Palaeobotanical studies from tropical Africa: relevance to the evolution of forest, woodland and savannah biomes

Fossil plants provide data on climate, community composition and structure, all of which are relevant to the definition and recognition of biomes. Macrofossils reflect local vegetation, whereas pollen assemblages sample a larger area. The earliest solid evidence for angiosperm tropical rainforest in Africa is based primarily on Late Eocene to Late Oligocene (ca. 39-26 Myr ago) pollen assemblages from Cameroon, which are rich in forest families. Plant macrofossil assemblages from elsewhere in interior Africa for this time interval are rare, but new work at Chilga in the northwestern Ethiopian Highlands documents forest communities at 28 Myr ago. Initial results indicate botanical affinities with lowland West African forest. The earliest known woodland community in tropical Africa is dated at 46 Myr ago in northern Tanzania, as documented by leaves and fruits from lake deposits. The community around the lake was dominated by caesalpinioid legumes, but included Acacia, for which this, to my knowledge, is the earliest record. This community is structurally similar to modern miombo, although it is different at the generic level. The grass-dominated savannah biome began to expand in the Middle Miocene (16 Myr ago), and became widespread in the Late Miocene (ca. 8 Myr ago), as documented by pollen and carbon isotopes from both West and East Africa.     

Bayesian analysis of combined chloroplast loci, using multiple calibrations, supports the recent arrival of Melastomataceae in Africa and Madagascar

A new biogeographic scenario for Melastomataceae (Morley and Dick, American Journal of Botany 90(11) pp. 1638-1645, 2003) accepts an ndhF-based phylogeny for the family by Renner et al. (American Journal of Botany 88(7): 1290-1300, 2001), but rejects those authors' divergence time estimates. Morley and Dick concluded that Gondwanan vicariance, rather than the more recent long dispersal proposed by Renner et al. explains the presence of the family in Africa and Madagascar. To assess the strength of this conclusion, a Bayesian analysis was conducted on three times the amount of sequence data used before (ndhF, rbcL, rpl16; 3100 base pairs [bp], excluding all gaps). The Bayesian approach to divergence time estimation does not rely on a strict molecular clock and employs multiple simultaneous minimal or maximal bounds on node ages. Reliance on northern mid-latitude fossils of Melastomataceae for calibrations was avoided or reduced by using alternative fossil and tectonic calibrations, including all those suggested by Morley and Dick. Results reaffirm the relatively recent spread of melastome lineages among the southern continents and refute the breakup of Gondwana as a plausible explanation for the presence of Dissochaeteae/Sonerileae in Madagascar and Africa and the presence of Melastomeae in Africa and Southeast Asia. Melastomeae appear to have reached Africa around 17-15 million years (my) ago, while Dissochaeteae and Sonerileae apparently reached Madagascar at 17-15 and 20-18 my ago. I also explored the effects of constraining Melastomeae to minimally 76 my old (to have reached Africa by island hopping as postulated by Morley and Dick). This resulted in an estimate for their arrival in Africa of 35 my ago and for Dissochaeteae and Sonerileae in Madagascar of 28 and 33 my ago, still implying long-distance dispersal. The Bayesian 95% credibility ranges around these dates, however, are large. Regardless of the increasing sophistication of molecular estimates of divergence time, Gondwanan scenarios will remain untestable as long as biases in the fossil record can justifiably be invoked to explain away the absence of fossils.     

New dinosaurs link southern landmasses in the Mid-Cretaceous

Abelisauroid predators have been recorded almost exclusively from South America, India and Madagascar, a distribution thought to document persistent land connections exclusive of Africa. Here, we report fossils from three stratigraphic levels in the Cretaceous of Niger that provide definitive evidence that abelisauroid dinosaurs and their immediate antecedents were also present on Africa. The fossils include an immediate abelisauroid antecedent of Early Cretaceous age (ca. 130-110 Myr ago), early members of the two abelisauroid subgroups (Noasauridae, Abelisauridae) of Mid-Cretaceous age (ca. 110 Myr ago) and a hornless abelisaurid skull of early Late Cretaceous age (ca. 95 Myr ago). Together, these fossils fill in the early history of the abelisauroid radiation and provide key evidence for continued faunal exchange among Gondwanan landmasses until the end of the Early Cretaceous (ca. 100 Myr ago).     

