Phillip V. Tobias

The brain of Homo habilis: A new level of organization in cerebral evolution☆

Abstract New studies have been made on endocranial casts of Olduvai specimens of Homo habilis. The results have been compared with those on other East African H. habilis and other hominoids. The mean absolute endocranial capacity of H. habilis is appreciably larger than the mean for australopithecine species: on the new estimates, the H. habilis mean is 45·1% greater than the A. africanus mean and 24·8% greater than that of A. boisei. New data for relative brain size, expressed by Jerisons Nc and EQ and Hemmers CC, strongly confirm that it was with H. habilis that there appeared the remarkable autapomorphy of Homo, disproportionate expansion of the brain. Encephalometric studies reveal marked transverse expansion of the cerebrum, especially the frontal and parieto-occipital parts, in H. habilis and increased bulk of the frontal and parietal lobes, a derived feature of Homo. There is moderate cerebral heightening, but little or no cerebral lengthening. The sulcal and gyral pattern of the lateral part of the frontal lobe of H. habilis differs from those of Australopithecus and resembles the derived pattern of Homo. The inferior parietal lobule is prominently developed—an autapomorphy of Homo. The two major cerebral areas governing spoken language in modern man are well represented in the endocasts of H. habilis, a functionally important autapomorphy of Homo. The pattern of middle meningeal vessels is more complex with more anastomoses than in australopithecines: H. habilis shares this derived feature with later forms of Homo. In all these features, the brain of H. habilis had made major advances, beyond the more ape-like australopithecine brain. With H. habilis, cerebral evolution had progressed beyond the stage of “animal hominids” (Australopithecus spp.) to that of “human hominids” (Homo spp.). In functional capacity, in particular, its possession of a structural marker of the neurological basis of spoken language, H. habilis had attained a new evolutionary level of organization.

Humanity from African Naissance to Coming Millennia

information, such as that provided by a reflection in a mirror (Gallup, 1979), which indicates that, like us, chimpanzees have a knowledge of self. These shared behavioral traits were presumably in the repertoire of our common ancestor, which means that we evolved from a species that had the mental capacities required by those traits. Some, but not all, of these capacities are shared with the other two great ape genera, the orangs and gorillas, as well Chiarelli25/07/00+indiceIV/Com2 8-12-2000 17:08 Seite 373

The negative secular trend

In the following paper the concept of secular trend is discussed. It is argued that secular processes should always be specified as to their direction. Such specification is not given in any of the current publications in which the term has been applied to changes in stature. A number of environmental causative factors are proposed, which can explain the historical development of the secular trend and the observed changes in its direction on a world-wide scale.

The mixed dentition and associated skull fragments of a juvenile fossil hominid from Sterkfontein, South Africa

In April-May 1983, the late A.R. Hughes and his field team recovered more than 40 bone fragments and teeth from a single solution pocket of the Sterkfontein Formation. After preparation and reconstruction by JMC, it was recognised that these fragments represent a single juvenile individual (Stw 151), consisting of more than 40 cranial and dental parts, with mixed dentition. It constitutes the most complete set of jaws and teeth of an early hominid child since the Taung child was recovered in 1924. In this paper, the morphological and metrical features of the individual teeth are described. The other associated skull fragments (right ramus of the mandible, left petrous bone, right glenoid region) are also described. Comparisons are made with other South (and East) African fossil hominids. The beautiful preservation simultaneously of most of the deciduous teeth and of the permanent teeth exposed in their crypts allows an accurate analysis of the developmental sequence. A report on the dental developmental status of this juvenile is presented. On the basis of the microanatomical study of the developing permanent teeth, the estimated age at death is 5.2-5.3 years. Reconstructions of the maxillary and mandibular arcades are also offered. The morphological and metrical features of Stw 151 raise the possibility that it may represent a hominid more derived towards an early Homo condition than the rest of the A. africanus sample from Member 4.

On the age of Border Cave 5 human mandible

An enamel fragment from the Border Cave 5 specimen was analysed with non-destructive ESR combined with laser ablation ICP-MS for uranium profiling. We obtained an age of 74+/-5 ka which fits exactly into the chronological framework that has been previously established for Border Cave by a variety of dating techniques. The result lays at rest the view that BC5 could be of Iron Age, as was implied by (Journal of Human Evolution, 31 (1996) 499) based on nitrogen contents and infra-red splitting factors.

