Publications by authors named "Fernando V Ramirez-Rozzi"

17 Publications

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The same growth pattern from puberty suggests that modern human diversity results from changes during pre-pubertal development.

Sci Rep 2021 Mar 1;11(1):4817. Epub 2021 Mar 1.

UMR 7206 Ecoanthropology, MNHN, CNRS, UP, Musée de l'Homme, 17 place du Trocadéro, 75016, Paris, France.

Patterns of human growth established for one population have rarely been tested in other populations. In a previous study, three growth curves from puberty were modelled for each sex in a longitudinal study of a Caucasian population based on stature, age at peak of growth and biological maturation. Each curve represents the canalisation of growth associated with the type of puberty. The high precision (± 3 cm) of individual adult stature predictions shows that growth kinetics are already set up at puberty and are canalised depending on biological maturity. Our aim is to assess whether this model can be extrapolated to other populations to test whether growth canalisation is a population-dependent phenomenon or if the model reflects a canalisation pattern specific to our species. The modelled curves predicted adult stature with the same high degree of precision in basketball players and the Baka pygmies. Therefore, (1) the relationship between growth kinetics and age at maturity is similar in all populations and (2) growth according to pubertal stages follows the same canalisation patterns in the populations despite the wide differences in their average adult statures. It suggests that morphological diversity in modern humans results from processes taking place in early development.
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http://dx.doi.org/10.1038/s41598-021-84327-1DOI Listing
March 2021

Age-related tooth wear in African rainforest hunter-gatherers.

Am J Phys Anthropol 2019 12 10;170(4):622-628. Epub 2019 Oct 10.

Departament de Biologia Evolutiva, Ecologia i Ciencies Ambientals, Secció Zoologia i Antropologia Biològica, Universitat de Barcelona, Barcelona, Spain.

Objectives: Central African small-scale foragers subsist primarily on hunting game activities and wild plant-food gathering. Starch-rich tubers are underground storage organs (USOs) and staple food resources in savanna and tropical rainforests. However, little is known about the effect of USO consumption on tooth wear development in living hunter-gatherers. We report age- and sex-dependent tooth wear rates in forest-dwelling Baka Pygmies with well-documented wild-yam-tuber-based diet to explore the long-term impact of USO mechanical hardness and abrasiveness on the wearing down of the teeth.

Materials And Methods: Percentages of dentine exposure (PDEs) of permanent left mandibular first molars (M ) were recorded using in vivo high-resolution replicas of Baka individuals (aged 8-33 years), inhabiting Le Bosquet district in Cameroon (Western Africa). Regression and covariance analyses were used to test the effect of individual aging by sex on PDE rates.

Results: We found a strong increase of PDE by age among Baka individuals. No evidence of sexual dimorphism in wear patterns suggests similar sex-related dietary and masticatory demands during growth. Overall, greatest dentine exposure values ≈4% denote unexpected slow wear down rates for foraging diets relying on USO consumption.

Discussion: The low molar wear rates with age found in Baka Pygmies contrast with extensive wear rates in savanna-dwelling foragers, reflecting differences in thermal processing techniques affecting fracture toughness and grittiness of mechanically challenging foods. Our findings reveal that culture-specific dietary proclivities influence tooth wear among foraging behaviors with important implications in hominin dietary versatility and abrasive stress on chewing surfaces.
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http://dx.doi.org/10.1002/ajpa.23934DOI Listing
December 2019

Tooth dimensions and body size in a Pygmy population.

Ann Hum Biol 2019 Sep 16;46(6):467-474. Epub 2019 Oct 16.

Departamento de Biotecnología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain.

