PSGB Winter Meeting 2005

Primate Evolution and the Environment

Friday 9th December 2005
Flett Theatre, The Natural History Museum, London

Organised by:
Christophe Soligo, The Natural History Museum,
C.Soligo@nhm.ac.uk
Tel: ++(0)20 7942 5669; Fax: ++(0)20 7942 5546

Programme

9:00 Registration

10:00 Bob Martin, The Field Museum:
Primate origins: implications of a Cretaceous ancestry.

10:30 Christophe Soligo, The Natural History Museum:
Invading Europe: did climate or geography trigger early Eocene primate dispersals?

11:00 Coffee

11:30 Erik Seiffert, Oxford University:
Primate response to climate change through the later Eocene and early Oligocene in North Africa.

12:00 Peter Andrews, The Natural History Museum:
Middle Miocene dispersal of apes out of Africa.

12:30 Primate Society AGM and lunch

14:00 Jussi Eronen / Mikael Fortelius, University of Helsinki:
Just how wet? Neogene primate distributions and the nature of the hypsodonty humidity proxy.

14:30 Susan Antón, New York University:
Size, scale and environment in early Homo.

15:00 Sarah Elton, University of Hull:
Environmental correlates of the cercopithecoid radiations.

15:30 Coffee

16:00 Jonathan Kingdon, Oxford University:
Primate signalling in a noisy environment.

16:30 Laurie Godfrey, University of Massachusetts:
Ecosystems in disequilibrium: anthropogenic impacts on the primate communities of Madagascar.

17:00 Urs Thalmann, University of Zürich:
Biodiversity, phylogeography, biogeography and conservation: lemurs as an example.

17:30 Poster Session and Real Ale Reception sponsored by Young's Brewery, London (http://www.youngs.co.uk).

Registration: student members: £10; student non-members: £15; members: £15; non-members: £25.

All registration will be at the door on the day of the conference. Non-members may join on the day and benefit from reduced members’ fees. If you intend to join on the day, please bring along a completed application form in order to reduce waiting times. Application forms are available here.

The meeting will be held in the Natural History Museum’s Flett Theatre and Foyer. Access is through the Earth Galleries entrance on Exhibition Road. The nearest Underground station is South Kensington (District, Circle and Picadilly lines). For a map and further access details see <http://www.nhm.ac.uk/visiting/where.html>.

Travel by car is discouraged, as public transport is very convenient while parking is very difficult. If you do need to come by car please contact the organiser for further information.Abstracts for podium presentations:

Primate origins: implications of a Cretaceous ancestry

Robert D. Martin
Academic Affairs, The Field Museum, Chicago, USA

It has long been accepted that the adaptive radiation of modern placental mammals (like that of modern birds) did not begin until after the Cretaceous/Tertiary (K/T) boundary 65 million years (Ma) ago, following the extinction of the dinosaurs. The first undoubted fossil primates appear in the record 55 Ma ago. However, a Cretaceous origin of primates 80-90 Ma ago is now indicated by a statistical analysis of the primate fossil record, allowing for major gaps, combined with evidence from molecular phylogenies calibrated with dates from denser parts of the record. If this interpretation is correct, primates overlapped with dinosaurs by some 20 Ma prior to the K/T boundary, and their initial radiation was doubtless truncated as part of the major extinction event at the end of the Cretaceous. Following a review of evidence for an early origin of primates, implications of this are discussed with respect to the likely ancestral condition for primates, including a southern continental area of origin and likely body size. Climatic implications of continental positions throughout the early evolution of primates are assessed and implications of the K/T extinction event for primates, other mammals and birds are examined. The known early Tertiary primates are re-interpreted as northern continental offshoots of a "second wave" of primate evolution.

Invading Europe: did climate or geography trigger early Eocene primate dispersals?

Christophe Soligo
Department of Palaeontology, The Natural History Museum, London, UK

The Palaeocene-Eocene transition is characterised by a significant turnover of mammalian taxa in the European, Asian and North American fossil records. In Europe the transition is marked by a minimum true extinctions rate of over half of latest Palaeocene taxa and the dispersal into Europe of new taxa that contribute over 60% to the earliest Eocene fauna. Primates are among the groups that make their first appearance in the fossil record of Europe at this time. The first appearance of primates in the European fossil record also coincides with their first appearances in Asia and North America and no unequivocal primate fossils have yet been recovered from anywhere in the world prior to the Palaeocene-Eocene transition. One of the many questions that remain to be solved with regard to the earliest evolution of primates is the reason for their sudden and virtually simultaneous appearance in the fossil records of Asia, Europe and North America. The most obvious environmental correlate of the Palaeocene-Eocene transition is a sharp but relatively short-lived warming event leading up to the Palaeocene-Eocene Thermal Maximum (PETM) and evidenced in the stratigraphic record by a negative ?13C excursion. It remains unclear however whether or how this warming event may have influenced Palaeocene-Eocene faunal turnovers. This paper will review existing evidence and present results from a new analysis to assess the extent to which changes in climatic conditions associated with the Palaeocene-Eocene transition may or may not have facilitated the dispersal of early Eocene primates into Europe and across the northern continents.

