Paleoanthropology

Paleoanthropology is the branch of physical anthropology (often called biological anthropology) that focuses on the study of human evolution, tracing the anatomic, behavioral and genetic linkages of pre-humans from millions of years ago up to modern times.

Paleoanthropologists study early hominids through fossil remains, traces, or impressions of ancient life; evidence such as preserved bones, tools, or footprints. Typically, a team is composed of scientists, students, and local workers, representing diverse backgrounds and academic fields.

The science arguably began in the late 1800s when important discoveries occurred which led to the study of human evolution. The discovery of the Neanderthal in Germany, Thomas Huxley's Evidence as to Man's Place in Nature, and Charles Darwin's The Descent of Man were all important to early paleoanthropological research.

Robert Ardrey's four books, African Genesis (1961), The Territorial Imperative (1966), The Social Contract (1970), and The Hunting Hypothesis (1976), explore a significant mid-20th century transition in paleoanthropological studies and methodology.

While Ian Tattersall once noted (Nature 2006, 441:155) that paleoanthropology is distinguished as the "branch of science [that] keeps its primary data secret," it is perhaps more accurate to observe that primary physical evidence in paleoanthropology is among the most difficult to obtain.

History of paleoanthropology
The modern field of paleoanthropology began in the 19th century with the discovery of "Neanderthal man" (the eponymous skeleton was found in 1856, but there had been finds elsewhere since 1830), and with evidence of so-called cave men. The idea that humans are similar to certain great apes had been obvious to people for some time, but the idea of the biological evolution of species in general was not legitimized until after Charles Darwin published On the Origin of Species in 1859. Though Darwin's first book on evolution did not address the specific question of human evolution&mdash; "light will be thrown on the origin of man and his history," was all Darwin wrote on the subject&mdash; the implications of evolutionary theory were clear to contemporary readers. Debates between Thomas Huxley and Richard Owen focused on the idea of human evolution. Huxley convincingly illustrated many of the similarities and differences between humans and apes in his 1863 book Evidence as to Man's Place in Nature. By the time Darwin published his own book on the subject, Descent of Man, it was already a well-known interpretation of his theory&mdash; and the interpretation which made the theory highly controversial. Even many of Darwin's original supporters (such as Alfred Russel Wallace and Charles Lyell) balked at the idea that human beings could have evolved their apparently boundless mental capacities and moral sensibilities through natural selection.

Since the time of Carolus Linnaeus, the great apes were considered the closest relatives of human beings, based on morphological similarity. In the 19th century, it was speculated that their closest living relatives were chimpanzees and gorillas, and based on the natural range of these creatures, it was surmised humans share a common ancestor with African apes and that fossils of these ancestors would ultimately be found in Africa.

However, prior to today's general acceptance of Africa as the root of genus Homo, 19th century naturalists sought after the origin of man in Asia. The recognition of human antiquity in the Far East was, of course, the fruit of Eugene Dubois' fervent pursuit in Indonesia for the missing link (between ape and man) and the subsequent discovery and naming of Pithecanthropus erectus near the Solo River on Java in the 1890s.

For a long time, western scholars were knowledgeable of the so-called "dragon bones" (fossil bones and teeth) from the Chinese apothecary shops. It was not until the early 1900s, however, that German paleontologist, Max Schlosser, first described a single human tooth from Beijing. Although Schlosser (1903) was very cautious, identifying the tooth only as “?''Anthropoide g. et sp. indet''?,” he was hopeful that future work would discover a new anthropoid in China.

Fast-forward 11 years, enter the Swedish geologist Johan Gunnar Andersson. Andersson was sent to China as a mining advisor, but he soon developed a passion for the “dragon bones.” It was he who, in 1918, discovered the sites around Zhoukoudian, a village about 50 kilometers southwest of Beijing proper. However, because of the sparse nature of the initial finds, the site was inevitably abandoned. Work did not resume again until 1921, when the Austrian paleontologist, Otto Zdansky, fresh with his doctoral degree from Vienna, came to Beijing to work for Andersson. Zdansky conducted short-term excavations at Locality 1 in 1921 and 1923, and recovered only two teeth of significance (one premolar and one molar) that he subsequently described, cautiously, as “?Homo sp.” (Zdansky, 1927). With that done, Zdansky returned to Austria and suspended all fieldwork.

