Human evolution has long been a topic of interest, intrigue, and even controversy. Though plenty of people refuse to believe in it, studying our evolution from early hominids into the complex, sentient beings we are today begins to help answer questions about who we are, where we came from, why we are here, and where we are going. As archaeologists, biologists, and anthropologists continue to discover and research the remains of our ancient hominid ancestors, the human family tree continues to change and adapt. From Darwin’s first position of his evolutionary theory until today, the human evolutionary tree has also been, for lack of a better word, evolving. Though discoveries of the sort have seemingly slowed in the past few decades, recently a skull was discovered at the bottom of a well in Harbin, China that may hold an important place in our evolutionary history. This is the story of the “Dragon Man.”
What exactly do we mean by “hominid”?
All life on earth can be, and is, identified by phylogenetic trees. Phylogenetic trees are essentially diagrams that trace the branching patterns of the evolution of certain species from proposed common ancestors. These “branches” can also be broken down and identified by their taxonomic rank, which breaks a specific creature’s identification down in the following descending and increasingly specific manner: domain, kingdom, phylum, class, order, family, genus, and species. For example, modern human beings (Homo sapiens) are from the kingdom Animalia, the phylum Chordata, the class Mammalia, the order Primates, the family Hominidae, the genus Homo and the species Homo sapiens. What we are focusing on when we identify something as a hominid is the family classification Hominidae, and all life that has fallen under it.
Traditionally, hominids were considered to just be modern human beings and their species ancestors. However, since around the 1990s, scientists have also come to recognize seven other extant species of great apes as hominids as well due to our extremely close genetic relationship and interrelated evolutionary patterns. The seven extant species besides Homo sapiens that are currently recognized as hominids are the Bornean, Sumatran, and Tapanuli orangutans, the eastern and western gorillas, and the chimpanzee and bonobos. Hominids are believed to have speciated, or genetically distinguished themselves, from their other most closely related ancestors, Hylobatidae, around 20 million years ago. All hominids are large, tailless, and omnivorous primates with advanced use of their hands and opposable thumbs.
Though we recognize that the seven extant species or hominids are scientifically accepted as such, for the purposes of clarity in this article, we will be using the term “hominid” to refer to Homo sapiens and their specifically mapped genetic history, excluding the evolution of modern great apes.
What came first, the cave or the man?
While it is quite possible that there are earlier hominids that field researchers and scientists have yet to discover and identify, hominids really began to speciate into recognizable groups just about six million years ago. Though six million years may seem like an extremely long time, in the grand scheme of the Earth’s biologic (and especially its mammalian) timeline, it was really not that long ago. Currently, archaeologists have divided the around eighteen species of known hominids into four distinct groups: Ardipithecus, Australopithecus, Paranthropus, and Homo.
Ardipithecus is our earliest known separation from other primates. This group evolved in Africa beginning some six million years ago. There are four identified species of Ardipithecus: Sahelanthropus tchadensis, Orrorin tugenensis, Ardipithecus kadabba, and Ardipithecus ramidus (also known as Ardipithecus afarensis). Sahelanthropus tchadensis was the earliest evolved of this grouping, and closely resembles what we would know now as the modern chimpanzee. However, unlike a chimpanzee (and very much like a human), S. tchadensis had small canine teeth, comparatively small faces, and were bipedal, meaning they walked on two legs. Unfortunately, since their discovery in 2001 in Chad, scientists have only been able to uncover nine skull fossils. While the skulls are useful in telling us how they walked and what they may have looked like and eaten, there is not much other information we can glean from them.
Orrorin tugenensis, discovered in 2001 (and thus also nicknamed the “Millenium Man”, was the next evolved species of Ardipithecus. This species is thought to have overlapped with the species before and after it. Like S.tchadensis, O.tugenensis had a combination of chimp and human-like features. Though they were smaller in stature, they had smaller, enameled teeth like humans, and, as evidenced by a fossilized femur, walked upright.
Ardipithecus kadabba, discovered in 1997, is one of our ancestors that the scientific community still does not know that much about. It is thought that Ar. kadabba lived approximately 5.8 to 5.2 million years ago, but is not as similar to modern humans as other species of Ardipithecus were. Unfortunately, we only have a few fossilized fragments to work off of when researching this species: a few teeth, some cranial bones, and some phalanges. From the wear on the toes, however, paleoanthropologists have been able to determine that Ardipithecus kadabba was likely able to walk on two legs, though how frequently we don’t yet know.
