Search results for "Biological evolution"
showing 10 items of 522 documents
Content, cost, and context: A framework for understanding human signaling systems
2019
Humans frequently perform extravagant and seemingly costly behaviors, such as widely sharing hunted resources, erecting conspicuous monumental structures, and performing dramatic acts of religious devotion. Evolutionary anthropologists and archeologists have used signaling theory to explain the function of such displays, drawing inspiration from behavioral ecology, economics, and the social sciences. While signaling theory is broadly aimed at explaining honest communication, it has come to be strongly associated with the handicap principle, which proposes that such costly extravagance is in fact an adaptation for signal reliability. Most empirical studies of signaling theory have focused on…
On the Age of Leprosy
2014
Leprosy is a chronic infection of the skin and nerves caused by Mycobacterium leprae and the newly discovered Mycobacterium lepromatosis. Human leprosy has been documented for millennia in ancient cultures. Recent genomic studies of worldwide M. leprae strains have further traced it along global human dispersals during the past ∼ 100,000 years. Because leprosy bacilli are strictly intracellular, we wonder how long humans have been affected by this disease-causing parasite. Based on recently published data on M. leprae genomes, M. lepromatosis discovery, leprosy bacilli evolution, and human evolution, it is most likely that the leprosy bacilli started parasitic evolution in humans or early h…
Discussion
1999
Homo sapiens L. has been described as the naked ape, and this nakedness undoubtedly constitutes one of the most striking differences in appearance between man and the apes. Nakedness has been attributed at various times to sexual selection [1], aquatic stage [2], hunting [3], cooling [4], sex [5], neoteny [6] and allometry [7], most proposed explanations logically revealing some aspect of the phenomenon. However, most fail to account for the distinctiveness of man's hairlessness among mammals of the same size. Unfortunately, fossils cannot help us to explain how denudation occurred, and how it helped hominids to survive. In this paper I will present an old hypothesis with a new point of vie…
Inflammation and Life-Span
2005
In their Review “Inflammatory exposure and historical changes in human life-spans” (17 Sept., p. [1736][1]), C. E. Finch and E. M. Crimmins reinforce earlier suggestions that many diseases and disabilities of older age have their roots in previous exposures to infectious agents and other sources
Symposium overview: Evolution of pheromonal communication in insects.
2009
1749-6632 (Electronic) 0077-8923 (Linking) Journal Article Review
Molecular evolution of the arthropod hemocyanin superfamily.
2001
Arthropod hemocyanins are members of a protein superfamily that also comprises the arthropod phenoloxidases (tyrosinases), crustacean pseudohemocyanins (cryptocyanins), and insect storage hexamerins. The evolution of these proteins was inferred by neighbor-joining, maximum-parsimony, and maximum-likelihood methods. Monte Carlo shuffling approaches provided evidence against a discernible relationship of the arthropod hemocyanin superfamily and molluscan hemocyanins or nonarthropodan tyrosinases. Within the arthropod hemocyanin superfamily, the phenoloxidase probably emerged early in the (eu-)arthropod stemline and thus form the most likely outgroup. The respiratory hemocyanins evolved from t…
To be or not to be heavier: The role of dermal bones in the buoyancy of the Late Triassic temnospondyl amphibian Metoposaurus krasiejowensis.
2022
Stereospondyli are a clade of large aquatic temnospondyls known to have evolved a large dermal pectoral girdle. Among the Stereospondyli, metoposaurids in particular possess large interclavicles and clavicles relative to the rest of the postcranial skel-eton. Because of the large size of these dermal bones, it was first proposed that they served as ballast during hydrostatic buoyancy control which assisted metoposaurids to live a bottom-dwelling mode of life. However, a large bone need not necessarily be heavy, for which determining the bone compactness becomes crucial for under-standing any such adaptation in these dermal bones. Previous studies on the evolu-tion of bone adaptations to aqu…
First record of Mesopithecus (Cercopithecidae, Colobinae) from the Miocene of the Iberian Peninsula
2015
We report dental remains of the extinct colobine monkey Mesopithecus from the Turolian (MN13, Late Miocene, ca. 6.23 Ma) locality of Venta del Moro (Valencia, Spain). They include most of the deciduous dentition and the unerupted germs of the first molars of a single infantile individual, as well as two lower left lateral incisors from two additional individuals. On the basis of morphometric comparisons, mainly based on the Ms, these remains are attributed to the Late Miocene species Mesopithecus pentelicus. They represent a significant addition to the knowledge of the deciduous dentition of this taxon, much less well-known than the permanent dentition. Although this genus was widely distri…
Asexual multiplication of larval parasitic worms: a predictor of adult life-history traits in Taeniidae?
2001
The hypothesis that asexual multiplication inside the intermediate host and adult life-history traits within the final host are independent is tested among Cestoda. Using phylogenetic relationships among the Cestoda species, we can show that asexual multiplication appears to have been lost and recovered several times throughout Taeniidae evolution; this allows a comparison of the adult life-history traits of species with and without asexual multiplication at the larval stage. The adult trait considered is the size of the parasite, since numerous life-history traits, such as fecundity and longevity, are correlated with size. If adult traits are independent of whether the larval stage reprodu…
Feces production as a form of social immunity in an insect with facultative maternal care
2015
Background Social animals have the unique capability of mounting social defenses against pathogens. Over the last decades, social immunity has been extensively studied in species with obligatory and permanent forms of social life. However, its occurrence in less derived social systems and thus its role in the early evolution of group-living remains unclear. Here, we investigated whether lining nests with feces is a form of social immunity against microbial growth in the European earwig Forficula auricularia, an insect with temporary family life and facultative maternal care. Results Using a total of 415 inhibition zone assays, we showed that earwig feces inhibit the growth of two GRAM+ bact…