Forward from Taung

The hominine grade of organization should preferably be defined by those morphological characters of the braincase and face which are first recognizable in Homo erectus. Provisionally, then, Olduvai hominid 24 and East Rudolf 1470 are regarded as protanthropine, irrespective of whether they both belong to “Homo habilis” or not. It is possible that either or both of these hominids can be considered directly prehominine, while A. africanus reflects an earlier prehominine stage.     

Was “Lucy” more human than her “child”? Observations on early hominid postcranial skeletons

Fully adult partial skeletons attributed to Australopithecus afarensis (AL 288-1, “Lucy”) and to Homo habilis (OH 62, “Lucy's child”), respectively, both include remains from upper and lower limbs. Relationships between various limb bone dimensions of these skeletons are compared to those of modern African apes and humans. Surprisingly, it emerges that OH 62 displays closer similarities to African apes than does AL 288-1. Yet A. afarensis, whose skeleton is dated more than 1 million years earlier, is commonly supposed to be the ancestor of Homo habilis. If OH 62, classified as Homo habilis by its discoverers, does indeed represent a stage intermediate between A. afarensis and later Homo, a revised interpretation of the course of human evolution would be necessary.     

The Casal de' Pazzi archaic parietal: comparative analysis of new fossil evidence from the late Middle Pleistocene of Rome

A fossilized fragment of human parietal bone has been recently recovered from the lowest layer of the Casal de' Pazzi fluvial deposit (stratigraphically dated at about 200–250 ky BP). The fossil presents characters-i.e., thickness, degree and development of curvature, type of endocranial vascularization-which distinguish it from the corresponding cranial regions of both Homo erectus and anatomically modern Homo sapiens. While a morphological orientation towards Neanderthal characters can be considered, the affinities of the Casal de' Pazzi parietal are primarily with other late Middle Pleistocene specimens. The authors conclude that the Casal de' Pazzi human find can be assigned to the “archaic Homo sapiens” group falling within the European pre-Neanderthal range. Its particular morphology constitutes new evidence of human evolution from the geographical area of Rome.     

Brain endocast asymmetry in pongids and hominids: Some preliminary findings on the paleontology of cerebral dominance

Observations on petalial asymmetry for 190 hominoid endocasts are reported, and their statistical differences assessed. While all taxa of hominoids show asymmetries to various degrees, the patterns or combinations of petalial asymmetries are very different, with fossil hominids and modern Homo sapiens showing an identical pattern of left-occipital, right-frontal petalias, which contrasts with those found normally in pongids. Of the pongids, Gorilla shows the greater degree of asymmetry in left-occipital petalias. Only modern Homo and hominids (Australopithecus, Homo erectus, Neandertals) show a distinct left-occipital, right-frontal petalial pattern. Analysis by x² statistics shows the differences to be highly significant. Due to small sample size and incompleteness of endocasts, small-brained hominids, i.e., Australopithecus, are problematical. To the degree that gross petalial patterns are correlated with cognitive task specialization, we speculate that human cognitive patterns evolved early in hominid evolution and were related to selection pressures operating on both symbolic and spatiovisual integration, and that these faculties are corroborated in the archaeological record.     

Human taxonomic diversity in the pleistocene: Does Homo erectus represent multiple hominid species?

Recently, nomina such as “Homo heidelbergensis” and “H. ergaster” have been resurrected to refer to fossil hominids that are perceived to be specifically distinct from Homo sapiens and Homo erectus. This results in a later human fossil record that is nearly as speciose as that documenting the earlier history of the family Hominidae. However, it is agreed that there remains only one extant hominid species: H. sapiens. Has human taxonomic diversity been significantly pruned over the last few hundred millennia, or have the number of taxa been seriously overestimated? To answer this question, the following null hypothesis is tested: polytypism was established relatively early and the species H. erectus can accommodate all spatio-temporal variation from ca. 1.7 to 0.5 Ma. A disproof of this hypothesis would suggest that modern human polytypism is a very recent phenomenon and that speciation throughout the course of human evolution was the norm and not the exception. Cranial variation in a taxonomically mixed sample of fossil hominids, and in a modern human sample, is analyzed with regard to the variation present in the fossils attributed to H. erectus. The data are examined using both univariate (coefficient of variation) and multivariate (determinant) analyses. Employing randomization methodology to offset the small size and non-normal distribution of the fossil samples, the CV and determinant results reveal a pattern and degree of variation in H. erectus that most closely approximates that of the single species H. sapiens. It is therefore concluded that the null hypothesis cannot be rejected. © 1993 Wiley-Liss, Inc.     

