Curator Emeritus
Negaunee Integrative Research Center
My book How We Do It: The Evolution and Future of Human Reproduction was released by Basic Books on June 11, 2013. In connection with the book, I recently started a regular monthly blog with Psychology Today. In the tree of life, human evolution is a very unusual case in many ways. If the focus of study is too narrow, it is difficult to avoid special pleading. My long-term research strategy has hence been rooted in the conviction that a wide-ranging approach is essential to identify reliable general principles. Secure interpretation of our biological origins demands comprehensive study of primate evolution from its earliest beginnings. In this spirit, I have conducted sweeping comparisons across primates, covering anatomy of both living and fossil representatives, ecology, behaviour, reproduction and molecular evolution. Study of size relationships (allometric scaling) has been a pervasive theme. A synthetic approach to primate evolution has several benefits. In addition to generating sound general principles, it can reveal relationships that otherwise escape detection. One illustrative example is provided by the endeavour to determine times of divergence in the primate tree, notably the split between humans and chimpanzees. Because of major gaps in the fossil record, estimation of divergence times from earliest known fossil relatives can be seriously misleading. Statistical analysis of the numbers of living and fossil primates in combination with an evolutionary tree based on DNA evidence reveals that divergence times within the primate tree are generally substantially earlier than has often been claimed. In particular, the divergence between humans and chimpanzees — widely held to be around 5 million years ago — in fact appears to be closer to 8 million years ago. Another good example is provided by the close connection between brain size and reproductive biology. Only by examining these features in tandem was it possible to infer that maternal energy resources played a vital part in the evolution of the brain. The "Maternal Energy Hypothesis" is particularly relevant to interpreting the evolution of our own very large brain since we diverged from chimpanzees.
Biographical Sketch:
Several continuing themes in my research originated with my PhD project (1964-67) on behaviour and evolution of tree-shrews (Tupaiidae). This was based on research with K. Lorenz and I. Eibl-Eibesfeldt (Max-Planck-Institut, Seewiesen), supervised by N. Tinbergen (University of Oxford). Tree-shrews were then widely thought to be the most primitive living primates and my initial aim was to study their behaviour as a model for inferring adaptations of the earliest primates. While breeding tree-shrews, I discovered a very unusual pattern of maternal behaviour: the infants are kept in a separate nest and the mother suckles them only once every 48 hours during a very brief visit. This finding not only stimulated my long-lasting interest in reproductive biology (particularly maternal behaviour) but also revealed a stark contrast with the intensive infant care that typifies primates, suggesting that tree-shrews are not in fact related to them. This led me to re-examine the evidence (largely morphological) for inclusion of tree-shrews in the order Primates. Data on size and structure of the brain had been very influential and so I initiated comparative studies of the brain that in turn revealed the pervasive importance of allometric scaling. In my PhD thesis, I concluded that tree-shrews are not close relatives of primates. This conclusion has since been reinforced by several other investigations and tree-shrews are now generally relegated to the separate mammalian order Scandentia. In fact, however, the process of excluding tree-shrews from the order Primates brought the key adaptations of real primates into sharper focus, revealing a very early origin for many key features of human biology. In a recent twist, molecular evidence has indicated that the little-studied colugos (Dermoptera) are the most likely sister group of primates.
Following my PhD, I decided to study relatively primitive undoubted primates and obtained a NATO postdoctoral grant (1967-69) to work with J.-J. Petter and A. Petter-Rousseaux (Museum National d'Histoire Naturelle, Brunoy). I made detailed studies of reproductive biology on their unique breeding colony of mouse lemurs while continuing my broad-based work on primate morphology. During this postdoctoral period, with support from the Royal Society (London), I also conducted my first behavioural/ecological field study in Madagascar (1968), including original observations on mouse lemurs. Combined field and laboratory observations indicated that mouse lemurs are in fact a suitable model for inferring the ancestral primate condition and that several key adaptations can be traced to a small nocturnal ancestor in the "fine-branch niche" of tropical and subtropical forests.
