Relationships between attrition and lingual tilting in human teeth

Associations between occlusal dental attrition and the lingual tilting of human teeth were investigated in two aboriginal California populations. A literature survey suggests lingual tilting is related geographically and temporally to the helicoidal occlusal plane in humans; if true, lingual tilting should be expected throughout the Homo osteological record. Buccal alveolar abscesses, exposed pulp chambers, extent of tooth attrition, angle of lingual tilt, and amount of overjet were observed for lingually tilted teeth. These attributes were analyzed statistically, leading to a conclusion that lingual tilting is slight and infrequent unless tooth attrition is pronounced. It is suggested that lingual tilting is due in part to masticatory stress. A feedback model considers lingual tilting as one conspicuous manifestation of a more complex “severe attrition syndrome,” the initial stimulus for which may derive from heavy occlusal tooth wear. Untested possibilities should be examined–e.g., age-related changes, the impact of the helicoidal occlusal plane, and the role of masticatory forces.     

Patterns of dental wear in the Lengua Indians of Paraguay

Wear patterns were examined on dental casts of 202 living Lengua Indians from the Chaco area of Paraguay. Consideration was given to the development of the molar helicoidal plane, age-related changes in occlusal attrition, coalescence of dentine exposures, interproximal attrition, and erupted crown height. This study lends support to Osborn's theory of the helicoidal plane development by showing that attrition enhances rather than modifies posteruption molar occlusal planes. The rate of interproximal attrition was found to slow down with the eruption and functional initiation of the third molars. Sinuous and cavo-convex interproximal contact areas that are generated with age, however, appeared to be less abrasion resistant than straight surfaces, hence leading to an increase in interproximal attrition rates with advanced age. Maximum crown height reduction occurred between the ages of 20 and 40 years in central incisors, canines, and first molars. Kruskal-Wallis tests and log linera models failed to demonstrate significant sexually dimorphic or antimeric differences in wear patterns of Lengua teeth.     

Enamel thickness and the helicoidal occlusal plane

In the present study 38 unworn maxillary molars (M¹ = 16, M²= 12, M³ = 10) of modern humans from a Slavic necropolis were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Five slightly worn M¹s and one slightly worn M³ were also used thus increasing the total sample to 44, but measurements made on the worn areas were coded as missing values. Seven measurements of enamel thickness as well as the heights of the protocone and the paracone dentine horns were recorded in order to analyze whether changes in these dimensions in anteroposterior direction can be related to the helicoidal occlusal plane. Uni- and multivariate analyses revealed that the distribution of enamel thickness within and between maxillary molars corresponds to a helicoidal occlusal wear pattern. Enamel thickness along the occlusal basin increases from anterior to posterior, which may lead to rapid development of a reverse curve of Monson in first molars when compared to posterior teeth. However, although these overall differences together with the serial, especially delayed eruption pattern of human molars, contribute to the marked expression of the helicoidal occlusal plane in Homo, differences in enamel patterning between molars indicate that a helicoidal plane is a structural feature of the orofacial skeleton. In contrast to first upper molars, second and third molars show absolutely and relatively thicker enamel under the Phase I wear facet of the paracone, i. e., the lingual slope of the paracone, than under the Phase II facet of the protocone, i. e., the buccal slope of that cusp. These proportional differences are most pronounced in M³, as evidenced by uni- and multivariate statistics. It thus appears that the pattern of enamel thickness distribution from M¹ to M³ follows a trend towards providing additional tooth material in areas that are under greater functional demands, that is, corresponding to a lingual slope of wear anteriorly and to a flat or even buccal one posteriorly. In addition, the heights of the dentine horns in anteroposterior direction change in a way that lends support to the hypothesis that the axial inclination of teeth could be one of the most important factors for the development of the helicoidal occlusal plane. Finally, the changes in morphology and enamel thickness distribution from first to third upper molars found in this study suggest that molars could be “specialized” in their function, i. e., from performing proportionally more shearing anteriorly to increased crushing and grinding activities posteriorly. © 1994 Wiley-Liss, Inc.     

