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World’s Oldest Engraving Upends Theory of Homo sapiens Uniqueness
December 3, 2014 | 4
It is getting harder and harder to figure out what distinguished Homo sapiens from other members of the human family and fueled our extraordinary success as a species. One popular notion holds that our propensity for symbolic thought, which underlies language, was key. For a long time, experts thought this capacity first emerged around 40,000 years ago in early Europeans, based on the seemingly sudden appearance of things like cave art and jewelry in the archaeological record there. But over the past two decades older evidence of art and body decoration, as well as other sophisticated practices, such as complex tool manufacture, have turned up at H. sapiens sites in the Near East and in Africa, where our species got its start. Furthermore, scientists have found evidence that our cousins the Neandertals were similarly capable in many respects.
Now comes news that an even older, more primitive human ancestor—Homo erectus from Asia—showed signs of symbolic thought, too. Researchers have discovered a shell engraved with a geometric pattern at a H. erectus site known as Trinil, on the Indonesian island of Java, that dates to between 540,000 and 430,000 years ago. The find is at least 300,000 years older than the oldest previously known engravings, which come from South Africa.
Analysis of the engraving, made on a freshwater mussel shell, suggests that its maker used a shark tooth or other hard, pointed object to create the zigzag design. “The engraving was probably made on a fresh shell specimen still retaining its brown [skin], which would have produced a striking pattern of white lines on a dark ‘canvas,’” Josephine C. A. Joordens of Leiden University in the Netherlands and her colleagues surmise in their report, published online December 3 by Nature. (Scientific American is part of Nature Publishing Group.)
Other shells from the site reveal that H. erectus opened them to eat their contents. And one specimen exhibits clear signs of having been modified to create a tool for cutting or scraping. It is the earliest known example of shell used as a raw material for tool manufacture, the authors say, and it may explain the lack of stone artifacts from this time period in Java: perhaps in the absence of good sources of stone suitable for making implements, H. erectus turned to shell instead.
It’s wild to think of H. erectus foraging for mollusks along an ancient riverbank, making shell knives and painstakingly decorating shells with designs half a million years ago. But perhaps the most thrilling aspects of this find are that it suggests that many more such items—300,000 years’ worth, in fact–are out there awaiting discovery, and it raises the question of just how much farther back in the human lineage such behaviors might have originated.
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Indonesia's "Java Man"
While searching for fossils in Java, physician Eugène Dubois uncovered the tophalf of an early human skull in 1891. This skull, Trinil 2, is long, with a flat forehead and distinct browridges and a sagittal keel, though many of its features have been worn flat with age. Dubois named a new species, Pithecanthropus erectus after this specimen in 1894, but Ernst Mayr reassigned Trinil 2 to Homo erectus in the 1950s.
Site:Trinil, Java, Indonesia
Date of discovery:1891
Discovered by:Eugene Dubois
Age:Between 1 million and 700,000 years old
From Wikipedia, the free encyclopedia
|Homo erectus erectus
Temporal range: Pleistocene
|The syntype fossils of Java Man (H. e. erectus), at Naturalis, Leiden|
|Subspecies:||H. e. erectus|
|Homo erectus erectus|
The fossil aroused much controversy. Less than ten years after 1891, almost eighty books or articles had been published on Dubois's finds Despite Dubois' argument, few accepted that Java Man was a transitional form between apes and humans. Some dismissed the fossils as apes and others as modern humans, whereas many scientists considered Java Man as a primitive side branch of evolution not related to modern humans at all. In the 1930s Dubois made the claim that Pithecanthropus was built like a "giant gibbon", a much misinterpreted attempt by Dubois to prove that it was the "missing link".