News of the fossil hominin teeth delighted the scientific community in Beijing, and plans soon began to formulate aimed at developing a larger, more systematic project at Zhoukoudian. At the epicenter of excitement was Davidson Black, a Canadian-born anatomist working at the Peking Union Medical College. Black shared Andersson’s interest, as well as his view that central Asia was a promising home for early humankind. In late 1926, Black channeled a formal proposal through the Union Medical College to the Rockefeller Foundation concerning financial support for the systematic excavation at Zhoukoudian, and the establishment of an institute for the study of human biology in China. The Zhoukoudian Project came to existence in the spring of 1927, and two years later, the Cenozoic Research Laboratory of the Geological Survey of China was formally established. Being the first institution of its kind, the Cenozoic Laboratory opened up new avenues for the studies of paleogeology and paleontology in China. Moreover, the Laboratory was the precursor of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Science, of which took its modern form after 1949.

The first of the major project finds should be attributed to the young Swedish paleontologist, Anders Birger Bohlin, then serving as the Field Advisor at Zhoukoudian. He recovered a left, lower molar which Black (1927) identified as unmistakably human (it compared favorably to the previous find made by Zdansky), and subsequently coined it Sinanthropus pekinensis, Black and Zdansky 1927. The news was at first met with skepticism, and many scholars had reservations that a single tooth was sufficient to justify the naming of a new type of early hominin. Yet within a little more than two years, in the winter of 1929, Pei Wenzhong, then the Field Director of Zhoukoudian, unearthed the first, complete calvaria of Peking Man. Twenty-seven years after Schlosser’s initial description, the antiquity of early humans in East Asia was no longer a speculation, but a reality.

Excavations continued at the site and remained fruitful until the outbreak of the Sino-Japanese War in 1937. The decade long research yielded a wealth of faunal and lithic materials, as well as hominin fossils. These included 5 more complete calvaria, 9 large cranial fragments, 6 facial fragments, 14 partial mandibles, 147 isolated teeth, and 11 postcranial elements-estimated to represent as least 40 individuals. Evidence of fire, marked by ash lenses and burned bones and stones, were apparently also present (Black, 1931), albeit recent studies have challenged this view (Weiner et al., 1998; Weiner et al., 1999). Franz Weidenreich came to Beijing soon after Black’s untimely death in 1934, and took over the academic affairs of studying the hominin specimens.

Following the tragic loss of the Peking Man materials in late 1941, scientific endeavors at Zhoukoudian and elsewhere slowed. For the most part, it was because of the lack of funding. Conversely, frantic search for the missing fossils also figured prominently, and efforts continued well into the 1950s. Nonetheless, after the establishment of the People’s Republic of China in 1949, excavations resumed at Zhoukoudian. But as the story goes, with political instability and social unrest brewing in China, beginning in 1966, and major discoveries at Olduvai Gorge and East Turkana (Koobi Fora), the paleoanthropological spotlights inevitably shifted westward to East Africa. While China re-opened its doors to the West in the late 1970s, national policy calling for self-reliance, coupled with a widened language barrier, thwarted all the possibilities of renewed scientific relationships. Indeed, Harvard anthropologist K. C. Chang noted, “international collaboration (in developing nations very often a disguise for Western domination) became a thing of the past” (1977: 139).

Of course, work did not stop everywhere. Back in South Africa, a notable and rare find came to light in 1924. In a cave site at Taung, Professor Raymond Dart discovered a remarkably well-preserved juvenile specimen (face and brain endocast) and named it Australopithecus africanus (Australopithecus = Souther Ape). Although the brain was small (410 cm³), its shape was rounded, unlike that of chimpanzees and gorillas, and more like a modern human brain. In addition, the specimen exhibited short canine teeth, and the foramen magnum was more anteriorly placed, hinting a bipedal mode of locomotion. All of these traits convinced Dart that the Taung child was a bipedal human ancestor, a transitional form between ape and man. Another 20 years would pass before Dart's claims were taken seriously, following the discovery of additional australopith fossils in Africa that resemble his type specimen. The prevailing view of the time was that a large brain evolved before bipedality. It was thought that intelligence on par with modern humans was a prerequisite to bipedalism.

Today, the australopiths are considered to be the last common ancestors leading to genus Homo, the group to which modern humans belong. Both australopiths and Homo sapiens are part of the tribe Hominini, but recent morphological data have brought into doubt the position of A. africanus as a direct ancestor of modern humans; it may well have been a dead-end cousin.

The australopiths were originally grouped based on size as either gracile or robust. The robust variety of Australopithecus has since been renamed as Paranthropus (P. robustus from South Africa, and P. boisei and P. aethiopicus from East Africa). In the 1930s, when the robust specimens were first described, the Paranthropus genus was used. During the 1960s, the robust variety was moved into Australopithecus. The recent consensus has been back to the original classification as a separate genus.