A phylogeny of the oil bee tribe Ctenoplectrini (Hymenoptera: Anthophila) based on mitochondrial and nuclear data: evidence for early Eocene divergence and repeated out-of-Africa dispersal

The bee tribe Ctenoplectrini, with two genera, comprises nine species in tropical Africa and ten in Asia and Australia. Most of them collect floral oil, pollen, and nectar from Cucurbitaceae, but three species are thought to be cleptoparasites. The unusual morphology of Ctenoplectrini has made it difficult to infer their closest relatives, in turn preventing an understanding of these bees' geographic and temporal origin. We used two mitochondrial and two nuclear markers (4741 nucleotides) generated for most of the species to test the monophyly of the tribe, its relationships to other Apidae, and its biogeographic history. Ctenoplectrini are strongly supported as monophyletic and closest to the Long-horned bees, Eucerini. The presumably cleptoparasitic species form a clade (Ctenoplectrina) that is sister to the remaining species (Ctenoplectra), confirming the independent evolution of cleptoparasitism in this tribe. Tree topology and molecular dating together suggest that Ctenoplectrini originated in Africa in the Early Eocene and that Ctenoplectra dispersed twice from Africa to Asia, sometime in the Late Eocene, 30-40 my ago, from where one species reached the Australian continent via Indonesia and New Guinea in the mid-Miocene, c. 13 my ago. Dry and cool mid-Miocene climates also coincide with the divergence between Ctenoplectra bequaerti from West Africa and Ctenoplectra terminalis from East and South Africa, perhaps related to fragmentation of the equatorial African rainforest belt.     

A view of early vertebrate evolution inferred from the phylogeny of polystome parasites (Monogenea: Polystomatidae)

The Polystomatidae is the only family within the Monogenea to parasitize sarcopterygians such as the Australian lungfish Neoceratodus poisteri and freshwater tetrapods (lissamphibians and chelonians). We present a phylogeny based on partial 18S rDNA sequences of 26 species of Polystomatidae and three taxon from the infrasubclass Oligonchoinea (= Polyopisthocotylea) obtained from the gills of teleost fishes. The basal position of the polystome from lungfish within the Polystomatidae suggests that the family arose during the evolutionary transition between actinopterygians and sarcopterygians, ca. 425 million years (Myr) ago. The monophyly of the polystomatid lineages from chelonian and lissamphibian hosts, in addition to estimates of the divergence times, indicate that polystomatids from turtles radiated ca. 191 Myr ago, following a switch from an aquatic amniote presumed to be extinct to turtles, which diversified in the Upper Triassic. Within polystomatids from lissamphibians, we observe a polytomy of four lineages, namely caudatan, neobatrachian, pelobatid and pipid polystomatid lineages, which occurred ca. 246 Myr ago according to molecular divergence-time estimates. This suggests that the first polystomatids of amphibians originated during the evolution and diversification of lissamphibian orders and suborders ca. 250 Myr ago. Finally, we report a vicariance event between two major groups of neobatrachian polystomes, which is probably linked to the separation of South America from Africa ca. 100 Myr ago.     

The role of immigrants in the assembly of the South American rainforest tree flora

The Amazon lowland rainforest flora is conventionally viewed as comprising lineages that evolved in biogeographic isolation after the split of west Gondwana (ca. 100 Myr ago). Recent molecular phylogenies, however, identify immigrant lineages that arrived in South America during its period of oceanic isolation (ca. 100-3 Myr ago). Long-distance sweepstakes dispersal across oceans played an important and possibly predominant role. Stepping-stone migration from Africa and North America through hypothesized Late Cretaceous and Tertiary island chains may have facilitated immigration. An analysis of inventory plot data suggests that immigrant lineages comprise ca. 20% of both the species and individuals of an Amazon tree community in Ecuador. This is more than an order of magnitude higher than previous estimates. We also present data on the community-level similarity between South American and palaeotropical rainforests, and suggest that most taxonomic similarity derives from trans-oceanic dispersal, rather than a shared Gondwanan history.     