Eventually, similarities between Pithecanthropus erectus (Java Man) and Sinanthropus pekinensis (Peking Man) led Ernst Mayr to rename both Homo erectus in 1950, placing them directly in the human evolutionary tree. To distinguish Java Man from other Homo erectus populations, some scientists began to regard it as a subspecies, Homo erectus erectus, in the 1970s. Other fossils found in the first half of the twentieth century in Java at Sangiran and Mojokerto, all older than those found by Dubois, are also considered part of the species Homo erectus. Estimated to be between 700,000 and 1,000,000 years old, at the time of their discovery the fossils of Java Man were the oldest hominin fossils ever found. The fossils of Java Man have been housed at the Naturalis in the Netherlands since 1900.
History of discoveries
BackgroundCharles Darwin had argued that humanity evolved in Africa, because this is where great apes like gorillas and chimpanzees lived. Though Darwin's claims have since been vindicated by the fossil record, they were proposed without any fossil evidence. Other scientific authorities disagreed with him, like Charles Lyell, a geologist, and Alfred Russel Wallace, who had thought of the theory of evolution around the same time as Darwin. Because both Lyell and Wallace believed that humans were more closely related to gibbons and orangutans, they identified Southeast Asia as the cradle of humanity because this is where these great apes lived. Dutch anatomist Eugène Dubois favored the latter theory, and sought to confirm it.
Trinil fossilsDutch East Indies (present-day Indonesia) to look for the fossilized ancestor of modern man. Having received no funding from the Dutch government for his eccentric endeavor – since no one at the time had ever found an early human fossil while looking for it – he joined the Dutch East Indies Army as a military surgeon. Because of his work duties, it was only in July 1888 did he begin to excavate caves in Sumatra. Having quickly found abundant fossils of large mammals, Dubois was relieved of his military duties (March 1889), and the colonial government assigned two engineers and fifty convicts to help him with his excavations. After he failed to find the fossils he was looking for on Sumatra he moved on to Java in 1890.
Again assisted by convict laborers and two army sergeants, Dubois began searching along the Solo River near Trinil in August 1891. His team soon excavated a molar (Trinil 1) and a skullcap (Tinil 2). Its characteristics were a long cranium with a sagittal keel and heavy browridge. Dubois first gave them the name Anthropopithecus, or "man-ape", as the chimpanzee was known at the time. He chose this name because a similar tooth found in the Siwalik Hills in India in 1878 had been named Anthropopithecus, and because Dubois first assessed the cranium to have been about 700 cubic centimetres (43 cu in), closer to apes than to humans.
In August 1892, Dubois's team found a long femur (thighbone) shaped like a human one, suggesting that its owner had stood upright. Believing that the three fossils belonged to a single individual, "probably a very aged female", Dubois renamed the specimen Anthropopithecus erectus. Only in late 1892, when he determined that the cranium measured about 900 cubic centimetres (55 cu in), did Dubois consider that his specimen was a transitional form between apes and humans. In 1894, he thus renamed it Pithecanthropus erectus ("upright ape-man"), borrowing the genus name Pithecanthropus from Ernst Haeckel, who had coined it a few years earlier to refer to a supposed "missing link" between apes and humans. This specimen has also been known as Pithecanthropus 1.
Comparisons with Peking Man
Further information: Peking ManIn 1927, Canadian Davidson Black identified two fossilized teeth he had found in Zhoukoudian near Beijing as belonging to an ancient human, and named his specimen Sinanthropus pekinensis, now better known as Peking Man. In December 1929, the first of several skullcaps was found on the same site, and it appeared similar but slightly larger than Java Man. Franz Weidenreich, who replaced Black in China after the latter's death in 1933, argued that Sinanthropus was also a transitional fossil between apes and humans, and was in fact so similar to Java's Pithecanthropus that they should both belong to the Hominidae family. Eugène Dubois categorically refused to entertain this possibility, dismissing Peking Man as a kind of Neanderthal, closer to humans than the Pithecanthropus, and insisting that Pithecanthropus belonged to its own family, the Pithecanthropoidae.
