Note: Today and tomorrow, biological anthropologist James Kidder continues to tell the story of the evolution of creatures on our own small branch of the primate family tree, the hominins. In his previous post, Kidder describes the rise of the archaic Homo sapiens 600 to 700 thousand years ago. From the river valleys in Indonesia, to the open savannas in Africa, to the caves in China, India and Europe, Homo erectus had mastered fire, standardized stone tool technology and incorporated hunting into its daily life. In these next posts, Kidder takes us on a tour of the transitional phase between Homo erectus and Homo sapiens.
Now we progress beyond Homo erectus in East Asia, an area that, as nearly as we can tell, appears to mirror the changes that occur in Africa and Europe in documenting the transition to archaic Homo sapiens. The catch phrase here is “as nearly as we can tell.”
When the incredible cache of human fossil remains from the site of Zhoukoudian disappeared toward the beginning of World War II, this was not only a sizeable setback for the study of human evolution in Asia, but represented the loss of the largest cache of human remains ever discovered in this region. That we have any information from this site is only due to the ingenuity of Franz Weidenreich in making high-quality casts of the fossils and the few remains discovered in 1966 at the same location.
If Africa was considered the Dark Continent in the glory years of exploration in the late 1800s, then Asia could reasonably be considered the Dark Continent for the study of human palaeontology, especially as it pertains to archaic Homo sapiens. Excavations have revealed very little in China, nothing whatsoever in Japan or Australasia, and only one notable site in Indonesia. Consequently, despite having a well-represented sequence from late Homo erectus to archaic Homo sapiens in Europe and Africa, the fossil trail between the two has grown quite cold in East Asia.
While there are more than seventy sites with Homo erectus, archaic Homo sapiens or early modern remains in East Asia, the vast majority of these consist of isolated teeth or scattered, small cranial fragments (Liu, Zhang, & Wu, 2005). To further exacerbate the problem, there are no securely dated fossil remains between approximately 150 thousand and 30 thousand years ago. As Brown (2001) points out, this is the time in which modern humans are either evolving or have just evolved elsewhere in the Old World.
The Fossil Evidence:
There are only three reasonably complete crania from China that date from the time period just post-Homo erectus. These are from the sites of Dali, Mapa and Jinniu Shan and are shown in Figure 1.
The Dali find represents a mostly complete cranium that was found in 1978 in a dating context that presented challenges for determining its age. The surrounding sediment was originally dated to around 200 thousand years ago (Pope, 1992) by uranium series analysis but it was found with riverine deposits and heavily worn artifacts and faunal remains, suggesting that the skull had been transported and that the date may not fit the cranium. Recently, Xiao et al (Xiao, Jin, & Zhu, 2002) have reanalyzed the surrounding wind-blown strata to determine an age of the original deposits and have concluded that the remains are roughly 270 thousand years old.
The cranium suffers from slight facial distortion and is missing a large section of the right side of the skull but is, otherwise, intact. It is long and low, with very well-developed brow ridges. What is undistorted in the face, however, shows considerable reduction over the Homo erectus condition and the face is flat, overall. Additionally, despite its length, there is considerable curvature at the back and the rear of the vault, which is less acutely angled. As with other East Asian Homo erectus remains, however, the skull possesses a sagittal keel.
Pope originally suggested that this cranium exhibits traits that are reminiscent of Neandertals, a conclusion that was not well received at the time but is now being re-thought based on recent genetic information. A recent re-evaluation by Wu and Athreya suggest that it possesses characteristics that are intermediate between Homo erectus and archaic Homo sapiens and resembles, in the sections of its cranial base, populations from Africa and Europe (Wu & Athreya, 2013).
