The TLDR: Over the weekend, scientists announced the discovery of not one, but two ancient human species. And one of them—nicknamed the Dragon Man—has the potential to overturn our understanding of our evolutionary history.

The great family tree

The ‘homo’ or human part of the tree of evolution looks something like this:

At the very beginning: While there were other more ancient species that were an ape-human mix, our story starts with Lucy—who is an Australopithecus afarensis, and is one of the longest-lived and best-known early human species. She lived in Africa over 3.85 and 2.95 million years ago. And the discovery of her remains helped us trace the origins of all humanity back to Africa—and taught us that learning to walk on two legs was the single biggest leap that helped us make the transition from ape to uniquely human.

Homo erectus: The next big jump in evolution is marked by this early human who possessed human-like body proportions, used crude implements like stone axes—and is considered to be the first human species to move out of Africa. Their remains have been found across China and Java. They lived around 1.89 million and 110,000 years ago.

The early humans: Soon after Homo erectus, there were a number of different human species—whose time on Earth overlapped with one another. We even mated and had babies during that time. But this time period represents a big muddle since we are still trying to figure out how many species there were—and struggling to differentiate one from another. Here are the ones we knew about before the latest discoveries were announced:

• Neanderthals lived 400,000 to 40,000 years ago and—until now—were considered our closest extinct relatives. Contrary to popular belief, they were highly evolved: “Neanderthals made and used a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects.”
• Homo floresiensis aka The Hobbit were a small-statured species lived 100,000 to 50,000 years ago. All their remains have been found on single island: Flores, Indonesia. Scientists suggest that isolation and inbreeding could have caused a form of dwarfism. 
• Homo heidelbergensis lived 700,000 to 200,000 years ago—and was the first human species to live in colder climates and build simple shelters out of wood and rock.

Two recent additions: include Homo luzonensis—whose remains were discovered in 2019 in the Philippines—and Homo naledi, whose fossils were unearthed in South Africa. But scientists are still unsure as to where they fit on the human family tree.

The biggest mystery: are the Denisovans named after a cave in the Altai mountains in Siberia—where their remains were first discovered in 2010. But we have such little evidence of their existence—a finger bone, a few teeth, and a scrap of skull—that they remain an unsolved puzzle. All we know is that they spread through Asia and interbred with us—homo sapiens—and Neanderthals. But are they one species or many distinct kinds of human? With so many unanswered questions, they have not yet been classified as a human species. But the Denisovan question now shadows every new discovery of a human species—including that of the Dragon man.

Point to note: These ancient species may have gone extinct, but we carry their essence within us. Neanderthal genes account for about 2% of the DNA of modern Europeans and Asians—who also carry small amounts of Denisovan genes. 

A handy chart: below helps you keep track of the various species, and when they lived:

New branch #1: Dragon Man

The backstory: The perfectly preserved skull was discovered in 1933 by a Chinese labourer when a bridge was built over a river in Harbin. Since China was under Japanese occupation at the time, the man did not turn it over to authorities, but hid the skull in a well for 85 years—finally telling his family about it when he was on his deathbed. The family then donated the skull to a museum in 2018. And the results of research into its origins were finally published over the weekend. 

The skull: is anywhere between 138,000 and 309,000 years old, and is “probably” that of a 50-year old man. It is viewed as evidence of a new human species now named Homo longi—derived from Heilongjiang, or Black Dragon River, where it was found. And it looks like this:

And the reconstruction of the face—which has a mix of homo sapien and primitive features—looks like this:

The significance: One of the lead researchers, Chris Stringer, describes the Harbin skull as “the most important fossil I've seen in 50 years.” The reason: It suggests that this now extinct human species may be more closely related to modern humans than even the Neanderthals. Xijun Ni, one of the other co-authors claims: “We see a mosaic of primitive and more modern human features. The combination of these features makes it unique. Our analyses suggest it is our sister species.”

OTOH: Many top scientists are skeptical about claims of a new ‘sister species’—and wonder if the skull isn’t more evidence of the mysterious Denisovans:

"The Denisovans are this fascinating mystery population from the past. There is a suggestion (from DNA evidence) that the jawbone found in the Tibetan Plateau might be a Denisovan. And now because the jawbone from Tibet and Dragon Man look like each other—now we might actually have the first face of the Denisovan."

Others say there simply isn’t enough information to reach any grand conclusions—especially since the skull was removed from its original location, and there is zero context for how this human may have lived:

“It’s exciting because it is a really interesting cranium, and it does have some things to say about human evolution and what’s going on in Asia. But it’s also disappointing that it’s 90 years out from discovery, and it is just an isolated cranium, and you’re not quite sure exactly how old it is or where it fits… The scientists do the best they can, but there’s a lot of uncertainty and missing information. So I expect a lot of reaction and controversy to this cranium.”

To which Li responded: "The results will spark a lot of debate and I am quite sure that a lot of people will disagree with us. But that is science and it is because we disagree that science progresses." 

New branch #2: Nesher Ramla Homo

The discovery: 140,000–120,000 years old fragments of a skull and a lower jaw with teeth were found at a site used by a cement plant in central Israel. Researchers uncovered the bones about 25 feet deep among stone tools and the bones of horses and deer. The new species have been dubbed Nesher Ramla Homo after the location where they were found.

The significance: While they are physically more similar to Neanderthals, they also share traits with homo sapiens: “Biologically, they still look very different and yet behaviorally they have a set of tools that are identical to the tools of the modern humans.” Lead researchers are convinced that this more ancient human species are a key part of the Neanderthal story: "The European Neanderthal actually began here in the Levant and migrated to Europe, while interbreeding with other groups of humans."

Above all, this find suggests that various human species were interacting extensively with one another:

“It was a surprise that archaic humans were using tools normally associated with Homo sapiens. This suggests that there were interactions between the two groups… We think that it is only possible to learn how to make the tools through visual or oral learning. Our findings suggest that human evolution is far from simple and involved many dispersals, contacts and interactions between different species of human."

The bottomline: Every new discovery teaches us how little we actually know about where we come from.

Reading list

CNN has a good overview of the Dragon Man find, while Science and Smithsonian magazine look at the controversy over the claims of a new species. BBC News and The Conversation have the most details on the Nesher Ramla study. Also on BBC News: How Lucy rewrote the story of our origins. This National Geographic video offers an excellent recap of our evolutionary history. Ars Technica looks at why the Denisova cave is so important to our family tree. If you want to deep dive into the stuff, we highly recommend spending time over at the ‘Human Origins’ website hosted by the National Museum of Natural History.