Other discoveries on JavaG. H. R. von Koenigswald recovered several other early human fossils in Java. Between 1931 and 1933 von Koenigswald discovered fossils of Solo Man from sites along the Bengawan Solo River on Java, including several skullcaps and cranial fragments. In 1936, von Koenigswald discovered a juvenile skullcap known as the Mojokerto child in East Java. Considering the Mojokerto child skull cap to be a closely related to humans, von Koenigswald wanted to name it Pithecanthropus modjokertensis (after Dubois's specimen), but Dubois protested that Pithecanthropus was not a human but an "ape-man".
Von Koenigswald also made several discoveries Sangiran, Central Java, where more fossils of early humans were discovered between 1936 and 1941. Among the discoveries was a skullcap of similar size to that found by Dubois at the Trinil 2 site. Von Koenigswald's discovers in Sangiran convinced him that all these skulls belonged to early humans. Dubois again refused to acknowledge the similarity. Ralph von Koenigswald and Franz Weidenreich compared the fossils from Java and Zhoukoudian and concluded that Java Man and Peking Man were closely related. Dubois died in 1940, still refusing to recognize their conclusion, and official reports remain critical of the Sangiran site's poor presentation and interpretation.
Early interpretationsRalph von Koenigswald recollected that, "No other paleontological discovery has created such a sensation and led to such a variety of conflicting scientific opinions." The Pithecanthropus fossils were so immediately controversial that by the end of the 1890s, almost 80 publications had already discussed them.
Until the Taung child – the 2.8 million-year-old remains of an Australopithecus africanus – were discovered in South Africa in 1924, Dubois's and Koenigswald's discoveries were the oldest hominid remains ever found. Some scientists of the day suggested that Dubois's Java Man was a potential intermediate form between modern humans and the common ancestor we share with the other great apes. This supposition has been confirmed, but the current consensus of anthropologists is that the direct ancestors of modern humans were African populations of Homo erectus (possibly Homo ergaster), rather than the Asian populations of the same species exemplified by Java Man and Peking Man.
Dubois first pulished his find 1894. Dubois's central claim was that Pithecanthropus was a transitional form between apes and humans, a so-called "missing link". Many disagreed. Some critics claimed that the bones were those of an upright walking ape, or that they belonged to a primitive human. This judgment made sense at a time when an evolutionary view of humanity had not yet been widely accepted, and scientists tended to view hominid fossils as racial variants of modern humans rather than as ancestral forms. After Dubois let a number of scientists examine the fossils in a series of conferences held in Europe in the 1890s, they started to agree that Java Man may be a transitional form after all, but most of them thought of it as "an extinct side branch" of the human tree that had indeed descended from apes, but not evolved into humans. This interpretation eventually imposed itself and remained dominant until the 1940s.
 In response to critics who refused to accept that Java Man was a "missing link", in 1932 Dubois published a paper arguing that the Trinil bones looked like those of a "giant gibbon". Dubois' use of the phrase has been widely misinterpreted as a retraction, but it was intended an argument to support his claim that Pithecanthropus was a transitional form. According to Dubois, evolution occurred by leaps, and the ancestors of humanity had doubled their brain-to-body ratio on each leap. To prove that Java Man was the "missing link" between apes and humans, he therefore had to show that its brain-to-body ratio was double that of apes and half that of humans. The problem was that Java Man's cranial capacity was 900 cubic centimeters, about two thirds of modern humans'.
Like many scientists who believed that modern humans evolved "Out of Asia", Dubois thought that gibbons were closest to humans among the great apes. To preserve the proportions predicted by his theory of brain evolution, Dubois argued that Java Man was shaped more like a gibbon than a human. Imagined "with longer arms and a greatly expanded chest and upper body", the Trinil creature became a gigantic ape of about 100 kilograms (220 lb), but "double cephalization of the anthropoid apes in general and half that of man". It was therefore halfway on the path to becoming a modern human. As Dubois concluded his 1932 paper: "I still believe, now more firmly than ever, that the Pithecanthropus of Trinil is the real 'missing link.'"