Helicoidal plane of dental occlusion

A helicoidal plane of postcanine occlusion has been patchily reported in many recent and fossil dentitions of man, and has been suggested as a taxonomic marker distinguishing between the dentitions of Homo and Australopithecines. The present paper describes the helicoidal plane in 19 out of 23 modern human (probably Indian) worn dentitions, in both gracile and robust Australopithecines and in extant anthropoids. It is suggested that tooth wear converts the plane of occlusion present in little-worn teeth, the Monson curve, into a helicoidal plane when 1) the diet is more abrasive, 2) the enamel is thinner and less abrasion resistant, and 3) a longer time separates the eruption of the three molar teeth in a jaw quadrant. A model demonstrates that during the power stroke of a chewing cycle the working side molars move in much the same direction whether the molar occlusal plan follows a Monson curve or a helicoidal plane. The difference is that in the former case the three molars work at the same time while in the latter case they work in sequence from anterior to posterior, thereby concentrating force on one tooth at a time. Because the occlusal plane changes during the life of individuals consuming an abrasive diet, the condition of most anthropoids and hominids, it is argued that the Monson curve has functional significance not because of its influence on occlusal relations and/or jaw movement but because the molar teeth are embedded in bone roughly perpendicular to it, a direction which resists tilting of the teeth during mastication. It is concluded that the helicoidal plane probably has little if any value as a taxonomic marker.     

Differentiation in phenotypic plasticity among populations of Arabis serrata Fr. & Sav. (Brassicaceae)

Studies on divergence of phenotypic plasticity in closely related species have suggested that character means and plasticity of these characters may evolve independently. Similar patterns of divergence between populations within a species have been reported although few plant species have been studied. Thus, in this paper, the patterns of differentiation between character means and phenotypic plasticity among eight populations of Arabis serrata are documented. Mean response and magnitude and pattern of phenotypic plasticity were measured and compared in plants growing under an environmental gradient of nutrients. Differences in means and coefficients of variation (CV as indicators of plasticity) among populations were compared using the Canberra metric and generating unrooted Wagner trees. Populations showed significant differences in character means in nine morphological traits. Magnitude and patterns of phenotypic plasticity showed a complex pattern of differentiation for each trait and population. Biomass traits were more plastic, in general, than characters associated with linear size. Comparisons between pairs of populations for nine morphological traits showed that in 28.6% of 252 possible cases, populations differed in means, magnitude and patterns of phenotypic plasticity. In almost 90% of the cases, populations differed in magnitude and/or pattern of plasticity. Considering all characters together, populations from similar habitats and with common life history features tended to respond in similar ways. The patterns of divergence, however, suggest that character means and character plasticities among populations are able to evolve independently.     

Changes in the pattern of tooth wear from prehistoric to recent periods in Japan

Although a number of studies have been performed on interpopulational variation of tooth wear patterns in recent humans, the major interest in the study of tooth wear so far has been in reconstructing the subsistence and behavior of prehistoric populations, and hence research on wear pattern changes in historic times has been superficial. The present study investigated temporal change in the pattern of wear on the permanent dentition of the Japanese through comparison of the following five groups: prehistoric hunter-gatherers, prehistoric agriculturists, medieval, premodern, and recent populations. The pattern of reduction of occlusal wear severity across thesechronological groups was not similar between the anterior and posterior portions of the dentition. Occlusal wear on the anterior teeth was noticeably lighter in the prehistoric agriculturists and later populations than in the prehistoric hunter-gatherers, while clear reduction of occlusal wear on the posterior teeth occurred after medieval times. The temporal variations in the degree of mesiodistal crown diameter loss due to wear and its anterior-posterior gradient within the dentition are generally consistent with those observed in the occlusal wear pattern. Possible causative factors of these temporal changes in the wear pattern are discussed. Am J Phys Anthropol 109:501–508, 1999. © 1999 Wiley-Liss, Inc.     