Human evolution

The common ancestor of modern humans and the great apes is estimated to have lived between 5 and 8 Myrs ago, but the earliest evidence in the human, or hominid, fossil record is Ardipithecus ramidus, from a 4.5 Myr Ethiopian site. This genus was succeeded by Australopithecus, within which four species are presently recognised. All combine a relatively primitive postcranial skeleton, a dentition with expanded chewing teeth and a small brain. The most primitive species in our own genus, Homo habilis and Homo rudolfensis, are little advanced over the australopithecines and with hindsight their inclusion in Homo may not be appropriate. The first species to share a substantial number of features with later Homo is Homo ergaster, or ‘early African Homo erectus’, which appears in the fossil record around 2.0 Myr. Outside Africa, fossil hominids appear as Homo erectus-like hominids, in mainland Asia and in Indonesia close to 2 Myr ago; the earliest good evidence of ‘archaic Homo’ in Europe is dated at between 600–700 Kyr before the present. Anatomically modern human, or Homo sapiens, fossils are seen first in the fossil record in Africa around 150 Kyr ago. Taken together with molecular evidence on the extent of DNA variation, this suggests that the transition from ‘archiac’ to ‘modern’ Homo may have taken place in Africa.     

The nature and affinities of the “robust” Australopithecines: a review

The fossil evidence of the “robust” australopithecines is reviewed with an emphasis on the taxonomic divisions and evolutionary relationships among this group of hominids. The hypodigms of A. robustus, A. crassidens and A. boisei are described, and the significance of morphological variation within and between these species is assessed. Phylogenetic relationships among the “robust” australopithecines are examined using maximum parsimony analysis, and evolutionary scenarios are evaluated in the light of recent discoveries in East Africa.     

The posterior border of the sphenoid greater wing and its phylogenetic usefulness in human evolution

The elucidation of patterns of cranial skeletal maturation and growth in fossil hominids is possible not only through dental studies but also by mapping different aspects of ossification in both extant African apes and humans. However, knowledge of normal skeletal development in large samples of extant great apes is flimsy. To remedy this situation, this paper offers an extensive survey and thorough discussion of the ossification of the posterior border of the sphenoid greater wing. Indeed, this area provides much information about basicranial skeletal maturation. We investigate three variants: the absence of the foramen spinosum and the position of both the foramen spinosum and the foramen ovale in relation to the sphenosquamosal suture. Providing original data about humans and 1,425 extant great ape skulls and using a sample of 64 fossil hominids, this study aimed to test whether different ossification patterns occurred during the course of human evolution. The incidence of three derived morphologies located on the posterior border of the sphenoid greater wing increases during human evolution at different geological periods. The evolutionary polarity of these three derived morphologies is assessed by outgroup comparison and ontogenetic methods. During human evolution, there is a clear trend for the foramen spinosum to be present and wholly located on the posterior area of the sphenoid greater wing. Moreover, in all the great ape species and in Australopithecus afarensis, the sphenosquamosal suture may split the foramen ovale. Inversely, the foramen ovale always lies wholly within the sphenoid greater wing in Australopithecus africanus, robust australopithecines, early Homo, H. erectus (and/or H. ergaster), and Homo sapiens. From ontogenetic studies in humans, we conclude that, during human evolution, the ossification of the posterior area of the sphenoid greater wing progressively surrounded the middle meningeal artery (passing through the foramen spinosum) and the small meningeal artery (passing through the foramen ovale). Am J Phys Anthropol 107:387–399, 1998. © 1998 Wiley-Liss, Inc.     