Reclassification as Homo erectus
Further information: Homo erectusBased on Weidenreich's work and on his suggestion that Pithecanthropus erectus and Sinanthropus pekinensis were connected through a series of interbreeding populations, German biologist Ernst Mayr reclassified them both as being part of the same species: Homo erectus.  Mayr presented his conclusion at the Cold Spring Harbor Symposium in 1950, and resulted in Dubois's erectus species being reclassified under the genus Homo. As part of the reclassification, Mayr included not only Sinanthropus and Pithecanthropus, but also Plesianthropus, Paranthropus, Javanthropus, and several other genera as synonyms, arguing that all human ancestors were part of a single genus (Homo), and that "never one more than one species of man existed on the earth at any one time". A "revolution in taxonomy", Mayr's single-species approach to human evolution was quickly accepted. It shaped paleoanthropology in the 1950s and lasted into the 1970s, when the African genus Australopithecus was accepted into the human evolutionary tree.
In the 1970s a tendency developed to regard the Javanese variety of H. erectus as a subspecies, Homo erectus erectus, with the Chinese variety being referred to as Homo erectus pekinensis.
Date of the fossils
Further information: Stratigraphy (archaeology)Dubois' complete collection of fossils were transferred between 1895 and 1900 to what is now known as the Naturalis, in Leiden in the Netherlands. The main fossil of Java Man, the skullcap cataloged as "Trinil 2", has been dated biostratigraphically, that is, by correlating it with a group of fossilized animals (a "faunal assemblage") found nearby on the same geological horizon, which is itself compared with assemblages from other layers and classified chronologically. Ralph von Koenigswald first assigned Java Man to the Trinil Fauna, a faunal assemblage that he composed from several Javanese sites. He concluded that the skullcap was about 700,000 years old, thus dating from the beginning of the Middle Pleistocene.
Though this view is still widely accepted, in the 1980s a group of Dutch paleontologists used Dubois's collection of more than 20,000 animal fossils to reassess the date of the layer in which Java Man was found. Using only fossils from Trinil, they called that new faunal assemblage the Trinil H. K. Fauna, in which H. K. stands for Haupt Knochenschicht, or "main fossil-bearing layer". This assessment dates the fossils of Java Man to between 900,000 and 1,000,000 years old.
Other fossils attest to the even earlier presence of H. erectus in Java. Sangiran 2 (named after its discovery site) may be as old as 1.66 Ma (million years). The controversial Mojokerto child, which Carl C. Swisher and Garniss Curtis once dated to 1.81 ± 0.04 Ma, has now been convincingly re-dated to a maximum age of 1.49 ± 0.13 Ma, that is, 1.49 million years with a margin of error of plus or minus 130,000 years.
Type SpecimenThe fossils found in Java are considered the type specimen for H. Erectus. Because the fossils of Java Man were found "scattered in an alluvial deposit" – they had been laid there by the flow of a river – detractors doubted that they belonged to the same species, let alone the same individual. German pathologist Rudolf Virchow, for instance, argued in 1895 that the femur was that of a gibbon. Dubois had difficulty convincing his critics, because he had not attended the excavation, and could not explain specifically enough the exact location of the bones. Because the Trinil thighbone looks very much like that of a modern human, it might have been a "reworked fossil", that is, a relatively young fossil that was deposited into an older layer after its own layer had been eroded. For this reason, there is still dissent about whether all the Trinil fossils represent the same species.
Physical characteristicswalked erect like modern humans. The femur is thicker than that of a modern human. The skull was characterized by thick bones and a retreating forehead and no chin, as well as protruding browridges and a massive jaw. With 900 ccm, his cranial capacity was smaller than that of later H. erectus specimens. He had human teeth with large canines. Judging from anatomical and archeological aspects as well as Java Man's ecological role, meat from vertebrates was likely an important part of their diet. Java Man, like other Homo erectus, was probably a rare species. There is evidence that Java Man used shell tools to cut meat.
