Seril

This is my blog on life and how I see things from my point of view. Whether it be the sun and ski, the trip to work, whatever I can be bothered to blog about. But lets start from the beginning. Humans, known taxonomically as Homo sapiens (Latin: “wise man” or “knowing man”),[3][4] are the only living species in the Homo genus of bipedal primates in Hominidae, the great ape family. Anatomically modern humans originated in Africa about 200,000 years ago, reaching full behavioral modernity around 50,000 years ago.[5]Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving. This mental capability, combined with an erect body carriage that frees the hands for manipulating objects, has allowed humans to make far greater use of tools than any other living species on Earth. Other higher-level thought processes of humans, such as self-awareness, rationality and sapience,[6][7][8] are considered to be defining features of what constitutes a “person”.[9][10]Like most higher primates, humans are social animals. However, humans are uniquely adept at utilizing systems of communication for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans have established an extremely wide variety of values, social norms, and rituals, which together form the basis of human society. With individuals widespread in every continent except Antarctica, humans are a cosmopolitan species. As of August 2010[update], the population of humans was estimated to be about 6.8 billion.[11]Humans are noted for their desire to understand and influence their environment, seeking to explain and manipulate phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the development of advanced tools and skills, which are passed down culturally; humans are the only species known to build fires, cook their food, clothe themselves, and use numerous other technologies. The study of humans is the scientific discipline of anthropology.The scientific study of human evolution encompasses the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. “Modern humans” are defined as the Homo sapiens species, of which the only extant subspecies is known as Homo sapiens sapiens. Homo sapiens idaltu (roughly translated as “elder wise human”), the other known subspecies, is now extinct.[15] Homo neanderthalensis, which became extinct 30,000 years ago, has sometimes been classified as a subspecies, “Homo sapiens neanderthalensis”; genetic studies now suggest that the functional DNA of modern humans and Neanderthals diverged 500,000 years ago.[16] Similarly, the few specimens of Homo rhodesiensis  have also occasionally been classified as a subspecies, but this is not widely accepted. Anatomically modern humans first appear in the fossil record in Africa about 195,000 years ago, and studies of molecular biology give evidence that the approximate time of divergence from the common ancestor of all modern human populations was 200,000 years ago.[17][18][19][20][21] The broad study of African genetic diversity headed by Dr. Sarah Tishkoff found the San people  to express the greatest genetic diversity among the 113 distinct populations sampled, making them one of 14 “ancestral population clusters”. The research also located the origin of modern human migration in south-western Africa, near the coastal border of Namibia and Angola.[22]The evolutionary history of the primates can be traced back 65 million years, as one of the oldest of all surviving placental mammal groups. The oldest known primate-like mammal species, the Plesiadapis, come from North America, but they were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene. Molecular evidence suggests that the last common ancestor between humans and the remaining great apes diverged between 8 and 4 million years ago, first the gorillas, and then the chimpanzees (genus Pan) split off from the line leading to the humans; the functional human DNA is approximately 98.4% identical to that of chimpanzees when comparing single nucleotide polymorphisms (see Human evolutionary genetics). The closest living relatives of humans are gorillas and chimpanzees, but humans did not evolve from these apes: instead they share a common ancestor with modern humans.[23]Humans are probably most closely related to two chimpanzee species: Common Chimpanzee and Bonobo.[23] Full genome sequencing has resulted in the conclusion that “after 6.5 [million] years of separate evolution, the differences between chimpanzee and human are ten times greater than those between two unrelated people and ten times less than those between rats and mice”.[attribution needed] Suggested concurrence between the functional human, seo sheffield and chimpanzee DNA sequences range between 95% and 99%;(see. also “junk” DNA[24][25][26][27] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from that of gorillas about eight million years ago. However, a hominid skull discovered in Chad in 2001, classified as Sahelanthropus tchadensis, is approximately seven million years old, which may indicate an earlier divergence.[28]Human evolution is characterised by a number of important morphological, developmental, physiological and behavioural changes, which have taken place since the split between the last common ancestor of humans and chimpanzees. The first major morphological change was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal one,[29] with all its attendant adaptations, such as a valgus knee, low intermembral index (long legs relative to the arms), and reduced upper-body strength.Later, ancestral humans developed a much larger brain – typically 1,400 cm³ in modern humans, over twice the size of that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), and allows for extended periods of social learning and language acquisition in juvenile humans. Physical anthropologists[who?] argue that the differences between the structure of human brains, wall clocks and those of other apes are even more significant than their differences in size.Other significant morphological changes included the evolution of a power and precision grip,[30] a reduced masticatory system, a reduction of the canine tooth, and the descent of the larynx and hyoid bone, making speech possible. An important physiological change in humans was the evolution of hidden oestrus, or concealed ovulation, which may have coincided with the evolution of important behavioural changes, such as pair bonding. Another significant behavioural change was the development of material culture, with human-made objects becoming increasingly common and diversified over time. The relationship between all these changes is the subject of ongoing debate.[31][32]The forces of natural selection have continued to operate on human populations, with evidence that certain regions of the genome display directional selection in the past 15,000 years.Anatomically modern humans evolved from archaic Homo sapiens in Africa in the Middle Paleolithic, about 200,000 years ago. By the beginning of the Upper Paleolithic 50,000 BP (Before Present), full behavioral modernity, including language, music and other cultural universals had developed.Homo sapiens sapiens (Anatomically modern humans) is supposed to have appeared in East Africa between 200,000 and 100,000 years ago (Homo sapiens idaltu, found at site Middle Awash in Ethiopia, lived about 160,000 years ago. is considered the oldest known anatomically modern human). [34]The out of Africa migration is estimated to have occurred about 70,000 years BP. Modern humans subsequently spread to all continents, replacing earlier hominids: they inhabited Eurasia and Oceania by 40,000 BP, and the Americas at least 14,500 years BP.[35] A popular theory is that they displaced Homo neanderthalensis and other species descended from Homo erectus[36] (which had inhabited Eurasia as early as 2 million years ago) through more successful reproduction and competition for resources.[37] The exact manner or extent of the coexistence and interaction of these species is unknown and remains a controversial subject.[citation needed]Evidence from archaeogenetics accumulating since the 1990s has lent strong support to the “out-of-Africa” scenario, and has marginalized the competing multiregional hypothesis, which proposed that modern humans evolved, at least in part, from independent hominid populations.[38]Geneticists Lynn Jorde and Henry Harpending of the University of Utah propose that the variation in human DNA is minute compared to that of other species. They also propose that during the Late Pleistocene, the human population was reduced to a small number of breeding pairs – no more than 10,000, and possibly as few as 1,000 – resulting in a very small residual gene pool. Various reasons for this hypothetical bottleneck have been postulated, one being the Toba catastrophe theory.[39] Source Wikipedia