PSGB Winter Meeting 2002

"Primate Evolution and Adaptation"

Friday 29th November at the Zoological Society of London Meeting Rooms

Register for the meeting on the day; registration from 9am; PSGB Student Members £5; Student Non-Members £10; Other PSGB Members £15; Other Non-Members £20

IMPORTANT TRAVEL INFORMATION

Regent's Park tube will be closed because of the firefighters' strike on Friday 29th. London Underground recommend using Great Portland Street instead, which is a short walk from Regent's Park. Walk through the park, or catch a 274 bus to get to the Zoo from Regent's Park tube. The 274 also goes from Oxford Circus and Baker Street tube stations, neither of which are closed. The C2 bus also goes near the zoo: get it at Oxford Circus or Great Portland Street.

Camden Town tube station will be open with no restrictions on the Friday, but is open for exit only between 13.00 and 15.30 on Saturday and Sunday (in case anyone is staying in the area over night on Friday). Camden Town is the nearest tube station to the zoo: follow the signs up 'Parkway' to the Zoo (12 minute walk).

Programme

9. 00 Registration

9.50 Welcome

Session 1

10.00 Dan Gebo, Northern Illinois University:Hedgehogs, Tarsiers or Basal Anthropoids: Asian Eosimiids

10.30 Peter Andrews, Natural History Museum, London: Middle Miocene apes from Turkey

11.00 Robin Crompton, University of Liverpool: Origins of knuckle walking, vertical climbing and bipedalism: a new hypothesis on locomotor diversity in Hominoidea

11.30 Coffee

Session 2

Osman Hill Memorial Lecture

12.00 Ian Tattersall (American Museum of Natural History, CUNY) will give the Osman Hill Memorial Lecture

12.50 PSGB AGM and lunch

Session 3

14.00 Kate E. Jones and Ann M. MacLarnon, Roehampton: Affording larger brains: what bats can tell us about primates

14.30 Christophe Soligo, Natural History Museum, London: Patterns of phyletic size change in Primates

15.00 Chris Dean, UCL: Variation in primate life history reflected through tooth development

15.30 Coffee

Session 4

16.00 Margaret Clegg, UCL: Comparing vocal tracts across primate species

16.30 Todd Rae, University of Durham: Paranasal pneumatization in fossil Cercopithecoidea and the evolution of the maxillary sinus

17.00 Paul OÕHiggins, UCL: Growth and the evolution of primate craniofacial variation

17.30 Poster session

For further details, please contact

Sarah Elton
Department of Anthropology
Eliot College
University of Kent at Canterbury
Canterbury
Kent
CT2 7NS
UK

Tel: 01227 823232
Fax: 01227 827289
Email: S.E.Elton@ukc.ac.uk

ABSTRACTS

Peter Andrews
Natural History Museum, London
Taxonomy and biogeography of middle Miocene apes from Turkey

Two species of fossil ape are known to be present at the middle Miocene site of Pasalar in Turkey. One of the species is represented by 11 mandibles and maxillae and over 1000 isolated teeth, and this is identified as Griphopithecus alpani, the type site of which is Candir, another middle Miocene site in Turkey. The other fossil ape is a new species assigned to the African genus Kenyapithecus, and this is based on two maxillae and 59 isolated teeth including all the incisors, canines and third premolars and the upper fourth premolars. The posterior teeth of the new species cannot at present be distinguished from those of Griphopithecus alpani despite good associations of anterior and posterior teeth on the maxillae. The biogeographic consequences of assigning a species of fossil ape from Turkey to an African genus suggest different conditions in the middle Miocene, for at the present time there is no genus of sub-Saharan primate known outside Africa other than Homo.

Margaret Clegg
University College, London
Comparing vocal tracts across primate species

Humans are considered to differ from all other primates in having an enlarged supralaryngeal or vocal tract. This increased length is regarded as particularly important in the wider range of sounds involved in human speech. Few studies however, exist to show the comparative lengths of the vocal tract or its constituent parts in various primate species. A variety of assertions have been made regarding the relationship between the different regions of the vocal tract. For example, humans are regarded as having a smaller oral cavity than other primates have. However, such assertions are rarely quantified either relatively or absolutely.

In this study the length of the vocal tract, oral cavity, tongue and larynx (including vocal folds) was measured in humans and a wide range of other primates. The measurements were compared to bodymass. The relationship between the component parts was compared.