My postdoctoral research was followed by my first university post as Lecturer in Biological Anthropology at University College London (1969-74). In this new post, I continued to work on reproduction of mouse lemurs in a newly founded colony, while simultaneously expanding comparative work on morphology of the skull, brain, postcranial skeleton and reproductive system in primates. I also conducted a second field study of mouse lemurs in Madagascar (1970). During this period at UCL, my interest in allometric scaling grew and I focused in particular on the size of the brain and its parts. My work also expanded to include studies of primate fossils, notably early forms such as Adapis, including study of endocasts of the cranial cavity.
At this point in my career, I moved to become Senior Research Fellow at the Wellcome Laboratories, Zoological Society of London (1974-78), where I was responsible for coordinating research on mammalian reproduction. The main projects involved breeding colonies of primates: mouse lemurs, owl monkeys and cottontop tamarins. Owl monkeys are the only nocturnal higher primates and were also of major interest for research on human malaria, so a grant was obtained from the Wellcome Trust to conduct, with A. Dixson, the first detailed study of their reproductive biology. In connection with the projects on primate reproduction, I established a laboratory for hormone radioimmunoassay. This opened up possibilities for conducting hormonal studies on easily-collected urine samples and combining these with studies of behaviour unaffected by sample collection. While applying this to gorillas, I initiated a long-standing research connection with the Jersey Wildlife Preservation Trust, becoming Chairman of the Scientific Advisory Committee in 1975 and a Council member in 1978 (both posts held until 2001). My connection with JWPT (now re-named as the Durrell Wildlife Conservation Trust) strengthened a growing interest in primate conservation biology and led me to focus on the topic of breeding endangered species in captivity.
In 1975, I also spent a semester at Yale University as Visiting Professor in the Department of Anthropology. This allowed me to visit several research centres and museums in the USA to study fossil specimens and develop my work on comparative morphology. One significant finding confirmed by comparative studies of endocasts of fossil and living primates is that brain size has increased over time in all lineages, so humans are in fact distinguished from other primates by an unusually high rate of brain expansion.
In parallel to other studies, I also organised a quantitative radiotelemetric field study of behaviour and ecology of lesser bushbabies in South Africa supported by the Royal Society (1975-77). The fieldwork was mainly conducted by S. Bearder, although I was able to join him for several months in the field. Apart from yielding detailed data on social organization, our observations confirmed my interpretation of the ancestral primate as a small-bodied nocturnal form occupying the fine-branch niche.
From the Zoological Society, I then moved back to University College London for eight years, first as Reader (1978-82) and then as Professor (1982-86) in Biological Anthropology. My primary research became focused on allometric scaling, particularly concerning the brain. A key development was the inference of a link between metabolic rate and brain size in mammals. The realization that this link must be indirect led to my hypothesis, linking brain size to reproductive biology, that resources provided by the mother have a major influence on the evolution of brain size. This "maternal energy hypothesis" was first published in Nature in 1981 and consolidated in the 1982 James Arthur Lecture on the Evolution of the Human Brain (American Museum of Natural History, New York). It also led to a 3-year project grant (1982-85) from the Medical Research Council (London) to investigate quantitative aspects of brain development and associated reproductive features of primates. In 1983, I spent a semester as Professeur Associe at the Musee de l'Homme, Paris and used this opportunity to study variation in modern human brain size. My interests in fieldwork on primate ecology also continued on a more modest scale during my second period at UCL. Two study visits were made to Brazil with support from the Royal Society (1980) and the British Council (1982-85). In 1981, I was invited to spend 2 months as Senior Visiting Fellow at the Smithsonian Tropical Research Institute, Panama, where I mainly conducted observations on behaviour and ecology of howler monkeys.
