Ian Tattersall

Encyclopedia of human evolution and prehistory

Amino-acid dating Austalopithecus Baring Basin/Tugen Hills Bone Biology Calcium-41 dating Catarrhini Colobinae Complex societies Europe Functional morphology Homo rudolfensis Jewellry Late Paleolithic Lemuriformes Locomotion Natron-Eyasi Basin Non-Darwinian evolution Paleolithic image Pilgrim, Guy Ellock Quantitative methods Sea level change Sexual dimorphism Taphonomy teeth Teilhard de Chardin, Pierre Turkana Basin Visual predation hypothesis Zhoukoudian

Species recognition in human paleontology

Whatever their exact nature (rarely if ever specified), current generalcriteria for distinguishing species in the human fossil record are deficient Moreover, in discussing species distinctions, inter- and intra-species variability are often confused. The decoupling of morphological from taxic change in the evolutionary process means that there can be no absolute criteria for recognizing species on morphological grounds; however, ranges of morphological variation in closely related species in the living fauna normally overlap substantially or completely in most characters; some closely related species cannot be distinguished on the basis of hard parts. Hence there is a tendency to underestimate the number of species in the fossil record, where only clear osteological or dental distinguishing featurcs can be used to discriminate between species. It is thus important to ensure that, where distinct morphs do exist in the fossil record, they are not relegated to the epiphenomenological status of subspecies unless there is compelling reason for doing so. It is not clear why all the various morphs distinguishable in the Middle-to-Late Pleistocene are generally subsumed within the single species Homo sapiens . Several distinct hominid species are represented in the fossil record of this time period.

Lemur diversity in Madagascar

A basic understanding of the taxonomy, diversity, and distributions of primates is essential for their conservation. This review of the status of the taxonomy of lemurs is based on a 5-d workshop entitled “Primate Taxonomy for the New Millennium,” held at the Disney Institute, Orlando, Florida, in February 2000. The aim is not to present a taxonomic revision, but to review our current understanding of the diversity and current and past ranges of lemurs and indicate where there is controversy, discrepancy, or lack of knowledge. Our goal therefore is to provide a baseline for future taxonomic investigation, as well as a clearer focus for research and conservation priorities. We here focus on the lemurs of Madagascar and recognize 5 families, 15 genera, and 99 species and subspecies. We list 39 species of lemurs described since 2000: 2 dwarf lemurs, Cheirogaleus; 11 mouse lemurs, Microcebus; a giant mouse lemur, Mirza; a bamboo lemur, Hapalemur; 17 sportive lemurs, Lepilemur; and 7 woolly lemurs, Avahi. Taxonomic revisions have resulted in the resurrection of a further 9 taxa. However, the figures do not represent the total diversity of Malagasy lemurs because more new species are being identified via new field studies and accompanying genetic research, and should be described in the near future.

The mystery of language evolution

Understanding the evolution of language requires evidence regarding origins and processes that led to change. In the last 40 years, there has been an explosion of research on this problem as well as a sense that considerable progress has been made. We argue instead that the richness of ideas is accompanied by a poverty of evidence, with essentially no explanation of how and why our linguistic computations and representations evolved. We show that, to date, (1) studies of nonhuman animals provide virtually no relevant parallels to human linguistic communication, and none to the underlying biological capacity; (2) the fossil and archaeological evidence does not inform our understanding of the computations and representations of our earliest ancestors, leaving details of origins and selective pressure unresolved; (3) our understanding of the genetics of language is so impoverished that there is little hope of connecting genes to linguistic processes any time soon; (4) all modeling attempts have made unfounded assumptions, and have provided no empirical tests, thus leaving any insights into languages origins unverifiable. Based on the current state of evidence, we submit that the most fundamental questions about the origins and evolution of our linguistic capacity remain as mysterious as ever, with considerable uncertainty about the discovery of either relevant or conclusive evidence that can adjudicate among the many open hypotheses. We conclude by presenting some suggestions about possible paths forward.