The final species of Ardipithecus is also perhaps the best known species: Ardipithecus ramidus, or “Ardi”. Ar. ramidus existed about four and a half million years ago, and its first fossilized examples were discovered in 1994. As anthropologists have uncovered over 100 skeletons of the species since the early nineties, we have a better idea of what they were like. “Ardi” was bipedal, lived in wooded regions, and ate a largely omnivorous diet. The discovery of Ar. ramidus helped to disprove the theory that climate caused bipedalism.
Australopithecus was the next “branch” off of the human family tree, and began speciating around 4 million years ago, near the time of Ar. ramidus. One of the earliest known species of Australopithecus was Australopithecus anamensis. These early hominids began to look more human-like, but still retained some chimpanzee-like features. While they were bipedal, their long and well-developed arms suggest that they frequently climbed trees. Though their faces were more “ape-like”, they had the more “modern” feature of projected cheekbones. This species overlapped with its next closest relative for a minimum of a hundred thousand years.
Overlapping with Au. anamensis was Australopithecus afarensis, which lived between 4 and 3 million years ago in eastern Africa. This species is best known because of the famous skeleton, nicknamed “Lucy”, discovered by researchers in Ethiopia in 1974. Paleoanthropologists posit that Au. afarensis were adapted to living in both trees and on the ground, and ate broader, omnivorous diets like humans.
Australopithecus africanus and Australopithecus garhi existed in much the same time period, around 2 and a half million years ago. These species were very similar, in both appearance and in their evolutionary importance. Both species showed evidence of having larger molar teeth, like modern humans, and were bipedal. Both species are believed to have used primitive tools, though this theory is more supported by evidence discovered near the fossilized remains of Au. garhi. Au. garhi used stone and bone tools which supports the idea that not only did they eat (and perhaps hunt) larger animals, but that this was the point in time that hominids first developed the capability to produce and use tools.
Paranthropus (“beside man”) was one of the most “recent” genera of hominids, but is less talked about in non-academic circles. Their timeline of existence overlapped with early members of the Homo genus. The earliest known member of this genus was Paranthropus aethiopicus, which first emerged an estimated 2.7 million years ago in Kenya and Ethiopia. Like some of the other hominids we have mentioned, very few examples of P. aethiopicus have been uncovered. They had distinct faces and strong jaws, and is considered a more “sophisticated” evolutionary version of Australopithecus afarensis.
Paranthropus robustus and Paranthropus boisei evolved at around the same time and lived from about two to one million years ago. P. robustus had large jaws with enameled teeth, and had noticeably wide faces. Though no tools of theirs have been discovered, it has been inferred by paleoanthropologists that they likely used tools to access their food sources. Paranthropus boisei were similar to P. robustus in that they had wide faces and jaws, though their molars were considerably larger. Unlike P. robustus, however, P. boisei skulls had a larger cranial cavity, indicating that this was the turning point in hominids brains enlarging.
There have been six total species identified in our own genus, Homo. The first two hominids in the genus Homo actually evolved after P. robustus and P. boisei. Homo rudolfensis evolved around 2 million years ago but are only believed to have been around for a short time. H. rudolfensis had a relatively large braincase, long faces, and large teeth. There isn’t any known evidence that this species used tools, but there have been tools discovered in their region that dated to their time period. Homo habilis was very similar to H. rudolfensis in appearance, but there has been evidence that they used tools. The discovery of H. habilis tools was important in the study of the human evolutionary tree because they are thought to be the first in our genus to have used tools.
Homo erectus was around from around 1.9 million years ago until only around a hundred thousand years ago. H. erectus had body proportions similar to modern humans, and there is evidence that they formed small groupings that cared for old and injured members. H. erectus also made handaxes, the earliest examples of major innovation in technology.
Homo heidelbergensis only existed for about five hundred thousand years, beginning seven hundred thousand years ago. They had large brow bones and short, broadly built bodies. This species was imperative to the evolution of modern humans (and technology!) as they were the first known species to use fire, use spears to hunt animals, and build freestanding shelters made with wood and stone.