In 1986, I moved to take up the post of Director and Professor at the Anthropological Institute in Zurich and built up a range of research activities. The breeding colony of New World monkeys (Callimico, Callithrix, Cebuella) became an important research resource for work on behaviour and reproduction. Major collections of primate specimens are also available for quantitative studies. After moving to Zurich, I completed work on an advanced textbook, Primate Origins and Evolution (1990), as a synthetic overview arising from my research. Two chapters cover the sense organs and the brain, which played a pivotal role in primate evolution. Together with S. Bunney, J.S. Jones and D.R. Pilbeam, I later coedited the award-winning Cambridge Encyclopedia of Human Evolution (1993). For the last eight years of my appointment in Zurich, I was a member of the national committee for biology and medicine of the Swiss National Science Foundation.
In September 2001, I took up an appointment at The Field Museum, first as Vice President and then as Provost for Academic Affairs. My responsibilities, with an emphasis on external relationships, were to coordinate research programmes, collections management, contributions to higher education and exhibit-related activities with a team of 40 curators and 60 professional staff in Anthropology, Botany, Geology and Zoology. In parallel to my administrative appointment, I held a post as curator in Anthropology. After stepping down from my administrative role as Provost in 2006, I became the A. Watson Armour III Curator of Biological Anthropology and have since been able to devote my energies predominantly to research, teaching and publication.
Education and Work
1964: B.A. (Honours) in Zoology. Worcester College, Oxford, England 1967: D.Phil. in Zoology (Animal Behaviour). Worcester College, Oxford, England
1969-1974: Lecturer in Physical Anthropology University College London 1974-1978: Senior Research Fellow, in charge of the Wellcome Laboratories of Comparative Physiology, Zoological Society of London 1975: Visiting Professor, Physical Anthropology, Yale University (USA) 1978-1982: Reader in Physical Anthropology, University College London 1978-1982: Visiting Professor in Zoology, Birkbeck College, London (organiser of Primate Biology course) 1982-1986: Professor of Physical Anthropology, University College London 1983: Professeur Associé, Musée de l'Homme, Paris, France 1986-2001: Professor and Director, Anthropologisches Institut und Museum, Universität Zürich-Irchel, Switzerland 2001-2003: Vice President for Academic Affairs, The Field Museum, Chicago 2003-2006: Provost, The Field Museum, Chicago 2006-present: A. Watson Armour III Curator of Biological Anthropology, The Field Museum, Chicago
Accomplishments
1968: Thomas Henry Huxley Award from the Zoological Society of London for Ph.D. thesis completed in 1967 1977: Elected Fellow of the Institute of Biology (London) 1982: Invited to give the 52nd James Arthur Lecture on the Evolution of the Human Brain, American Museum of Natural History, New York 1983: Invited to give the 11th Curl Lecture in Anthropology by the Royal Anthropological Institute (London) 1989: Invited to give a special guest lecture at the symposium "Fertility in the Great Apes" in Atlanta, Georgia 1990: Invited to give the Osman Hill Memorial Lecture in Primatology (with Memorial Medal) by the Primate Society (Great Britain) 1993: Award for Excellence in the category "Best Specialist Reference Work 1992" from the Literati Club (UK) for The Cambridge Encyclopedia of Human Evolution (shared with S.Bunney, J.S.Jones and D.R.Pilbeam). 1995: D.Sc. degree awarded by the University of Oxford 1998: Invited to give the Gerald Durrell Lecture by the Jersey Wildlife Preservation Trust 2001: Elected Professor Emeritus by the University of Zürich, Switzerland 2003: Invited to give the Ernst Mayr Lecture by the Berlin-Brandenburgische Akademie der Wissenschaften and the Wissenschaftskolleg zu Berlin 2004: Elected Fellow of the American Association for the Advancement of Science, Section on Anthropology