Hunter-Schreger band orientation in interproximal enamel of modern human molars with complex morphological traits

A recent paper concerning characteristic groove-shaped wear in interproximal attritional facets of Neandertal posterior teeth correlated groove formation with deep enamel structural traits (Villa & Giacobini, 1995). Further studies were carried out on modern human teeth in order to evaluate a possible correlation between deep enamel structure and some crown complex morphological features. Seventy-five isolated molars from medieval and recent ossuaries as well as five molars recently extracted for therapeutic purpose were examined using scanning electron and optic microscope ground sections of interproximal enamel. The results showed possible correlations between deep enamel structural characteristics (i.e., Hunter-Schreger band verticalization) and some crown complex traits (i.e., occlusal groove pattern, mesial and distalfovea, mesial and distal accessory tubercules, interproximal marginal ridges). Observations reported in this study showed a significantly higher frequency of Hunter-Schreger band verticalization in lower molars with an occlusal complex pattern (i.e. primitive fissure pattern “Y” or “+”). This observation suggests a positive correlation among crown complex traits (which occur frequently in Neandertal teeth) with deep enamel structural characteristics. In addition, analysis of teeth grouped according to individual showed crown morphological traits and deep enamel structural characteristics corresponding to the same individual. This observation supports a genetic basis in occlusal shape and microstructural dental traits.     

Variation in migration propensity among individuals maintained by landscape structure

Metapopulation dynamics lead to predictable patterns of habitat occupancy, population density and trophic structure in relation to landscape features such as habitat patch size and isolation. Comparable patterns may occur in behavioural, physiological and life‐history traits but remain little studied. In the Glanville fritillary butterfly, females in newly established populations were more mobile than females in old populations. Among females from new populations, mobility decreased with increasing connectivity (decreasing isolation), but in females from old populations mobility increased with connectivity. The [ATP]/[ADP] ratio of flight muscles following controlled activity showed the same pattern as mobility in relation to population age and connectivity, suggesting that physiological differences in flight metabolic performance contribute to the observed variation in mobility. We demonstrate with an evolutionary metapopulation model parameterised for the Glanville fritillary that increasing spatial variation in landscape structure increases variance in mobility among individuals in a metapopulation, supporting the general notion that complex landscape structure maintains life‐history variation.     

Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report

ABSTRACT: INTRODUCTION: A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. CASE PRESENTATION: A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebroafferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthoticsyntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. CONCLUSIONS: A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be useful in patients with asymmetric hemodynamics of cerebro-afferent vessels and dental occlusal proprioceptive rebalance can integrate the complex therapy of patients with increased chronic sympathetic activity.     

Age-related variability in occlusal wear planes

Investigation of two populations of 136 individuals shows several patterns of occlusal wear plane change which are positively correlated with age. For individuals up to the age of 18, there is a characteristic pattern in which the occlusal wear planes of the mandibular teeth are lingually sloped and those of the maxillary dentition buccally sloped, with the exception of the maxillary premolars, which are also lingually sloped. The long axes of the mandibular teeth give them a lingual orientation relative to the maxillary teeth, and the long axes of the maxillary molars, by contrast, are buccally oriented. In the 18-30 age range for all sexes, the mandibular M1 becomes buccally sloped on its occlusal surface while the occlusal wear plane on the maxillary M1 becomes lingually sloped. Later age changes indicate a trend for the mandibular premolars to become buccally sloped, while the wear planes of the maxillary premolars remain lingually sloped. There is a corresponding tendency for the maxillary and mandibular second molars to undergo changes in the initial orientation of the occlusal wear planes.     

The natural history of the helicoidal occlusal plane and its evolution in early Homo