Homo floresiensis was a recent relative of ours, living from about a hundred thousand years ago to fifty thousand years ago. This species has only been discovered in Asia, specifically in Indonesia. These small statured hominids more closely resembled earlier relatives, but used stone tools, hunted large animals, and used fire.
Our best known relative was also the one we survived the longest alongside: Homo neanderthalensis. Neanderthals first emerged four hundred thousand years ago, and lasted until around forty thousand years ago. Besides their broader builds, heavy brows, and wide noses, Neanderthals closely resembled us. Their brains were of comparable size, and are thought to actually have been larger than our own. Also like us, Neanderthals made sophisticated tools, controlled fires, wore clothing, hunted, made shelters, created art, and were the first hominids to practice symbolic burials of their dead. And, while modern humans may have contributed to the dissolution of this species, there is evidence that H. neanderthalensis and Homo sapiens lived alongside each other and even interbred.
The final species in our genus is us, Homo sapiens. We emerged as a distinct species around three hundred thousand years ago. Compared to the length of time some of our ancestors were around, we’ve been here for pretty much no time at all. We also have relatively slighter builds, larger brains, smaller jaws, and thinner skulls than our ancestors. We are the most populous and most sophisticated hominid as of yet.
The missing link
While geneticists and paleoanthropologists alike have established that all of these hominids are related and come from the same evolutionary tree, there has been some debate historically around what the exact path of our own evolution was and how closely related we are to our ancestors. For many years, there has been talk of a “missing link”, a hominid or set of DNA that would clear up any evolutionary mystery. This was partially answered in 2010, when “y” chromosome DNA from Neanderthals and Denisovans was sequenced for the first time. This study showed that Neanderthals and modern humans shared 99.7% of the same DNA, and that Denisovans split over seven hundred thousand years ago from the modern human/Neanderthal line. But who were the Denisovans, and how do they factor into human evolution?
The Denisovans are a mysterious species of hominid that scientists still know almost nothing about. While we have been able to sequence the majority of their DNA, there are only five confirmed Denisovan specimens that have been discovered: the tip of a finger, three molars, a piece of a mandible, a fragment of an extremity, and a fragment of a parietal bone. One of these fragments, the extremity, doesn’t even come from a full Denisovan, but from the progeny of a Denisovan-Neanderthal pairing. While we know what they most likely looked like and that Denisovan DNA still exists in some groups of modern humans, we really have no idea what they were like and how important they were to our own development. So what do these mysterious hominids and all of this build up have to do with the so-called “Dragon Man”?
“The Dragon Man” is the nickname given to a skull first discovered in 1933 in a construction zone in Harbin, a region in the northeast of China. The skull was unearthed by a laborer, who, recognizing that it was a non-human hominid, hid it in a well on his property. Three generations later, his decedents learned of his skull shortly before his death in 2018. They donated it to Hebei GEO University’s paleoanthropology department to be studied later that same year.
What we know so far
Researchers at Hebei GEO have used varying methods to date the skull, as it was damaged from decades of being stored in the well. They believe that it is around 146,000 years old, making it the hominid from the Middle Pleistocene, indicating the hominid was alive at the same time as modern humans, Neanderthals, and other members of the Homo genus. The owner of the skull was male, and most likely around fifty years old at the time of his death.
The Dragon Man’s skull was unlike any hominid previously discovered. The skull boasts a large nose and mouth, square eye-sockets, and a broad face, but, more distinctly, had a huge brain, comparable (and perhaps even larger) to those of Neanderthals and humans. Because of its unique skull morphology and the results so far from DNA sequencing, paleoanthropologists have officially classified the Dragon Man as his own species: Homo longi.
Though not confirmed, some scientists believe that the Dragon Man, and thus any other H. longi remains we discover, could be the Denisovans that we have waited so long to reconstruct and fully identify. DNA sequencing from this skull is only preliminary, however, and it may be quite a while before we see official results comparing the DNA.
Significance in Anthropology
No matter which theory about the Dragon Man skull is correct, the discovery is incredibly important to the study of human evolution and paleoanthropology. If the skull represents a new species that is different than the Denisovans, then we will have discovered a brand new hominid and will be able to expand the human evolutionary tree even further. But, if the skulls DNA turns out to match what we have collected from the Denisovan samples, then we will finally have answers to decades old questions about who and what the Denisovans were. Either way, the coming weeks and months of research into the skull will change what we know about human evolution forever.