Primate response to climate change through the later Eocene and early Oligocene in north Africa

Erik R. Seiffert
Department of Earth Sciences and Museum of Natural History, University of Oxford, UK

The extinction of adapiform and omomyiform primates in Europe and North America is generally considered to have been directly related to changes in climate that took place at the Eocene-Oligocene boundary, around 34 million years ago. The later Paleogene fossil record now documents that a number of other primate clades independently persisted through this phase of early Oligocene cooling in Afro-Arabia (catarrhine and parapithecid anthropoids, galagid and lorisid strepsirrhines) and Asia (tarsiids, sivaladapids, amphipithecids); the same must be true of platyrrhine anthropoids (in Afro-Arabia or South America) and lemuriform strepsirrhines (in Madagascar), although neither group has a late Eocene or early Oligocene fossil record.

The Fayum Depression in northern Egypt preserves a number of primate communities ranging in age from earliest late Eocene (~37 Ma) to early Oligocene (~33 Ma), and these records provide our most detailed insights into patterns of continuity and change in primate community structure across the Eocene-Oligocene boundary. Recent work in the Fayum area has revealed a number of interesting differences between late Eocene and early Oligocene north African primate communities: 1) the upper body size distribution of late Eocene primate communities was dominated by prosimians (primarily folivorous adapiform primates), and not anthropoids as might have been predicted from Afro-Arabia's post-Eocene primate fossil record; 2) at least three stem strepsirrhine lineages appear to have gone extinct near the Eocene-Oligocene boundary; and 3) at least three anthropoid lineages (catarrhines, platyrrhines, and parapithecids) persisted into the early Oligocene, and independently evolved mandibular symphyseal fusion, presumably due to changes in diet and increases in body size.

Middle Miocene dispersal of apes out of Africa

Peter Andrews
Department of Palaeontology, The Natural History Museum, London, UK

The earliest record of fossil apes outside Africa is in the middle Miocene of Turkey and eastern Europe. There were at least two, and perhaps four, species of ape, which were found associated with subtropical mixed environments of forest and more open woodland. Postcranial evidence indicates mainly arboreal adaptations, with similar morphology to most of the early Miocene primates indicating generalized arboreal quadrupedal adaptations analogous to that of Old World monkeys while lacking the morphology of specialized arboreal primates. Robust jaws and thick enameled teeth indicate a hard fruit diet.

The two best-known species of fossil ape are known from the site of Pasalar in Turkey. They have almost identical molar and jaw morphology, and molar morphology is also similar to the other two species from Germany and the Czech Republic, but there are significant differences in their anterior teeth and postcrania. The more common species, Griphopithecus alpani, retains mainly primitive characters from early and middle Miocene apes in Africa, and it is similar phenetically to Equatorius africanus from Maboko Island and Kipsaramon. The second species is assigned to a new species of Kenyapithecus, an African genus from Fort Ternan in Kenya, on the basis of a number of shared derived characters of the anterior dentition, and it is considered likely that there is a phylogenetic link between them. The African sites all date from the middle Miocene, similar in age to the Turkish and European ones, and the emigration from Africa coincides with one of the closures of the Tethys Sea. Environments indicated for the African sites are mixtures of abundant seasonal woodland with some forest vegetation. The postcrania of both African taxa again indicate apes with generalized arboreal adaptation but lacking specialized arboreal function.

This middle Miocene radiation of both African and non-African apes was preceded by a large radiation of arboreal apes in the early Miocene. The earliest Miocene apes in the genus Proconsul were arboreal, and because of their association with the fruits of evergreen rain forest plants, it would appear that they were forest-adapted. Later species of the same genus, however, together with other genera such as the leaf-eating Rangwapithecus and the small ape Limnopithecus, have been found associated with plants and animals indicating seasonal woodland environments. While the stem ancestors of the Hominoidea were almost certainly forest-adapted, the evidence of environments associated with apes in the later part of the early Miocene and the middle Miocene indicates more seasonal woodlands, similar to those reconstructed for the middle Miocene of Pasalar in Turkey. This environmental shift was probably a requisite for the successful emigration of apes out of Africa.

Just how wet? Neogene primate distributions and the nature of the hypsodonty humidity proxy

Jussi Eronen and Mikael Fortelius
Department of Geology and Institute of Biotechnology, University of Helsinki, Finland

There is a fuzzy but statistically highly significant relationship between local mean annual precipitation and the local mean hypsodonty (molar tooth crown height) of modern large mammal communities. Hypsodonty does not differentiate between seasonal or continuous aridity and is best described as a response to generalised water stress. Estimates at the dry end of the rainfall range are noisy owing to the low numbers of herbivore species in arid and subdesertic habitats.

