Yawning: An evolutionary perspective

Yawning is a ubiquitous activity among humans, nonhuman primates, mammals, birds and other vertebrates. Comparative analysis suggests that yawning has two major features: (1) communication — whereby the behavior of other individuals is affected, and (2) direct physiological benefit — whereby the organism is receiving some direct physiological benefit from yawning. Various functional hypotheses used to explain yawning in an evolutionary context are reviewed. The contagious nature in humans and the manifest lack of contagion in other species suggests that yawning in humans has a different and as yet poorly understood evolutionary history.     

Osteoporosis: an evolutionary perspective

Increased life expectancy has led to an overall aging of the population and greater numbers of elderly people. Therefore, the number of people with osteoporosis has increased substantially, accompanied with an epidemic of hip fractures. Osteoporosis is an age-related systemic condition that naturally occurs, among mammals, only in humans. Osteoporosis is known to be highly heritable. However, assuming a genetic determinant for this post-reproductive disease to be transmitted from one generation to the next is counter-intuitive, based on the principles of human evolution, I will attempt to provide an explanation of the phenomenon from the point of view of evolution, selection, and changed environment in humans, which contributed to human longevity, while on other hand, contribute to diseases of civilization, including osteoporosis. There is a need to delve into evolution of human species in search for adaptive patterns to a specific environment that humans are operating in the last couple of millennia, to clarify whether “good” and “bad” genes exist, and how to find and correct them. The answer to the above questions will help us to identify causes of the current epidemic of osteoporosis and to pin-point a tailored treatment.     

从进化谈细菌细胞间的群体感应信号传递

传统观念认为细菌是一种个体的、非社会性的生物体。近年来的研究表明细菌可以产生化学信号并通过它们实现细菌间信息传递。细菌的群体感应调节系统(Quorum sensing,QS)调节着个体细胞之间的相互合作,使其表现出类似多细胞的群体行为。文章以近年来的一些最新研究进展为基础,在了解细菌间的信息传递系统的基础上,从进化角度讨论了QS系统的遗传产生过程,探讨了细菌细胞间的相互作用。细菌间的信息交流是一种动态的过程,受到了环境中的营养物质的水平、温度、pH等多种因素的影响。作者推测细菌信号传递系统的进化是受到环境条件以及基因交换、所在微生物群体变化等因素影响下的一种不断变化的动态过程,这也许有别于动植物这类的高等生物的进化过程。这种动态的变化过程也就暗示:从长远来看,信息传递系统中的偷机者只是在一定条件下的暂时存在。     

Human prosociality from an evolutionary perspective: variation and correlations at a city-wide scale

Prosociality is a fundamental theme in all branches of the human behavioral sciences. Evolutionary theory sets an even broader stage by examining prosociality in all species, including the distinctive human capacity to cooperate in large groups of unrelated individuals. We use evolutionary theory to investigate human prosociality at the scale of a small city (Binghamton, NY), based on survey data and a direct measure of prosocial behavior. In a survey of public school students (Grades 6–12), individual prosociality correlates strongly with social support, which is a basic requirement for prosociality to succeed as a behavioral strategy in Darwinian terms. The most prosocial individuals receive social support from multiple sources (e.g., family, school, neighborhood, religion and extracurricular activities). Neighborhood social support is significant as a group-level variable in addition to an individual-level variable. The median income of a neighborhood does not directly influence individual prosociality, but only indirectly through forms of social support. Variation in neighborhood quality, as measured by the survey, corresponds to the likelihood that a stamped addressed letter dropped on the sidewalk of a given neighborhood will be mailed. We discuss the results in relation to evolutionary theory, the experimental economics literature and the social capital literature in an effort to integrate the study of human prosociality across disciplines.     

Hyphal morphogenesis: an evolutionary perspective

Two modes of cellular morphogenesis predominate within the fungal kingdom; yeast growth and hyphal growth. The availability of complete genome sequences that span the kingdom has made possible the use of comparative approaches that address important questions regarding the evolution of these growth modes. These comparisons have also emphasized the point that not all hyphae are the same despite outward appearances. Topics considered here include the origins of hyphal growth, as well as the potential causes of and the consequences resulting from the loss of hyphal growth in yeast lineages. The mechanisms that enable distinct morphological outputs (i.e., yeast vs. hyphae) using an essentially identical inventory of gene products are also considered. Finally, processes implicated in the regulation of hyphal tip complexes are addressed from an evolutionary perspective.     

Prions: an evolutionary perspective.

