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.     

Australopithecines: Ancestors of the African Apes?

Since australopithecines display humanlike traits such as short ilia, relatively small front teeth and thick molar enamel, they are usually assumed to be related toHomo rather than toPan orGorilla. However, this assumption is not supported by many other of their features. This paper briefly surveys the literature concerning craniodental comparisons of australopith species with those of bonobos, common chimps, humans and gorillas, adult and immature. It will be argued, albeit on fragmentary data, that the large australopiths of East Africa were in many instances anatomically and therefore possibly also evolutionarily nearer toGorilla than toPan orHomo, and the South African australopiths nearer toPan andHomo than toGorilla. An example of a possible evolutionary tree is provided. It is suggested that the evidence concerning the relation of the different australopithecines with humans, chimpanzees and gorillas should be re-evaluated.     

The history of the genusHomo

The genusHomo was established by Carolus Linnaeus in 1758. During the course of the past 150 years, the addition of fossil species to the genusHomo has resulted in a genus that, according to the taxonomic interpretation, could span as much time as 2.5 Myr, and include as many as ten species. This paper reviews the fossil evidence for each of the species involved, and sets out the case for their inclusion inHomo. It suggests that while the case for the inclusion of some species in the genus (e.g.Homo erectus) is well-supported, in the case of two of the species,Homo habilis andHomo rudolfensis, the case for their inclusion is much weaker. Neither the cladistic evidence, nor evidence about adaptation suggest a particularly close relationship with laterHomo.     

Conclusions: implications of the Liang Bua excavations for hominin evolution and biogeography

Excavations at Liang Bua, on the Indonesian island of Flores, have yielded a stratified sequence of stone artifacts and faunal remains spanning the last 95 k.yr., which includes the skeletal remains of two human species, Homo sapiens in the Holocene and Homo floresiensis in the Pleistocene. This paper summarizes and focuses on some of the evidence for Homo floresiensis in context, as presented in this Special Issue edition of the Journal of Human Evolution and elsewhere. Attempts to dismiss the Pleistocene hominins (and the type specimen LB1 in particular) as pathological pygmy humans are not compatible with detailed analyses of the skull, teeth, brain endocast, and postcranium. We initially concluded that H. floresiensis may have evolved by insular dwarfing of a larger-bodied hominin species over 880 k.yr. or more. However, recovery of additional specimens and the numerous primitive morphological traits seen throughout the skeleton suggest instead that it is more likely to be a late representative of a small-bodied lineage that exited Africa before the emergence of Homo erectus sensu lato. Homo floresiensis is clearly not an australopithecine, but does retain many aspects of anatomy (and perhaps behavior) that are probably plesiomorphic for the genus Homo. We also discuss some of the other implications of this tiny, endemic species for early hominin dispersal and evolution (e.g., for the “Out of Africa 1” paradigm and more specifically for colonizing Southeast Asia), and we present options for future research in the region.     

African ape ancestry

It is commonly believed that the australopithecines are more closely related to humans than to African apes. This view is hardly compatible with the biomolecular data which place theHomo/Pan split at the beginning of the australopithecine period. Nothing in the fossil hominid morphology precludes the possibility that some australopithecines were ancestral to gorillas or chimpanzees and others to humans.     

Phylogeny of Bonatea (Orchidaceae: Habenariinae) based on molecular and morphological data

The genus Bonatea is widely distributed throughout southern and eastern Africa. Considerable debate surrounds the generic status of Bonatea, but there have been neither previous studies of evolutionary relationships among Bonatea species, nor any tests of the monophyly of the genus in relation to its close relative Habenaria. We investigated phylogenetic relationships between Bonatea and selected Habenaria species using morphology, as well as sequences of the chloroplast gene matK and the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA. A fully resolved cladogram was obtained using morphological data, but neither the ITS, matK, nor combined data sets yielded well-resolved and well-supported phylogenetic structure for Bonatea. There is poor congruence between ITS and matK data for interspecific relationships in Bonatea, whilst the morphological results are largely congruent with the ITS analysis. Relative to Habenaria, there is little sequence variation between Bonatea species, which could indicate a recent and rapid radiation of Bonatea. Although the sampled Bonatea species form a distinct clade, more extensive sampling of Habenaria would be required to establish unambiguously whether or not Bonatea is monophyletic.     

Size and shape of the australopithecine pelvic bone

The recovery of several specimens allows to have a good knowledge of australopithecine pelvic bone anatomy. But despite this, differences of opinion still exist regarding locomotory interpretations. The aim of this paper is to present results of a new morphometric analysis of australopithecine pelvic bones to try to understand the reasons of this situation. It appears that australopithecines exhibit the same overall architectural pattern as extant humans, the hominid pattern, just as all African apes also exhibit the same pongid pattern. But, in this pattern, it is possible to clearly depict two subpatterns corresponding to both generaAustralopithecus andHomo. Locomotory interpretations depend on the fact that some studies emphasize traits related to the hominid pattern (concluding then on modern bipedalism) and others focus on trains characterizing australopithecine sub-pattern (concluding then on non-modern bipedalism).     

