Social evolution in toothed whales

Two contrasting results emerge from comparisons of the social systems of several odontocetes with terrestrial mammals. Researchers have identified remarkable convergence in prominent features of the social systems of odontocetes such as the sperm whale and bottlenose dolphin with a few well-known terrestrial mammals such as the elephant and chimpanzee. In contrast, studies on killer whales and Baird's beaked whale reveal novel social solutions to aquatic living. The combination of convergent and novel features in odontocete social systems promise a more general understanding of the ecological determinants of social systems in both terrestrial and aquatic habitats, as well as the relationship between relative brain size and social evolution.     

Distribution of oak forests in Eastern Europe over the last 13000 years

The dynamics and distribution of oak forests on the territory of Eastern Europe over the last 12500 years have been studied. The basic materials used in this study are spore-pollen diagrams converted into the PALAEO database. As a result of this study, a series of maps describing the paleohabitat of oak forests with a 500-year increment has been constructed. Different structures of the paleohabitat of English oak (Quercus robur L.) and the basic forest paleocommunities including this species have been identified and described. The main migration pathways and refugia of oak forests have been determined, including the Volynskaya and Podolskaya uplands, the southern part of the Central Russian and Privolzhskaya uplands, Meshchera, Kodry, and the Mozyrsk-Ovruch-Slovechan refugium.     

Climate change and evolving human diversity in Europe during the last glacial

A link between climate change and human evolution during the Pleistocene has often been assumed but rarely tested. At the macro-evolutionary level Foley showed for hominids that extinction, rather than speciation, correlates with environmental change as recorded in the deep sea record. Our aim is to examine this finding at a smaller scale and with high-resolution environmental and archaeological archives. Our interest is in changing patterns of human dispersal under shifting Pleistocene climates during the last glacial period in Europe. Selecting this time frame and region allows us to observe how two hominid taxa, Neanderthals and Crô-Magnons, adapted to climatic conditions during oxygen isotope stage 3. These taxa are representative of two hominid adaptive radiations, termed terrestrial and aquatic, which exhibited different habitat preferences but similar tolerances to climatic factors. Their response to changing ecological conditions was predicated upon their ability to extend their societies in space and time. We examine this difference further using a database of all available radiocarbon determinations from western Europe in the late glacial. These data act as proxies for population history, and in particular the expansion and contraction of regional populations as climate changed rapidly. Independent assessment of these processes is obtained from the genetic history of Europeans. The results indicate that climate affects population contraction rather than expansion. We discuss the consequences for genetic and cultural diversity which led to the legacy of the Ice Age: a single hominid species, globally distributed.     

A hominid tooth from Bulgaria: the last pre-human hominid of continental Europe

A hominid upper premolar was discovered in the Azmaka quarry, near Chirpan (Bulgaria). The associated fauna, especially the co-occurrence of Choerolophodon and Anancus among the proboscideans, and Cremohipparion matthewi and Hippotherium brachypus among the hipparions, constrains the age of the locality to the second half of the middle Turolian (ca. 7 Ma), making it the latest pre-human hominid of continental Europe and Asia Minor. The available morphological and metric data are more similar to those of Ouranopithecus from the Vallesian of Greece than to those of the early to middle Turolian hominids of Turkey and Georgia, but the time gap speaks against a direct phyletic link, and Turolian migration from the east cannot be rejected.     

Convective heat transfer characteristics of toothed leaves

Summary Model leaves were used to test the hypothesis that serrate leaves have more convective heat loss than entire leaves of the same average size. Convection coefficients were positively correlated with size of teeth, supporting the hypothesis. Experimental results were in close agreement with theoretical predictions, which assumed an inverse correlation between depth of serration and effective leaf dimension.Abbreviations A total surface area of model (cm²) - D characteristic dimension of model (cm) - h convection coefficient (cal cm^-2 min^{-1 o}K^-1) - I radiant energy flux (cal cm^-2 min^-1) - Q radiant energy absorbed by leaf (cal min^-1) - q_c convective heat transfer (cal min^-1) - q_e evaporative heat loss (cal min^-1) - q_k conductive heat loss (cal min^-1) - q_r radiative heat loss (cal min^-1) - T_a air temperature (^oK) - T₁ model temperature (^oK) - V wind speed (m s^-1) - emissivity - Stefan-Boltzmann constant (8.130x10^-11 cal min^-1 cm^{-2 o}K^-4)     

Changes in the sexual dimorphism of the human mandible during the last 1200 years in Central Europe

According to many investigations, changes in mandibular morphology can occur synchronously with changes in the environment, and sexual dimorphism of the mandible can be influenced by the environment. Sexual dimorphism during the last 1200 years was evaluated using geometric morphometric analysis of virtual cranial models. The method of geometric morphometrics allows differences in size and shape to be assessed separately. We analyzed groups of adult individuals dating to Early Middle Ages, High Middle Ages, Early Modern Ages and from a modern Czech population (21st century). Significant sexual dimorphism in mandibular size was found in all populations. A trend in the sexual dimorphism of size was seen, with differences between the sexes increasing gradually over time. Size changes in female mandibles were a better reflection of environmental conditions and climate than size changes in male mandibles. Regarding changes in the sexual dimorphism of shape, significant dimorphism was found in all four samples. However, the pattern of mandibular shape dimorphism was different and varied considerably between samples. There was only one stable shape trait showing sexual dimorphism across all four samples in our study: the gonion lies more laterally in male than in female mandibles and male mandibles are relatively wider than female mandibles. Sexual dimorphism of shape is not influenced by the climate; instead sexual selection might play a role. This research supports earlier studies that have found that the degree and pattern of sexual dimorphism is population-specific and the factors regulating sexual dimorphism today may not be the same as those in the past.     

The last common bilaterian ancestor

Many regulatory genes appear to be utilized in at least superficially similar ways in the development of particular body parts in Drosophila and in chordates. These similarities have been widely interpreted as functional homologies, producing the conventional view of the last common protostome-deuterostome ancestor (PDA) as a complex organism that possessed some of the same body parts as modern bilaterians. Here we discuss an alternative view, in which the last common PDA had a less complex body plan than is frequently conceived. This reconstruction alters expectations for Neoproterozoic fossil remains that could illustrate the pathways of bilaterian evolution.