Nepali Wanderer

The origin of the human species is a topic that is intriguing and controversial. In fact, it has generated more alternative theories than the origin of the Universe. For a long portion of history, people from different parts have had different theories on this subject, all of which have one common entity — God.

So, when the idea that humans evolved from apes first made the rounds, the theory was considered blasphemous for two reasons. First, it contradicted the common religious narrative. Second, people could not accept the fact that they could be descendants of apes.

Thankfully, due to years of scientific research and evidence, we seem to have reached a consensus now. Humans are descendants of apes, members of a big family known as the Great Apes, with chimpanzees, gorillas, and orangutans as our nearest relatives.
To understand how humans evolved from this primate heritage, picture a female ape about 6 million years ago. This single female ape would have two daughters. One would give rise to chimpanzees, and the other to humans. Interestingly, along with other descendants of apes, we also had other human species. But before diving into our family tree, let us get familiar with the concept of family, genus, and species.

Species are groups of closely related animals capable of exchanging genes or interbreeding. A genus includes a large number of closely related species that can mate (if induced to) but cannot produce fertile offspring (like a horse and a donkey giving rise to an infertile mule). A family groups animals that descended from a common ancestor (like tigers, lions, and domestic cats, which all come from a common ancestor and are thus placed together in the same family, Felidae).

The scientific name for us modern humans is Homo sapiens, where Homo stands for the human genus. Homo means “human” in Latin, so all other animals having the genus Homo (whatever their species) are our siblings. Sapiens means “wise” — not very surprising given how we like to think of ourselves.

The first humans are believed to have originated around 2.5 million years ago in East Africa, evolving from an earlier genus of apes known as Australopithecus. After these early humans migrated from East Africa to North Africa, Europe, and Asia, changes in their respective environments and different adaptations led to the rise of various human species. For example, those who migrated toward Central Asia and Europe evolved into Homo neanderthalensis, while those who migrated toward Eastern Asia evolved into Homo erectus.

One important fact to keep in mind is that evolution didn’t follow a linear trajectory — there is no straight line of descent, contrary to what many believe. It is not as if H.erectus evolved into H.neanderthalensis, which then evolved into other human species. Multiple human species coexisted at various times. Our species, H. sapiens, is considered to have originated in Eastern Africa around 150,000 years ago. Around 70,000 years ago, they spread into the Arabian Peninsula and then quickly populated Europe and Asia.

So, what really happened to other species when Homo sapiens began populating most of the world? The Interbreeding Theory posits that early humans of different species were able to mate and produce fertile offspring, leading to present-day humans. The contrasting Replacement Theory suggests that all other human species were replaced by our species, resulting in modern humans being purely Homo sapiens.

To sum up, early humans originated from apes in Eastern Africa, with different human species emerging and migrating at various times. Ultimately, Homo sapiens either partially or completely replaced all other human species.

Before we conclude, two important questions remain. First, how were Homo sapiens—seemingly innocuous-looking animals of average size—able to leapfrog far more formidable animals to take control of the world? Second, what enabled these sapiens to replace entirely (or almost entirely) their own siblings, the other human species?

We will address these two questions in our next story, which will be a short summary of the entire human history.