2001-present: Member of the Committee on Evolutionary Biology, University of Chicago 2001-present: Adjunct Professor, Department of Anthropology, University of Illinois at Chicago 2003-present: Adjunct Professor, Department of Anthropology, Northwestern University, Chicago 2010-present: Adjunct Professor, Department of Anthropology, University of Chicago
Research Sketch
Main Themes
- Reconstructing Primate Evolution Reconstruction of evolutionary relationships among primates (lemurs, lorises, tarsiers, monkeys, apes and humans) has been the consistent primary focus of my research from the outset. This core interest began with my doctoral thesis on tree-shrews, which many contemporary authors included in the order Primates. My research revealed striking differences between tree-shrews and primates, notably in their reproductive behaviour and anatomy, and led to the conclusion that these two groups of mammals should be clearly separated. Tree-shrews are now widely classified in their own order (Scandentia), while molecular evidence indicates that colugos (order Dermoptera) may in fact be the sister group of primates. After completing my doctoral thesis, I gradually expanded my studies to cover an ever-expanding range of genuine primates, both living and fossil. I also extended my behavioural investigations to fieldwork because evolution depend on adaptation to the natural environment. My field studies began with lemurs in Madagascar and subsequently included both New World and Old World monkeys. A major milestone in my goal of achieving a synthetic view of primate evolution was publication of my textbook Primate Origins in 1990, and I am currently completing a successor (Pimate Evolution) for the University of Chicago Press. Phylogenetic Tree for Primates (Martin, 2006; adapted from Martin, 1993): [[{"type":"media","viewmode":"mediaoriginal","fid":"21476","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] Principal References Martin,R.D. (1967) Behaviour and Taxonomy of Tree-Shrews (Tupaiidae). Ph.D. Thesis, University of Oxford (UK). Martin,R.D. (1968) Towards a new definition of primates. Man 3:377-401. Charles-Dominique,P. & Martin,R.D. (1970) Evolution of lorises and lemurs. Nature 227:257-260. Martin,R.D. (1972) Adaptive radiation and behaviour of the Malagasy lemurs. Phil. Trans. Roy. Soc. (Lond.) B 264:295-352. Martin,R.D. (1973) Comparative anatomy and primate systematics. Symp. zool. Soc. Lond. 33:301-337. Martin,R.D. (1978) Major features of prosimian evolution: A discussion in the light of chromosomal evidence. pp. 3-26 in: Recent Advances in Primatology. Vol. 3: Evolution. (eds. Chivers,D.J. & Joysey,K.A.) London: Academic Press. Martin,R.D. (1986) Primates: a definition. pp. 1-31 in: Major Topics in Primate and Human Evolution. (eds. Wood,B.A., Martin,L.B. & Andrews,P.) Cambridge: Cambridge University Press. Martin,R.D. (1990) Primate Origins and Evolution: A Phylogenetic Reconstruction. London/New Jersey: Chapman Hall/Princeton University Press. Martin,R.D. (1993) Primate origins: plugging the gaps. Nature 363:223-234. Martin,R.D. (2006) New light on primate evolution. Ber. Abhandl. Berlin-Brandenburg. Akad. Wiss. 11:379-405. Martin,R.D. (2008) Colugos: Obscure mammals glide into the evolutionary limelight. J. Biol. 7, Art 13:1-5.
