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HUMAN Modern  humans  ( Homo sapiens  or  Homo sapiens sapiens ) are the only extant members of the  hominin   claDe , a branch of great apes characterized byerect posture and bipedal locomotion; manual dexterity and increased tool use; and a general trend toward larger, more complex  brainsandsocieties . [ 3  Early hominids, such as the australopithecines whose brains and anatomy in many ways more similar to non-human apes, are less often thought of or referred to as "human" than hominids of the genus  Homo ]  some of whom used fiRe , occupied much of Eurasia.


HISTORY The genus  Homo  diverged from other  hominins  in Africa, after the human clade split from the chimpanzee lineage of the hominids (great ape) branch of the primates. Modern humans, defined as the species  Homo sapiens  or specifically to the single extant subspecies  Homo sapiens sapiens , proceeded to colonize all the continents and larger islands, arriving in Eurasia 125,000–60,000 years ago , [  Australia around 40,000 years ago, the Americas around 15,000 years ago, and remote islands such as Hawaii, Easter Island, Madagascar, and New Zealandbetween the years 300 and 1280 . Evidence from molecular biology


EVIDENCE FROM FOSSIL RECORD There is little fossil evidence for the divergence of the gorilla, chimpanzee and hominin lineages .  The earliest fossils that have been proposed as members of the hominin lineage are  Sahelanthropus tchadensis  dating from 7 million years ago, and  Orrorin tugenensis  dating from5.7 million years ago and  Ardipithecus kadabba  dating to  5.6million years ago. Each of these has been argued to be a bipedal ancestor of later hominins , but in each case the claims have been contested. It is also possible that either of these species is an ancestor of another branch of African apes, or that they represent a shared ancestor between hominins and other Hominoidea . The question of the relation between these early fossil species and the hominin lineage is still to be resolved.


ANATOMICAL ADAPTATIONS Human evolution is characterized by a number of morphological, developmental,  physiological , and behavioral changes that have taken place since the split between the last common ancestor of humans and chimpanzees . The most significant of these adaptations are 1. bipedalism, 2. increased brain size, 3. lengthened ontogeny (gestation and infancy), 4. decreased sexual dimorphism. The relationship between all these changes is the subject of ongoing debate .  Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in  H. erectus . Bipedalism is the basic adaption of the hominin line, and it is considered the main cause behind a suite of skeletal changes shared by all bipedal hominins . The earliest bipedal  hominin  is considered to be either  Sahelanthropus  or  Orrorin , with  Ardipithecus , a full bipedal, coming somewhat later.

Habitat and population:

Habitat and population Early human settlements were dependent on proximity to water and, depending on the lifestyle, other natural resources used for subsistence, such as populations of animal prey for hunting and arable land for growing crops and grazing livestock. But humans have a great capacity for altering theirhabitats  by means of technology, through irrigation, urban planning, construction, transport, manufacturing goods, deforestation and desertification. Deliberate habitat alteration is often done with the goals of increasing material  wealth , increasing thermal comfort, improving the amount of food available, improving aesthetics, or improving ease of access to resources or other human settlements. With the advent of large-scale trade andtransport infrastructure, proximity to these resources has become unnecessary, and in many places, these factors are no longer a driving force behind the growth and decline of a population.

Anatomy and physiology:

Anatomy and physiology Most aspects of human physiology are closely homologous to corresponding aspects of  animal  physiology. The human body consists of the  legs , thetorso , the arms, the neck, and the head. An adult human body consists of about 100 trillion (10 14 )  cells . The most commonly defined body systems in humans are the nervous, the cardiovascular, the circulatory, the digestive, the endocrine, the immune, the integumentary, the lymphatic, themuscoskeletal , the reproductive, the respiratory, and the urinary system . Humans, like most of the apes, lack external  tail , have several blood type systems, have opposable thumbs, and are sexually dimorphic. The comparatively minor anatomical differences between humans and chimpanzees are a result of human bipedalism.


G enetics Like all mammals, humans are a diploid eukaryotic species. Each somatic cell has two sets of 23 chromosomes, each set received from one parent;gametes  have only one set of chromosomes, which is a mixture of the two parental sets. Among the 23 pairs of chromosomes there are 22 pairs ofautosomes  and one pair of sex chromosomes. Like other mammals, humans have an XY sex-determination system, so that females have the sex chromosomes XX and males have XY. One human genome was sequenced in full in 2003, and currently efforts are being made to achieve a sample of the genetic diversity of the species (see International HapMap Project). By present estimates, humans have approximately 22,000 genes  The variation in human DNA is very small compared to other species, possibly suggesting a population bottleneck during the Late Pleistocene (around 100,000 years ago)

life cycle:

life cycle As with other mammals, human reproduction takes place as internal fertilization by sexual intercourse. During this process, theerect  penis of the male is inserted into the female's vagina until the male ejaculates semen, which contains sperm. The sperm travels through the vagina and cervix into the uterus or Fallopian tubes for fertilization of the ovum. Upon fertilization andimplantation , gestation then occurs within the female's uterus. The zygote divides inside the female's uterus to become an embryo, which over a period of 38 weeks (9 months) of  gestationbecomes a fetus.