Origin of the endemic fern genus Diellia coincides with the renewal of Hawaiian terrestrial life in the Miocene

The enigmatic fern genus Diellia, endemic to the Hawaiian archipelago, consists of five extant and one recently extinct species. Diellia is morphologically highly variable, and a unique combination of characters has led to several contrasting hypotheses regarding the relationship of Diellia to other ferns. A phylogenetic analysis of four chloroplast loci places Diellia within 'black-stemmed' rock spleenworts of the species-rich genus Asplenium, as previously suggested by W. H. Wagner. Using an external calibration point, we estimate the divergence of the Diellia lineage from its nearest relatives to have occurred at ca. 24.3 Myr ago matching an independent estimate for the renewal of Hawaiian terrestrial life (ca. 23 Myr ago). We therefore suggest that the ancestor of the Diellia lineage may have been among the first successful colonists of the newly emerging islands in the archipelago. Disparity between morphological and nucleotide sequence variation within Diellia is consistent with a recent rapid radiation. Our estimated time of the Diellia radiation (ca. 2 Myr ago) is younger than the oldest island of Kaua'i (ca. 5.1 Myr ago) but older than the younger major islands of Maui (ca. 1.3 Myr ago), Lana'i (ca. 1.3 Myr ago) and Hawaii (ca. 0.43 Myr ago).     

Molecular systematics of dormice (Rodentia: Gliridae) and the radiation of Graphiurus in Africa

The phylogenetic relationships among the Gliridae (order Rodentia) were assessed using 3430 nucleotides derived from three nuclear fragments (beta-spectrin non-erythrocytic 1, thyrotropin and lecithin cholesterol acyl transferase) and one mitochondrial gene (12S rRNA). We included 14 glirid species, representative of seven genera of the three recognized subfamilies (Graphiurinae, Glirinae and Leithiinae) in our analysis. The molecular data identified three evolutionary lineages that broadly correspond to the three extant subfamilies. However, the data suggest that the genus Muscardinus, previously regarded as falling within the Glirinae, should be included in the Leithiinae. Molecular dating using local molecular clocks and partitioned datasets allowed an estimate of the timing of cladogenesis within the glirids. Graphiurus probably diverged early in the group's evolution (40-50 Myr ago) and the three subfamilies diverged contemporaneously, probably in Europe. The radiation within Graphiurus is more recent, with the colonization of Africa by this lineage estimated at ca. 8-10 Myr ago.     

A new Triassic procolophonoid reptile and its implications for procolophonoid survivorship during the Permo-Triassic extinction event

A reptile specimen from the Lystrosaurus Assemblage Zone of the Beaufort Group, lowermost Triassic of South Africa, represents a new procolophonoid parareptile. Sauropareion anoplus gen. et sp. nov. is identified as the sister taxon of Procolophonidae in a phylogenetic analysis of procolophonoids. Stratigraphic calibration of the most parsimonious tree reveals that four of the six procolophonoid lineages originating in the Permian Period extended into the succeeding Triassic Period. This relatively high taxic survivorship (67%) across the Permo-Triassic boundary strongly suggests that procolophonoids were little if at all affected by the mass extinction event that punctuated the end of the Palaeozoic Era (ca. 251 million years ago).     

A phylogenetic review of the African leaf chameleons: genus Rhampholeon (Chamaeleonidae): the role of vicariance and climate change in speciation

The phylogenetic associations among 13 currently recognized African leaf chameleon species were investigated by making use of mitochondrial and nuclear DNA sequence data (44 taxa and 4145 characters). The gene tree indicates two divergent clades within Rhampholeon; this finding is congruent with previous morphological suggestions. The first clade (I) comprises three taxa (R. kerstenii, R. brevicaudatus and R. brachyurus) and is widely distributed in lowland forest and or non-forest biomes. The second clade (II) comprises the remaining Rhampholeon species and can be subdivided into three subclades. By contrast, most taxa belonging to clade II are confined to relict montane forest biotopes. Based on geographical, morphological and molecular evidence, it is suggested that the taxonomy of Rhampholeon be revised to include two genera (Rieppeleon and Rhampholeon) and three subgenera (Rhampholeon, Bicuspis and Rhinodigitum). There is a close correlation between geographical distribution and phylogenetic relatedness among Rhampholeon taxa, indicating that vicariance and climate change were possibly the most influential factors driving speciation in the group. A relaxed Bayesian clock suggests that speciation times coincided both with the northern movement of Africa, which caused the constriction of the pan African forest, and to rifting in east Africa ca. 20 Myr ago. Subsequent speciation among taxa was probably the result of gradual desiccation of forests between 20 and 5 Myr ago.     

