Deciduous dental morphology of the prehistoric Jomon people of Japan: Comparison of nonmetric characters

Morphological variations of the deciduous dentition are as useful as those of the permanent dentition for determining the biological affinities of human populations. This paper provides material on morphological variations of deciduous teeth of the prehistoric Japanese population from the Late and the Latest Jomon Period (ca. 2000–ca. 300 B.C.). The expression of nonmetric traits of the deciduous teeth in the Jomon sample shows a closer affinity with modern Japanese and Native American samples than with American White, Asiatic Indian, and African samples. However, the frequency of shoveling in deciduous upper incisors in the Jomon sample is lower than those in modern Japanese and Native American samples. The Jomon sample also expresses a much higher frequency of cusp 6 in deciduous lower second molars than seen in modern Japanese, Ainu, and Native American samples. The frequency in the Jomon sample is equal to that in the Australian Aboriginal sample, which shows cusp 6 most frequently among the samples compared. A somewhat low incidence of incisor shoveling in the Jomon sample was also reported in the permanent dentition (Turner [1976] Science 193:911–913, [1979] Am. J. Phys. Anthropol. 51:619–635, [1987] Am. J. Phys. Anthropol. 73:305–321, [1990] Am. J. Phys. Anthropol. 82:295–317; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:163–182, 88:183–196). However, the frequency of cusp 6 in the Jomon sample shows no significant difference from those of Northeast Asian or Native American samples in the permanent dentition (Turner [1987] Am. J. Phys. Anthropol. 73:305–321; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:1–182, 88:183–196). Evidently, some nonmetric traits express an inter-group difference only in the deciduous dentition. © 1995 Wiley-Liss, Inc.     

On the taxonomic affinities of the Dmanisi mandible (Georgia)

The recent discovery of unexpectedly ancient human remains has fuelled interest about the first dispersion of Homo outside Africa. The Dmanisi mandible is perhaps one of the most interesting findings, as it supposedly represents one of the oldest hominids outside of Africa. Recently, different interpretations have been published about this specimen. Our comparison of the Dmanisi mandible with a large sample of mandibles and teeth has led us to a new interpretation. In our view, the Dmanisi mandible exhibits a unique combination of traits. Some of its features, taken in isolation, may be attributed to morphological extremes within the genus Homo. The architecture of the mandible as well as the morphology and dimensions of incisors, canines, and P3s are clearly primitive. However, dental traits such as the reduction of the talonid in the P4s and a distally decreasing molar series seems to be derived. Some combinations of these traits are found in specimens of Homo ergaster and differ from those generally present in later hominids. Thus, we propose that the Dmanisi mandible might be taxonomically classified as Homo sp. indet. (aff. ergaster). Furthermore, some aspects of the dentition in Dmanisi display close similarities to Asian Homo erectus. If the 1.8–1.6 Myr dating for the Dmanisi mandible is correct, the differentiation of the Asian branch of the genus Homo could be regarded as a very ancient event. Am J Phys Anthropol 107:145–162, 1998. © 1998 Wiley-Liss, Inc.     

Canine tip wear in male and female anthropoids

One component of the “dual selection hypothesis” (Greenfield [1992a] Year. Phys. Anthropol. 35:153–185) is that the tips of female canines are commonly blunted and more frequently so than those of conspecific males. Data derived from two randomly selected age-graded samples of Macaca fascicularis (n = 70) and Colobus badius (n = 59) show that at least 80% of the females exhibit tip blunting on one or both canines and that frequencies of blunting are far greater than those of conspecific males in both jaws. Sexual dimorphism in mandibular canine morphology and wear and other recently critiqued aspects of the “dual selection hypothesis” (Plavcan and Kelley [1996] Am. J. Phys. Anthropol. 99:379–387.) are also discussed. Am J Phys Anthropol 107:87–97. © 1998 Wiley-Liss, Inc.     