Perinatal adaptation in mammals: the impact of metabolic rate

Mammalian birth is accompanied by profound changes in metabolic rate that can be described in terms of body size relationship (Kleiber's rule). Whereas the fetus, probably as an adaptation to the low intrauterine pO₂, exhibits an “inappropriately” low, adult-like specific metabolic rate, the term neonate undergoes a rapid metabolic increase up to the level to be expected from body size. A similar, albeit slowed, “switching-on” of metabolic size allometry is found in human preterm neonates whereas animals that are normally born in a very immature state are able to retard or even suppress the postnatal metabolic increase in favor of weight gain and O₂ supply. Moreover, small immature mammalian neonates exhibit a temporary oxyconforming behavior which enhances their hypoxia tolerance, yet is lost to the extent by which the size-adjusted metabolic rate is “locked” by increasing mitochondrial density. Beyond the perinatal period, there are no other deviations from metabolic size allometry among mammals except in hibernation where the temporary “switching-off” of Kleiber's rule is accompanied by a deep reduction in tissue pO₂. This gives support to the hypothesis that the postnatal metabolic increase represents an “escape from oxygen” similar to the evolutionary roots of mitochondrial respiration, and that the overall increase in specific metabolic rate with decreasing size might contribute to prevent tissues from O₂ toxicity.     

<Emphasis Type="Italic">Ancient Hunters and Their Modern Representatives</Emphasis>: William Sollas’s (1849–1936) Anthropology from Disappointed Bridge to Trunkless Tree and the Instrumentalisation of Racial Conflict

During the first decades of the 20th century, many anthropologists who had previously adhered to a linear view of human evolution, from an ape via Pithecanthropus erectus(today Homo erectus) and Neanderthal to modern humans, began to change their outlook. A shift towards a branching model of human evolution began to take hold. Among the scientific factors motivating this trend was the insight that mammalian evolution in general was best represented by a branching tree, rather than by a straight line, and that several new fossil hominids were discovered that differed significantly in their morphology but seemed to date from about the same period. The ideological and practical implications of imperialism and WWI have also been identified as formative of the new evolutionary scenarios in which racial conflict played a crucial role. The paper will illustrate this general shift in anthropological theory for one particular scientist, William Sollas (1849–1936). Sollas achieved a synthesis of human morphological and cultural evolution in what I will refer to as an imperialist model. In this theoretical framework, migration, conflict, and replacement became the main mechanisms for progress spurred by ‘ ȁ8nature’s tyrant,’ natural selection.     

The Belohdelie frontal: new evidence of early hominid cranial morphology from the Afar of Ethiopia

Study of the Belohdelie frontal has demonstrated that this four-million-year-old specimen belongs to a very generalized hominid that may be close to the divergence point of the hominid and African ape clades. Features associated with the temporalis muscle in the Belohdelie frontal and other new hominids from Hadar (AL 333-125) and West Turkana (KNM-ER 17000) suggest that the earliest hominids shared a large anterior component of this muscle relative to the extinct and extant apes. Results of this study support the phylogenetic hypothesis put forward by many workers that A. afarensis gave rise to the “robust” Australopithecus and A. africanus clades.     