- Inferring Divergence Times in the Primate Tree Traditionally, the earliest-known fossil representative has been used to date the time of origin for any group of organisms. In 1986, I suggested that this approach could well lead to lead to serious underestimation of divergence times for primates because of large gaps in the known fossil record. Direct interpretations of that record indicated a Tertiary date of 60-65 million years ago (mya) for the origin of primates. In an invited review article for Nature (Martin, 1993), I presented preliminary calculations to reinforce my suggestion that the actual origin was probably considerably earlier, back in the Cretaceous. But some primate palaeontologists challenged this proposal. In collaboration with several colleagues (Tavaré et.al., 2002), I went on to develop a novel statistical approach explicitly allowing for gaps in the fossil record. This yielded a Cretaceous date of about 85 mya for the common ancestor of extant primates. The inference that primates originated far earlier than commonly believed has been supported by several studies of molecular evidence using divergence dates based on mammal groups with better fossil representation. This has implications for inferring times of origin throughout the primate tree, including human origins. Recent extension of the statistical work has developed a more sophisticated approach that permits simultaneous estimation of two dates in the primate tree: (1) the last common ancestor of all primates (about 85 mya); (2) the last common ancestor of monkeys, apes and humans (about 45 mya). Using these dates to calibrate a primate tree based on a large molecular dataset yields a date of about 8 mya for the divergence between human and chimpanzee. This is considerably earlier than the date of 5 mya, based on a direct reading of the fossil record, that has been widely accepted in the past. Times of Origin in the Primate Tree (adapted from Wilkinson et al., 2011): [[{"type":"media","viewmode":"mediaoriginal","fid":"21486","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] Principal References Martin,R.D. (1986) Primates: a definition. pp. 1-31 in: Major Topics in Primate and Human Evolution. (eds. Wood,B.A., Martin,L.B. & Andrews,P.) Cambridge: Cambridge University Press. Martin,R.D. (1990) Primate Origins and Evolution: A Phylogenetic Reconstruction. London/New Jersey: Chapman Hall/Princeton University Press. Martin,R.D. (1993) Primate origins: plugging the gaps. Nature 363:223-234. Tavaré,S., Marshall,C.R., Will,O., Soligo,C. & Martin,R.D. (2002) Using the fossil record to estimate the age of the last common ancestor of extant primates. Nature 416:726-729. Miller,E.R., Gunnell,G.F. & Martin,R.D. (2005) Deep time and the search for anthropoid origins. Yrbk. phys. Anthropol. 48:60-95. Martin,R.D. (2006) New light on primate evolution. Ber. Abhandl. Berlin-Brandenburg. Akad. Wiss. 11:379-405. Martin,R.D., Soligo,C. & Tavaré,S. (2007) Primate origins: Implications of a Cretaceous ancestry. Folia Primatol. 78:277-296. Soligo,C., Will,O., Tavaré,S., Marshall,C.R. & Martin,R D. (2007) New light on the dates of primate origins and divergence. pp. 29-49 in: Primate Origins: Adaptations and Evolution. (eds. Ravosa,M.J. & Dagosto,M.). New York: Springer. Wilkinson,R.D., Steiper,M.E., Soligo,C., Martin,R.D., Yang,Z. & Tavaré,S. (2011) Dating primate divergences through an integrated analysis of palaeontological and molecular data. Syst. Biol. 60:16-31.
- Scaling Analyses Body size has a pervasive influence on virtually every aspect of an animal’s body, and individual features are scaled to fit an animal’s size as a crucial part of its overall adaptation. A prime example is provided by basal metabolic rate (BMR), a standard measure of an animal’s energy turnover while inactive. Across mammals, BMR is scaled to body size in a very consistent fashion (Kleiber’s Law). One of my major collaborative projects, now close to fruition, is a re-analysis of the scaling of basal metabolic rate using rigorously selected comparative data. Scaling of individual features to body size requires a special approach because scaling is non-linear (allometric). So simply calculating a ratio by dividing the size of a feature by body size is inappropriate. Allometric analysis is generally based on the empirical equation Y = k.Xa, where X is body size, a is a power function and Y is a feature of interest (e.g. BMR). That equation can be converted to a linear relationship by using logarithmic values: log Y = a . log X + log k. Part of my research has been concerned with exploring statistical issues connected with the allometric equation, such as choice of a best-fit line and coping with the potential problem of bias because of different degrees of relatedness among species in the Tree of Life. One outcome has been development of a novel non-parametric line-fitting technique (Isler et al., 2002) to circumvent the problem that data are often not normally distributed as required by standard parametric approaches Isee also Martin et al., 2005). Basic Model for Scaling Analyses, Illustrating Logarithmic Axes and a Grade Shift Between 2 Groups of Species (A and B): [[{"type":"media","viewmode":"mediaoriginal","fid":"21506","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] Principal References Martin,R D. (1980) Adaptation and body size in primates. Z. Morph. Anthropol. 71:115-124. Martin,R.D., Chivers,D.J., MacLarnon,A.M. & Hladik,C.M. (1985) Gastrointestinal allometry in primates and other mammals. pp. 61-89 in: Size and Scaling in Primate Biology. (eds. Jungers,W.L.) New York: Plenum Press. Martin,R.D. & Barbour,A.D. (1989) Aspects of line-fitting in bivariate allometric analyses. Folia primatol. 53:65-81. Martin,R.D. (1989) Size, shape and evolution. pp. 96-141 in: Evolutionary Studies - A Centenary Celebration of the Life of Julian Huxley. (ed. Keynes,M.) London: Eugenics Society. Martin,R.D. (1993) Allometric aspects of skull morphology in Theropithecus. pp. 273-298 in: Theropithecus: the Rise and Fall of a Primate Genus. (ed. Jablonski,N.G.) Cambridge: Cambridge University Press. Isler,K., Barbour,A.D. & Martin,R.D. (2002) Line-fitting by rotation: A nonparametric method for bivariate allometric analysis. Biometr. J. 44:289-304. Martin,R.D., Genoud,M. & Hemelrijk,C.K. (2005) Problems of allometric scaling analysis: Examples from mammalian reproductive biology. J. exp. Biol. 208:1731-1747.