Comparing apples and oranges—the influence of food mechanical properties on ingestive bite sizes in lemurs

Previously we found that Maximum Ingested Bite Size (V_b)—the largest piece of food that an animal will ingest whole without biting first—scales isometrically with body size in 17 species of strepsirrhines at the Duke Lemur Center (DLC). However, because this earlier study focused on only three food types (two with similar mechanical properties), it did not yield results that were easily applied to describing the broad diets of these taxa. Expressing V_b in terms of food mechanical properties allows us to compare data across food types, including foods of wild lemurs, to better understand dietary adaptations in lemurs. To this end, we quantified V_b in five species of lemurs at the DLC representing large and small frugivores and folivores using ten types of food that vary widely in stiffness and toughness to determine how these properties relate to bite sizes. We found that although most species take smaller bites of stiffer foods, this negative relationship was not statistically significant across the whole sample. However, there is a significant relationship between bite size and toughness. All three of the more frugivorous taxa in our sample take significantly smaller bites of tougher foods. However, the two more folivorous lemurs do not. They take small bites for all foods. This suggests that the species most adapted to the consumption of tough foods do not modulate their ingestive sizes to accommodate larger pieces of weak foods. Am J Phys Anthropol 157:513–518, 2015. © 2015 Wiley Periodicals, Inc.     

Patterns of astragalar fibular facet orientation in extant and fossil primates and their evolutionary implications

A laterally sloping fibular facet of the astragalus (=talus) has been proposed as one of few osteological synapomorphies of strepsirrhine primates, but the feature has never been comprehensively quantified. We describe a method for calculating fibular facet orientation on digital models of astragali as the angle between the planes of the fibular facet and the lateral tibial facet. We calculated this value in a sample that includes all major extant primate clades, a diversity of Paleogene primates, and nonprimate euarchontans (n = 304). Results show that previous characterization of a divide between extant haplorhines and strepsirrhines is accurate, with little overlap even when individual data points are considered. Fibular facet orientation is conserved in extant strepsirrhines despite major differences in locomotion and body size, while extant anthropoids are more variable (e.g., low values for catarrhines relative to non‐callitrichine platyrrhines). Euprimate outgroups exhibit a mosaic of character states with Cynocephalus having a more obtuse strepsirrhine‐like facet and sampled treeshrews and plesiadapiforms having more acute haplorhine‐like facets. Surprisingly, the earliest species of the adapiform Cantius have steep haplorhine‐like facets as well. We used a Bayesian approach to reconstruct the evolution of fibular facet orientation as a continuous character across a supertree of living and extinct primates. Mean estimates for crown Primatomorpha (97.9°), Primates (99.5°), Haplorhini (98.7°), and Strepsirrhini (108.2°) support the hypothesis that the strepsirrhine condition is derived, while lower values for crown Anthropoidea (92.8°) and Catarrhini (88.9°) are derived in the opposite direction. Am J Phys Anthropol 151:420–447, 2013.© 2013 Wiley Periodicals, Inc.     

(Un‐)expected nocturnal activity in “Diurnal” Lemur catta supports cathemerality as one of the key adaptations of the lemurid radiation

The ability to operate during the day and at night (i.e., cathemerality) is common among mammals but has rarely been identified in primates. Adaptive hypotheses assume that cathemerality represents a stable adaptation in primates, while nonadaptive hypotheses propose that it is the result of an evolutionary disequilibrium arising from human impacts on natural habitats. Madagascar offers a unique opportunity to study the evolution of activity patterns as there we find a monophyletic primate radiation that shows nocturnal, diurnal, and cathemeral patterns. However, when and why cathemeral activity evolved in lemurs is the subject of intense debate. Thus far, this activity pattern has been regularly observed in only three lemurid genera but the actual number of lemur species exhibiting this activity is as yet unknown. Here we show that the ring‐tailed lemur, Lemur catta, a species previously considered to be diurnal, can in fact be cathemeral in the wild. In neighboring but distinct forest areas these lemurs exhibited either mainly diurnal or cathemeral activity. We found that, as in other cathemeral lemurs, activity was entrained by photoperiod and masked by nocturnal luminosity. Our results confirm the relationship between transitional eye anatomy and physiology and 24‐h activity, thus supporting the adaptive scenario. Also, on the basis of the most recent strepsirrhine phylogenetic reconstruction, using parsimony criterion, our findings suggest pushing back the emergence of cathemerality to stem lemurids. Flexible activity over 24‐h could thus have been one of the key adaptations of the early lemurid radiation possibly driven by Madagascar's island ecology. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Subocclusal dental morphology of sahelanthropus tchadensis and the evolution of teeth in hominins