In modern man the pitch of the occlusal plane may vary along the tooth-row. When anterior cheek-teeth show a plane sloping upward palatally, whilst that on posterior cheek-teeth slopes upward buccally, there results a twisted or helicoidal occlusal plane (Ackermann). Several hypotheses have been proposed for the structural basis of the helicoidal occlusal plane. Campbell's proposal ('25) has gained widest acceptance, namely that the helicoid results from anteroposterior differences in upper and lower alveolar arch width. In the early 1960s, while studying the Olduvai hominids assigned to Homo habilis, the author noted changing occlusal slopes along the tooth-row and a slight helicoid, although these featues had not been noted in other early hominids. Subsequently, Wallace showed a total absence of the helicoid from South African australopithecines, and its presence in Swartkrans Homo, SK 45 and SK 80. Recent studies confirm the presence of the helicoid in all available specimens of H. habilis, including Stw 53 found at Sterkfontein in 1976. Hence, this trait may distinguish between Australopithecus and early Homo. Measurements of the maxillary arch widths have shown that, whereas in Australopithecus arch widths increase to a maximum at M3, in early Homo maxillary arch widths are greatest at M2. The decline in posterior maxillary arch width is part of a general reduction of that region. Thus despite striking elongation of premolars and M1 in early Homo, M2 and M3 are mesiodistally abbreviated. It is hypothesized that the onset of posterior arch reduction, with the appearance of a helicoid, was a structural and functional concomitant of the transition from the presumed australopithecine ancestor to H. habilis.     

Plio-Pleistocene evolution of the genus Castor (Rodentia, Mammalia) in Europe: C. fiber plicidens of Pietrafitta (Perugia, Central Italy)

In the lignite sediments of Pietrafitta (Tiberino Basin, Umbria, Central Italy), a rich fossil assemblage of vertebrate, invertebrate and plant remains belonging to the Farneta Faunal Unit (Late Villafranchian, Early Pleistocene) was collected. Among them fossil beaver cranial remains are relatively abundant. Western-Central Europe Villafranchian beaver remains were assigned to C. plicidens by some authors because molar occlusal surface patterns show complex enamel crenulations. Several recent authors have classified them as C. fiber while analysing other morphological patterns. Our samples have been compared to Plio-Pleistocene fossil remains and to living European populations of the genus Castor. New morphometric parameters on molar occlusal surfaces have been defined and statistical analyses (One-Way MANOVA, Principal Component Analysis and Canonical Discriminant Analysis) have been performed on them. The results point out a subspecific separation between the Late Villafranchian beaver of Pietrafitta, Quarata and San Giovanni in Valdarno (Umbria and Tuscany) and C. fiber populations. St. Vallier (France) Late Pliocene and Mosbach 2 (Germany) Middle Pleistocene beavers classified respectively by Viret and Friant as C. plicidens, show a C. f. fiber molar teeth pattern. Therefore, C. fiber plicidens did not occur in Central-Western Europe and this subspecific name may be used only for the local populations of Valdarno and Tiberino Basin (San Giovanni in Valdarno, Quarata, Pietrafitta and a few localities of the same area), at that time peripheral populations, probably semi-isolated during the Late Villafranchian, and at the southern limit of the geographic range of C. fiber.     

Negritos, Australian aborigines, and the "proto-sundadont" dental pattern: the basic populations in east Asia, V.

Five evolutionarily significant dental traits were identified from a B-square distance analysis of nine crown characters recorded for several populations of East Asia and Oceania. Intergroup variation in these traits distinguishes three major divisions of the Mongoloid dental complex: sundadonty, sinodonty, and the dental pattern of Australian Aborigines. The Australian crown features may be characterized as having high frequencies of evolutionarily conservative characters. Negritos, one of the probable representatives of indigenous inhabitants of Southeast Asia who may have shared a common ancestor with Australians, possess the more derived sundadont dental pattern. As far as the five crown traits treated here are concerned, Australian dental features may be described as conforming to a "proto-sundadont" dental pattern, applying Turner's terminology. This pattern may represent a microevolutionary step prior to the emergence of the sundadont and sinodont patterns.     

Complex clines: the predictivity of complicated patterns of geographic variation portrayed by multivariate analysis