We used a dataset from the NOW-database (http://www.helsinki.fi/science/now) to investigate how in the Neogene of Europe primates reacted to changes in humidity as reflected by mean hypsodonty at fossil localities. The results show that the distribution of primates followed the distribution of humid areas through time. A comparison between primate and non-primate localities shows differences in mammalian community structure between 11.2 Ma (MN9) and 3.4 Ma (MN15) ago. A major environmental change affecting the distribution pattern and occurrence context of primates took place during this time.

In the time slice 11.2-9.5 Ma ago (MN9) the distribution of primate localities in Europe was the widest of the entire Neogene. About 7.1-5.3 Ma ago (MN13) the hominoid primates disappeared, Mesopithecus was restricted to humid areas in central Europe, Italy and Greece, and we see the first appearance of the genus Macaca in Europe. Unlike before, community structure was now different between primate and non-primate localities. In the time period 5.3-3.4 Ma ago (MN14-15) humid conditions returned to most of Europe and we see the appearance of Dolichopithecus (MN14) and Paradolichopithecus (MN15). The distribution of primates covered most of Europe, and the community structure of non-primate and primate localities became again quite similar.

Size, scale and environment in early Homo

Susan C. Antón
Department of Anthropology, New York University, USA

Early in the evolutionary history of the genus Homo, body size increases and hominins disperse out of Africa, apparently for the first time. Body size changes and dispersal are linked to changes in climate in complex ways. Increases in body size have implications for dispersal capability, as well as for heat-dissipation capability. Far-ranging dispersal, particularly into island Southeast Asia, is also influenced by climatic shifts. Two issues complicate the understanding of this web: 1) the scale at which changes in climate are known and the ability to correlate them with hominin remains and 2) the scant remains themselves, which hamper understanding of the range of variation in body size within and between species of Homo. My data suggest that while average body size may increase at the origin of H. ergaster, the scaling relationships between brain and body size and between size and anatomical characters, is similar to that of earlier Homo. This is unlike the case in H. sapiens in which these scaling relationships change and a grade shift might be argued. Such similarity in scaling across early Homo may argue for better nutritional resources, perhaps facilitated by climate change, cultural shifts, or some combination of the two. Similarly, sparse body-size data available for the worldwide sample of H. erectus (sensu lato), suggest ecogeographic patterning of body size in this species that is also mitigated by presumed resource scarcity for some populations – such as those in Georgia. The differentiation of subpopulations among Asian H. erectus appears related to climatic influences on sea-level and the resulting pattern of land-bridge connections.

Environmental correlates of the cercopithecoid radiations

Sarah Elton
Hull York Medical School, University of Hull, UK

Modern Old World monkeys inhabit an array of different habitats but are especially adept at exploiting relatively open, terrestrial and seasonal environments. This ability was probably established early in cercopithecoid history, with Victoriapithecus showing adaptations to frugivory and semiterrestriality in mosaic habitats. The Old World monkey fossil record in the Miocene is patchy, but by the Plio-Pleistocene, there is evidence of extensive adaptive radiations in Eurasia and Africa. The African radiation is the focus of this paper. Environments associated with the earlier colobines, including Microcolobus and Kuseracolobus, were fairly closed. However, this did not preclude some Plio-Pleistocene species from being terrestrial and exploiting more open habitats, and at least one terrestrial colobine overlapped in time and space with a more arboreal species. The cercopithecine fossil record in the Pliocene and Pleistocene is dominated by two genera, Parapapio and Theropithecus, that were apparently able to exploit mosaic woodland, bushland and grassland habitats. As with the colobines, congeneric species likely to have been adapted to different habitats overlap considerably in time, often at the same locality (for example, Pp. jonesi and Pp. broomi at Sterkfontein, and T. brumpti and T. oswaldi in the Turkana Basin). Furthermore, a clear link between cercopithecid species turnover and global climate change cannot be made. This indicates that there was no simple replacement of one closely-related species by another in response to abrupt environmental change, and attests to the mosaic nature of many Plio-Pleistocene environments in southern and East Africa. Interspecific competition coupled with regional environmental change is thus likely to have influenced Old World monkey radiations much more than did global, abiotic factors.

Primate signalling in a noisy environment

Jonathan Kingdon
Department of Zoology, Oxford University, UK

Primates communicate using transmitters and receivers that involve all the senses.
Signal types are:
1) Hearing = vocalizing/replying
2) Touching = feeling/responding
3) Smelling = scenting/marking
4) Seeing = posture-gesture-presenting/responding.
All signal types are used by primates.
1) Environments, especially forest ones, are literally "noisy". Most primates employ species-specific vocalizations.
2) Most primate social structures employ some degree of physical touching, especially grooming, for bonding or status definition.
3) Strepsirhine and nocturnal primates are especially dependent on scent signals that need to be species and context-specific. Anthropoid primates less so.
4) All primates depend on species-specific visual signals that involve postures, gestures and colour patterns that have evolved to serve communication. This has been taken to extremes in some lemurs, South American monkeys and African guenons, genus Cercopithecus.
This paper concentrates on visual signals and guenons and humans are examined to exemplify some general features of visual communication, especially in visually "noisy" environments. Visual patterns and their signal functions can be shown to be constrained by both the physical and social environment.