The evolution of the teeth in hominins is characterized by, among other characters, major changes in root morphology. However, little is known of the evolution from a plesiomorphic, ape‐like root morphology to the crown hominin morphology. Here we present a study of the root morphology of the Miocene Chadian hominin Sahelanthropus tchadensis and its comparison to other hominins. The morphology of the whole lower dentition (I₁–M₃) was investigated and described. The comparison with the species Ardipithecus kaddaba and Ardipithecus ramidus indicates a global homogeneity of root morphology in early hominins. This morphology, characterized notably by a reduction of the size and number of the roots of premolars, is a composite between an ape‐like morphology and the later hominin morphology. Trends for root evolution in hominins are proposed, including the transition from a basal hominoid to extant Homo sapiens. This study also illustrates the low association between the evolution of tooth root morphology and the evolution of crowns in hominins. Am J Phys Anthropol 153:116–123, 2014. © 2013 Wiley Periodicals, Inc.     

Platyrrhine dental eruption sequences

To determine dental eruption sequences of extant platyrrhines, 367 mandibles and maxillae of informative juvenile specimens from all 16 genera were scored for presence of permanent teeth including three intermediate eruption stages following Harvati (Am J Phys Anthropol 112 (2000) 69-85). The timing of molar eruption relative to that of the anterior dentition is variable in platyrrhines. Aotus is precocious, with all molars erupting in succession before replacement of any deciduous teeth, while Cebus is delayed in M2-3 eruption relative to I1-2. Callitrichines have a distinct tendency toward delayed canine and premolar development. Platyrrhine eruption sequences presented here show some evidence of conformity to Schultz's Rule, with relatively early replacement of deciduous dentition in "slower"-growing animals. The relationship of dental eruption sequences to degree of folivory, body mass, brain mass, and dietary quality is also examined. The early eruption of molars relative to anterior teeth in Pithecia, Chiropotes, and Cacajao, in comparison to genera such as Ateles, Lagothrix, and Alouatta, showing relatively later eruption of the molars, appears to be consistent with current phylogenetic hypotheses. Schultz (Am J Phys Anthropol 19 (1935) 489-581) postulated early relative molar eruption as the primitive dental eruption schedule for primates. The extremely early molar eruption of Aotus versus Callicebus (where both incisors erupt before M2 and M3, with M3 usually last) may lend support to the status of Aotus as a basal taxon. The early relative molar eruption of the fossil platyrrhine species Branisella boliviana is also consistent with this hypothesis (Takai et al.: Am J Phys Anthropol 111 (2000) 263-281).     

Ape-like endocast of “ape-man” Taung

I have identified and illustrated a spherical “dimple” or “depression” on the Taung endocast as indicating the most likely position of the medial end of the lunate sulcus but have not drawn an actual lunate sulcus on Taung because one is not visible. In a recent paper, R.L. Holloway (Am. J. Phys. Anthropol. 77:27–33, 1988) drew a lunate sulcus on his copy of the Taung endocast, incorrectly attributed this sulcus to me, and used it to obtain a ratio of 0.254 to describe “Falk's” position of the lunate sulcus. My published ratio of 0.242 for Taung (Falk: Am. J. Phys. Anthropol. 67:313–315, 1985a) was not considered, although the focus of Holloway's paper was my assessment of the position of the lunate sulcus. Holloway also excluded published ratios for a chimpanzee in my collection from his statistical analysis but, even so, my published ratio for Taung is still only 1.5 standard deviations from his chimpanzee mean. If my chimpanzee brain is included in the sample, the ratio for Taung is 1.2 standard deviations from the mean. Furthermore, one of Holloway's own chimpanzees (B60–7) has a ratio of 0.241, just 0.001 below my ratio for Taung. There is no sulcus where Holloway has drawn one on Taung, his “F(LS)” is not mine, his 2 mm error is not mine, and the correct ratio for my measurement of Tuang is the one that I published, not the one that Holloway attributes to me. Assessment of Holloway's chimpanzee data supports my claim that the dimple on the Taung endocast is within the chimpanzee range for the medial end of the lunate sulcus.     