Human origins: Out of Africa

Our species, Homo sapiens, is highly autapomorphic (uniquely derived) among hominids in the structure of its skull and postcranial skeleton. It is also sharply distinguished from other organisms by its unique symbolic mode of cognition. The fossil and archaeological records combine to show fairly clearly that our physical and cognitive attributes both first appeared in Africa, but at different times. Essentially modern bony conformation was established in that continent by the 200–150 Ka range (a dating in good agreement with dates for the origin of H. sapiens derived from modern molecular diversity). The event concerned was apparently short-term because it is essentially unanticipated in the fossil record. In contrast, the first convincing stirrings of symbolic behavior are not currently detectable until (possibly well) after 100 Ka. The radical reorganization of gene expression that underwrote the distinctive physical appearance of H. sapiens was probably also responsible for the neural substrate that permits symbolic cognition. This exaptively acquired potential lay unexploited until it was “discovered” via a cultural stimulus, plausibly the invention of language. Modern humans appear to have definitively exited Africa to populate the rest of the globe only after both their physical and cognitive peculiarities had been acquired within that continent.

How could language have evolved

How could language have evolved? What is the key innovation underlying the evolution of human language? This Essay argues that the ability to “merge” two syntactic elements uniquely explains the recentness and stability of language. [SK to check before publishing on the homepage] CM 16/7

Species concepts and species identification in human evolution

Little is known about the process of speciation. However, while this process is clearly independent of morphological differentiation, if one species arises from (and thus within) another, anatomical differentiation associated with speciation cannot initially exceed that possible within a species. Beyond this, however, theory provides no help in the practical business of species recognition in the fossil record. The “biological” species concept, whilst having the merit of stressing the historical importance of genetic disjunction, provides no general guidelines for identifying species either in the living biota or in the fossil record. For paleontological purposes, the same is also broadly true for the “recognition” concept. The “phylogenetic” species concept, which views species as the minimum diagnosable unit, remedies this deficiency but blurs the distinction, critical in the living biota, between species, which are both taxically and morphologically differentiated, and subspecies, which are only differentiated morphologically. Empirical appraisal of closely related extant species suggests, however, that intraspecific variants are rarely recognizable on the basis of hard-tissue morphology, and that distinctive hard-tissue “morphs” will almost certainly correspond to disjunct species or even to closely related groups. This has major implications for interpreting the human fossil record, especially over the last half million years, where use of the term Homo sapiens to cover a spectrum of morphologies has served to obscure evolutionary patterns.

Distribution, Abundance, and Putative Ecological Strategy of Macaca fascicularis on the Island of Mauritius, Southwestern Indian Ocean

We estimate that between 25,000 and 35,000 long-tailed macaques, Macaca fascicularis, live on the island of Mauritius, 1,865 km2, in the western Indian Ocean, and we deta

Reconstruction of hominid phylogeny: A testable framework based on cladistic analysis*

The cladistic method of systematic analysis is applied to the taxa of Hominidae (s.l.), from Dryopithecus to Homo, Pan and Pongo. This method is based on determination of shared derived character states among all taxa studied, and only this kind of similarity links taxa into subgroups. Each branching point is characterized by its reconstructed morphotype or list of deduced characters common to it and (at least some of) its descendants. Ancestor-descendant relationships are not sought but concentration is on hypotheses as to relative recency of common ancestry. Morphologically, Dryopithecus is found to be conservative, Gigantopithecus widely divergent and Ramapithecus linked with later men. Australopithecus africanus is also conservative but potentially linked to Homo, while A. robustus is divergent.

Molecular phylogeny and taxonomic revision of the sportive lemurs (Lepilemur, Primates).

BackgroundThe number of species within the Malagasy genus Lepilemur and their phylogenetic relationships is disputed and controversial. In order to establish their evolutionary relationships, a comparative cytogenetic and molecular study was performed. We sequenced the complete mitochondrial cytochrome b gene (1140 bp) from 68 individuals representing all eight sportive lemur species and most major populations, and compared the results with those obtained from cytogenetic studies derived from 99 specimens.ResultsInterspecific genetic variation, diagnostic characters and significantly supported phylogenetic relationships were obtained from the mitochondrial sequence data and are in agreement with cytogenetic information. The results confirm the distinctiveness of Lepilemur ankaranensis, L. dorsalis, L. edwardsi, L. leucopus, L. microdon, L. mustelinus, L. ruficaudatus and L. septentrionalis on species level. Additionally, within L. ruficaudatus large genetic differences were observed among different geographic populations. L. dorsalis from Sahamalaza Peninsula and from the Ambanja/Nosy Be region are paraphyletic, with the latter forming a sister group to L. ankaranensis.ConclusionOur results support the classification of the eight major sportive lemur taxa as independent species. Moreover, our data indicate further cryptic speciation events within L. ruficaudatus and L. dorsalis. Based on molecular data we propose to recognize the sportive lemur populations from north of the Tsiribihina River, south of the Betsiboka River, and from the Sahamalaza Peninsula, as distinct species.