Ecosystems in disequilibrium: anthropogenic impacts on the primate communities of Madagascar

Laurie R. Godfrey1 and Mitchell T. Irwin2
1Department of Anthropology, University of Massachusetts, Amherst, USA
2Department of Anthropology, Stony Brook University, USA

There are two possible approaches to understanding natural and human-induced changes in the primate communities of Madagascar. One is to begin with present-day and recent historic interactions, and work backwards. A second is to begin with paleoecological records of Malagasy primate communities before and immediately following human arrival, and the associated evidence of human and nonhuman primate interactions, and work forwards.

On the basis of biological and climatic studies as well as historic and ethnohistoric records, we are beginning to understand the abiotic and biotic characteristics of Madagascar’s habitats, the lemurs’ ecological adaptations to these unique habitats, the extent of forest loss, fragmentation and other forms of disturbance such as hunting, and the differential vulnerability of extant lemur species to these pressures. On the basis of paleoecological, archaeological, and paleontological research, researchers have begun to construct a detailed chronology for late prehistoric Madagascar. We are beginning to understand the sequence of events that led to one of the most dramatic of recent megafaunal extinction/extirpation events.

Combining the perspectives of the past and the present, we see a complex set of interactions affecting an initially rich but vulnerable fauna. The total evidence refutes any simple, unicausal (e.g., hunting / habitat destruction / climate change) explanation of megafaunal extinctions, yet unequivocally supports a major role – both direct and indirect – for humans as the trigger of the extinction process.

Biodiversity, phylogeography, biogeography and conservation: lemurs as an example

Urs Thalmann
Anthropological Institute, University of Zurich, Switzerland

The lemurs of Madagascar represent a spectacular example of adaptive radiation among primates. Given the special setting under which they evolved (i.e. long isolation, geographical location, geological relief), they provide excellent models for study in many realms, at different levels and scales, including diversity. At the same time, they occur in a 'hottest hotspot' region for biodiversity conservation. Although there is no single definition of biodiversity, the most commonly used units to measure biodiversity are species - species richness, species abundance, and for conservation purposes especially species endemism. It is, however, an unresolved issue, what a species actually is, or how it should exactly be defined. Many species concepts have been proposed and several have been used in primatology in recent years. One of the more common approaches to measure diversity and eventually infer species status nowadays is genetic diversity as reflected by mitochondrial DNA differences. Not enough attention has been paid, however, to the different levels at which genetic differences may occur. Lemurs provide instructive examples to highlight the questions involved in species recognition and definition. Starting from examples I will highlight strengths and limits of some analytical tools such as phylogeography and cladistic biogeography, and especially emphasize resulting questions arising at the interface of scientific and conservational perceptions. Both influence decisions for applied conservation of biodiversity.

Poster presentations and abstracts:

Biogeographic evolution of South East Asian primates

Helen J. Chatterjee1, Ian Barnes1, Paul Upchurch2 and Rachel Shore1
1Department of Biology, University College London, UK
2Department of Earth Sciences, University College London, UK

The phylogenetic and biogeographic history of many South East Asian taxa is poorly understood. This is partly due to a sparse fossil record and a limited understanding of the environmental history of the area. Here two primate genera, with distributions across South East Asia, have been selected for study: Macaca and Hylobates. Published molecular data from a range of genetic loci are analysed in both single gene and multiple gene phylogenetic analyses for each genera, in independent and combined reconstructions. Resultant phylogenies are incorporated into cladistic biogeography analyses, using a range of programmes, to reconstruct the biogeographic history of these taxa. The congruence between these analyses for each genus was tested, to predict their patterns of radiation across mainland and archipelagic South East Asia. Molecular clock analyses, conducted in the BEAST program, are used to estimate the timings of these radiations. The resultant biogeographic trees are interpreted in light of current hypotheses regarding the environmental history of the area, and the results of the analyses are combined to provide a new interpretation for the phylogenetic and biogeographic history of macaques and gibbons in South East Asia.

Funded by Wellcome Trust grant VS/05/UCLA11

Evolutionary processes in the primate masticatory system: the case of Theropithecus gelada.

Laura C. Fitton & Gabriele A. Macho
Centre for Research in Evolutionary Anthropology, Roehampton University, London, UK

Variations in the masticatory apparatus of primates are often associated with adaptations, yet when examining overall morphology it is difficult to infer which structures have responded to a particular environmental change and how. A three-dimensional computer model of symmetrical jaw opening was created using C++ and OpenGL based on the principles of forward dynamics. Based on actual morphology (i.e., co-ordinate data) aspects of the skull were changed to determine the effects of certain structures on overall masticatory performance. This is demonstrated for the specialised Theropithecus gelada and the closely-related Papio. While the former is specialised both with regard to morphology and ecology, the latter species retains a more generalized morphology, diet and ecology.