Discovered in 1984, a partial skull was unearthed from the site of Jinniu Shan. Although not quite as complete as the Dali specimen, this cranium displays many of the same features as Dali and has been comfortably designated archaic Homo sapiens. Electron spin resonance (Now electron paramagnetic resonance) dating of five fossil animal teeth reveals a date of approximately 200 thousand years B.P. (Tiemei, Quan, & En, 1994)
As with the Dali find, this skull exhibits advanced traits over theHomo erectus condition, including a more rounded rear and side of the vault, facial flattening, and a general thinning of the cranial bones. Brown (2001) writes that the cranium has a volume of around 1400 CCs, just under the average for anatomically modern humans. Archaic traits are still present, however. There is a very well-developed brow ridge, although there is some separation just above the nose (glabella). The cranial height is low, similar to that of Homo erectus and cranial length is similar to those of archaicHomo sapiens in Europe and Africa, being longer than those of modern humans.
The Mapa cranium, discovered in 1958, is not as complete as either the Dali or Jinniu Shan crania. It has been dated by Uranium Series to between 135 and 129 thousand years ago (Brown, 2001). It consists of several large cranial fragments that comprise the front and right side of the skull, including the region of the nose. Of the three crania mentioned, this is the most archaic, with a broad upper face, large brow ridges and overall longer vault. Additionally, the cranial vault bones are thicker than those of either Jinniu Shan or Dali, recalling the Homo erectus condition.
The only notable cache of archaic Homo sapiens remains from Southeast Asia come from the site of Ngandong. Originally excavated by Oppenoorth in the 1930s, this site yielded some eleven crania, most of which were vaults. These were discovered near the town of Ngandong on the banks of the Solo River, in what is known as the “high terrace.” These fossils had been traditionally dated to between 150 and 200 thousand years ago but, in the late 1990s, Swisher and colleagues released a set of radiometric dates from this terrace that placed the hominins at approximately 30,000 years before the present (Swisher et al., 1996), a date that left many scratching their heads due to the patently archaic nature of the fossil material. Grün and Thorne (Grün & Thorne, 1997), in a later examination of the stratigraphy, state that this terrace is “a mélange” of material from different levels and sites. As such, they contend that these layers are very hard to date chronometrically. A recent paper by Indriati and colleagues have has suggested that these remains cannot be dated more securely than between 140 and 500 thousand years B.P. Some stone tools that were non-Acheulean but generally post-Oldowan and Palaeolithic in nature were found in the strata and it is tempting to relate them directly to the hominins but the nature of the deposits precludes that definitively (Indriati et al., 2011).
Oppenoorth described these crania as Homo javanthropus and they were also referred to as Homo soloensis (Zeitoun, Détroit, Grimaud-Hervé, & Widianto, 2010). One worker in the region, GHR von Koenigswald, referred to them as “tropical Neanderthals” (Bartstra, Soegondho, & Wijk, 1988). These crania exhibit a range of traits that are progressive over the Homo erectus condition, such as slightly expanded breadths and higher vaults. The morphology is peculiar, however, in that a number of traits present on these hominins found on the cranial base cannot be found on crania that succeed them spatially or chronologically. Consequently, Durband (pers. comm.) has suggested that these crania represent a relic population that did not give rise to any successor groups.
Human Evolution in East Asia
Taken as a whole, these skulls clearly represent a transitional phase between Homo erectus and modern Homo sapiens, occupying the same general period of time as those from Europe and Africa, although it is harder to ascertain chronological dates for these finds. Rightmire (Rightmire, 2007) has suggested that these fossils resemble in many ways the archaic Homo sapiens crania from Europe and Africa and that it is difficult to argue persuasively that these populations were separated to any large degree genetically. Liu et al. (2005), as well as Pope and Wu suggest that there is a regional set of features that link the Homo erectus populations with those of the later archaic Homo sapiens in China and cite as evidence the facial flattening and the presence of shovel-shaped incisors seen in the archaic Homo sapiens crania. Weidenreich, who examined the Zhoukoudian Homo erectusremains in depth, also saw this continuity and suggested that as many as twelve morphological features were present in the Homo erectus remains that are present in later, modern crania. It has also been suggested independently by Pope and Wu that there are links to Neandertals in these crania, a position that has, historically, not received much support but which, with the advent of new genetic information, has received a more serious hearing.