- Scaling of Brain and Reproduction in Primates Much of my research has concentrated on exploring allometric scaling relationships involving the brain and reproduction. This led to the discovery of previously unrecognized connections between reproductive biology and brain size. My starting point was identification of a potential link between brain size and basal metabolic rate in mammals, reported in a Naturepaper (Martin, 1981). It emerged that this link is mediated by the mother because maternal resources during pregnancy and lactation provide the basis for most of brain growth. Eventually, this led to explicit formulation of the Maternal Energy Hypothesis (Martin, 1996), which has recently received welcome support from a number of independent statistical studies. Additional scaling analyses have examined allied reproductive features in primates and other mammals (e.g. Martin, 2003), including the structure of the placenta (Martin, 2008). Several conclusions of direct relevance to human biology emerge from these comparative studies (Martin, 2007). Illustration of the Maternal Hypothesis of Brain Evolution in Mammals, Including Humans: [[{"type":"media","viewmode":"mediaoriginal","fid":"21516","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] Martin,R.D. (1981) Relative brain size and metabolic rate in terrestrial vertebrates. Nature 293:57-60. Martin,R.D. (1982) Allometric approaches to the evolution of the primate nervous system. pp. 39-56 in: Primate Brain Evolution: Methods and Concepts. (eds. Armstrong,E. & Falk,D.) New York: Plenum Press. Martin,R.D. (1984) Scaling effects and adaptive strategies in mammalian lactation. Symp. zool. Soc. Lond. 51:87-117. Martin,R.D. & MacLarnon,A.M. (1985) Gestation period, neonatal size and maternal investment in placental mammals. Nature 313:220-223. Martin,R.D. & Harvey,P.H. (1985) Brain size allometry: Ontogeny and phylogeny. pp. 147-173 in: Size and Scaling in Primate Biology. (ed. Jungers,W.L.) New York: Plenum Press. Martin,R.D. & MacLarnon,A.M. (1988) Comparative quantitative studies of growth and reproduction. Symp. zool. Soc. Lond. 60:39-80. Martin,R.D. (1996) Scaling of the mammalian brain: the maternal energy hypothesis. News Physiol. Sci. 11:149-156. Martin,R.D. (1998) Primate brain evolution: the maternal contribution. Am. J. phys. Anthropol. 26:155-156. Martin,R.D. (1998) Comparative aspects of human brain evolution: Scaling, energy costs and confounding variables. pp. 35-68 in: The Origin and Diversification of Language. (ed. Jablonski,N.G. & Aiello,L.C.) San Francisco: California Academy of Sciences. Martin,R.D. (2003) Human reproduction: A comparative background for medical hypotheses. J. Reprod. Immunol. 59:111-135. Martin,R.D. (2007) The evolution of human reproduction: A primatological perspective. Yrbk. phys. Anthropol. 50:59-84. Martin,R.D. (2008) Evolution of placentation in primates: Implications of mammalian phylogeny. Evol. Biol. 35:125–145. Martin,R.D. & Isler,K. (2010) The maternal energy hypothesis of brain evolution: An update. pp. 15-35 in: The Human Brain Evolving: Paleoneurological Studies in Honor of Ralph L. Holloway. (eds. Broadfield,D., Yuan,M., Schick,K. & Toth,N.). Bloomington, Indiana: Stone Age Institute Press.