Re-creating ancient hominid virtual endocasts by CT-scanning †

Probably the first radiographic study of human fossils, that by D. Gorganovic‐Kramberger on Neandertal remains from Krapina, Croatia, was published in 1906, only 11 years after Röntgen announced the discovery of X‐rays. Many subsequent studies on fossil hominids used regular clinical diagnostic radiological apparatus, as depicted in Atlas of Radiographs of Early Man by M.F. Skinner and G.H. Sperber (1982). Some specimens such as crania filled with heavily calcified matrix proved intractable. Ordinary radiographs of such specimens usually failed to reveal endocranial structure, as fossilized bone and calcified endocast were approximately equally radio‐opaque. Thus, neither endocranial volume nor structural details were detectable. The only invasive method that could have been employed involved mechanical removal of the solid matrix, but this entailed hazards to the cranial vault and the destruction of the natural endocranial cast. In 1983–1984, G.C. Conroy and M. Vannier utilized recent advances in high‐resolution computed tomography to produce non‐invasive, intracranial capacity measurements of matrix‐filled fossil skulls. They tried the method on two fossil mammal skulls filled with hard sandstone matrix (1984, Science 26:456–458), and then successfully applied it to a South African, matrix‐filled cranium of the ancient hominid (hominin) species, Australopithecus africanus from Makapansgat (Conroy et al. 1990, Science 247:838–841). Details of the morphology of the endocranial surface of the braincase were revealed, including the pattern of venous sinus drainage in the posterior cranial fossa. A group based in St. Louis, Vienna, Paris, Rome, and Johannesburg has taken such studies further. Beautiful “virtual endocasts” have been produced on a large male specimen of A. africanus from Sterkfontein, South Africa, and the endocranial capacity has been determined (1998). The methods make it possible to re‐create “virtual endocasts” of ancient hominids. Clin. Anat. 14:134–141, 2001.

Physical anthropology and somatic origins of the Hottentots

SYNOPSIS The history of studies on the physical anthropology of the Hottentots falls into three phases: (I) 1872–1923: recognition of the Hottentots as physically distinct (Fritsch to Broom); (II) 1923–37: recognition of the Boskop type as a component of the Old Yellow South Africans (Drennan, Dart, Galloway); (III) 1937–51: discovery of the Kakamas physical type and recognition of its contribution to the Hottentots (Dreyer, Meiring, Wells). It is demonstrated that the Hottentots are not a physically homogeneous group. A variety of racial elements can be recognized among those practising the Hottentot culture; of these, it seems that the Kakamas type actually brought the Hottentot culture to Southern Africa from East Africa, North‐Eastern Africa or Asia Minor. On their arrival in Southern Africa, these Kakamas people hybridized with the Bush‐Boskop already present, as well as with Gerontomorphic and Europsid strains which had reached the sub‐continent hybrids earlier. The resulting hybrids, still practisi...

Search for secular trends in calvarial diameters, cranial base height, indices, and capacity in South African Negro crania

Two hundred eighteen South African Negro male crania were arranged in 5‐year birthdate cohorts from 1880–1884, 1890–1894, up to 1930–1934 inclusive and investigated for the presence of a secular trend in their dimensions. Maximum breadth, maximum length, basibregmatic height, cranial base height, and bi‐auricular breadth (BAB) were measured, and cranial index (CI), cranial capacity (CC), and cranial base height index (CBHI) were determined. Cranial length exhibited a significant increase from 1890 to 1930. Cranial base height and CBHI exhibited statistically significant declines over the same period. The absence of secular trends in the other dimensions studied corresponds to previous analyses of the lengths of the femora and tibiae of the same sample. The secular trends in cranial length, cranial base height and its index, and the absence of trends in the other dimensions, are discussed in relation to an apparent decrease in the standard of living occurring in this population after 1900. It is unlikely that the absence of a positive secular trend denotes the attainment of a genetically determined ceiling to the physical size of the subjects represented by these skeletons. It is more likely that the environmental factors believed to produce a positive secular trend were absent in the years from which this sample was drawn and that signs of improvement in these factors, if any, would be so recent that evidence of their effect is not yet available from our cadaver‐derived skeletons.

On the scientific, medical, dental and educational value of collections of human skeletons

Having been approached from time to time by various museum, university and governmental authorities in Australia, California and Scotland, I have set down some brief notes on the scientific, medical, dental and educational importance and value of collections of recent human skeletons drawn from populations in all parts of the world.This article does not pretend to completeness. It has been set down in the hope that it may be of assistance to those officiers in charge of such collections and who may be pondering upon the worthwhileness of such collections being retained and maintained.

New Discoveries in Tanganyika: Their Bearing on Hominid Evolution [and Comments and Reply]

Homo habilis IS THE NAME which Leakey, Tobias and Napier (1964) have given to a taxon represented by a group of hominid remains from Olduvai Gorge in Tanganyika. It may be asked: (1) Do these remains differ sufficiently from all of the species and subspecies of Australopithecus to justify regarding them as belonging to a different taxon? (2) If sufficient morphological evidence can be adduced to justify their recognition as a separate species, why has this species been assigned to the genus Homo rather than to the genus Australopithecus? (3) What other hominids are possibly related to Homo habilis? (4) If we accept the coexistence in the Lower Pleistocene of at least 2 horninids, 1 being Australopithecus, the other being a lowly member of the genus Homo, what are the implications for hominid phylogeny prior to that time? (5) What is the relationship between Homo habilis and Homo erectus? (6) What are the taxonomic implications of the recognition of this new species of early man? I shall endeavour to answer each of these questions in turn.