Biological variation:

Biological variation No two humans – not even monozygotic twins – are genetically identical. Genes and environment influence human biological variation from visible characteristics to physiology to disease susceptibly to mental abilities. The exact influence of genes and environment on certain traits is not well understood . Most current genetic and  archaeological  evidence supports a recent single origin of modern humans in East Africa ,  with first migrations placed at 60,000 years ago. Compared to the  great apes,  human gene sequences  – even among African populations – are remarkably homogeneous .  On average, genetic similarity between any two humans is 99.9 %.  There is about 2–3 times more genetic diversity within the wild chimpanzee population on a single hillside in  Gombe , than in the entire human gene pool


C ulture Humans are highly social beings and tend to live in large complex social groups. More than any other creature, [ citation needed  humans are adept [ clarification needed  at utilizing systems of communication for self-expression, the exchange of ideas, and organization, and as such have created complex  socialstructures  composed of many cooperating and competing groups. Human groups range from families to nations. Social interactions between humans have established an extremely wide variety [ clarification needed ]  of values, social norms, and rituals, which together form the basis of human society. Culture is defined here as patterns of complex symbolic behavior, i.e. all behavior that is not innate but which has to be learned through social interaction with others; such as the use of distinctive material and symbolic systems, including language, ritual, social organization, traditions, beliefs and technology.


RELIGION AND SPIRITUALITY Religion is generally defined as a belief system concerning the supernatural, sacred or divine, and practices, values, institutions and rituals associated with such belief. Some religions also have a  moralcoDe . The evolution and the history of the first religions have recently become areas of active scientific investigation . ]  However, in the course of itsdevelopmeNt , religion has taken on many forms that vary by culture and individual perspective. Some of the chief questions and issues religions are concerned with include life after death (commonly involving belief in an afterlife), theorigin of life, the nature of the universe (religious cosmology) and its ultimate fate (eschatology), and what is moral or immoral. A common source for answers to these questions are beliefs in transcendent divine beings such as deities or a singular God, although not all religions are theistic. Spirituality, belief or involvement in matters of the soul or spirit, is one of the many different approaches humans take in trying to answer fundamental questions about humankind's place in the universe, the meaning of life, and the ideal way to live one's life. 


PHILOSOPHY AND SELF REFLECTION Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of reality, reasoning and values. Major fields of philosophy include logic, metaphysics,  epistemology,philosophy of mind, and axiology (which includes ethics and aesthetics). Philosophy covers a very wide range of approaches, and is used to refer to aworldview , to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy.


SCIENCE SND MATHEMATICS Another unique aspect of human culture and thought is the development of complex methods for acquiring knowledge through observation and quantification. The scientific method has been developed to acquire knowledge of the physical world and the rules, processes and principles of which it consists, and combined with mathematics it enables the prediction of complex patterns of causality and consequence. Some other animals are able to recognize differences in small quantities, [ citation needed  but humans are able to understand and recognize much larger, even abstract, quantities, and to recognize and understand algorithmic patterns which enables infinite counting routines and algebra, something that is not found in any other species.


ART,MUSIC,LITERATURE Art is a cultural universal, and humans have been producing artistic works at least since the days of  Cro Magnon . As a form of cultural expression, art may be defined by the pursuit of diversity and the usage of  narrativesof liberation and exploration (i.e. art history, art criticism, and art theory) to mediate its boundaries. This distinction may be applied to objects or performances, current or historical, and its prestige extends to those who made, found, exhibit, or own them. In the modern use of the word, art is commonly understood to be the process or result of making material works that, from concept to creation, adhere to the "creative impulse" of human beings. Art is distinguished from other works by being in large part unprompted by necessity, by biological drive, or by any undisciplined pursuit of recreation. Music is a natural intuitive phenomenon based on the three distinct and interrelated organization structures of rhythm, harmony, and melody. Listening to music is perhaps the most common and universal form of  entertainmeNt , while learning and understanding it are popular  disciplinesThere are a wide variety of music genres and ethnic musics



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