Brief communication: Noninvasive measuring of operational tongue length in callitrichids

Callitrichids use their tongue in various social, ecological, and hygienic contexts. Using a noninvasive measuring device, we obtained data on the operational tongue length (OTL) in seven species from the family Callitrichidae. OTL (defined as the maximum tongue extension into the device) varied significantly between species and the width of the device, but did not correlate with mandible length; it is smaller in relation to mandible length in Leontopithecus chrysomelas compared to species from the genera Saguinus and Callithrix. Current information does not allow concluding which of the various functions of the tongue is selecting for tongue length. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

New Pedal Remains of Megaladapis and Their Functional Significance. Am J Phys Anthropol 100:115–139

Erratum: Wunderlich RE, Simons EL, Jungers WL. 1996. New Pedal Remains of Megaladapis and Their Functional Significance. Am J Phys Anthropol 100:115–139.     

Brief communication: Prehistoric dentistry in the American Southwest: A drilled canine from Sky Aerie,Colorado

A prehistoric Native American mandible from a Fremont site (circa AD 1025) in Colorado has a conical pit in the worn occlusal surface of the lower right canine. Natural causes for this modification are ruled out by the presence of internal striae, a finding confirmed by experimental replication. The canine was artificially drilled before the individual's death and is associated with a periapical abscess. This is one of a very few examples of prehistoric dentistry in the world, and the first from the American Southwest. Am J Phys Anthropol 103:409–414, 1997. © 1997 Wiley-Liss, Inc.     

Additional postcranial elements of Teilhardina belgica: The oldest European primate

Teilhardina belgica is one of the earliest fossil primates ever recovered and the oldest fossil primate from Europe. As such, this taxon has often been hypothesized as a basal tarsiiform on the basis of its primitive dental formula with four premolars and a simplified molar cusp pattern. Until recently [see Rose et al.: Am J Phys Anthropol 146 (2011) 281–305; Gebo et al.: J Hum Evol 63 (2012) 205–218], little was known concerning its postcranial anatomy with the exception of its well‐known tarsals. In this article, we describe additional postcranial elements for T. belgica and compare these with other tarsiiforms and with primitive adapiforms. The forelimb of T. belgica indicates an arboreal primate with prominent forearm musculature, good elbow rotational mobility, and a horizontal, rather than a vertical body posture. The lateral hand positions imply grasps adaptive for relatively large diameter supports given its small body size. The hand is long with very long fingers, especially the middle phalanges. The hindlimb indicates foot inversion capabilities, frequent leaping, arboreal quadrupedalism, climbing, and grasping. The long and well‐muscled hallux can be coupled with long lateral phalanges to reconstruct a foot with long grasping digits. Our phyletic analysis indicates that we can identify several postcranial characteristics shared in common for stem primates as well as note several derived postcranial characters for Tarsiiformes. Am J Phys Anthropol 156:388–406, 2015. © 2014 Wiley Periodicals, Inc.     

Manual lateralization in wild redfronted lemurs (Eulemur rufifrons) during spontaneous actions and in an experimental task

The dominant use of one hand is a striking feature of humans, but manual lateralization can be found in a variety of other species as well. In primates, the lateralization in hand use varies among species and several theories such as the “postural origin,” “task complexity,” or “development theory” have been suggested to explain this variation. In order to contribute comparative data on this phenomenon from a basal primate, we studied manual lateralization in wild redfronted lemurs (Eulemur rufifrons). Data were collected on four groups at Kirindy Forest, western Madagascar, during spontaneous actions and by confronting them with artificial feeding boxes. The lemurs did not exhibit manual lateralization on a group level in either condition. More individuals showed a hand preference in the experimental task, and the preferences were stronger compared to spontaneous actions. The direction of individual hand preferences was not consistent across the two conditions. The results of this study show that measuring manual laterality in different contexts can yield different results. Manual lateralization in wild redfronted lemurs therefore seems to be flexible and situation dependent and probably not ecologically relevant in their natural habitat. Am J Phys Anthropol 153:61–67, 2014. © 2013 Wiley Periodicals, Inc.     