The stability of complex patterns of geographic variation was investigated by assessing the congruence between multivariate ordinations derived from randomly chosen real characters. Two series of populations were analysed representing two situations with complex patterns of geographic variation. The first, a ‘Eurasian’ series of populations, showed a strongly structured hierarchical pattern, the second, an ‘eastern’ series of populations, showed a more subtle complex pattern of smooth clines and steps. The characters were selected from a total of 81 (Eurasian) or 61 (eastern) within-population independent characters from six different systems. The congruence between ordinations of the geographical populations was measured by the rotational fit statistic, R². Three procedures were used to compare ordinations based on from two to up to 80 characters randomly chosen to give: A, completely independent character sets; B, subsets compared to the total set; and C, potentially overlapping sets. All three procedures showed that congruence between the ordinations was asymptotic in relation to character number. This relationship was described by one of two mathematical models (procedure B did not result in a hyperbolic model as found with simple patterns of geographic variation). Generally speaking, once a sufficient number of characters are used, the complex patterns of geographic variation are stable, reliable and predictive and not substantially influenced by character choice. The strongly structured hierarchical pattern required 15 or so characters to achieve reliability whilst the more subtle patterns required 20 or so characters. However, the addition of further characters does improve reliability in both cases. The greater percentage of variance portrayed by three-dimensional ordinations compared to two-dimensional ordinations is achieved at the cost of lower congruence when a sufficient number of characters are used. If case studies of geographic variation were to adopt these procedures (preferably using completely independent character sets; procedure A) the reliability of their results would be indicated).     

Spatial and temporal regulations in helicoidal extracellular matrices: comparison between plant and animal systems.

This paper proposes an overview of the last few years' investigations regarding the helicoid formation in extracellular matrices (ECMs). Despite the architectural polymorphism displayed among the layered ECM throughout the living kingdom, helicoidal structures are often described in ECMs and appear as an optimal mechanical device. Helicoids correspond to complex two-phases composites, formation and regulation of which are still a source of debate. Taking the time-event into consideration, it is clear that helicoid in ECMs are regulable structures. On the other hand, analogies with helicoidal formations in cholesteric liquid crystals strongly support the hypothesis of involvement of self-assembly processes. Therefore the balance between self-assemblies and cell regulation is questioned. By gathering animal and plant data on the topic and by analysing the characteristics of these helicoids in ECMs, it is clear that cells have the necessary machinery to interfere with the self-assembly processes in response to physiological or mechanical mechanisms. They are able to modify the physicochemical conditions outside the plasma membrane, therefore acting on the pattern of self-assembly. Several mechanisms are proposed to explain sudden variations occurring in the helicoidal formation with time.     

Genetic constraints on wing pattern variation in Lycaeides butterflies: A case study on mapping complex,multifaceted traits in structured populations

Patterns of phenotypic variation within and among species can be shaped and constrained by trait genetic architecture. This is particularly true for complex traits, such as butterfly wing patterns, that consist of multiple elements. Understanding the genetics of complex trait variation across species boundaries is difficult, as it necessitates mapping in structured populations and can involve many loci with small or variable phenotypic effects. Here, we investigate the genetic architecture of complex wing pattern variation in Lycaeides butterflies as a case study of mapping multivariate traits in wild populations that include multiple nominal species or groups. We identify conserved modules of integrated wing pattern elements within populations and species. We show that trait covariances within modules have a genetic basis and thus represent genetic constraints that can channel evolution. Consistent with this, we find evidence that evolutionary changes in wing patterns among populations and species occur in the directions of genetic covariances within these groups. Thus, we show that genetic constraints affect patterns of biological diversity (wing pattern) in Lycaeides, and we provide an analytical template for similar work in other systems.     

SNP identification, linkage disequilibrium, and haplotype analysis for a 200-kb genomic region in a Korean population

Understanding patterns of linkage disequilibrium (LD) across genomes may facilitate association mapping studies to localize genetic variants influencing complex diseases, a recognition that led to the International Haplotype Mapping Project (HapMap). Divergent patterns of haplotype frequency and LD across global populations require that the HapMap database be supplemented with haplotype and LD data from additional populations. We conducted a pilot study of the LD and haplotype structure of a genomic region in a Korean population. A total of 165 SNPs were identified in a 200-kb region of 22q13.2 by direct sequencing. Unphased genotype data were generated for 76 SNPs in 90 unrelated Korean individuals. LD, haplotype diversity, and recombination rates were assessed in this region and compared with the HapMap database. The pattern of LD and haplotype frequencies of Korean samples showed a high degree of similarity with Japanese data. There was a strong correlation between high LD and low recombination frequency in this region. We found considerable similarities in local LD patterns between three Asian populations (Han Chinese, Japanese, and Korean) and the CEPH population. Haplotype frequencies were, however, significantly different between them. Our results should further the understanding of distinctive Korean genomic features and assist in designing appropriate association studies.     

