, you’re either a homo, or an extraterrestrial intelligence that’s very tolerant of our immaturity.)

(Man, I love that pun.)