Journal of the Anatomical Society of India

School of Archaeology & Anthropology, Australian National University, Canberra, AUSTRALIA. * Department of Anthropology, Punjab University, Chandigarh, INDIA

Abstract

Here the authors review, skeletal biological aspects of Homo erectus as described by various scholars and evaluate the taxonomical and stratigraphical status of this critical member of the genus homo and the mystery of its origin. They also analyse the probability of the natural process of evolution in isolation, of two geographically widely separated species such as Homo heidelbergensis and Homo erectus.

Key words: Homo erectus, Homo heidelbergensis, stone age, evolution.

Introduction:

The arguments/debates based on the marathon palaeoanthropological and geohistorical research activities focused on the origin and dispersal events of our primitive ancestor Homo erectus have yielded agreement among the experts all over the world by pronouncing a sensible judgment that the origin of the species is in Asia. This land mark of Palaeoanthropology was the sensational discovery of Pithecanthropus erectus from Java in 1892, where Dr. Eugene Dubios was lucky enough to recover a cranium and a left femur from the sediments of Kendeng Hills of Trinil, in Eastern Java. Since then Indonesia has yielded a magnificent data base for the geohistory of Homo erectus. So far nearly 110 Homo erectus individuals, have been recovered. The quaternary hominid fossil localities of Indonesia including Kendungbrubus, Sangiran, Ngangdong, Sambungmacan, Ngawi, Mojokerto and Patiayam have represented nearly 75% of world's Homo erectus population. In recent times Sangiran has become the main treasure trove by providing some wonderful skeletal remains of Homo erectus.

On the basis of the aspects of skeletal biology - metrical and non metrical features several fossil species were created. These are Pithecanthropus robustus, Pithecanthropus dubius, Meganthropus Palaeojavanicus and Homo modjokertensis. They have been recovered from the Lower Pleistocene Pucangan Series where as Pithecanthropus erectus was from the presumed Middle Pleistocene, Kobuh Series. Widianto (1998) noticed after studying the entire fossil collection mainly from the Sangiran locality that within the span of one million years no noticeable changes occurred in the skull of Homo erectus.

Salient characters on the cranial architecture of Homo erectus such as a torus angularis, torus supra orbitalis, a planum occipitalis which is significantly shorter than the planum nuchalis and inion located at the same point as opisthocranion are observed in all samples and indicate the typical characters of this species. The major difference between the skulls of Lower Pleistocene and Middle Pleistocene is the vault thickness. The earlier ones are more robust than the later who are of gracile nature.

Widianto's model of Homo erectus evolution in Java was constructed on the basis of morphological and biometric characters.

1. Three stages of Home erectus evolution in Java: Most archaic to the most developed stages are the Robust Group, Trinil - Sangiran Group and Ngandong Group.

2. The Robust Group = Pucangan Series Lower Plesitocene The Trinil - Sangiran Group = Lower and Middle Kabuh Series (Mid Pleistocene period at Trinil and Sangiran)

3. The fossils from Ngandong, Sambungmacan and Ngawi might have originated when the upper portion of the Kabuh Series was laid down during the Middle Pleistocene times.

Localities, Stratigrahy and Age (after Widianto, 1998)

Most of the localities were found along the Solo Depression, the main depression of Java. Some are located at the fold series of the Kendeng Hills. Another important locality is Patiayam site which is to the north at the foot of Mount Muria.

Sangiran Site:

1. Kalibeng Series (called the Pucan Formation at Sangiran) -Upper part dominates the central part of the Sangiran Dome-Late Pliocene about 2.4 Ma, probably ending around 2 Ma.

2. Pucangan Series (at Sangiran called the Sangiran Formation). Some fossil hominids came from the Pucangan series appros. 1, 7 Ma.

3. The Grenzbank is key layer to marking the boundary betwen the Pucagan and Kabuh Series. It has yielded many important hominid and general mammalian fossils. Recent dating by Larick et al (2001) puts it at 1.5 Ma.