- Brain Size in the Flores Hominid The discovery of a hominid skeleton (LB1) in a cave on the Indonesian island of Flores was reported in 2004. The skeleton and other fragmentary remains were attributed to the new species Homo floresiensis, interpreted as a dwarfed insular descendant of Homo erectus. However, the age of the LB1 skeleton (widely known as "the hobbit") is only 18,000 y and there are two very puzzling features: (1) That individual had a tiny grapefruit-sized brain of only 400 cc, less than a third of modern human brain size. (To find another hominid with a brain that small, we have to go back in time more than 3 million years.) (2) The associated deposits contained sophisticated stone tools, some produced with the advanced prepared-core technique. The discoverers attributed the tiny brain of LB1 to island dwarfing, but that phenomenon was previously recognized only for body size, not for brain size. Moreover, the degree of proposed reduction in brain size greatly exceeds the expectation from brain size scaling. I therefore joined forces with my Field Museum colleague Dr. James Phillips (an expert on stone tools), Dr. Ann MacLarnon (a biological anthropologist with experience in scaling analyses at Roehampton University, UK) and Dr. William Dobyns (a human geneticist at the University of Chicago with special interests in brain development). Together, we concluded that LB1 could in fact be a modern human suffering from the pathological condition microcephaly. This potentially explains the sophisticated stone tools, which would have been produced by unaffected members of the local population. Subsequent to our publications implicating microcephaly as an explanation, I have launched projects to test various claims that brain size reduction is quite common among mammals, notably bats, with or without island dwarfism. Research interns Lu Yao (Northwestern University) and Meghan White (University of Chicago) have examined brain size in fossil bats and collected data on brain and body size in malnland and island-dwelling mammals of South-East Asia. On April 2nd 2010, I took part in the inaugural session of the Boston University Dialogues in Biological Anthropology organized by Dr. Matt Cartmill and Dr. Kaye Brown. The session, entitled The Biology and Status of the Flores “Hobbit”: Species or Disease?, began with a debate with Dr. Fred Smith (Chair, Department of Sociology and Anthropology, Illinois State University), followed by a public panel discussion. Both the debate and the panel discussion can be visited under the following urls: http://www.bu.edu/anthrop/dialogues/hobbits/webcast-debate/ http://www.bu.edu/anthrop/dialogues/hobbits/webcast-roundtable/ Plot of brain size against time for fossil hominds, with the size for LB1 indicated with a red dot: [[{"type":"media","viewmode":"mediaoriginal","fid":"21871","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] [[{"type":"media","viewmode":"mediaoriginal","fid":"21876","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] [[{"type":"media","viewmode":"mediaoriginal","fid":"21886","attributes":{"alt":"","class":"media-image","title":"","typeof":"foaf:Image","wysiwyg":"1"}}]] Principal References Martin,R.D., MacLarnon,A.M., Phillips,J.L., Dussubieux,L., Williams,P.R. & Dobyns,W.B. (2006) Comment on 'The brain of LB1, Homo floresiensis' (Technical Comment). Science 312:999b. Martin,R.D., MacLarnon,A.M., Phillips,J.L. & Dobyns,W.B. (2006) Flores hominid: New species or microcephalic dwarf? Anat. Rec. 288A:1123-1145. Martin,R.D. (2007) Problems with the tiny brain of the Flores hominid. pp. 9-23 in: Recent Advances on Southeast Asian Paleoanthropology and Archaeology. (ed. Indriati,E.) Yogyakarta: Laboratory of Bioanthropology and Paleoanthropology, Faculty of Medicine, Gadjah Mada University.