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Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics, exposure to the sun, natural and sexual selection, or all of these. Differences across populations evolved through natural selection or sexual selection, because of social norms and differences in environment, as well as regulations of the biochemical effects of ultraviolet radiation penetrating the skin.
Megaladapis, informally known as the koala lemur, was a genus belonging to the family Megaladapidae, consisting of three extinct species of lemurs that once inhabited the island of Madagascar. The largest measured between 1.3 to 1.5 m in length.
Sodium/potassium/calcium exchanger 5 (NCKX5), also known as solute carrier family 24 member 5 (SLC24A5), is a protein that in humans is encoded by the SLC24A5 gene that has a major influence on natural skin colour variation. The NCKX5 protein is a member of the potassium-dependent sodium/calcium exchanger family. Sequence variation in the SLC24A5 gene, particularly a non-synonymous SNP changing the amino acid at position 111 in NCKX5 from alanine to threonine, has been associated with differences in skin pigmentation.
Thadeosaurus is an extinct genus of diapsid reptile belonging to the family Younginidae. Fossils have been found in the Lower Sakamena Formation of the Morondava Basin, Madagascar in 1981, and date to the late Permian to the early Triassic period.
The Leeuwenhoek Lecture is a prize lecture of the Royal Society to recognize achievement in microbiology. The prize was originally given in 1950 and awarded annually, but from 2006 to 2018 was given triennially. From 2018 it will be awarded biennially.
Rugoconites is a genus of Ediacaran biota found as fossils in the form of a circular or oval-like impression preserved in high relief, six or more centimeters in diameter. The fossils are surrounded by frills that have been interpreted as sets of tentacles. The bifurcating radial ribs, spreading from a central dome, serve to distinguish this genus from the sponge Palaeophragmodictya, and may represent the channels of the gastrovascular system. Fossils of Rugoconites have been interpreted as early sponges, although this is countered by Sepkoski et al. (2002), who interpreted the organism as a free-swimming jellyfish-like cnidarian; similar to Ovatoscutum. However, the fossil is consistently preserved as a neat circular form and its general morphology does not vary, therefore a benthic and perhaps slow-moving or sessile lifestyle is more likely. Ivantstov & Fedonkin (2002), suggest that Rugoconites may possess tri-radial symmetry and be a member of the Trilobozoa.
Light skin is a human skin color that has a base level of eumelanin pigmentation that has adapted to environments of low UV radiation. Light skin is most commonly found amongst the native populations of Europe and Northeast Asia as measured through skin reflectance. People with light skin pigmentation are often referred to as "white" or "fair", although these usages can be ambiguous in some countries where they are used to refer specifically to certain ethnic groups or populations.
Gephyrostegus is an extinct genus of gephyrostegid reptiliomorph amphibian. It was a small animal, 22 cm in total length, of generally lizard-like build and presumably habit. It had large eyes and a large number of small, pointed teeth, indicating it was an active insectivorous hunter. The remains have been found in Nýřany, Czech Republic, dating from around 310 million years ago.
"The Chemical Basis of Morphogenesis" is an article that the English mathematician Alan Turing wrote in 1952. It describes how patterns in nature, such as stripes and spirals, can arise naturally from a homogeneous, uniform state. The theory, which can be called a reaction–diffusion theory of morphogenesis, has become a basic model in theoretical biology. Such patterns have come to be known as Turing patterns. For example, it has been postulated that the protein VEGFC can form Turing patterns to govern the formation of lymphatic vessels in the zebrafish embryo.
Sexual selection in humans concerns the concept of sexual selection, introduced by Charles Darwin as an element of his theory of natural selection, as it affects humans. Sexual selection is a biological way one sex chooses a mate for the best reproductive success. Most compete with others of the same sex for the best mate to contribute their genome for future generations. This has shaped human evolution for many years, but reasons why humans choose their mates are not fully understood. Sexual selection is quite different in non-human animals than humans as they feel more of the evolutionary pressures to reproduce and can easily reject a mate. The role of sexual selection in human evolution has not been firmly established although neoteny has been cited as being caused by human sexual selection. It has been suggested that sexual selection played a part in the evolution of the anatomically modern human brain, i.e. the structures responsible for social intelligence underwent positive selection as a sexual ornamentation to be used in courtship rather than for survival itself, and that it has developed in ways outlined by Ronald Fisher in the Fisherian runaway model. Fisher also stated that the development of sexual selection was "more favourable" in humans.
