On top of Homo sapiens, at least eight other species of our genus have walked Earth: Homo habilis, Homo rudolfensis, Homo erectus, Homo antecessor, Homo heidelbergensis, Homo naledi, Homo floresiensis, and Homo neanderthalensis (Neanderthals). Plus, it's likely in the future there will be more that are recognized or unrecognized.
That’s not even mentioning Denisovans, which may be a distinct species or subspecies, plus the unknowable number of human species that may be out there, yet to be discovered by science.
All of these animals (that includes us) belong to the genus Homo, which comes from the Latin name for “human”. Members of the Homo family are part of a group called hominins. This should not be confused with hominids – the latter refers to modern humans and the other living great apes, such as chimpanzees, bonobos, gorillas, and orangutans.
Members of the Homo genus are all closely related to modern humans (relatively speaking), belonging to the same genus as us – just as tigers, lions, jaguars, and leopards belong to the genus of Panthera.
All of them except for H. sapiens have since fallen into extinction, but there were points where we inhabited a world shared by several human species. Our species even interbred with some of them – and it was far from a one-night stand.
Bear in mind that none of these species evolved directly from one another in a linear development. H. erectus didn't suddenly turn into H. sapiens one day like a Pokémon evolving. If only it were so simple. The human family tree is messy, deeply intertwined, and complex – not to mention full of gaps due to the fragmentary fossil record.
We do, however, know a lot about some of the Homo species that have wandered the planet over the past few million years.
The earliest known member of the genus Homo is Homo habilis, which evolved over 2.4 million years ago. Fossils of this species have been discovered in present-day Tanzania, Kenya, Ethiopia, and South Africa, indicating they once lived across a significant portion of eastern and southern Africa.
H. habilis is a crucial character in the story of hominin evolution as their brain was larger than other apes, marking a significant milestone in the development of complex behavior. Also known as the “handyman,” they were skilled makers of stone tools, which consisted of knapped flakes that could be used as blades.
Most researchers believe H. habilis was bipedal and walked upright, although it would have looked relatively ape-like by our standards. After this pioneering species arrived on the scene, human evolution accelerated – for reasons that remain unclear.
The first known remains of Homo rudolfensis were discovered in 1972 along Lake Turkana in East Rudolf, Kenya. The species lived between 2.4 to 1.8 million years ago, around the same time as H. habilis in similar parts of Africa.
Anatomically speaking, it was also relatively similar to H. habilis, although fossil evidence shows the species had a notably bigger skull. This similarity has led to debates among paleoanthropologists about the classification and evolutionary relationships of these early hominins.
Homo erectus is arguably one of the most significant and successful hominins to ever live, depending on how you define those terms.
It is undoubtedly the longest-surviving hominin, with evidence showing the species lived between around 1.89 million and 110,000 years ago – that’s almost 2 million years, compared to modern humans that have only been around for 200,000 to 300,000 years.
H. erectus is the first known hominin to have migrated out of Africa. This feat gave the species a huge geographical distribution, with fossils showing the species spanned Africa, Asia, and Europe. In another first, there’s some decent evidence that H. erectus was also the first species to control fire.
Remains of H. erectus show it was a highly varied species, which isn’t surprising considering its huge geographical and temporal extent. However, most specimens show signs of a human-like body, like elongated legs and shorter arms in comparison to its torso.
Homo antecessor lived about 800,000 to 1.2 million years ago in Europe.
After first discovering their remains at the Gran Dolina cave in Spain in 1994, they were formally described as the last common ancestor of modern humans and Neanderthals. Later work showed this wasn’t exactly the case, although they’re perhaps an offshoot of hominin that was formed just before the split between modern humans and Neanderthals.
Fossils show that Homo heidelbergensis lived approximately 700,000 to 200,000 years ago in Africa, Europe, and possibly Asia.
The species had a blend of features seen in both earlier hominins, like Homo erectus, and later species, such as Homo sapiens. Just as these features would suggest, they were a versatile and transitional hominin that wielded a relatively large brain, could craft sophisticated tools, and inhabited diverse environments.
One of the more recent additives to the gang, remains of Homo naledi were first discovered in 2013 by exploring the Rising Star Cave system in the Cradle of Humankind, South Africa.
Early work suggests that H. naledi lived millions of years ago, owing to their relatively small brain size. However, subsequent dating revealed they overlapped with Homo sapiens, some 250,000 years ago.
The species has become one of the most controversial characters in this cast of extinct humans. As detailed in a popular Netflix documentary, the Rising Star Cave system contains rock art and decorated graves, which some have said were created by H. naledi. The cave also suggests that species buried their dead, implying they had advanced emotional intelligence.
This claim is remarkable since N. naledi had brains not much bigger than that of a chimpanzee. It’s so remarkable, in fact, many paleoanthropologists don’t buy it.
Don’t let their small stature fool you into thinking they were archaic, however. They lived on the Indonesian island of Flores just 100,000 to 50,000 years ago until modern humans arrived in the region. That means there’s a chance we came across this species in the flesh.
Some anthropologists have speculated that H. floresiensis could still be living on the small Indonesian island based on the folk tales of the indigenous Lio people. However, that’s a pretty wild claim that not many other researchers like to entertain.
Better known as the Neanderthals, Homo neanderthalensis is a bit like the “sister species” of H. sapiens. Genetically, we're 99.7 percent identical and it is starkly clear that rampant interbreeding occurred between the species time and time again.
In years gone by, Neanderthals were often portrayed as the heavy-browed, lumbering "caveman" cousin of H. sapiens. However, mounting evidence shows that they were artistic, adaptable, and highly intelligent.
They died out around 40,000 years ago for reasons that a hotly debated by scientists. Some anthropologists believe it could have been climate change or a disease outbreak that drove them into extinction, while others pin the blame on Homo sapiens for outcompeting them or introducing tropical diseases on their migration from Africa. Some even argue that the demise of Neanderthals could have been caused by a genocide at the hands of modern humans.
Last but not least, it’s H. sapiens, aka modern humans. Etymologically, their name means “wise man” or “knowledgeable man”, which is pretty arrogant considering they created the name.
This species emerged around 300,000 to 200,000 years ago, but it wasn’t until 100,000 years ago that their brain shape became “modern” like today’s individuals. H. sapiens first appeared in Africa and went on to inhabit every continent of Earth. This tendency for exploration has even seen them land on the Moon a couple of times and have plans to return shortly.
They are the sole living member of the Homo genus - and for good. They are adaptable, creative, intelligent, social, highly competitive, and have the potential to be fiercely aggressive.
This unusual blend of characteristics means have H. sapiens have somewhat of a paradoxical nature. While they have made amazing cultural achievements and great technological advancements, they are wracked by conflicts within their own species and face severe challenges regarding their impact on the environment.
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