Compared to the masticatory morphology of Papio, T.gelada are more orthognathic and have more dominant anterior fibres of M. temporalis compared to posterior fibres. However, the sequence in which these changes occurred and the possible underlying reasons are unclear. In the model, while keeping all other aspects of morphology the same, the palate of Papio was decreased in length until the final length represented that of T.gelada. The reverse procedure was applied to the palate of T.gelada, i.e., increasing it in length until the palatal length of Papio was attained. M. temporalis muscle morphology was also altered in both; the dominance of the muscle pull was shifted from the anterior belly to the posterior belly in T.gelada and vice versa in Papio. These changes were first considered in isolation and, subsequently, in combination; intermediate stages were created in both Papio and T.gelada and the effect on efficiency was examined. The results shed light on possible sequences of morphological changes and are interpreted within an environmental and ecological context. Parallels are drawn with extinct hominin lineages.

Supported by The National Environmental Research Council: NER/A/S/2003/00347 and NER/S/J/2003/12056

Determination of strontium-calcium ratios in tooth enamel from Papio anubis using LA-ICP-MS

Louise T. Humphrey1, M. Christopher Dean2, Wendy Dirks3, Teresa E. Jeffries4 and Don J. Reid5
1Department of Palaeontology, The Natural History Museum, London, UK
2Department of Anatomy and Developmental Biology, University College London, UK
3Department of Anthropology, Oxford College of Emory University, USA
4Department of Mineralogy, The Natural History Museum, London, UK
5Department of Oral Biology, School of Dental Sciences, University of Newcastle-upon-Tyne, UK

Analysis of tooth enamel using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) provides a basis for systematic evaluation of variation in the chemical composition of enamel in relation to tooth crown geometry. Analysis of thin sections allows the position of discrete samples to be cross-referenced to incremental growth structures in tooth enamel and these markers can be used to determine the age of onset of enamel mineralisation at each sampling point. Strontium and calcium are incorporated into developing teeth in a manner that reflects changing physiological concentrations in the body. Changes are expected to occur in response to marked dietary transitions such as those experienced during the weaning period. Thin sections of three teeth from a single female baboon (Papio anubis) were systematically analysed. The average Sr/Ca ratio increases between successively later forming teeth, consistent with a gradual shift in diet during this period. Distribution maps for Sr/Ca ratios are interpreted in relation to tooth crown geometry and incremental growth lines for each section. Sr/Ca ratios typically decrease between adjacent sampling points along trajectories running from the enamel dentine junction towards the enamel surface. Disturbances in this underlying trend are evaluated for chronological consistency, and used to identify possible dietary transitions.

Funding for this project was provided by the University Research Committee of Emory University.

Environmental influences on the kinematics of vertical climbing in primates

Karin Isler
Anthropologisches Institut und Museum, Universität Zürich-Irchel, Switzerland

In comparative studies on the evolution of locomotor adaptations in primates we are mainly concerned with the interrelationship between morphological traits and locomotor performance. However, in any attempt to reconstruct the evolutionary history of primate locomotor habits, influences of the environment must also be considered. In the present study, such influences were examined through an intraspecific comparison of the gait parameters and kinematics of hominoids, atelines and snub-nosed monkeys climbing vertically on different substrates or in different habitats. We demonstrate that individual exposure to locomotor opportunities does not alter the basic characteristics of species-specific climbing kinematics, but it may affect locomotor speed. Kinematic differences between climbing on different substrates are mainly influenced by substrate diameter, and much less by orientation or flexibility of the substrate. A habitat change leading to an increased frequency of terrestrial locomotion could favour the evolution of a higher degree of sexual dimorphism in body size, which in turn leads to sexually dimorph locomotor habits and climbing performance, as shown, e.g., by Rhinopithecus bieti and Gorilla gorilla. Nevertheless, an interspecific comparison shows that climbing kinematics are remarkably similar between Rhinopithecus, Pan paniscus and Ateles. This result provides further evidence for the independent acquisition of hominoid-like locomotor specialisations in distantly related lineages of primates.

VNTRs and adaptation to changing climates during human evolution

Ursula Paredes-Esquivel1,2, John. P. Quinn1, Vivien J. Bubb1 and Gabriele A. Macho1,2
1Department of Human Anatomy and Cell Biology, University of Liverpool, UK
2Centre for Research in Evolutionary Anthropology, Roehampton University, London, UK

Hominin evolution during the Pleistocene is marked by a series of migrations (Foley & Lahr, 1998), probably triggered by changes in climate and environmental conditions. This was accompanied by morphological and behavioural changes and technological innovations. Increased reliance on high-protein and energy-rich foods, like meat, probably also occurred during this period. This may have been mediated by serotonin neurotransmission, which regulate complex social responses, diet preferences and emotional behaviour.