The age and diversification of terrestrial New World ecosystems through Cretaceous and Cenozoic time

Eight ecosystems that were present in the Cretaceous about 100 Ma (million years ago) in the New World eventually developed into the 12 recognized for the modern Earth. Among the forcing mechanisms that drove biotic change during this interval was a decline in global temperatures toward the end of the Cretaceous, augmented by the asteroid impact at 65 Ma and drainage of seas from continental margins and interiors; separation of South America from Africa beginning in the south at ca. 120 Ma and progressing northward until completed 90-100 Ma; the possible emission of 1500 gigatons of methane and CO(2) attributed to explosive vents in the Norwegian Sea at ca. 55 Ma, resulting in a temperature rise of 5°-6°C in an already warm world; disruption of the North Atlantic land bridge at ca. 45 Ma at a time when temperatures were falling; rise of the Andes Mountains beginning at ca. 40 Ma; opening of the Drake Passage between South America and Antarctica at ca. 32 Ma with formation of the cold Humboldt at ca. 30 Ma; union of North and South America at ca. 3.5 Ma; and all within the overlay of evolutionary processes. These processes generated a sequence of elements (e.g., species growing in moist habitats within an overall dry environment; gallery forests), early versions (e.g., mangrove communities without Rhizophora until the middle Eocene), and essentially modern versions of present-day New World ecosystems. As a first approximation, the fossil record suggests that early versions of aquatic communities (in the sense of including a prominent angiosperm component) appeared early in the Middle to Late Cretaceous, the lowland neotropical rainforest at 64 Ma (well developed by 58-55 Ma), shrubland/chaparral-woodland-savanna and grasslands around the middle Miocene climatic optimum at ca. 15-13 Ma, deserts in the middle Miocene/early Pliocene at ca. 10 Ma, significant tundra at ca. 7-5 Ma, and alpine tundra (páramo) shortly thereafter when cooling temperatures were augmented by high elevations attained, for example, in the Andes<10 Ma and especially after 7-6 Ma.     

Phytogeographical Implication of Bridelia Will. (Phyllanthaceae) Fossil Leaf from the Late Oligocene of India

Background

The family Phyllanthaceae has a predominantly pantropical distribution. Of its several genera, Bridelia Willd. is of a special interest because it has disjunct equally distributed species in Africa and tropical Asia i.e. 18–20 species in Africa-Madagascar (all endemic) and 18 species in tropical Asia (some shared with Australia). On the basis of molecular phylogenetic study on Bridelia, it has been suggested that the genus evolved in Southeast Asia around 33±5 Ma, while speciation and migration to other parts of the world occurred at 10±2 Ma. Fossil records of Bridelia are equally important to support the molecular phylogenetic studies and plate tectonic models.

Results

We describe a new fossil leaf of Bridelia from the late Oligocene (Chattian, 28.4–23 Ma) sediments of Assam, India. The detailed venation pattern of the fossil suggests its affinities with the extant B. ovata, B. retusa and B. stipularis. Based on the present fossil evidence and the known fossil records of Bridelia from the Tertiary sediments of Nepal and India, we infer that the genus evolved in India during the late Oligocene (Chattian, 28.4–23 Ma) and speciation occurred during the Miocene. The stem lineage of the genus migrated to Africa via “Iranian route” and again speciosed in Africa-Madagascar during the late Neogene resulting in the emergence of African endemic clades. Similarly, the genus also migrated to Southeast Asia via Myanmar after the complete suturing of Indian and Eurasian plates. The emergence and speciation of the genus in Asia and Africa is the result of climate change during the Cenozoic.

Conclusions

On the basis of present and known fossil records of Bridelia, we have concluded that the genus evolved during the late Oligocene in northeast India. During the Neogene, the genus diversified and migrated to Southeast Asia via Myanmar and Africa via “Iranian Route”.     

Phylogeny of Chaetanthera (Asteraceae: Mutisieae) reveals both ancient and recent origins of the high elevation lineages