Craniodental mechanics and diet in Asian colobines: Morphological evidence of mature seed predation and sclerocarpy

Folivory has been accepted as the general dietary pattern for colobines. However, recent ecological studies have revealed that extensive seed eating is found in some colobine species. The ripeness of foraged seeds is also reported to differ between seed eaters. As seeds are generally stress‐limited and may pose greater mechanical demands, seed‐eating species are predicted to exhibit morphological features adaptive for seed predation. In addition, species that feeds on seeds from unripe fruits with hard pericarp is predicted to exhibit increased leverage for anterior dentition. To test these hypotheses, we compared the craniodental morphology of seed‐eating Asian colobines (Presbytis rubicunda and Trachypithecus phayrei) with those of species that rarely exploit seeds (Presbytis comata, Trachypithecus obscurus, and Semnopithecus vetulus). The results show that the seed‐eating colobines possess a masticatory system with enhanced leverage at postcanine bite points. The sclerocarpic forager P. rubicunda also exhibits markedly greater masticatory leverage at anterior dental bite points, while the mature‐seed‐eating T. phayrei shows no such advantage for canine and incisor use. These observations suggest that P. rubicunda is well adapted to husking the resistant pericarps of unripe fruits, using the anterior dentition and to gain access to the immature seeds, whereas such sclerocarpic feeding behavior may be less important for T. phayrei. Our findings indicate that the distinctive craniodental variations of colobines may be linked to mature and/or immature seed eating and suggest the significance of seed predation for the evolution of colobine monkeys. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

The mixed dentition and associated skull fragments of a juvenile fossil hominid from Sterkfontein,South Africa

In April–May 1983, the late A.R. Hughes and his field team recovered more than 40 bone fragments and teeth from a single solution pocket of the Sterkfontein Formation. After preparation and reconstruction by JMC, it was recognised that these fragments represent a single juvenile individual (Stw 151), consisting of more than 40 cranial and dental parts, with mixed dentition. It constitutes the most complete set of jaws and teeth of an early hominid child since the Taung child was recovered in 1924. In this paper, the morphological and metrical features of the individual teeth are described. The other associated skull fragments (right ramus of the mandible, left petrous bone, right glenoid region) are also described. Comparisons are made with other South (and East) African fossil hominids. The beautiful preservation simultaneously of most of the deciduous teeth and of the permanent teeth exposed in their crypts allows an accurate analysis of the developmental sequence. A report on the dental developmental status of this juvenile is presented. On the basis of the microanatomical study of the developing permanent teeth, the estimated age at death is 5.2–5.3 years. Reconstructions of the maxillary and mandibular arcades are also offered. The morphological and metrical features of Stw 151 raise the possibility that it may represent a hominid more derived towards an early Homo condition than the rest of the A. africanus sample from Member 4. Am J Phys Anthropol 106:425–465, 1998. © 1998 Wiley-Liss, Inc.     

The functional correlates of jaw‐muscle fiber architecture in tree‐gouging and nongouging callitrichid monkeys

Common (Callithrix jacchus) and pygmy (Cebuella pygmaea) marmosets and cotton‐top tamarins (Saguinus oedipus) share broadly similar diets of fruits, insects, and tree exudates. Marmosets, however, differ from tamarins in actively gouging trees with their anterior dentition to elicit tree exudates flow. Tree gouging in common marmosets involves the generation of relatively wide jaw gapes, but not necessarily relatively large bite forces. We compared fiber architecture of the masseter and temporalis muscles in C. jacchus (N = 18), C. pygmaea (N = 5), and S. oedipus (N = 13). We tested the hypothesis that tree‐gouging marmosets would exhibit relatively longer fibers and other architectural variables that facilitate muscle stretch. As an architectural trade‐off between maximizing muscle excursion/contraction velocity and muscle force, we also tested the hypothesis that marmosets would exhibit relatively less pinnate fibers, smaller physiologic cross‐sectional areas (PCSA), and lower priority indices (I) for force. As predicted, marmosets display relatively longer‐fibered muscles, a higher ratio of fiber length to muscle mass, and a relatively greater potential excursion of the distal tendon attachments, all of which favor muscle stretch. Marmosets further display relatively smaller PCSAs and other features that reflect a reduced capacity for force generation. The longer fibers and attendant higher contraction velocities likely facilitate the production of relatively wide jaw gapes and the capacity to generate more power from their jaw muscles during gouging. The observed functional trade‐off between muscle excursion/contraction velocity and muscle force suggests that primate jaw‐muscle architecture reflects evolutionary changes related to jaw movements as one of a number of functional demands imposed on the masticatory apparatus. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.