The relationship between tooth size and stature has been analysed extensively at the interspecies level but has received less attention at the intraspecies level. The relationship between these two parameters does not seem to be the same among modern human populations. The aim of this study is to analyse the relationship between tooth dimensions and body measurements in the Baka Pygmies. Height, weight, and tooth dimensions were obtained for 45 adult Baka females and 17 males from Le Bosquet (Cameroon). Correlations were obtained between the variables and compared to results for other human populations. The Baka population is distinctive in the small number of significant correlations. Only two buccolingual diameters among Baka females show any significant correlation with height. The lack of significant correlations between tooth dimensions and body dimensions among the Baka means that changes in body size are accompanied by random variations in tooth dimensions. The absence of correlations may be accounted for by the impact of environmental effects on the somatic growth of the Baka producing a Pygmy phenotype adapted to live in the forest. It is worth noting that many correlations become significant when sexes are pooled.
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http://dx.doi.org/10.1080/03014460.2019.1673482DOI Listing
September 2019

Reproduction in the Baka pygmies and drop in their fertility with the arrival of alcohol.

Proc Natl Acad Sci U S A 2018 07 18;115(27):E6126-E6134. Epub 2018 Jun 18.

UMR 5288 Laboratoire Anthropologie Moléculaire et Imagerie de Synthèse, CNRS, Faculté de Chirurgie Dentaire, 92120 Montrouge, France

To understand the diversity of human growth and development from an evolutionary point of view, there is an urgent need to characterize the life-history variables of vanishing forager societies. The small body size of the Baka pygmies is the outcome of a low growth rate during infancy. While the ages at sexual maturity, menarche, and first delivery are similar to those in other populations, fertility aspects are unknown. In the Le Bosquet district in Cameroon, thanks to systematic birth records kept from 1980 onwards, we were able to assign ages to individuals with certainty. This study, based on chronological records and on data collected from 2007 to 2017, presents life-history variables related to fertility and mortality among the Baka pygmies: total fertility rate, age-specific fertility rate, completed family size, reproductive span, age at menopause, and infant and juvenile mortality. The Baka present low infant and juvenile mortality, and their fertility pattern differs from that of other forager societies in the higher age-specific fertility rates found in the two lower age classes. Future studies will need to assess whether this particular pattern and the short interbirth interval are related to highly cooperative childrearing, which in the Baka is associated with slow growth. The fertility rate has fallen drastically since 2011, and this matches the arrival of cheap alcohol in the community. Our data provide a first-hand record of the impact of alcohol on fertility in a hunter-gatherer society which appears to be seriously compromising the survival of the Baka.
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http://dx.doi.org/10.1073/pnas.1719637115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6142234PMC
July 2018

Dental size variability in Central African Pygmy hunter-gatherers and Bantu-speaking farmers.

Am J Phys Anthropol 2018 07 22;166(3):671-681. Epub 2018 Mar 22.

Departament de Biologia Evolutiva, Ecologia i Ciencies Ambientals, Secció Zoologia i Antropologia Biològica, Universitat de Barcelona, Barcelona, 08028, Spain.

Objectives: Odontometric studies of African populations show high within-group variation in tooth size. Overall, North Africans exhibit smaller dimensions than groups from eastern and southern sub-Saharan regions, but no previous studies have analyzed the full dental metrics among extant African Pygmy hunter-gatherers and Bantu-speaking farmers. Furthermore, the population variability in tooth crown sizes from equatorial rainforest regions remains to be elucidated.

Materials And Methods: The mesiodistal and buccolingual diameters of the permanent teeth (I1-M2) were measured in vivo using high-resolution replicas from Baka Pygmies and Mvae and Yassa Bantu-speakers from Cameroon (western Africa). Analyses of variance were used to record sex-related and population-level differences in tooth sizes, and a principal component analysis of geometrically scaled measures was used to plot the odontometric variability among groups.

Results: Cameroonian Baka Pygmies differ in dental size from their Bantu-speaking neighbors. Molar teeth are larger in Pygmies than in Bantu individuals, while the anterior dentition is larger in the Bantu. Baka males exhibit significantly larger teeth than females, whereas sexual dimorphism in non-Pygmies is only present in the anterior dentition.