4. Kabuh Series (called the Bapang, Formation at Sangiran)-found above Grenzbank as volcanic deposits with fluviatile facies dated to Mid. Pleistocene but according to Larick et al (2001), beginning at 1.5 Ma and lasting till about 1 Ma, hence entirely Lower Pleistocene in age. This has yielded the major portion of the Sangiran hominids.

5. Notopuro Series- The uppermost deposits lying unconformably on the Bapang and overlying Phojajar Formation. Dated at around 0.2 + /- 0, 07 Ma, but some of the fossils may be as late as 35 Ka.

Kendungbrubus Site:

Located to the southeast of Ngawi lies in a group of the Kendeng Hills. It has yielded the very first find of Pithecanthropus erectus.

Trinil Site:

Situated at one of the meanders of the Solo River, it yielded the earliest historic finding of Pithecanthropus erectus (skull cap and several femora. Sediments may be around 0,8 Ma.

Ngandong Site:

The Ngandong skulls, 12 in total were recovered along with 5 post cranial elements. A direct date based on Gamma-spectrometry at the Institut de Paleontologie Humane, Paris produced a minimal age of 300, 000 yrs.

Sambungmacan Site:

Yielded two skull caps, one of which was offered for a sale in a New York store in 1999 and promptly returned to Indonesia from which it had previously been exported illegally. The deposits are of the order of 300 Ka old.

Perning Site, Mojokerto:

Von Koesingswald (1936) recovered a skull cap of child 3-5 yrs of age at death. The skull cap demonstrates the typical characters of Pithecanthropus (now Homo erectus) such as the post orbital constriction and accentuated occipital. Absolute dating by the Argon / Argon method on a pumice sample from the presumed find - site gives a date of 1.18 Ma but its straitgraphic provenance has been contested and the skull cap may be younger.

Patiayam Site:

Recovery of numerous skeletal elements of a hominid species were found with mammalian and reptilian fossils. Tuffaceous clay material of this region produced an age of 0.85 Ma + / - 0.02 Ma.

So far the Sangiran locality has provided remains more than 70 fossil individuals of Homo erectus spanning a very long period of geohistory ranging from Lower Pleistocene to Middle or even the Upper Pleistocene, total it was about one million years or more.

Standardized cranial features of Javanese Homo erectus

Cranial transformations generally caused changes in the brain. The development of the brain is reflected on the internal and external cranial architecture, for example cranial contour, anteroposteriorly as well as transversely, has grown higher and more rounded. On the other hand the post cranial parts have changed very little, and the morphology of the Trinil femur (if needed it does belong to Homo erectus which seems dubious) shows a high degree of similarity with modern humans.

Variations in the cranial architecture:

Sangiran and Trinil Skulls: Lower and longer cranial vault, sphenoid shape- a very low and posterior position of the maximum breadth of the skull; the narrowing of the parietal walls anteriorly towards the frontal indicates strong post orbital constriction; long parietals.

Ngandong, Sambungmacan and Ngawi: Higher and shorter cranial vault-squatter and flatter skull; brisoid shape; maximum breadth at a higher angle and more anterior parietal walls open widely in the frontal region.

Cranial features of Ngandong, Sambungmacan and Ngawi specimens are more advanced in than those from Sangiran and Trinil localities. These progressive features include more curved frontal squama, on both sides, a more vertically oriented frontal bone in norma lateralis and a weaker posterior constriction in the Ngandong members. Skulls from Trinil and Sangiran show the longest parietal and they differ notably from most of those from Ngandong, Sambungmacan and Ngawi localities. According to Dellatre and Fenart, 1960 the more anterior and lowerly placed asterion indicates displacement of squama occipitalis.

Comparative study of the cranial capacity of the fossil hominids:

The above table shows that the Ngandong fossils had undergone an increase in cranial capacity. (Text Fig 1) Widianto (1993) pointed out that the planum occipitalis of Sangiran specimens 4, 13a and 31 are shorter than the other skulls and 13a and 31, exhibit deep and wide fossac occipitalis superior and inferior (Widianto, 1998)

Interpretation of intelligence:

A detailed study of the brain of Homo erectus by Jacob (1998), pointed out that besides the occipital, the rest of the cerebral lobes are smaller than in modern Homo sapiens. The development of the speech centre, would have been started but the supralarygeal (vocal apparatus) never adopted for a complete speech process. These conclusions of Jacob were based on of the skull base which shows a long anterior portion, the position of the pharyngeal structures, the occurrence and orientation of the foramen magnum and the balance of the head on the cervical column.