Phylogeography of the pharaoh cuttle Sepia pharaonis based on partial mitochondrial 16S sequence data

The pharaoh cuttle Sepia pharaonis Ehrenberg, 1831 (Mollusca: Cephalopoda: Sepiida) is a broadly distributed species of substantial fisheries importance found from east Africa to southern Japan. Little is known about S. pharaonis phylogeography, but evidence from morphology and reproductive biology suggests that Sepia pharaonis is actually a complex of at least three species. To evaluate this possibility, we collected tissue samples from Sepia pharaonis from throughout its range. Phylogenetic analyses of partial mitochondrial 16S sequences from these samples reveal five distinct clades: a Gulf of Aden/Red Sea clade, a northern Australia clade, a Persian Gulf/Arabian Sea clade, a western Pacific clade (Gulf of Thailand and Taiwan) and an India/Andaman Sea clade. Phylogenetic analyses including several Sepia species show that S. pharaonis sensu lato may not be monophyletic. We suggest that “S. pharaonis” may consist of up to five species, but additional data will be required to fully clarify relationships within the S. pharaonis complex.     

Karyotaxonomic study of some species ofPeucedanum (Umbelliferae)

A study of morphometric karyotype characters was carried out in 14 species ofPeucedanum s. lat. (Umbelliferae — Apioideae) and in one species of the related genusLomatium. The differences of the species in their karyotype characters are correlated only to a limited degree with their similarities of dissimilarities in morphological (i. a. carpological) characters, and thus with their taxonomic position. The evolution of these two sets of characters seems to have proceeded not synchronously or even in different directions in the group of platycarpousUmbelliferae united in the genusPeucedanum. Therefore, it is unlikely that morphometric chromosome characters revealed by monochrome staining can be used appropriately in the taxonomic revision of the polymorphous genusPeucedanum.     

Pollination of sevenPlectranthus spp. (Lamiaceae) in southern Natal, South Africa

The genusPlectranthus (Lamiaceae) shows remarkable radiation on the sandstones of southern Natal and northern Transkei in South Africa, where six endemic species occur. Two of these endemic species,P. hilliardiae andP. oribiensis, are included in this study, as well asP. reflexus, for which only limited data are available. The other species that were studied areP. ambiguus, P. ciliatus, P. ecklonii, P. madagascariensis andP. zuluensis. Four of these taxa,P. ambiguus, P. hilliardiae, P. reflexus andP. saccatus var.longitubus, have uniquely long corolla-tubes (20–30mm) and this is related to pollination by nemestrinid flies of the genusStenobasipteron that have proboscides of similar length. Other nemestrinid species of the genusProsoeca have shorter proboscides and pollinate two species ofPlectranthus with shorter corolla-tube lengths (6–15mm). Acrocerid flies, tabanid flies and anthophorid bees are also important visitors to these species. This study on the pollination of seven species of varying corolla-tube lengths shows a correlation between floral tube length and proboscis length of insect visitors, many of which are recorded for the first time as pollinators ofPlectranthus.     

Lipochaeta and Melanthera (Asteraceae: Heliantheae subtribe Ecliptinae): establishing their natural limits and a synopsis

We restrict the genusLipochaeta to the allopolyploid species of the typical section.Lipochaeta s.str. is interpreted to be the result of an intergeneric hybridization betweenMelanthera and a presently unknown taxon, perhaps of the genusWedelia. Lipochaeta is characterized, in addition to its allopolyploidy (n=26), by having both flavonols and flavones, disk corollas with 4 lobes, achenes tuberculate at maturity, the disk achenes flattened to slightly biconvex, and ray achenes obcompressed.Lipochaeta sect.Aphanopappus andWollastonia are here reduced to synonymy underMelanthera. We transfer 14 HawaiianLipochaeta and one New Caledonian species as well as the AsianWedelia prostrata toMelanthera. These transfers, along with the species in Africa and North America, bring the number of species in the genus to 35.Melanthera is delimited by an abruptly narrowed to truncate and flattened top of the achene, (0−)1–15(−20) often unequal, ciliate or barbellate, caducous pappus bristles immediately surrounding the corolla, involucral bracts and receptacular paleae with many veins forming longitudinal striations, and n=15. The florets are 5-merous, the corollas are yellow or white, and rays are absent (in white-flowered species) or present and neutral or fertile. In dealing with species formerly placed inLipochaeta, the GalapagosL. laricifolia is here transferred from the illegitimate generic nameMacraea toTrigonopterum and the BrazilianL. goyazensis is transferred toAngelphytum. We maintain the earlier reduction ofEchinocephalum underMelanthera and reduce all three taxa originally described in it to one,M. latifolia.     