In apes and old world monkeys the 5HTT gene presents two VNTRs (Variable Number of Tandem Repeat). Human VNTRs are functional, modulating gene expression and possibly affecting serotonin neurotransmission. Since it is modulation of gene expression that produces phenotypic differentiation we screened the I2 VNTR region in the 5HTT gene in 8 species of apes and old world monkeys (N=50) using PCR. We cloned all VNTR variants into a reporter gene system to quantify gene expression in vitro. Homo exhibits the smallest VNTR when compared to Pan and Gorilla while functional analyses revealed Homo I2 VNTRs showing a higher gene expression activity compared to apes and cercopithecines.

Our results imply differences in serotonin availability between humans and apes, possibly as a result of different VNTR modulation leading to increased serotonin transporter activity and, hence, decreased levels of serotonin in modern humans. Low concentrations of serotonin have been correlated with increased explorative behaviour (Treflov et al., 2000), heightened dominant-aggression in primates (Mehlman et al., 1994) and preference for fatty foods (Schwartz et al., 2000). Given the correlation between these factors and their importance in human evolution/dispersion, we tentatively propose a causal link between VNTR polymorphisms and behavioural and cultural changes seen in human evolution.

Hominid evolution and seasonality

Gabriele A. Macho
Center for Research in Evolutionary Anthropology, Roehampton Unversity, London, UK

Climatic changes and their consequences on the environment are commonly considered driving forces in evolution. Both global temperature fluctuations (e.g., deMenocal, 2004) and smaller-scale local variations (e.g., Bonnefille et al., 2004; Trauth et al., 2005) may have influenced hominin evolution, but the exact mechanisms and causal relationships are still poorly understood. Here we contribute to the debate by adding information about predictability of seasonal rainfall to the database.

Seasonal fluctuations in rainfall, food availability and, consequently, metabolic stress are often recorded in biological structures (e.g., tree-rings, gastropod shells). Dental tissue similarly retains a permanent record of developmental processes and of the disturbances resulting from recurrent environmental stressors. Histological sections of teeth (and sequences of teeth) from 4 different time periods were analysed for recurrent stress patterns. Only browsers and mixed feeders were used as a previous study (Macho et al., 2003) revealed a more complex pattern in these animals than is the case for grazers, thus reducing the probability of the findings being due to chance.

All results are statistically significant, with the pattern of rainfall seasonality at 3.9Ma being comparable to present day conditions. However, the dry seasons became apparently prolonged at about 2 Ma, while at 0.7 Ma their length was outside the range of the conditions found today. This, together with global changes at about 0.7 Ma may have put hominins under considerable stress. The emergence of Homo heidelbergensis, brain expansion after a long period of relative stasis, and advances in lithic technologies could thus be explained.

Supported by the Leverhulme Trust (F/25/BK)

Episodic early human occupation of Britain

Chris Stringer
Department of Palaeontology, The Natural History Museum, London, UK

Until recently it was generally believed that the Pleistocene human occupation of Britain was near continuous from the Middle Pleistocene onwards. However, recent research suggests that instead there were repeated colonisation events, followed by local extinctions, and recolonisations. The unique palaeogeographic position of Britain meant that periods of low sea level with the maximum extent of land connection with continental Europe were also the least hospitable due to climatic deterioration, while the establishment of the English Channel during the Middle Pleistocene meant that at times of climatic optima, Britain became an island, isolating existing inhabitants, or preventing the arrival of new ones.

The Ancient Human Occupation of Britain project is a 5- year collaborative enterprise between archaeologists, palaeontologists and geologists to reconstruct the pattern of early colonisations, and investigate the factors controlling these. Approaches include excavation, faunal and archaeological collections research, stratigraphic and chronometric studies, and isotope analyses. Project results so far include evidence that Boxgrove does not mark the earliest occupation of Britain and that there was population decline during later Middle Pleistocene interglacials, culminating in complete human absence during the last interglacial.

Supported by the Leverhulme Trust.

Climate and chronology of the Late Palaeolithic in Northern and Eastern Morocco

Nick Barton1, Abdeljalil Bouzouggar2, Christopher Bronk-Ramsey3, Simon Collcutt4, Tom Higham3, Louise T. Humphrey5, Simon Parfitt6, Ed Rhodes7, Jean-Luc Schwenninger3, Chris Stringer5 and Steven Ward8
1Institute of Archaeology, Oxford University, UK
2Institut National des Sciences, de l'Archéologie et du Patrimoine, Rabat, Morocco
3Oxford Radiocarbon Accelerator Dating Service, Oxford University, UK
4Oxford Archaeological Associates, Oxford, UK
5Department of Palaeontology, The Natural History Museum, London, UK
6Department of Archaeology, University College London, UK
7Australian National University, Canberra, Australia
8School of Geography and the Environment, Oxford University, UK

Northwest Africa has long been considered a key region for investigating human evolution and dispersals in the Upper Pleistocene, and the local archaeological record for this period can be subdivided into the Middle Palaeolithic, the Aterian and the Ibéromaurusien (Upper Palaeolithic). The Ibéromaurusien is closely identified with modern human skeletal remains (e.g. at Taforalt, Morocco and Afalou, Algeria) but the origins of this cultural entity are obscure, as is the relationship to the earlier Aterian and Middle Palaeolithic, and their associated fossil remains (e.g. the fossils from Dar es Soltan 2, and Jebel Irhoud). Certain authors have raised the possibility of continuity with the Aterian, but there is alternative evidence for a clear temporal break between the Ibéromaurusien and the preceding Aterian.