The human mouth contributes less to vocal tract length than in other primates. However, humans have an oral cavity of the length expected for a primate of their body size. The re-organisation of the vocal tract in humans has altered the contribution of the component parts. However, when the larynx is examined, humans often fall within the confidence intervals and are thus like other primates. Larger laryngeal sizes were found in those species with loud calls. The major exception being in human female vocal folds which are shorter than expected for laryngeal size. The opposite pattern was found in the colobus monkey. It would seem that humans are not different from other primates on all the parameters examined.

Robin Crompton
University of Liverpool
Origins of knuckle walking, vertical climbing and bipedalism: a new hypothesis on locomotor diversity in Hominoidea

Biomechanical evidence suggests that hominid bipedality arose in an arboreal context, in a behaviour similar to the orthograde scrambing and hand assisted bipedality of modern orang-utans, which also appears more typical of African apes when studied in the deep forest. If bipedalism is traced back to arboreal, orthograde locomotion on relatively small supports in the high canopy, in a common great ape or even hominoid ancestor, we require to explain how knuckle walking (in particular) arose. This paper suggests that habitual, terrestrial bipedalism (in human ancestors) and a locomotor repertoire including knuckle walking and vertical climbing (in those of chimpanzees and gorillas) were contrasting responses to fragmentation of the continuous forest canopy in the late Miocene/Pliocene.

Chris Dean
University College, London.
Variation in primate life history reflected through tooth development

Both the period of growth and development and, for example, lifespan vary among primates. These and other life history attributes co-vary in a complex way but one suggestion is that adult mortality rates may be one of the key determinants influencing many life history variables. There is evidence that the earliest fossil hominids resembled living great apes in the time they took to become dentally mature, but the question that has remained less clear is when and why during human evolution hominids came to resemble modern humans in their development. As a test of the hypothesis that tooth development must keep pace with the time available for growth and development, the rate of enamel development was recorded in both human deciduous and permanent teeth as well as in the teeth of a spectrum of primates with different periods of development. It seems likely that rate of enamel formation is just one of several things that can vary in a way that alters the time taken to grow a tooth. Among early fossil hominids (including Homo erectus), the growth rates of enamel are faster than in human permanent teeth and, superficially, some early hominids even resemble human deciduous enamel. So far, only in the enamel of a Neanderthal (Tabun C) do rates of formation appear identical to modern humans but obviously we need to look more carefully at other hominids dated to within the last 500,000 years. These findings allow us to reconsider what it was (post Homo erectus) that triggered a shift in life history schedules and in particular to ponder whether there is a relation between increasing brain size and adult mortality rates among hominids.

Dan Gebo
Northern Illinois University
Hedgehogs, Tarsiers or Basal Anthropoids: Asian Eosimiids.

Mid-Eocene eosimiid fossils from China have had a controversial history since their initial description at Duke University in 1992. In this talk, I will briefly review this history and re-examine eosimiid morphology in light of new fossils recovered from China and Myanmar. So far, the Shanghaung fissures in China have produced four distinct groups of haplorhine primates, including the eosimiids. These forms range in body size from shrews to callitrichids. At Myanmar, besides the genus Bahinia (400 g), a small calcaneus from Pondaung (Late Eocene) is currently in press. This calcaneus is much smaller than Bahinia and resembles calcanei attributed to Eosimias. It certainly represents a new 100g eosimiid. Thus known eosimiids span a considerable geographic range in the mid to late Eocene of Asia and perhaps to the Oligocene of Africa with dental similarities to Afrotarsius.

Kate Jones and Ann MacLarnon
University of Surrey, Roehampton
Affording larger brains: what bats can tell us about primates

Several major hypotheses have been proposed to explain how larger brains, such as those of many primates, are afforded in energetic terms. To date, these theories have largely been tested only on primates, with some cross-mammal analyses. In addition, almost all the analyses presented as testing the maternal energy hypotheses have not actually tested it adequately. In this paper, we present analyses testing the three hypotheses on bats, an order, like primates, that encompasses a broad range of relative brain sizes, and considerable dietary variation. For a general hypothesis for the energetic solution to affording larger brains to be correct, it should be applicable to bats as well as to primates. Analyses demonstrate that the direct metabolic constraint and expensive tissue hypotheses are not supported in bats; indeed the results produced are opposite to those predicted by the latter hypothesis. However, the maternal energy hypothesis is supported when the combined effects of basal metabolic rate and gestation length on brain size are analysed. Together with results of previous studies on primates and across mammals, these results demonstrate that the investment capacity of mammalian mothers during gestation is fundamental to the adult brain size finally attained.