Discussion: Odontometric patterns and the degree of sexual dimorphism in dental size differ among Central African groups, indicating adaptation to their different forager and farmer lifestyles. In particular, the admixture of Bantu-speakers in Baka populations is smaller than that in other western Pygmy groups. The greater dental phenetic diversity in Baka compared to that of the smaller-toothed farmers suggests that ecogenetic and microevolutionary factors are influencing a particular divergence scenario.
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http://dx.doi.org/10.1002/ajpa.23458DOI Listing
July 2018

Growth pattern from birth to adulthood in African pygmies of known age.

Nat Commun 2015 Jul 28;6:7672. Epub 2015 Jul 28.

INSERM, UMR1153 Epidemiology and Biostatistics Sorbonne Paris Cité Center (CRESS), Team 'Early Origin of the Child's Health and Development' (ORCHAD) and University Paris-Sud, Faculty of Pharmacy, 91400 Orsay, France.

The African pygmy phenotype stems from genetic foundations and is considered to be the product of a disturbance in the growth hormone-insulin-like growth factor (GH-IGF) axis. However, when and how the pygmy phenotype is acquired during growth remains unknown. Here we describe growth patterns in Baka pygmies based on two longitudinal studies of individuals of known age, from the time of birth to the age of 25 years. Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life. It then more or less follows the standard pattern, with a growth spurt at adolescence. Their life history variables do not allow the Baka to be distinguished from other populations. Therefore, the pygmy phenotype in the Baka is the result of a change in growth that occurs during infancy, which differentiates them from East African pygmies revealing convergent evolution.
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http://dx.doi.org/10.1038/ncomms8672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525207PMC
July 2015

Diet-related buccal dental microwear patterns in Central African Pygmy foragers and Bantu-speaking farmer and pastoralist populations.

PLoS One 2013 19;8(12):e84804. Epub 2013 Dec 19.

Universitat de Barcelona, Departament de Biologia Animal, Barcelona, Spain.

Pygmy hunter-gatherers from Central Africa have shared a network of socioeconomic interactions with non-Pygmy Bantu speakers since agropastoral lifestyle spread across sub-Saharan Africa. Ethnographic studies have reported that their diets differ in consumption of both animal proteins and starch grains. Hunted meat and gathered plant foods, especially underground storage organs (USOs), are dietary staples for pygmies. However, scarce information exists about forager-farmer interaction and the agricultural products used by pygmies. Since the effects of dietary preferences on teeth in modern and past pygmies remain unknown, we explored dietary history through quantitative analysis of buccal microwear on cheek teeth in well-documented Baka pygmies. We then determined if microwear patterns differ among other Pygmy groups (Aka, Mbuti, and Babongo) and between Bantu-speaking farmer and pastoralist populations from past centuries. The buccal dental microwear patterns of Pygmy hunter-gatherers and non-Pygmy Bantu pastoralists show lower scratch densities, indicative of diets more intensively based on nonabrasive foodstuffs, compared with Bantu farmers, who consume larger amounts of grit from stoneground foods. The Baka pygmies showed microwear patterns similar to those of ancient Aka and Mbuti, suggesting that the mechanical properties of their preferred diets have not significantly changed through time. In contrast, Babongo pygmies showed scratch densities and lengths similar to those of the farmers, consistent with sociocultural contacts and genetic factors. Our findings support that buccal microwear patterns predict dietary habits independent of ecological conditions and reflect the abrasive properties of preferred or fallback foods such as USOs, which may have contributed to the dietary specializations of ancient human populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084804PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868657PMC
July 2014

Brief communication: Molar development and crown areas in early Australopithecus.

Am J Phys Anthropol 2012 Aug 24;148(4):632-40. Epub 2012 May 24.

Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA.