Material cultureH. erectus arrived in Eurasia approximately 1.8 million years ago, in an event considered to be the first African exodus. There is evidence that the Java population of H. erectus lived in an ever-wet forest habitat. More specifically the environment resembled a savannah, but was likely regularly inundated ("hydromorphic savanna"). The plants found at the Trinil excavation site included grass (poaceae), ferns, ficus, and indigofera, which are typical of lowland rainforest.
Control of fireThe control of fire by Homo erectus is generally accepted by archaeologists to have begun some 400,000 years ago, with claims regarding earlier evidence finding increasing scientific support. Burned wood was been found in layers that carried the Java Man fossils in Trinil, dating to around from 500,000 to 830,000 BP. However, because Central Java is a volcanic region, the charring may have resulted from natural fires, and there is no conclusive proof that Homo erectus in Java controlled fire. It has been proposed that Java Man was aware of the use of fire, and that the frequent presence of natural fires may have allowed Java Man "opportunistic use [... that] did not create an archeologically visible pattern".
- List of fossil sites (with link directory)
- Sundaland: Pleistocene Java was part of this large peninsula attached to the Asian continent
- Trinil tiger: an extinct mammal found in the same site as Java Man
- Meganthropus the mysterious giant java man whose fossils were found in Sangiran
- Swisher, Curtis & Lewin 2000, p. 70.
- Swisher, Curtis & Lewin 2000, pp. 58–59.
- Swisher, Curtis & Lewin 2000, p. 58; de Vos 2004, p. 270.
- Swisher, Curtis & Lewin 2000, pp. 59 ["unorthodox" venture; was refused government funding; hired as medical officer] and 61 ["he was the first person to set out on a deliberate search for fossils of human ancestors"].
- Swisher, Curtis & Lewin 2000, p. 61.
- Swisher, Curtis & Lewin 2000, pp. 61–62.
- Theunissen 1989, p. 41–43.
- "Java Man (extinct hominid) – Encyclopaedia Britannica". brittanica.com. Retrieved 2013-06-05.
- de Vos 2004, p. 272 [citation from an assessment Dubois made in 1893]; Swisher, Curtis & Lewin 2000, p. 61 [name Anthropopithecus].
- Swisher, Curtis & Lewin 2000, p. 67.
- Mai, Larry L., Marcus Young Owl, M. Patricia Kersting. The Cambridge Dictionary of Human Biology and Evolution, Cambridge University Press 2005, p. 30
- Swisher, Curtis & Lewin 2000, pp. 66–7.
- "Images of Trinil 2". Retrieved 2013-02-08.
- Swisher, Curtis & Lewin 2000, p. 75.
- Schmalzer 2008, pp. 44–45 [date of discovery]; Swisher, Curtis & Lewin 2000.
- Swisher, Curtis & Lewin 2000, pp. 74–76.
- Schwartz, Jeffrey H.; Tattersall, Ian (2005). The Human Fossil Record, Craniodental Morphology of Genus Homo (Africa and Asia). John Wiley & Sons. p. 450.
- Swisher, Curtis & Lewin 2000, p. 42.
- Theunissen, Bert (Jan 1, 1989). Eugène Dubois and the Ape-Man from Java: The History of the First `Missing Link' and Its Discoverer. Springer Science & Business Media. pp. 161–162.
- "Sangiran Early Man Site". UNESCO World Heritage Centre. Retrieved 2014-07-02.
- Swisher, Curtis & Lewin 2000, pp. 76–79.
- UNESCO World Heritage Committee (2002), State of conservation of properties inscribed on the World Heritage List, pp. 29–30.
- Swisher, Curtis & Lewin 2000, p. 69, citing von Koenigswald's Meeting Prehistoric Man (1956).
- Schwartz 2005, p. [page needed].
- Hetherington & Reid 2010, p. 64.
- The Discovery of Java Man in 1891 In: Athena Review, Vol.4, no.1: Homo erectus, p. 15.