Penalized likelihood analysis of previously published chloroplast DNA (cpDNA) ndhF sequences suggests that the central-southern Andean genus Chaetanthera diverged ca. 16.5 million years (my) ago, well before the uplift of the Andes to their present heights. Penalized likelihood analysis based on new nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequences indicates that the most relictual lineages occupy high elevation Andean habitats that did not exist until some 10my later. This result is contrary to the expectation that younger habitats should be occupied by phylogenetically younger lineages. The results are interpreted with respect to the development of aridity in lowland habitats during the Miocene and Pliocene, which presumably extinguished the lowland relatives of the high elevation taxa or, in effect, forced them upwards in search of adequate moisture. As the more northerly lineages were being displaced upward, others diversified in the mediterranean-type climate area of central Chile, giving rise to additional high elevation taxa again, at an early date, as well as lowland taxa. Some species of Chaetanthera from lowland central Chile appear as the phylogenetically youngest taxa, suggesting secondary adaptation to lowland aridity. At the same time, at least two high elevation species, Chaetanthera peruviana and Chaetanthera perpusilla, appear to have been derived recently from a lower elevation ancestor, while some middle to low elevation taxa seem to have evolved recently out of a high elevation complex. The results suggest that the younger high elevation habitats have served as both "cradle" and "museum" for Chaetanthera lineages.     

Les premières étapes de la colonisation de l’Europe et l’arrivée de l’Homme sur les rives de la Méditerranée

Over recent years, many discoveries have renewed our knowledge about the oldest stone industries and also about the behaviour and lifestyle of the hominids that made them, not only in East Africa, but also in the Near East, in Trans Caucasia and in southern Europe. If the first tools making hominids appear in East Africa as early as 2.55 million years ago, they are present in the Levant a little over 2 million years ago, as early as 1.81 million years ago at the gates of Europe in Trans-Caucasia, and a little over 1.4 million years ago on the Mediterranean coasts of Europe.     

Later Stone Age human hair from Vaalkrans Shelter,Cape Floristic Region of South Africa,reveals genetic affinity to Khoe groups

Previous studies show that the indigenous people of the southern Cape of South Africa were dramatically impacted by the arrival of European colonists starting ~400 years ago and their descendants are today mixed with Europeans and Asians. To gain insight on the occupants of the Vaalkrans Shelter located at the southernmost tip of Africa, we investigated the genetic make-up of an individual who lived there about 200 years ago. We further contextualize the genetic ancestry of this individual among prehistoric and current groups. From a hair sample excavated at the shelter, which was indirectly dated to about 200 years old, we sequenced the genome (1.01 times coverage) of a Later Stone Age individual. We analyzed the Vaalkrans genome together with genetic data from 10 ancient (pre-colonial) individuals from southern Africa spanning the last 2000 years. We show that the individual from Vaalkrans was a man who traced ~80% of his ancestry to local southern San hunter–gatherers and ~20% to a mixed East African-Eurasian source. This genetic make-up is similar to modern-day Khoekhoe individuals from the Northern Cape Province (South Africa) and Namibia, but in the southern Cape, the Vaalkrans man's descendants have likely been assimilated into mixed-ancestry “Coloured” groups. The Vaalkrans man's genome reveals that Khoekhoe pastoralist groups/individuals lived in the southern Cape as late as 200 years ago, without mixing with non-African colonists or Bantu-speaking farmers. Our findings are also consistent with the model of a Holocene pastoralist migration, originating in Eastern Africa, shaping the genomic landscape of historic and current southern African populations.     

First Early Hominin from Central Africa (Ishango,Democratic Republic of Congo)

Despite uncontested evidence for fossils belonging to the early hominin genus Australopithecus in East Africa from at least 4.2 million years ago (Ma), and from Chad by 3.5 Ma, thus far there has been no convincing evidence of Australopithecus, Paranthropus or early Homo from the western (Albertine) branch of the Rift Valley. Here we report the discovery of an isolated upper molar (#Ish25) from the Western Rift Valley site of Ishango in Central Africa in a derived context, overlying beds dated to between ca. 2.6 to 2.0 Ma. We used µCT imaging to compare its external and internal macro-morphology to upper molars of australopiths, and fossil and recent Homo. We show that the size and shape of the enamel-dentine junction (EDJ) surface discriminate between Plio-Pleistocene and post-Lower Pleistocene hominins, and that the Ishango molar clusters with australopiths and early Homo from East and southern Africa. A reassessment of the archaeological context of the specimen is consistent with the morphological evidence and suggest that early hominins were occupying this region by at least 2 Ma.     