Recent studies suggest that the hypodigms representing the two earliest Australopithecus (Au. anamensis and Au. afarensis) form an ancestor-descendant lineage. Understanding the details of this possible transition is important comparative evidence for assessing the likelihood of other examples of ancestor-descendant lineages within the hominin clade. To this end we have analyzed crown and cusp base areas of high resolution replicas of the mandibular molars of Au. anamensis (Allia Bay and Kanapoi sites) and those of Au. afarensis (Hadar, Laetoli, and Maka). We found no statistically significant differences in crown areas between these hypodigms although the mean of M(1) crowns was smaller in Au. anamensis, being the smallest of any Australopithecus species sampled to date. Intraspecies comparison of the areas of mesial cusps for each molar type using Wilcoxon signed rank test showed no differences for Au. anamensis. Significant differences were found between the protoconid and metaconid of Au. afarensis M(2)s and M(3)s. Furthermore, the area formed by the posterior cusps as a whole relative to the anterior cusps showed significant differences in Au. afarensis M(1)s and in Au. anamensis M(2)s but no differences were noted for M(3)s of either taxon. Developmental information derived from microstructural details in enamel shows that M(1) crown formation in Au. anamensis is similar to Pan and shorter than in H. sapiens. Taken together, these data suggests that the overall trend in the Au. anamensis-Au. afarensis transition may have involved a moderate increase in M(1) crown areas with relative expansion of distal cusps.
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http://dx.doi.org/10.1002/ajpa.22089DOI Listing
August 2012

Different cranial ontogeny in Europeans and Southern Africans.

PLoS One 2012 27;7(4):e35917. Epub 2012 Apr 27.

División Antropología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata - CONICET, La Plata, Buenos Aires, Argentina.

Modern human populations differ in developmental processes and in several phenotypic traits. However, the link between ontogenetic variation and human diversification has not been frequently addressed. Here, we analysed craniofacial ontogenies by means of geometric-morphometrics of Europeans and Southern Africans, according to dental and chronological ages. Results suggest that different adult cranial morphologies between Southern Africans and Europeans arise by a combination of processes that involve traits modified during the prenatal life and others that diverge during early postnatal ontogeny. Main craniofacial changes indicate that Europeans differ from Southern Africans by increasing facial developmental rates and extending the attainment of adult size and shape. Since other studies have suggested that native subsaharan populations attain adulthood earlier than Europeans, it is probable that facial ontogeny is linked with other developmental mechanisms that control the timing of maturation in other variables. Southern Africans appear as retaining young features in adulthood. Facial ontogeny in Europeans produces taller and narrower noses, which seems as an adaptation to colder environments. The lack of these morphological traits in Neanderthals, who lived in cold environments, seems a paradox, but it is probably the consequence of a warm-adapted faces together with precocious maturation. When modern Homo sapiens migrated into Asia and Europe, colder environments might establish pressures that constrained facial growth and development in order to depart from the warm-adapted morphology. Our results provide some answers about how cranial growth and development occur in two human populations and when developmental shifts take place providing a better adaptation to environmental constraints.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0035917PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338763PMC
September 2012

Diversity among African pygmies.

PLoS One 2010 Oct 26;5(10):e13620. Epub 2010 Oct 26.

UPR 2147 CNRS, Paris, France.

Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013620PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2964320PMC
October 2010

Molar crown development in Australopithecus afarensis.

J Hum Evol 2010 Feb 30;58(2):201-6. Epub 2009 Dec 30.

Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles CA 90033 USA.

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http://dx.doi.org/10.1016/j.jhevol.2009.11.007DOI Listing
February 2010

Cutmarked human remains bearing Neandertal features and modern human remains associated with the Aurignacian at Les Rois.

J Anthropol Sci 2009 ;87:153-85

UPR 2147, Dynamique de l'Evolution Humaine, CNRS, 44 Rue de l'Amiral Mouchez, 75014 Paris, France.