India at the cross-roads of human evolution

The Indian palaeoanthropological record, although patchy at the moment, is improving rapidly with every new find. This broad review attempts to provide an account of (a) the Late Miocene fossil apes and their gradual disappearance due to ecological shift from forest dominated to grassland dominated ecosystem around 9-8 Ma ago, (b) the Pliocene immigration/evolution of possible hominids and associated fauna, (c) the Pleistocene record of fossil hominins, associated fauna and artifacts, and (d) the Holocene time of permanent settlements and the genetic data from various human cultural groups within India. Around 13 Ma ago (late Middle Miocene) Siwalik forests saw the emergence of an orangutan-like primate Sivapithecus. By 8 Ma, this genus disappeared from the Siwalik region as its habitat started shrinking due to increased aridity influenced by global cooling and monsoon intensification. A contemporary and a close relative of Sivapithecus, Gigantopithecus (Indopithecus), the largest ape that ever-lived, made its first appearance at around 9 Ma. Other smaller primates that were pene-contemporaneous with these apes were Pliopithecus (Dendropithecus), Indraloris, Sivaladapis and Palaeotupia. The Late Pliocene and Early Pleistocene witnessed northern hemisphere glaciations, followed by the spread of arid conditions on a global scale, setting the stage for hominids to explore “Savanahastan”. With the prominent expansion of grassland environments from East Africa to China and Indonesia in the Pliocene, monkeys and baboons dispersed into the Indian subcontinent from Africa along with other mammals. Though debated, there are several claims of the presence of early hominins in this part of the world during the Late Pliocene, based primarily on the recovery of Palaeolithic tools. Fossils of our own ancestor and one of the first globe-trotters, early Homo erectus, has been documented from the Early Pleistocene of East Africa, Western Asia and Southeast Asia, thus indirectly pointing towards Indian subcontinent as a possible migration corridor between these regions. The only definite pre-Homo sapiens fossil hominin remains come from the Central Narmada Valley and are thought to be of Middle to late Pleistocene age, and the cranium has been shown to be closely linked to archaic Homo sapiens/H. heidelbergensis of Europe. Around ∼74,000 yrs ago, a super volcanic eruption in Sumatra caused the deposition of Youngest Toba Tephra, that covered large parts of the Indian peninsula. Just around this time anatomically-and-behaviorally modern humans or Homo sapiens possibly arrived into India as evidenced by the so called Middle and Upper Palaeolithic assemblages and associated symbolic evidence. The available genetic data reveals that the gene pool to which modern Indians races belong was extremely diverse and had variable mixed links with both European and Asian populations.     

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

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 Jerison's Nc and EQ and Hemmer's 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.     

Hallucal grasping behavior in Caluromys (Didelphimorphia: Didelphidae): Implications for primate pedal grasping

A key feature in primate evolution is a foot with a divergent opposable hallucal metatarsal bearing a large peroneal process. Extant primates are characterized by a powerful hallucal grasp—an either “euprimate” or “plesiadapoid-euprimate” ancestor acquisition—that facilitates the exploitation of fine branches, an ability that increased the fitness of ancestral euprimates. In this context, the didelphid marsupial Caluromys has been used as the extant analog to this primate morphotype stage due to some morphological, ecological, and behavioral features. However, the extent to which and the positional and support contexts in which Caluromys uses powerful hallucal grasping are not known. This renders analogies to any mode of “euprimate” or “stem primate” grasping poorly substantiated. The present paper quantifies locomotor and postural behavior, support use, and associated frequencies of hallucal grasping in captive Caluromys philander via analysis of video recordings. During locomotion, Caluromys primarily used diagonal sequence walk, clamber, and climb, whereas stand, foot-hang, and bipedal stand were the dominant postures. Small, fine, horizontal, and moderately inclined branches were frequently used. Overall rates of “apparently powerful hallucal grasps” were high, but were exceptionally high during clamber, climb, foot-hang, and bipedal stand. Additionally, an “apparently powerful hallucal grasp” was very common upon fine, small, steep, and vertical branches. The extensive use of such powerful hallucal grasping provided stability and safety that enabled Caluromys to proficiently utilize fine branches of various orientations. The ability to negotiate such unstable supports, further reflected in foot anatomy, provides evidence that the morphobehavioral complex of Caluromys can serve as an extant analog to the plesiadapoid-euprimate ancestor, represented as a terminal branch feeder with effective hallucal grasping.     