Studies in both prion-due diseases in mammals and some non-Mendelian hereditary processes in yeasts have demonstrated that certain proteins are able to transmit structural information and self-replication. This induces the corresponding conformational changes in other proteins with identical or similar sequences. This ability of proteins may have been very useful during prebiotic chemical evolution, prior to the establishment of the genetic code. During this stage, proteins (proteinoids) must have molded and selected their structural folding units through direct interaction with the environment. The proteinoids that acquired the ability to propagate their conformations (which we refer to as conformons) would have acted as reservoirs and transmitters of a given structural information and hence could have acted as selectors for conformational changes. Despite the great advantage that arose from the establishment of the genetic code, the ability to propagate conformational changes did not necessarily disappear. Depending on the degree of involvement of this capacity in biological evolution, we propose two not mutually exclusive hypotheses: (i) extant prions could be an atavism of ancestral conformons, which would have co-evolved with cells, and (ii) the evolution of conformons would have produced cellular proteins, able to transmit structural information, and, in some cases, participating in certain processes of regulation and epigenesis. Therefore, prions could also be seen as conformons of a conventional infectious agent (or one that co-evolved with it independently) that, after a longer or shorter adaptive period, would have interacted with conformons from the host cells.     

An evolutionary perspective of biological invasions

The workshop on the Evolutionary Perspective of Biological Invasions in Terrestrial Ecosystems was held in Halle, Germany from 30 September to 3 October 2002.     

Epigenetic modifications in plants: an evolutionary perspective

Plant genomes are modified by an array of epigenetic marks that help regulate plant growth and reproduction. Although plants share many epigenetic features with animals and fungi, some epigenetic marks are unique to plants. In different organisms, the same epigenetic mark can play different roles and/or similar functions can be carried out by different epigenetic marks. Furthermore, while the enzymatic systems responsible for generating or eliminating epigenetic marks are often conserved, there are also cases where they are quite divergent between plants and other organisms. DNA methylation and methylation of histone tails on the lysine 4, 9, and 27 positions are among the best characterized epigenetic marks in both plants and animals. Recent studies have greatly enhanced our knowledge about the pattern of these marks in various genomes and provided insights into how they are established and maintained and how they function. This review focuses on the conservation and divergence of the pathways that mediate these four types of epigenetic marks.     

Dominance-seeking strategies in primates: an evolutionary perspective

The thesis advanced in this paper is that there are basic social influence strategies and attendant principles that are characteristic of social primates. A model for analyzing and comparing social influence strategies in primates, with particular attention to dominance-seeking strategies, is advanced. The utility of the model is illustrated by reference to studies of social influence strategies in baboons, chimpanzees, and humans. Emphasis is placed on the role of communication as the vehicle for social competence. Speculation is offered about the importance of the evolution of symbolic communication in expanding the repertoire of dominance-seeking strategies in human primates. Paper presented at the XII Congress of the International Primatological Society, Brasilia, Brasil 24–29, July, 1988.     

Human evolutionary research in eastern germany

Human evolutionary research in Eastern Germany, limited in this paper to the origins and evolution of Pleistocene man, has mainly focused during the last decade on theoretical aspects of the evolution of man and human society from multiple and interdisciplinary perspectives. An interdisciplinary working group ‘Probleme der Menschwerdung’ was founded in 1977. About 30 specialists from various fields have discussed problems of the origins and evolution of man and human society under interdisciplinary aspects. The activities, difficulties and results of this cooperation will be outlined in this paper. There will also be given a progress report on the disciplinary initiated research on local sites as well as on general aspects and problems. Paper dedicated to Professor Dr. rer. nat. Dr.sc.med. Hans Grimm, Berlin, on his 80th birthday, February 7, 1990.     

Polycomb Group proteins: an evolutionary perspective

The chromatin-associated Polycomb Group (PcG) proteins were first identified in genetic screens for homeotic transformations in Drosophila melanogaster. In addition to body patterning in metazoans, members of the PcG are now known to regulate epigenetic cellular memory, pluripotency and stem cell self-renewal. Here, we discuss the functional versatility of the PcG family and the evolutionary history of a subset of these proteins including Drosophila E(z), Pc, Psc, dRing and their homologs in plants and animals. We propose that PcG gene expansion and diversification contributed significantly to the complexity of heritable gene repression mechanisms in extant multicellular organisms.     

An evolutionary perspective on caching by corvids

A principal finding in the food-caching literature is that species differences in hoarding propensity are positively correlated with species differences in degree of adaptations to caching behaviour, such as performance on spatial memory tasks and hippocampal volume. However, there are examples that do not fit this pattern. We argue that these examples can be better understood by considering the phylogenetic relatedness between species. We reconstruct the ancestral state for caching behaviour in corvids and assess when transitions in caching behaviour occurred within the corvid phylogeny. Our analysis shows that the common ancestor of all corvids was a moderate cacher. This result suggests that corvids followed a bi-directional evolutionary trajectory in which caching was secondarily lost twice and there were at least two independent transitions from moderate to specialized caching. The independent evolution of specialized cachers in the two groups must, therefore, be a case of convergent evolution. This is exemplified by the fact that specialized cachers show structurally different adaptations serving the same function to intense caching, such as different pouches to transport food. Finally, we argue that convergent evolution may have led to adaptations in memory and hippocampus that serve the same function but differ in design, and that these different adaptations may explain the examples that do not fit the pattern predicted by the adaptive specialization hypothesis.