The view that Aurignacian technologies and their associated symbolic manifestations represent the archaeologicalproxy for the spread of Anatomically Modern Humans into Europe, is supported by few diagnostic human remains, including those from the Aurignacian site of Les Rois in south-western France. Here we reassess the taxonomic attribution of the human remains, their cultural affiliation, and provide five new radiocarbon dates for the site. Patterns of tooth growth along with the morphological and morphometric analysis of the human remains indicate that a juvenile mandible showing cutmarks presents some Neandertal features, whereas another mandible is attributed to Anatomically Modern Humans. Reappraisal of the archaeological sequence demonstrates that human remains derive from two layers dated to 28-30 kyr BP attributed to the Aurignacian, the only cultural tradition detected at the site. Three possible explanations may account for this unexpected evidence. The first one is that the Aurignacian was exclusively produced by AMH and that the child mandible from unit A2 represents evidence for consumption or, more likely, symbolic use of a Neandertal child by Aurignacian AMH The second possible explanation is that Aurignacian technologies were produced at Les Rois by human groups bearing both AMH and Neandertal features. Human remains from Les Rois would be in this case the first evidence of a biological contact between the two human groups. The third possibility is that all human remains from Les Rois represent an AMH population with conserved plesiomorphic characters suggesting a larger variation in modern humans from the Upper Palaeolithic.
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September 2009

Crown-formation time in Neandertal anterior teeth revisited.

J Hum Evol 2007 Jul 10;53(1):108-13; discussion 114-8. Epub 2007 May 10.

UPR 2147, Dynamique de l'Evolution Humaine, CNRS, 44, rue de l'Amiral Mouchez, 75014 Paris, France.

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http://dx.doi.org/10.1016/j.jhevol.2007.01.009DOI Listing
July 2007

Variation of functional cranial components in six Anthropoidea species.

Zoology (Jena) 2006 3;109(3):231-43. Epub 2006 Jul 3.

Centro de Investigaciones en Genética Básica y Aplicada (CIGEBA, FCV, UNLP), La Plata, Argentina.

Sixty male crania from three Platyrrhini and three Catarrhini genera were measured by means of the craniofunctional method. The aim was to analyze functional components of the skull and relate their function and the degree of encephalization to life history variables. We recognized two major and eight minor functional components. The objectives were to test (1) if within-taxa (Platyrrhini or Catarrhini) and/or between-taxa (Platyrrhini and Catarrhini) comparisons showed minor-component differentiation; and (2) if encephalization affects both primate groups differently. After standardization by size and scaling, 15 possible within-taxa and between-taxa comparisons were made. We found a strong phylogenetic signal, i.e., cranial differences were not randomly distributed, with the between-taxa variation being greater than within-taxa. Both hypotheses tested were accepted since: (1) There was no random variation between functional cranial components. They followed definite patterns for ancestral and derived traits. (2) Encephalization was present in all scaled comparisons, with Platyrrhini showing a higher degree of encephalization than Catarrhini. We conclude that major and minor craniofunctional components should be considered as correlated traits related to life history, because we found different patterns between platyrrhines and catarrhines, and within species of both taxa.
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http://dx.doi.org/10.1016/j.zool.2006.02.002DOI Listing
October 2006

A cross-sectional study of human craniofacial growth.

Ann Hum Biol 2005 May-Jun;32(3):390-6

Dynamique de l'Evolution Humaine, Centre National de la Recherche Scientifique, Paris, France.

It is generally accepted that different cranial regions do not follow the same growth pattern. In this study, size changes of the functional cranial components (FCCs) in 228 human skulls of age at death between 0 and 20 years were evaluated. The skull is considered as divided into anteroneural, midneural, posteroneural, otic, optic, respiratory, masticatory and alveolar FCCs. Age-related changes of FCCs were assessed by fitting curves with the smoothing spline method, and quantifying the proportional increments at different stages. All FCCs show a high growth rate in the first 3-5 years of life. Two groups of growth trajectories can be distinguished. The anteroneural, midneural, posteroneural and optic FCCs are more advanced at all stages; they show a high growth rate before 3-5-years-old and a low rate later. This difference is less pronounced in the group comprising the respiratory, masticatory and otic FCCs. The alveolar FCC shows an independent pattern. The similarities among FCCs of the two groups are best explained by their common embryological origin. In contrast, the participation in a common function cannot be associated with the co-ordinated variation, given that the masticatory and alveolar FCCs show independent trajectories.
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http://dx.doi.org/10.1080/03014460400027441DOI Listing
December 2005

Cranial growth in normal and low-protein-fed Saimiri. An environmental heterochrony.