Body weight prediction in early fossil hominids: Towards a taxon-“independent” approach

The choice of a model taxon is crucial when investigating fossil hominids that clearly do not resemble any extant species (such as Australopithecus) or show significant differences from modern human proportions (such as Homo habilis OH 62). An “interhominoid” combination is not adequate either, as scaling with body weight is strongly divergent in African apes and humans for most skeletal predictors investigated here. Therefore, in relation to a study of seven long bone dimensions, a new taxon-“independent” approach is suggested. For a given predictor, its taxonomic “independence” is restricted to the size range over which the body weight-predictor relationship for African apes and humans converges. Different predictors produce converging body weight estimates (BWEs) for different size ranges: taxon-“independent” estimates can be calculated for small- and medium-sized hominids (e. g., for weights below 50 kg) using femoral and tibial dimensions, whereas upper limb bones provide converging results for large hominids (above 50 kg). If the remains of Australopithecus afarensis really belong to one species, the relationship of male (above 60 kg) to female body weight (approximately 30 kg) does not fall within the observed range of modern hominoids. Considering Sts 14 (22 kg) to represent a small-sized Australopithecus africanus, the level of encephalization lies well above that of extant apes. If OH 62 (approximately 25 kg), with limb proportions less human-like than those of australopithecines, indeed represents Homo habilis (which has been questioned previously), an increase in relative brain size would have occurred well before full bipedality, an assumption running counter to current assumptions concerning early human evolution. © 1993 Wiley-Liss, Inc.     

Comparison of the Antimicrobial Adhesion Potential of Human Body Fluid Glycoconjugates Using Fucose-Binding Lectin (PA-IIL) of Pseudomonas aeruginosa and Ulex europaeus Lectin (UEA-I)

Pseudomonas aeruginosa produces a fucose-binding lectin (PA-IIL) which strongly binds to human cells. This lectin was shown to be highly sensitive to inhibition by fucose-bearing human milk glycoproteins. Since the glycans of these glycoproteins mimic human cell receptors, they may function as decoys in blocking lectin-dependent pathogen adhesion to the host cells. Human saliva and seminal fluid also contain such compounds, and body fluids of individuals who are “secretors” express additional fucosylated (alpha 1,2) residues. The latter are selectively detected by Ulex europaeus lectin UEA-I. The aim of the present research was to compare the PA-IIL and UEA-I interactions with human salivas and seminal fluids of “secretors” and “nonsecretors” with those obtained with the respective milks. Using hemagglutination inhibition and Western blot analyses, we showed that PA-IIL interactions with the saliva and seminal fluid glycoproteins were somewhat weaker than those obtained with the milk and that “nonsecretor” body fluids were not less efficient than those of “secretors” in PA-IIL blocking. UEA-I, which interacted only with the “secretors” glycoproteins, was most sensitive to those of the seminal fluids.     

Brain size at birth throughout human evolution: a new method for estimating neonatal brain size in hominins

An increase in brain size is a hallmark of human evolution. Questions regarding the evolution of brain development and obstetric constraints in the human lineage can be addressed with accurate estimates of the size of the brain at birth in hominins. Previous estimates of brain size at birth in fossil hominins have been calculated from regressions of neonatal body or brain mass to adult body mass, but this approach is problematic for two reasons: modern humans are outliers for these regressions, and hominin adult body masses are difficult to estimate. To accurately estimate the brain size at birth in extinct human ancestors, an equation is needed for which modern humans fit the anthropoid regression and one in which the hominin variable entered into the regression equation has limited error. Using phylogenetically sensitive statistics, a resampling approach, and brain-mass data from the literature and from National Primate Research Centers on 362 neonates and 2802 adults from eight different anthropoid species, we found that the size of the adult brain can strongly predict the size of the neonatal brain (r² = 0.97). This regression predicts human brain size, indicating that humans have precisely the brain size expected as an adult given the size of the brain at birth. We estimated the size of the neonatal brain in fossil hominins from a reduced major axis regression equation using published cranial capacities of 89 adult fossil crania. We suggest that australopiths gave birth to infants with cranial capacities that were on average 180 cc (95% CI: 158–205 cc), slightly larger than the average neonatal brain size of chimpanzees. Neonatal brain size increased in early Homo to 225 cc (95% CI: 198–257 cc) and in Homo erectus to approximately 270 cc (95% CI: 237–310 cc). These results have implications for interpreting the evolution of the birth process and brain development in all hominins from the australopiths and early Homo, through H. erectus, to Homo sapiens.     