Opabiniidae is an extinct family of marine stem-arthropods. Its type and best-known genus is Opabinia. It also contains Utaurora. Opabiniids closely resemble radiodonts, but their frontal appendages were basally fused into a proboscis. Opabiniids also distinguishable from radiodonts by setal blades covering at least part of the body flaps and serrated caudal rami.
The hypobranchial gland is a glandular structure which is part of the anatomy of many mollusks, including several different families of gastropods, and also many protobranch bivalves. This gland produces mucus as well as biologically active compounds. The cephalopod ink sac is a modified hypobranchial gland.
Dark skin is a type of human skin color that is rich in melanin pigments. People with very dark skin are often referred to as "black people", although this usage can be ambiguous in some countries where it is also used to specifically refer to different ethnic groups or populations.
Nina G. Jablonski is an American anthropologist and palaeobiologist, known for her research into the evolution of skin color in humans. She is engaged in public education about human evolution, human diversity, and racism. In 2021, she was elected to the U.S. National Academy of Sciences and in 2009, she was elected to the American Philosophical Society. She is an Evan Pugh University Professor at The Pennsylvania State University, and the author of the books Skin: A Natural History, Living Color: The Biological and Social Meaning of Skin Color, and the co-author of Skin We Are In.
David Andrew Whiten, known as Andrew Whiten is a British zoologist and psychologist, Professor of Evolutionary and Developmental Psychology, and Professor Wardlaw Emeritus at University of St Andrews in Scotland. He is known for his research in social cognition, specifically on social learning, tradition and the evolution of culture, social Machiavellian intelligence, autism and imitation, as well as the behavioral ecology of sociality. In 1996, Whiten and his colleagues invented an artificial fruit that allowed to study learning in apes and humans.
Neoanguimorpha is a clade of anguimorphs comprising Monstersauria and Diploglossa. Morphological studies in the past had classified helodermatids with the varanoids in the clade Platynota, while the Chinese crocodile lizard was classified as a xenosaurid. However molecular work found no support in these groupings and instead has found the helodermatids more related to Diploglossa, while the Chinese crocodile lizard and varanoids to form the clade Paleoanguimorpha.
Pathogen avoidance, also referred to as, parasite avoidance or pathogen disgust, refers to the theory that the disgust response, in humans, is an adaptive system that guides behavior to avoid infection caused by parasites such as viruses, bacteria, fungi, protozoa, helminth worms, arthropods and social parasites. Pathogen avoidance is a psychological mechanism associated with the behavioral immune system. Pathogen avoidance has been discussed as one of the three domains of disgust which also include sexual and moral disgust.
Papposaurus is an extinct genus of proterogyrinid embolomere which lived in the Mississippian of Scotland. It is known from a single species, Papposaurus traquiairi, which is based on an isolated femur discovered in ironstone near Loanhead. Though originally compared closely to reptiles, subsequent study has revealed closer similarity to basal embolomeres such as Proterogyrinus and Archeria. With such limited remains, Papposaurus may not be a valid genus. The femur was redescribed in 1986 by T. R. Smithson, who considered Papposaurus traquairi a nomen vanum possibly synonymous with Proterogyrinus scheelei.
Of the many characteristics of humans, nakedness and clothing are highly related. The loss of body hair distinguishes humans from other primates. The current evidence indicates that anatomically modern humans were naked in prehistory for at least 90,000 years before the invention of clothing. Today, isolated Indigenous peoples in tropical climates continue to be without clothing in many everyday activities.
Mieridduryn is a genus of extinct dinocaridid arthropod that lived during the Middle Ordovician of what is now the United Kingdom. This animal was described in 2022 based on a singular fossil found in Castle Bank, a Burgess shale type lagerstätte located in the country of Wales. This animal's taxonomic affinities are somewhat unclear, but there are some hypotheses. One is that this animal represents a new grade of Stem-euarthropods that evolved features similar to the Cambrian aged opabiniids. Another is that if the features seen in Mieridduryn are convergent, and not homologous, to those seen in radiodonts, then this animal represents a late surviving opabiniid.
References
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