Haplotypes in the dystrophin DNA segment point to a mosaic origin of modern human diversity

Although Africa has played a central role in human evolutionary history, certain studies have suggested that not all contemporary human genetic diversity is of recent African origin. We investigated 35 simple polymorphic sites and one T(n) microsatellite in an 8-kb segment of the dystrophin gene. We found 86 haplotypes in 1,343 chromosomes from around the world. Although a classical out-of-Africa topology was observed in trees based on the variant frequencies, the tree of haplotype sequences reveals three lineages accounting for present-day diversity. The proportion of new recombinants and the diversity of the T(n) microsatellite were used to estimate the age of haplotype lineages and the time of colonization events. The lineage that underwent the great expansion originated in Africa prior to the Upper Paleolithic (27,000-56,000 years ago). A second group, of structurally distinct haplotypes that occupy a central position on the tree, has never left Africa. The third lineage is represented by the haplotype that lies closest to the root, is virtually absent in Africa, and appears older than the recent out-of-Africa expansion. We propose that this lineage could have left Africa before the expansion (as early as 160,000 years ago) and admixed, outside of Africa, with the expanding lineage. Contemporary human diversity, although dominated by the recently expanded African lineage, thus represents a mosaic of different contributions.     

Twenty years of research on primordial germ cells.

Just twenty years ago I was preparing a research project centred on establishing methods for the isolation and culture of mouse primordial germ cells (PGCs). The project had been suggested to me by Anne McLaren and was to be developed at the Medical Research Council (MRC) "Mammalian Development Unit" in London under the direction of Anne herself. At that time I was a young postdoctoral researcher at the Institute of Histology and Embryology of the University of Rome "La Sapienza" and did not imagine that my decision to be involved in this project would signal a profound switch in my scientific life. From then on my research would mostly concentrate on primordial germ cell biology. I feel like saying that the modern history of mammalian primordial germ cells began twenty years ago at the MRC Mammalian Development Unit under Anne McLaren's impulse. It is not surprising that among the most active researchers in the last twenty years in studying mammalian primordial germ cells, three, namely Chris Wylie, Peter Donovan and myself, began their studies under Anne McLaren's guidance. Over the years, Anne's suggestions and encouragement were always precious for my studies and her presence marked my most important findings on PGC biology. She often invited me to present the results obtained in my laboratory to workshops and congresses. In the present article some of these results particularly influenced by Anne's teaching and suggestions will be briefly reviewed.     

Bio- and sequence stratigraphy and microfacies analysis of the Oligocene Asmari Formation at Sepidar Anticline,Interior Fars sub-Basin,SW Iran

In this research, biostratigraphy, microfacies analysis and sequence stratigraphic framework of the Asmari Formation are discussed at Sepidar Anticline, Interior Fars sub-Basin. The strata are Rupelian to Chattian in age. According to the distribution of benthic foraminifera, two assemblage zones were recognised (I-) Nummulites vascus–Nummulites fichteli and (II-) Archaias asmaricus/hensoni–Miogypsinoides complanatus. Eight microfacies types which can be grouped into three depositional environments are recognised. Distribution of Oligocene foraminifera together with other constituents allowed the identification of three third-order sequences at Asmari Formation. Correlation of analysed sections through Interior Fars sub-Basin represents the development of a carbonate ramp with a deepening trend from SE to NW along the Rupelian/Chattian boundary.     

African and Asian perspectives on the origins of modern humans.

The ways in which the cultural evidence - in its chronological context - can be used to imply behavioural patterning and to identify possible causes of change are discussed. Improved reliability in dating methods, suites of dates from different regional localities, and new, firmly dated fossil hominids from crucial regions such as northeast Africa, the Levant, India and China, are essential for clarification of the origin and spread of the modern genepool. Hominid ancestry in Africa is reviewed, as well as the claims for an independent origin in Asia. The cultural differences and changes within Africa, West and South Asia and the Far East in the later Middle and early Upper Pleistocene are examined and compared, and some behavioural implications are suggested, taking account of the evolutionary frameworks suggested by the 'multiregional evolution' and 'Noah's Ark' hypotheses of human evolution. A possible explanation is proposed for the cultural differences between Africa, West Asia and India on the one hand, and southeast Asia and the Far East on the other. The apparent hiatus between the appearance of the first anatomically modern humans, ca. 100 ka ago, and the appearance of the Upper Palaeolithic and other contemporaneous technological and behavioural changes around 40 ka ago, is discussed. It is suggested that the anatomical changes occurred first, and that neurological changes permitted the development of fully syntactic language some 50 ka later. The intellectual and behavioural revolution, best demonstrated by the 'Upper Palaeolithic' of Eurasia, seems to have been dependent on this linguistic development - within the modern genepool - and triggered the rapid migration of human populations throughout the Old World.