In this poster we present our current research at several sites in Morocco, providing chronological and stratigraphic evidence for the earliest Upper Palaeolithic in northern and eastern Morocco. Among the issues to be considered: when does the Upper Palaeolithic first appear in this area, should it be regarded as synonymous with the Ibéromaurusien, and is there any correlation between episodes of human activity and climatically induced environmental changes?

At the Grotte des Pigeons at Taforalt (Eastern Morocco), we have investigated a long sequence of deposits spanning the Middle to Upper Palaeolithic and containing rich archaeological, environmental and palaeontological evidence. New AMS and luminescence dating evidence seems to push the Upper Palaeolithic further back in time than previously known in the region with the Ibéromaurusien potentially spanning at least 13,000 – 22,000 radiocarbon years ago, and an earlier Upper Palaeolithic at about 25,000 radiocarbon years. The dating and study of underlying Aterian levels is still in progress but on stratigraphic grounds, at least, there seems to be a noticeable break between the Aterian and the Upper Palaeolithic part of the sequence. Comparing marine isotope, palaeoenvironmental and archaeological evidence from several sites, the relationship between the marine and terrestrial records remains complex, but palynological studies indicate synchroneity between major vegetational changes and millennial scale marine oscillations.

A new method for the quantitative analysis of cut-mark micromorphology

Silvia Bello and Christophe Soligo
Department of Palaeontology, The Natural History Museum, London, UK

Cut-marks left on the bones of butchered animals (and occasionally humans) form some of the earliest available direct evidence of behaviour in the evolutionary lineage leading to modern humans. As such, they can provide an unparalleled window into the cognitive ability of early to anatomically modern humans. Issues such as the anatomical elements on which cut-marks are found, their arrangement and placement on these elements and the species affected are frequently reported in the literature. Accurate descriptions of cut-mark micromorphology, however, are rare. Here we present a new method that allows a three-dimensional reconstruction of cut-mark morphology and the quantification of profile parameters. We have tested this new technique on cut-marks that were experimentally inflicted on a pig rib using both a knife and a modern flint flake at different angles. The slopes and depth of the resulting cut-marks, their shoulder heights and the radius of a circle fitted to the bottom profile of the cut-mark were recorded. The data show that knife mark sections are characterised by a V-shape or √-shape depending on the inclination of the knife. Cut-marks produced with the flint flake were less clearly defined with a generally larger bottom radius than that of the knife marks. The results demonstrate the method's potential for assessing the force and direction of cutting action as well as for identifying the types of tools that were used. Preliminary implications for the interpretation of cut marks found on a fossil human parietal from Gough's Cave (Somerset, England) are discussed.

The length of the 2nd to 4th digit ratio (2D:4D) and its relationship to primate mating strategies and the evolution of human sociality

Emma Nelson
Department of Archaeology, University of Liverpool, UK

The length of 2nd to 4th digit ratio (2D:4D) differs between the sexes in humans, non-human primates and probably other mammals and reflects exposure to differing levels of foetal sex hormones. 2D:4D has been studied extensively in humans and correlates with some gender specific diseases and behaviours, particularly those relating to reproductive ability. 2D:4D also varies between ethnic groups; polygamous societies tending to have more masculinised 2D:4D’s than monogamous groups. Within a population high foetal testosterone may enhance a male’s ability to attract and compete for females resulting in lower digit ratios.

Non-human primate digit data are rare. From the limited data that are available, it seems that non-human primates have lower digit ratios than humans, implying a greater prenatal testosterone effect and/or an increased sensitivity to foetal androgens compared to humans. This study aims to collect non-human primate digit data to see if there is a relationship between inter-specific mating strategies and 2D:4D. It also aims to put this into a wider evolutionary context by asking why humans experience a more oestrogenised foetal environment than other primates and how this may have affected human social evolution.

Four years of rainforest baboons at Gashaka

James Higham1, Caroline Ross1, Ymke Warren1, Ann MacLarnon1, Volker Sommer2 and Jeremiah Adanu3
1Centre for Research in Evolutionary Anthropology, Roehampton University, UK
2Department of Anthropology, University College London, UK
3Department of Forestry and Wildlife, Federal University of Technology Yola, Adamawa State, Nigeria.