J Hum Evol 2005 Oct;49(4):515-35

UPR 2147 Dynamique de l'volution humaine (CNRS), 44, rue de l'Amiral Mouchez, 75014 - Paris, France.

Protein malnutrition has a significant and measurable effect on the rate and timing of growth. Heterochrony is generally viewed as the study of evolutionary changes in the relative rates and timing of growth and development. Although changes in growth commonly result from experimental manipulations of diet, nobody has previously attempted to explain such changes from a heterochronic perspective. We use a heterochronic perspective to compare a group of squirrel monkeys fed a low-protein diet to individuals on a high-protein diet, but, in contrast to previous works, we focus particularly on the effects of environmental and not genetic factors. In the present study, Gould's (1977) and Godfrey and Sutherland's (1996) methodologies for studying heterochrony, as well as geometric morphometrics, are used to compare two groups of Saimiri sciureus boliviensis. Two groups of Saimiri were constructed on the basis of the protein content in their diets: a high-protein group (HP) (N=12) and a low-protein group (LP) (N=12). All individuals are males born in captivity. Two major functional components of the skull, the neurocranium and the face, were analysed. Four minor components were studied in each major component. Comparison of craniofacial ontogeny patterns based on major and minor components suggests that changes in the skull of LP animals can be explained by heterochrony. The skull of LP animals exhibits isomorphism produced by proportioned dwarfism. Our results suggest that heterochrony can be environmentally, rather than exclusively genetically, induced. The study of genetic assimilation (Waddington, 1953, 1956; see Scharloo, 1991; Hallgrimsson et al., 2002) has demonstrated that environmentally induced phenotypes often have a genetic basis, and thus parallel changes can be easily induced genetically. It is possible that proportioned dwarfism is far more common than currently appreciated.
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http://dx.doi.org/10.1016/j.jhevol.2005.06.002DOI Listing
October 2005

Surprisingly rapid growth in Neanderthals.

Nature 2004 Apr;428(6986):936-9

UPR 2147, Dyamique de l'Evolution Humaine, CNRS, 44, Rue de l'Amiral Mouchez, 75014 Paris, France.

Life-history traits correlate closely with dental growth, so differences in dental growth within Homo can enable us to determine how somatic development has evolved and to identify developmental shifts that warrant species-level distinctions. Dental growth can be determined from the speed of enamel formation (or extension rate). We analysed the enamel extension rate in Homo antecessor (8 teeth analysed), Homo heidelbergensis (106), Homo neanderthalensis ('Neanderthals'; 146) and Upper Palaeolithic-Mesolithic Homo sapiens (100). Here we report that Upper Palaeolithic-Mesolithic H. sapiens shared an identical dental development pattern with modern humans, but that H. antecessor and H. heidelbergensis had shorter periods of dental growth. Surprisingly, Neanderthals were characterized by having the shortest period of dental growth. Because dental growth is an excellent indicator of somatic development, our results suggest that Neanderthals developed faster even than their immediate ancestor, H. heidelbergensis. Dental growth became longer and brain size increased from the Plio-Pleistocene in hominid evolution. Neanderthals, despite having a large brain, were characterized by a short period of development. This autapomorphy in growth is an evolutionary reversal, and points strongly to a specific distinction between H. sapiens and H. neanderthalensis.
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http://dx.doi.org/10.1038/nature02428DOI Listing
April 2004