- de Vos 2004, p. 272; Swisher, Curtis & Lewin 2000, p. 69.
- de Vos 2004, p. 272.
- Swisher, Curtis & Lewin 2000, p. 54.
- de Vos 2004, pp. 272–73 ["extinct side branch of human evolution"].
- Schmalzer 2008, p. 258 ["While at the turn of the century a linear model of human evolution was widely accepted, from around 1910 to the 1940s, the dominant model placed fossil hominids like Java Man, Peking Man, and the Neanderthals on side branches of the family tree. These 'cousins' were understood to have become extinct, replaced by our unknown direct ancestors."].
- Theunissen 1989, p. 152; Swisher, Curtis & Lewin 2000, p. 68; Gould 1993, p. 134.
- Gould 1993, p. 136 ["Dubois's ingenious attempt to retain Pithecanthropus as a direct human ancestor has been widely misread in a precisely opposite manner as an ultimate surrender, almost comical in its transmogrification of a human forebear into a giant gibbon."].
- Gould 1993, pp. 133–34.
- Gould 1993, p. 135 ["Dubois desperately wanted Pithecanthropus as a direct ancestor under his evolutionary view. But the brain of Java Man ranked with embarrassing bulk at some 900 cm3, or two-thirds human volume."].
- Swisher, Curtis & Lewin 2000, p. 74 ["In common with other anthropologists of the time, Dubois believed that the human stock was rooted in some kind of gibbonlike ancestor."].
- Gould 1993, p. 135 [the second citation is from Dubois's paper].
- Boaz & Ciochon 2004, p. 66–67.
- Schmalzer 2008, p. 98. The original paper is Mayr 1950.
- Delisle 2007, p. 298, citing Mayr's 1950 paper.
- Boaz & Ciochon 2004, p. 67.
- Schmalzer 2008, p. 98 ("the "single-species" thesis to which he was committed became the theoretical foundation for paleoanthropology for years to come"); Boaz & Ciochon 2004, p. 67 ("was to sweep anthropology in the 1950s" ... "Thus was born the single-species hypothesis, a powerful model that endured until the late 1970s when fossil discoveries in Africa disproved it, at least for the early part of the hominid fossil record").
- Sartono, S. Implications arising from Pithecanthropus VIII In: Paleoanthropology: Morphology and Paleoecology. Russell H. Tuttle (Ed.), p. 328.
- de Vois, John. "The Dubois collection: a new look at an old collection". Naturalis.nl. Retrieved 3 December 2014.
- de Vos 2004, p. 275.
- Kaifu et al. 2010, p. 145; de Vos 2004, pp. 274–75.
- Kaifu et al. 2010, p. 145.
- de Vos 2004, pp. 275–76 [explanation of the Trinil H. K. Fauna]; Zaim 2010, p. 103 [Trinil H. K. Fauna, citing de Vos et al. 1982 and de Vos & Sondaar 1994].
- Dennell 2010, p. 155.
- Dennell 2009, p. 155 ["The maximum age of this specimen is thus 1.49 million years, and not 1.81 million years, as implied by Swisher et al. 1994"]; Ciochon 2010, p. 112 ["As the relocated discovery bed proved to be ~20 m above the horizon that Swisher et al. (1994) dated, the skull is certainly younger than had been previously reported" (Huffman et al. 2006)"]; Rabett 2012, p. 26 ["the 1994 estimate of its age has now been credibly refuted (Huffman et al. 2006)"]; Dennell 2010, p. 266 ["the recent re-discovery of the precise provenance of the Mojokerto cranium that is now dated to a maximum of 1.49 Ma (Morwood et al. 2003) clarifies long-standing uncertainties over the age of this important specimen"].
- Schmalzer 2008, p. 34.
- Gould 1993, p. 135.
- Swisher, Curtis & Lewin 2000, p. 69.
- & Dennell 2009, pp. 159–61.