Paul OHiggins
UCL
Growth and the evolution of primate craniofacial variation

The primate craniofacial skeleton varies both within and between species. Principally these variations are in proportioning rather than in patterning and often form the basis of phylogenetic, functional and ecological interpretations of fossil material. Several difficulties arise in relation to such studies, not least because facial morphology often shows convergences and parallelisms between species and it is difficult to distinguish sexual dimorphism from interspecific variation. Given that adult morphology is the product of ontogeny, insights from studies of ontogenetic transformations are of importance in relation to understanding the basis of evolutionary transformation and so the significance of differences in craniofacial form.

In this presentation geometric morphometric methods will be briefly described and their potential in the analysis of ontogenetic shape and size transformations of the facial skeleton will be illustrated. Some recent work will be reviewed that examines the ontogeny of sexual dimorphism and interspecific differences in papionins and hominoids. In particular these studies address the extent to which inter and intra specific differences are already present in infancy and the extent to which growth further modifies such differences. Given this background, new studies of variations amongst living and fossil hominins will be presented. These investigate the extent to which post natal ontogeny accounts for the differences amongst hominins and lead to some novel conclusions regarding the hominin radiation.

Todd Rae
University of Durham
Paranasal pneumatization in fossil Cercopithecoidea and the evolution of the maxillary sinus

Unlike most primate groups, Old World monkeys generally lack the maxillary sinus, an air pocket of the cranium lateral of the nasal cavity proper. Character state analysis of living cercopithecoids across well-supported topologies suggests that the sinus was lost near the origin of the group, only to have evolved again convergently in extant macaques. Until recently, testing the 'early loss' hypothesis with reference to extinct taxa had been difficult, given the paucity of descriptions of cranial pneumatization in fossil monkeys.

To assess the pattern of cercopithecoid sinus evolution, fossil taxa from both subfamilies (Colobinae, Cercopithecinae) were examined, both visually and by computed tomography (CT). The observations were evaluated according to standard anatomical criteria for defining sinus spaces, and compared with data from all extant Old World monkey genera.

Most taxa examined conformed to the pattern already discerned from extant cercopithecoids. The lack of the sinus in Victoriapithecus confirms the 'early loss' hypothesis; similarly, maxillary sinus absence in Theropithecus oswaldi, Mesopithecus, and Rhinocolobus is also typical for the Papionina, Colobinae, and Colobina, respectively. The fossil macaque Macaca majori possesses a well-developed maxillary sinus, as do all living species of the genus. Cercopithecoides, on the other hand, differs from all other colobines in possessing a maxillary sinus. This indicates that paranasal pneumatization has re-emerged at least twice in cercopithecoids. Along with the unusual nasal cavity of the extant Rhinopithecus, these results suggest that maxillary sinus absence in cercopithecoids is due to suppression, rather than complete loss.

Christophe Soligo
Zurich-Irchel University and Natural History Museum, London
Patterns of phyletic size change in Primates

Body size is directly linked to numerous aspects of the biology of an animal. As a result, there has been a long history of interest in patterns of size distributions and size change in the fossil record. One principle that is often quoted as underlying phyletic size change in mammals in general is known as Cope's Rule. Cope's Rule is usually understood to describe a widespread tendency of animal groups to evolve towards larger body size. Such an inherent trend towards larger size within species lineages has recently been demonstrated by John Alroy (Science 280: 731-734.) for Cenozoic North American mammals.

In a different approach, John Fleagle (Paleobiology 4: 67-76.) compared the size distribution within a range of fossil and extant primate adaptive radiations, and within a number of selected time periods that were significant to the evolution of the order. He concluded that distinctive ecological and behavioural adaptations within primates are associated with particular size distributions. He suggested that size displacement had taken place between the two major groups of Eocene primates and documented the fact that the size distributions of particular taxonomic groups of primates were influenced by the presence or absence of other such groups. Alroy's deterministic interpretation of Cope's Rule together with the observations made by Fleagle raises a question: Is an inherent trend to increase size within species lineages recognisable in primate evolution or are size changes driven by environmental factors?

To address this question I analysed patterns of phyletic size change in the primate fossil record in relation to global temperature, trends in global temperature and latitudinal distribution of species. The analyses were aimed at detecting trends in size change within evolving lineages. No overall within-lineage trends in size change were detected within the primate fossil record. There is no difference between size changes in higher and lower latitudes. Furthermore there is no detectable difference between average size changes during periods of global cooling, periods of global warming and relatively stable periods. However, there is some evidence that, during the Eocene, omomyoids were unable to increase their size above a certain weight due to competition from the radiation of the larger-bodied adapoids.

No generalised causes for size change in primates were identified. Similarly, there is no evidence that primate lineages follow an inherent trend towards increased size. This implies that the observed increase in the average size of primate radiations through time is the result of shifts between adaptive radiations, rather than an inherent trend to increase size as predicted by Cope's Rule.