Scientists have found a number of human ancestors, and it can be quite confusing to keep track of all of them. It's like keeping track of which cousin belongs to which side of your family, except a whole lot more complicated. At least your cousins are the same species (yes, even the weird one that used to eat glue).
We know that modern humans are Homo sapiens. But who are the Homo erectus, the Denisovans, the Homo habilis, and the other rungs on our evolutionary ladder? Human evolution is quite complicated, so let's keep it simple for now. Here are six important branches in the tree of human evolution.
The Homo habilis evolved in Africa over two million years ago and went extinct about 1.5 million years ago. The discovery of this species of human ancestors led scientists to the conclusion that our roots originated in Africa.
The Homo habilis evolved from the Australopithecus afarensis, a species to which the famous Lucy belongs. Homo habilis is the species that filled the gap in the connection between the australopiths and modern humans.
The Homo erectus evolved in Africa around two million years ago and spread out to Eurasia. Homo erectus may have evolved from a Homo habilis population. Scientists are unsure about when the Homo erectus went extinct, but recent estimates point to 143,000 years ago. This species was the first of human ancestors to travel long distances, and was also more human-like than its predecessors.
They were also probably the first to discover how to control fire, and thus may have been the first to cook.
The Homo neanderthalensis evolved in Eurasia about 200,000 years ago and went extinct about 40,000 years ago. Scientists discovered this species in 1829.
Neanderthals may be a cousin of modern humans. We and the neanderthals may have had a common ancestor that scientists call Homo heidelbergensis. The Homo heidelbergensis's ancestor may have been the Homo erectus. Researchers think that a Eurasian branch of our human ancestors evolved into the Neanderthals and Denisovans, while the African branch evolved into modern humans.
The Denisovans possibly evolved in eastern Asia between 50,000 to 200,000 years ago.
The way scientists discovered Denisovans is different from the way they discovered other human ancestors. Unlike the other species, we don't actually know much about what Denisovans are like. Scientists discovered the existence of Denisovans through genetic analysis of ancient human teeth and bone fragments. The researchers discovered that the fragments belonged to a population that shared a common ancestor with Neanderthals.
The Homo floresiensis evolved on the Indonesian Island of Flores 50,000 to 100,000 years ago. Scientists affectionately call this species the “hobbit” due to its strange physical features. The Homo floresiensis was short, had long feet, and a small brain. We could have expected these features in a species that evolved more than two million years ago, but not in a species that evolved relatively recently. Also, in spite of having a small brain, the Homo floresiensis may have been able to control fire and cook.
There are a number of theories on how the Homo floresiensis came to existence. However, there isn't enough fossil evidence to make conclusions.
The Homo naledi evolved in South Africa, possibly between 200,000 to 300,000 years ago. Like the Homo floresiensis, the Homo naledi had a strange mix of features. It had bones that resembled those of modern humans and apes. Members of the species also placed their dead in rock chambers and exhibited other modern human-like behavior.
Because the Homo naledi is so strange, scientsits aren't quite sure about how the species fits into the human family tree. It may fit between Homo habilis and Homo erectus, but this may change with further study.
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