Upper limits of temperature for growth inChlorella (Chlorophyceae)

The upper limit of temperature for growth is a species-specific character in the genusChlorella. The limits of 14Chlorella species range from 26–30°C (C. saccharophila) to 38–42°C (C. sorokiniana), withC. fusca var.vacuolata (34°C) andC. kessleri (34–36°C) assuming an intermediate position. Thus, there is no wide gap in the temperature limits between the normal (“low-temperature”) species ofChlorella and the “high-temperature” species,C. sorokiniana.     

Species-specific albumin in fossil bones from Orce, Granada, Spain

A skull fragment (VM-0) from Orce, Granada, Spain, dated palaeomagnetically at about 1.6 Myr, is thought by some palaeontologist to be hominid, while others maintain it is equid. If hominid, it would be by far the oldest evidence ofHomo in Europe. Immunological studies on residual albumin in this fossil were carried out independently, and with different immunological methods, at the University of California, San Francisco (radioimmunoassay), and at the University of Granada, Spain (enzyme immunoassay). Other fossils attributed to hominids also studied wereVM1960 from Venta Micena, andCV-1 from Cueva Victoria, Murcia, Spain. Undisputed equid and bovid fossils from the same deposits and dated to a similar period as the Orce skull were also analyzed. Our results showed that species-specific albumin can be detected in 1.6 Myr-old hominid, equid and bovid fossils. The albumin from the Orce skull fragment and fromVM-1960 was immunologically closer to human albumin. These findings support the contention that theVM-0 andVM-1960 are hominid and that members of the genusHomo occupied southern Spain 1.6 Myr ago.     

Body size and body shape in early hominins - implications of the Gona Pelvis

Discovery of the first complete Early Pleistocene hominin pelvis, Gona BSN49/P27, attributed to Homo erectus, raises a number of issues regarding early hominin body size and shape variation. Here, acetabular breadth, femoral head breadth, and body mass calculated from femoral head breadth are compared in 37 early hominin (6.0-0.26 Ma) specimens, including BSN49/P27. Acetabular and estimated femoral head sizes in the Gona specimen fall close to the means for non-Homo specimens (Orrorin tugenesis, Australopithecus africanus, Paranthropus robustus), and well below the ranges of all previously described Early and Middle Pleistocene Homo specimens. The Gona specimen has an estimated body mass of 33.2 kg, close to the mean for the non-Homo sample (34.1 kg, range 24-51.5 kg, n = 19) and far outside the range for any previously known Homo specimen (mean = 70.5 kg; range 52-82 kg, n = 17). Inclusion of the Gona specimen within H. erectus increases inferred sexual dimorphism in body mass in this taxon to a level greater than that observed here for any other hominin taxon, and increases variation in body mass within H. erectus females to a level much greater than that observed for any living primate species. This raises questions regarding the taxonomic attribution of the Gona specimen. When considered within the context of overall variation in body breadth among early hominins, the mediolaterally very wide Gona pelvis fits within the distribution of other lower latitude Early and Middle Pleistocene specimens, and below that of higher latitude specimens. Thus, ecogeographic variation in body breadth was present among earlier hominins as it is in living humans. The increased M-L pelvic breadth in all earlier hominins relative to modern humans is related to an increase in ellipticity of the birth canal, possibly as a result of a non-rotational birth mechanism that was common to both australopithecines and archaic Homo.     

Coexistence of predatoryMuscina stabulans andophyra aenescens [Dipt.: Muscidae] with dipterous prey in poultry manure

Significant relationships between the emergence of adult predatory species,Ophyra aenescens (Wiedemann) andMuscina stabulans (Fallen) and prey,Musca domestica L.,Fannia femoralis (Stein) andF. canicularis (L.) existed on 10 poultry ranches in southern California. Predatory species may function in natural control at intervals throughout the year, especially on predominant prey,F. femoralis andF. canicularis. Dipterous species, especiallyO. aenescens andF. femoralis, were only moderately influenced by the surface area of breeding habitat available. Accuracy in the measurement of population trends in Diptere may be enhanced by increasing the number of samples at any given ranch rather than the addition of study ranches. Parasitism, ranging from 22.6–37.8% of collected puparia, involved principally 3 species,Muscidifurax zaraptor Kogan & Legner,M. raptor Girault & Sanders andSpalangia cameroni Perkins.      