- Stom, Paul. A carnivorous niche for Java Man? A preliminary consideration of the abundance of fossils in Middle Pleistocene Java Comptes Rendus Palevol 11(2012), pp. 191-202
- Choi, Kildo and Dubel Driwantoro. Shell tool use by early members of Homo erectus in Sangiran, central Java, Indonesia: cut mark evidence Journal of Archaeological Science Volume 34, Issue 1, January 2007, Pages 48–58
- Matsubayashi, Kozo. Geriatric issues from the standpoint of human evolution Geriatrics & Gerontology International Volume 14, Issue 4, pages 731–734, 18 OCT 2014, retrieved 21 November 2014, doi:10.1111/ggi.12224
- Ingicco, Thomas, John de Vos, and O. Frank Huffman. The Oldest Gibbon Fossil (Hylobatidae) from Insular Southeast Asia: Evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene In: PloS One, June 10, 2014 doi:10.1371/journal.pone.0099531
- James, Steven R. (February 1989). "Hominid Use of Fire in the Lower and Middle Pleistocene: A Review of the Evidence". Current Anthropology (University of Chicago Press) 30 (1): 1–26. doi:10.1086/203705. Retrieved 2012-04-04.
- Luke, Kim. "Evidence That Human Ancestors Used Fire One Million Years Ago". Retrieved 2013-10-27.
An international team led by the University of Toronto and Hebrew University has identified the earliest known evidence of the use of fire by human ancestors. Microscopic traces of wood ash, alongside animal bones and stone tools, were found in a layer dated to one million years ago
- Alsberg, Paul (2013). In Quest of Man: A Biological Approach to the Problem of Man's Place in Nature. Elsevier. p. 149. ISBN 9781483151557.
- Roebroeksa, Wil; Villa, Paola. "On the earliest evidence for habitual use of fire in Europe". US National Library of Medicine National Institutes of Health. Retrieved 20 November 2014.
- Boaz, Noel T.; Ciochon, Russell L. (2004), Dragon Bone Hill: An Ice-Age Saga of Homo Erectus, – via Questia (subscription required), Oxford and New York: Oxford University Press, ISBN 0-19-515291-3.
- Ciochon, Russell L. (2010), "Divorcing Hominins from the Stegodon–Ailuropoda Fauna: New Views on the Antiquity of Hominins in Asia", in John G. Fleagle et al. (eds), Out of Africa I: The First Hominin Colonization of Eurasia, Vertebrate Paleobiology and Paleoanthropology Series, Dordrecht: Springer, pp. 111–26, doi:10.1007/978-90-481-9036-2_8, ISBN 978-90-481-9035-5. ISBN 978-90-481-9036-2 (online).
- Delisle, Richard G. (2007), Debating Humankind's Place in Nature, 1860–2000: The Nature of Paleoanthropology, Advances in Human Evolution Series, Upper Saddle River (NJ): Pearson Prentice Hall, ISBN 0-13-177390-9.
- Dennell, Robin (2009), The Palaeolithic Settlement of Asia, Cambridge World Archaeology, Cambridge: Cambridge University Press, ISBN 978-0-521-84866-4. ISBN 978-0-521-61310-1 (paperback).
- Dennell, Robin (2010), "'Out of Africa I': Current Problems and Future Prospects", in John G. Fleagle et al. (eds), Out of Africa I: The First Hominin Colonization of Eurasia, Vertebrate Paleobiology and Paleoanthropology Series, Dordrecht: Springer, pp. 247–74, doi:10.1007/978-90-481-9036-2_15, ISBN 978-90-481-9035-5. ISBN 978-90-481-9036-2 (online).
- Gould, Stephen Jay (1993), Eight Little Piggies: Reflections in Natural History, – via Questia (subscription required), New York and London: W. W. Norton & Company, ISBN 0-393-03416-X.
- Hetherington, Renée; Reid, Robert G. B. (2010), The Climate Connection: Climate Change and Modern Human Evolution, Cambridge and New York: Cambridge University Press, ISBN 978-0-521-19770-0. ISBN 978-0-521-14723-1 (paperback).