The evolution of brain size and intelligence in man

The brain size of hominids has increased approximately threefold during the evolution of the hominids fromAustralopithecus toHomo sapiens. It is proposed that the principal reason for this increase is that larger brains conferred greater intelligence, and greater intelligence conferred a selection advantage. A number of anthropologists have difficulty accepting this thesis because they believe that brain size is not associated with intelligence in man. Evidence is reviewed, and new evidence from two studies is presented, to show that brain size as measured by head size is positively correlated with intelligence as measured by intelligence tests. On two recent samples statistically significant correlations of .21 and .30 were obtained between estimates of brain size and IQ. It is considered that brain size is positively associated with intelligence in man and that this is the major reason for the increase in brain size of the hominids during the last 3.2 million years.     

Climatic adaptation and hominid evolution: The thermoregulatory imperative

Anthropologists have long recognized the existence among modern humans of geographical variations in body form that parallel climatic gradients, part of more general zoological phenomena commonly referred to as Bergmann's or Allen's “Rules”. These observations have rarely been applied to earlier hominids, in part because fossil skeletons usually are so incomplete that it is difficult to reconstruct body morphology accurately. However, within the past two decades two early hominids have been discovered that preserve enough of the skeleton to allow confident assessment of their body size and shape. Comparison of these specimens—the Australopithecus afarensis A.L. 288-1 (“Lucy”) and the Homo erectus KNM-WT 15000—with others that are less complete make it evident that the evolution of Homo erectus was accompanied by not only a marked increase in body size, but also a similarly dramatic increase in the linearity of body form. That is, relative to their heights, small australopithecines had very broad bodies, whereas large early Homo had narrow bodies. This difference in body form cannot be explained on the basis of obstetric or biomechanical factors, but is consistent with thermoregulatory constraints on body shape. Specifically, to maintain the same ratio of body surface area to body mass, which is an important thermoregulatory mechanism, increases in height should be accompanied by no change in body breadth, which is exactly what is seen in comparisons of A.L. 288-1 and KNM-WT 15000. Conversely, Neandertals living in colder climates had much wider bodies, which are adaptive for heat retention. Differences in limb length proportions between fossil hominids are also consistent with thermoregulatory principles and the geographic variation observed among modern humans. Climatic adaptation during hominid evolution may have wide-ranging implications, not only with regard to interpreting body morphology, but also in relation to ecological scenarios, population movements, and the evolution of the brain.     

Behavioral inferences from Early Stone artifact assemblages: an experimental model

A methodological approach for assessing the nature and palaeographic distribution of early stone artifact assemblages is presented, modeled after an approach originally used for faunal analysis. By combining experimental replicative studies with careful analysis of Palaeolithic archaeological occurrences, it is potentially possible to reconstruct entire technological systems and to assess what stages of lithic reduction may be preferentially represented at high density artifact concentrations that we normally call archaeological “sites”, and what stages of reduction are found in lower density (“off site”) scatters.Based upon the results of this approach, alternative explanations for certain stages of lithic reduction being preferentially represented at a number of Plio-Pleistocene archaeological sites at Koobi Fora, Kenya are considered and evaluated with regard to early hominid organizational patterns. It appears that hominid stone technology was a relatively complex system by 1·9 to 1·4 million years B.P., involving significant transport and carrying of stone artifacts representing various stages of reduction and suggesting more foresight and planning than observed among extant nonhuman primates.The application of this approach to other Palaeolithic occurrences should enable anthropologists to obtain a better understanding of the organizational patterns of tool-making hominids throughout the course of human evolution.