Chloroplast DNA restriction site variation in theVernonieae (Asteraceae), an initial appraisal of the relationship of New and Old World taxa and the monophyly ofVernonia

Chloroplast DNA restriction site variation was examined for 35 taxa in theVernonieae and four outgroup tribes, using 17 restriction enzymes mapped for ca. 900 restriction sites per species; 139 mutations were found to be phylogenetically informative. Phylogenetic trees were constructed using Wagner and weighted parsimony, and evaluated by bootstrap and decay analyses. Relationships of Old and New World taxa indicate complex geographical relationships; there was no clear geographic separation by hemisphere. The relationships between Old and New World Vernonias found here support prior morphological analyses. The sister group to all New and most Old World taxa was composed of a small group of Old World species including yellow-flowered, trinervate-leaved species previously postulated to be basal in the tribe. The majority of both New and Old World taxa are derived from a lineage beginning with the monotypic genusStokesia, an endemic of the southeastern United States. The genusVernonia was also found to be paraphyletic within both the New and Old World. Available data do not support either the separation ofVernonia or the tribeVernonieae into geographically distinct lineages. The pattern of relationships within theVernonieae for taxa from North America, Asia, Africa, Central and South America is most similar to that of several other groups of both plants and animals with a boreotropical origin, rather than an origin in Gondwanaland. Such a pattern of distribution suggests more ancient vicariant events than are routinely postulated for theAsteraceae.     

Molecular systematics of the Old World Astragalus (Fabaceae) as inferred from nrDNA ITS sequence data

This study represents a nuclear rDNA ITS-based phylogenetic analyses of a greater sampling of the Old WorldAstragalus compared to our previous work (212 vs. 134 taxa). Phylogenetic relationships among 212 species (213 accessions) of the Old WorldAstragalus, including newly segregated monotypic genusPodlechiella, the two aneuploid New WorldAstragalus, and five related genera, were inferred from analyses of nuclear rDNA ITS sequences using maximum parsimony. A total of 658 nucleotide sites and four binary characters for indels were analyzed. The results of phylogenetic analyses suggest sect.Phyllolobium, comprising mostly the Chinese species, is placed outside of the so-calledAstragalus s. str. and is a well-supported monophyletic group. The monotypic annual segregate genusThlaspidium (≡Astragalus sect.Thlaspidium, A. thlaspi), is clearly nested withinAstragalus s. str. Among the many sections analyzed here, only sects.Cenanthrum, Caraganella, Eremophysa, Incani, Laxiflori, andLotidium are strongly supported as monophyletic. Our analysis, in agreement with previous studies, shows that the North American euploidAstragalus species are scattered throughout the Old World groups of the genus.     

Craniofacial diversity in earlyHomo and the affinities of the Sterkfontein Valley

The Sterkfontein Valley specimens SK 847 (Swartkrans Member 1) and Stw 53 (Sterkfontein Member 5) provide important evidence of earlyHomo in southern Africa. However, specific identity has been disputed, with that of SK 847 especially contentious. Opinions differ markedly as to whether the specimens are conspecific or not, whether they should be referred to East African earlyHomo species, or whether they represent new species. Morphometric analysis of facial dimensions reveals contrasting affinities for the two South African fossils, and so does not support claims for their conspecifity. Stw 53 is very like smaller East African crania referred toH. habilis, whereas SK 847 has a distinctive facial pattern. In some respects it resembles early AfricanH. erectus (=H. ergaster), but with a markedly more projecting mid-face, prominent zygomatic and unexpanded frontal region, all of which militate against inclusion in that species. The taxonomic implications of these contrasting facial affinities are briefly discussed.     

Allozyme divergence among species ofWolffia (Lemnaceae)

The genusWolffia was surveyed electrophoretically at 14 allozyme loci. A total of 133 clones representing 10 of the 11 recognized species was examined. Genetic identities among most pairs of species are zero, with non-zero values ranging from 0.14 to 0.40.Wolffia angusta and the newly describedW. neglecta show the highest similarity, and the former species has an identity of 0.14 withW. australiana. The next highest similarity (0.34) occurs betweenW. globosa of Southeast Asia andW. cylindracea of southern Africa, which until recently, had generally been viewed as members of the same species. Other species showing some common alleles are members of a complex involvingW. arrhiza, W. columbiana, W. cylindracea, andW. globosa. WithinW. arrhiza, plants from South Africa and Europe are easily distinguished electrophoretically because each contains unique alleles at two loci. Strains from other parts of Africa vary at these loci and are not totally distinct from either the plants from South Africa or from Europe. Species ofWolffia are much more divergent at allozyme loci than the majority of congeners of flowering plants. This suggests that the species are quite old and that the difficulties in distinguishing taxa morphologically are the result of reduction rather than lack of divergence due to recent speciation. Because of the lack of shared alleles between the majority of species pairs inWolffia, enzyme electrophoresis provides limited resolution of species relationships in the genus.