- Huffman, O. Frank; Y. Zaim; J. Kappelman; D. R. Ruez, Jr.; J. de Vos; Y. Rizal, et al. (2006), "Relocation of the 1936 Mojokerto skull discovery site near Perning, East Java", Journal of Human Evolution 48: 321–63.
- Kaifu, Yousuke; Etty Indriati; Fachroel Aziz; Iwan Kurniawan; Hisao Baba (2010), "Cranial Morphology and Variation of the Earliest Indonesian Hominids", in Christopher J. Norton and David R. Braun (eds), Asian Paleoanthropology: From Africa to China and Beyond, Vertebrate Paleobiology and Paleoanthropology Series, Dordrecht: Springer, pp. 143–57, doi:10.1007/978-90-481-9094-2_11, ISBN 978-90-481-9093-5. ISBN 978-90-481-9094-2 (online).
- Mayr, Ernst (1950), "Taxonomic Categories in Fossil Hominids", Cold Spring Harbor Symposia on Quantitative Biology 15: 109–18, doi:10.1101/sqb.1950.015.01.013.
- Morwood, Michael J.; P. O'Sullivan; E. E. Susanto; F. Aziz (2003), "Revised age for Mojokerto 1, an early Homo erectus cranium from East Java, Indonesia", Australian Archaeology 57: 1–4.
- Rabett, Ryan J. (2012), Human Adaptation in the Asian Palaeolithic: Hominin Dispersal and Behaviour during the Late Quaternary, Cambridge: Cambridge University Press, ISBN 978-1-107-01829-7.
- Schmalzer, Sigrid (2008), The People's Peking Man: Popular Science and Human Identity in Twentieth-Century China, Chicago: University of Chicago Press, ISBN 978-0-226-73859-8. ISBN 978-0-226-73860-4 (paperback).
- Schwartz, Jeffrey H. (2005), The Red Ape: Orangutans and Human Origins (Rev. and updated ed.), Cambridge (MA): Westview, ISBN 0-8133-4064-0.
- Swisher, Carl C. III; Garniss H. Curtis; Roger Lewin (2000), Java Man: How Two Geologists Changed Our Understanding of Human Evolution, Chicago: University of Chicago Press, ISBN 0-226-78734-6.
- Swisher, Carl C. III; Garniss H. Curtis; Teuku Jacob; A. G. Getty; A. Suprijo; Widiasmoro (1994), – via HighBeam (subscription required), "Age of the earliest known hominin in Java, Indonesia", Science 263: 1118–21, doi:10.1126/science.8108729, PMID 8108729.
- Theunissen, Bert (1989), Eugène Dubois and the Ape-Man from Java, Boston: Kluwer Academic Publishers, ISBN 1-55608-081-6. ISBN 1-55608-082-4 (paperback).
- Vos, John de (2004), "The Dubois collection: a new look at an old collection", Scripta Geologica, Special Issue 4: 267–85, ISSN 0922-4564.
- Vos, John de; S. Sartono; S. Hardjasasmita; P. Y. Sondaar (1982), "The fauna from Trinil, type locality of Homo erectus: a reinterpretation", Geologie en Mijnbouw 61: 207–11.
- Vos, John de; P. Y. Sondaar (1994), "Dating hominid sites in Indonesia", Science 266: 1726–27, doi:10.1126/science.7992059.
- Zaim, Yahdi (2010), "Geological Evidence for the Earliest Appearance of Hominins in Indonesia", in John G. Fleagle et al. (eds), Out of Africa I: The First Hominin Colonization of Eurasia, Vertebrate Paleobiology and Paleoanthropology Series, Dordrecht: Springer, pp. 97–110, doi:10.1007/978-90-481-9036-2_7, ISBN 978-90-481-9035-5. ISBN 978-90-481-9036-2 (online).