Baboons (Papio spp.) are the most successful and ubiquitous African primate, renowned for their behavioural and reproductive flexibility. These qualities have enabled them to extend their range into a wide variety of habitat types over much of Africa, including desert, savannah and forest environments. Despite this they appear to be excluded from the wet, forested areas of Central and West Africa, leading to speculation about mechanisms, such as competition and disease, that may exclude baboons from closed rainforest. Here we present 4 years of demographic data from a group of Papio anubis inhabiting lowland rainforest and guinea savannah mosaic at the southern-most tip of the Anubis range in Gashaka-Gumti National Park, Nigeria. Rainfall in the study area is high, averaging over 2000mm and reaching a maximum of over 2300mm per annum, making it by far the wettest baboon site studied to date. Infant mortality in the study group (Kwano troop, n=26) is high (60%, 9/15 births), and these deaths are clustered in time, largely during the rains (April – October). Age at death varied from 0 - 9 months. In addition, there is high adult female mortality (33%, 3/9), which occurred exclusively during the rains. Data from a sympatric group of baboons (Gashaka troop, n=19) that supplement their diet by crop raiding show substantially lower mortality (infant - 17%, 2/12 births, no adult female deaths), demonstrating that improved nutrition may help to buffer against environmental conditions. This suggests that the clearing of forests in Central and West Africa for agricultural land may allow baboons to extend their range into regions from which they are currently excluded.

Faecal progesterone and oestrogen metabolite excretion and embryonic and foetal development in the grey mouse lemur (Microcebus murinus)

Barbara Daffner1,2, Ann-Kathrin Oerke2, Ute Radespiel3, Elke Zimmermann3, Michael Heistermann2, Ann MacLarnon1 and J. Keith Hodges2
1School of Human & Life Sciences, Roehampton University, London, UK
2Department of Reproductive Biology, German Primate Centre, Göttingen, Germany
3Department of Zoology, Hannover Veterinary School (TiHo), Germany

Although prosimians are of considerable importance to our understanding of primate reproduction in an evolutionary context, information on most aspects of the physiology of reproduction in this taxon is extremely limited. As part of a comparative study on selected lemur species, the aim of this study was 1) to generate basic data on profiles of reproductive hormones during pregnancy and 2) to provide information on milestones of embryonic development and foetal growth in a cheirogaleid species, the grey mouse lemur.

Data were collected on 8 pregnancies in 5 adult females with known breeding history. Transabdominal real-time ultrasonography was performed weekly following oestrus on unsedated animals (2 complete, 6 incomplete pregnancies monitored). Faecal samples, collected 3-4 times per week until 1 week after parturition were measured for immunoreactive progesterone and oestrogen metabolites using enzyme-immunoassays for pregnanediol (PdG) and total oestrogens (Et).

Median total gestation length (TGL) was 64 days (day 1 indicated by presence of sperm and/or vaginal cytology). According to ultrasound, diagnosis of pregnancy (indicated by a fluid-filled lumen in either uterine horn) was possible by day 13 (20% TGL); visualization of the embryo by day 20 (31% TGL), detection of embryonic heart beat by day 27 (42% TGL), and initial measurement of foetal biparietal diameter (BPD) by day 34 (53% TGL). By indicating an embryonic-foetal shift around day 30-34 (50% TGL), the data suggest a relatively long period of embryonic development. Faecal PdG and Et concentrations remained at non-pregnant levels for at least the first half of pregnancy. Thereafter (around day 40, 58% TGL), there was a modest increase in PdG levels (3-4 fold) and a much more marked rise in Et (up to 50 fold) to reach maximum levels 5-10 days before birth. The relatively late increase in hormone excretion, occurring shortly after the projected time of the embryonic-foetal shift, suggests a placental and/or foetal, rather than ovarian origin of gestational hormones.

Study on natural behaviours of captive Varecia variegata in two semi-free ranging enclosures in the UK

Simon Downs
MSc Course in Primate Conservation, Oxford Brookes University, Oxford, UK

Captive Varecia variegata housed in different sized free ranging enclosures at Woburn Safari Park and Cricket St Thomas, UK were studied to evaluate levels of behaviours compared to the wild. Arboreal enrichment was applied to measure the extent to which the lemurs from each enclosure could enhance: levels of activity, feeding and foraging, arboreal locomotion, and suspensory postures. Results were compared between enclosures and with studies on Varecia conducted in the wild and discussed in terms of the potential for enclosures to be used as ‘boot camps’ for future reintroductions. Resting behaviour remained the most common behaviour in both control and enrichment conditions at both sites. Enrichment had greatest impact on the smaller sized enclosure, producing significantly higher levels of activity, feeding/foraging and arboreality. At one large naturalistic enclosure the Varecia escaped on a regular basis and this allowed the opportunity to compare behaviours between inside and outside the enclosure. Results demonstrated that, given an increased free ranging environment, the lemurs significantly increased levels of activity, feeding and foraging, arboreal locomotion and suspensory postures. Levels of arboreality remained unchanged. Feeding on natural vegetation exceeded feeding on provisioned food throughout the study inside and outside the naturalistic enclosure. Comparisons with wild studies showed similarities prompting the author to recommend the site for consideration as a ‘boot camp’ for any future reintroduction attempt for the species.