Multivariate patterns of geographic variation between the island and mainland populations of the Eastern grass snake (Natrix natrix natrix)

The substantial racial variation between the mainland and island populations of the Eastern grass snake ( Natrix natrix natrix ) is analysed by a range of multivariate methods, including principal component and canonical analysis. These techniques reveal a complex pattern of geographic variation which include sharp transition zones, gradual clines, a wide range of divergence of island populations and greater divergence per distance in the south than in the north. These patterns relate to the phylogenesis of this "incipient" species, and its post-Pleistocene range expansion as presented here and elsewhere. These racial patterns do not generally relate to physiographic features, conventional subspecies or CURRENT physical or biotic factors.     

Tool use in animals: Cognition and ecology. Edited by Crickette M. Sanz,Josep Call,and Christophe Boesch. New York,NJ: Cambridge University Press. 2013. 313 pp. ISBN 978‐1‐107–01119‐9. $110 (hardcover).

Enamel thickness has been linked to functional aspects of masticatory biomechanics and has been demonstrated to be an evolutionary plastic trait, selectively responsive to dietary changes, wear and tooth fracture. European Late Paleolithic and Mesolithic hunter‐gatherers mainly show a flat wear pattern, while oblique molar wear has been reported as characteristic of Neolithic agriculturalists. We investigate the relationships between enamel thickness distribution and molar wear pattern in two Neolithic and medieval populations. Under the assumption that dietary and/or non‐dietary constraints result in directional selective pressure leading to variations in enamel thickness, we test the hypothesis that these two populations will exhibit significant differences in wear and enamel thickness patterns. Occlusal wear patterns were scored in upper permanent second molars (UM2) of 64 Neolithic and 311 medieval subadult and adult individuals. Enamel thickness was evaluated by microtomography in subsamples of 17 Neolithic and 25 medieval individuals. Eight variables describing enamel thickness were assessed. The results show that oblique molar wear is dominant in the Neolithic sample (87%), while oblique wear affects only a minority (42%) of the medieval sample. Moreover, in the Neolithic molars, where buccolingually directed oblique wear is dominant and greatest enamel lost occurs in the distolingual quadrant, thickest enamel is found where occlusal stresses are the most important—on the distolingual cusp. These results reveal a correlation between molar wear pattern and enamel thickness that has been associated to dietary changes. In particular, relatively thicker molar enamel may have evolved as a plastic response to resist wear. Am J Phys Anthropol 155:162–172, 2014. © 2014 Wiley Periodicals, Inc.     

Unravelling a biogeographical knot: origin of the 'leapfrog' distribution pattern of Australo-Papuan sooty owls (Strigiformes) and logrunners (Passeriformes)

Molecular analysis of two Australo-Papuan rainforest birds exhibiting correlated 'leapfrog' patterns were used to elucidate the evolutionary origin of this unusual pattern of geographical differentiation. In both sooty owls (Tyto) and logrunners (Orthonyx), phenotypically similar populations occupy widely disjunct areas (central-eastern Australia and upland New Guinea) with a third, highly distinctive population, occurring between them in northeastern Queensland. Two mechanisms have been proposed to explain the origin of leapfrog patterns in avian distributions: recent shared ancestry of terminal populations and unequal rates or phenotypic change among populations. As the former should generate correlated patterns of phenotypic and genetic differentiation, we tested for a sister relationship between populations from New Guinea and central-eastern Australia using nuclear and mitochondrial DNA sequences. The resulting phylogenies not only refute recent ancestry as an explanation for the leapfrog pattern, but provide evidence of vastly different spatio-temporal histories for sooty owls and logrunners within the Australo-Papuan rainforests. This incongruence indicates that the evolutionary processes responsible for generating leapfrog patterns in these co-distributed taxa are complex, possibly involving a combination of selection and drift in sooty owls and convergence or retention of ancestral characteristics in logrunners.