Jacob's view on demographical aspects:

According to Jacob (1998), a probable population size of Homo erectus during the Mid. Pleistocene would have been half a million but authors feel that a lot of assumption and imagination would have gone into Jacob's estimate. He calculated that an average life span of Chinese and Indonesian Homo erectus would have been slightly more than 20 years which includes every body from infants to 50 plus age groups. Survival rate of males were more than females due to perinatal maternal deaths. Bone pathological studies suggested pronounced infirmities of old age and neoplastic disorders. Two contrasting skeletal textures suggest the existence of gracile and robust groups. We feel that some temporal overlap occurred with coexistence of gracile and robust groups. We feel that some temporal overlap occurred with co-existence. There were undoubtedly several subspecies of Homo erectus in different geographical zones and they would have doubtless differed in ecology and behavior. In addition ageing the adult skull is problematic even in Homo sapiens and Homo erectus with its different rates of growth and senescences the prospects of ageing te skull are minimal.

Tracks and traces of Genus: Homo

The fossil human remains of the Pleistocene period have a wide geographical distribution. They occupied most of the parts of the Old World. After careful study over a number of years, Prof. Colin Groves of Australian National University at Canberra has proposed a model evolutionary tree of the genus :Homo in which Homo ergaster is the stem ancestor of all species of Homo this is known from the Turkana deposits - Koobi Fora and Nariokotome including the famous the West Turkana boy, dating mainly between 1.8 and 1.6 Ma, although some skull fragments are from 2.0 Ma levels at Koobi Fora as well. The describers of the first two Dmanisi skulls (Georgia, 1.6Ma) ascribed them to H. ergaster as well. Homo ergaster gave rise to both Homo erectus and Homo heidelbergensis. The earliest Homo erectus from Java seems to be some what over 1.5Ma, so probably after H. ergaster spread its range from Africa there was evolution in isolation occurred in South East Asia (Text Fig. 2).

H. erectus is much more thick skulled with strong frontal and parietal keels, parasagittal flattering occipital angulation and thick straight - not curved supra orbital torus. Also the cranial capacity is larger H. ergaster 650cc - 850cc. H. erectus is about 800cc - 1300cc. 600,000 yrs ago another split produced Homo neanderthalensis (named after the Neandertal valley in Germany) and archaic Homo sapiens. Homo erectus is an exclusively East Asian species where as Homo neanderthalensis thrived in Africa and Europe at the same period. Similarly many species of Neanderthalensis in Europe and Western Asia and the ancestors of Homo sapiens at the same time evolved in Africa, surprisingly a small male fossil hominid in South China very closely resembles Neanderthal species. the Chinese version -Homo erectus originally called Sinanthropus pekinensis or "Peking Man", differs so considerable from the Javanese Homo erectus samples that Prof, Groves feels that they are different species altogether. The Chinese specimens have midfrontal convexity, erectus does not. H. pekinensis lacks glabella prominence erectus has it. In contemporary western species, Homo heidelbergensis the supraorbital torus curves over each orbit and it is dorsoventrally thicker over mid-orbit than over medial or lateral part and it retained the styloid process Homo ergaster has one so is presumably a primitive feature of Homo.

References:

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6. Widianto, Harry, (1998): The perspectie on the evolution of Javanese homo erectus based on morphological and stratigraphic characteristics - Sangiran : Man, Culture, and Environment in Pleistocene Time Proceedings of the International Colloquium on Sangiran: pp. 24-45
7. Widianto, Harry, (1993): Unite et diversite des hominids fossils de Java : presentation des restes humains fossils inedits (These), Institut de Pleontologie Humaine, Paris: 301.
8. Weidenreich, F., (1951): "Morphology of Solo Man" Anthropological Papers of the American Museum of Natural History, Vol. 43: 205 - 290

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Fig. 2