Book Bfb Human

[Jeremias Resendez]

Genesand the environment influence human biological variation in visible characteristics, physiology, disease susceptibility, mental abilities, body size, and life span. Though humans vary in many traits, humans are among the least genetically diverse species. Any two humans are at least 99.5% genetically similar. Humans are sexually dimorphic: generally, males have greater body strength and females have a higher body fat percentage. At puberty, humans develop secondary sex characteristics. Females are capable of pregnancy, usually between puberty, at around 12 years old, and menopause, around the age of 50. As omnivorous creatures, they are capable of consuming a wide variety of plant and animal material, and have used fire and other forms of heat to prepare and cook food since the time of Homo erectus. Humans can survive for up to eight weeks without food and several days without water. Humans are generally diurnal, sleeping on average seven to nine hours per day. Childbirth is dangerous, with a high risk of complications and death. Often, both the mother and the father provide care for their children, who are helpless at birth.

Humans have a large, highly developed, and complex prefrontal cortex, the region of the brain associated with higher cognition. Humans are highly intelligent and capable of episodic memory; they have flexible facial expressions, self-awareness, and a theory of mind. The human mind is capable of introspection, private thought, imagination, volition, and forming views on existence. This has allowed great technological advancements and complex tool development through complex reasoning and the transmission of knowledge to subsequent generations through language.

Humans have had a dramatic effect on the environment. They are apex predators, being rarely preyed upon by other species.[1] Human population growth, industrialization, land development, overconsumption and combustion of fossil fuels have led to environmental destruction and pollution that significantly contributes to the ongoing mass extinction of other forms of life.[2][3] Within the last century, humans have explored challenging environments such as Antarctica, the deep sea, and outer space.[4] Human habitation within these hostile environments is restrictive and expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions.[4] Humans have briefly visited the Moon and made their presence felt on other celestial bodies through human-made robotic spacecraft.[5][6][7] Since the early 20th century, there has been continuous human presence in Antarctica through research stations and, since 2000, in space through habitation on the International Space Station.[8]

All modern humans are classified into the species Homo sapiens, coined by Carl Linnaeus in his 1735 work Systema Naturae.[9] The generic name "Homo" is a learned 18th-century derivation from Latin homō, which refers to humans of either sex.[10][11] The word human can refer to all members of the Homo genus.[12] The name "Homo sapiens" means 'wise man' or 'knowledgeable man'.[13] There is disagreement if certain extinct members of the genus, namely Neanderthals, should be included as a separate species of humans or as a subspecies of H. sapiens.[12]

Despite the fact that the word animal is colloquially used as an antonym for human,[16] and contrary to a common biological misconception, humans are animals.[17] The word person is often used interchangeably with human, but philosophical debate exists as to whether personhood applies to all humans or all sentient beings, and further if a human can lose personhood (such as by going into a persistent vegetative state).[18]

The "out of Africa" migration took place in at least two waves, the first around 130,000 to 100,000 years ago, the second (Southern Dispersal) around 70,000 to 50,000 years ago.[36][37] H. sapiens proceeded to colonize all the continents and larger islands, arriving in Eurasia 125,000 years ago,[38][39] Australia around 65,000 years ago,[40] the Americas around 15,000 years ago, and remote islands such as Hawaii, Easter Island, Madagascar, and New Zealand in the years 300 to 1280 CE.[41][42]

Human evolution was not a simple linear or branched progression but involved interbreeding between related species.[43][44][45] Genomic research has shown that hybridization between substantially diverged lineages was common in human evolution.[46] DNA evidence suggests that several genes of Neanderthal origin are present among all non sub-Saharan-African populations, and Neanderthals and other hominins, such as Denisovans, may have contributed up to 6% of their genome to present-day non sub-Saharan-African humans.[43][47][48]

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 hairlessness,[49] obligate bipedalism, increased brain size and decreased sexual dimorphism (neoteny). The relationship between all these changes is the subject of ongoing debate.[50]

Until about 12,000 years ago, all humans lived as hunter-gatherers.[51][52] The Neolithic Revolution (the invention of agriculture) first took place in Southwest Asia and spread through large parts of the Old World over the following millennia.[53] It also occurred independently in Mesoamerica (about 6,000 years ago),[54] China,[55][56] Papua New Guinea,[57] and the Sahel and West Savanna regions of Africa.[58][59][60]

Access to food surplus led to the formation of permanent human settlements, the domestication of animals and the use of metal tools for the first time in history. Agriculture and sedentary lifestyle led to the emergence of early civilizations.[61][62][63]

In the 5th century BCE, history started being recorded as a discipline, which provided a much clearer picture of life at the time.[83] Between the 8th and 6th century BCE, Europe entered the classical antiquity age, a period when ancient Greece and ancient Rome flourished.[84][85] Around this time other civilizations also came to prominence. The Maya civilization started to build cities and create complex calendars.[86][87] In Africa, the Kingdom of Aksum overtook the declining Kingdom of Kush and facilitated trade between India and the Mediterranean.[88] In West Asia, the Achaemenid Empire's system of centralized governance became the precursor to many later empires,[89] while the Gupta Empire in India and the Han dynasty in China have been described as golden ages in their respective regions.[90][91]

Following the fall of the Western Roman Empire in 476, Europe entered the Middle Ages.[92] During this period, Christianity and the Church would provide centralized authority and education.[93] In the Middle East, Islam became the prominent religion and expanded into North Africa. It led to an Islamic Golden Age, inspiring achievements in architecture, the revival of old advances in science and technology, and the formation of a distinct way of life.[94][95] The Christian and Islamic worlds would eventually clash, with the Kingdom of England, the Kingdom of France and the Holy Roman Empire declaring a series of holy wars to regain control of the Holy Land from Muslims.[96]

In the Americas, between 200 and 900 CE Mesoamerica was in its Classic Period,[97] while further north, complex Mississippian societies would arise starting around 800 CE.[98] The Mongol Empire would conquer much of Eurasia in the 13th and 14th centuries.[99] Over this same time period, the Mali Empire in Africa grew to be the largest empire on the continent, stretching from Senegambia to Ivory Coast.[100] Oceania would see the rise of the Tuʻi Tonga Empire which expanded across many islands in the South Pacific.[101] By the late 15th century, the Aztecs and Inca had become the dominant power in Mesoamerica and the Andes, respectively.[102]

A tenuous balance of power among European nations collapsed in 1914 with the outbreak of the First World War, one of the deadliest conflicts in history.[121] In the 1930s, a worldwide economic crisis led to the rise of authoritarian regimes and a Second World War, involving almost all of the world's countries.[122] The war's destruction led to the collapse of most global empires, leading to widespread decolonization.

Following the conclusion of the Second World War in 1945, the United States[123] and the USSR emerged as the remaining global superpowers. This lead to a Cold War that saw a struggle for global influence, including a nuclear arms race and a space race, ending in the collapse of the Soviet Union.[124][125] The current Information Age, spurred by the development of the Internet and Artificial Intelligence systems, sees the world becoming increasingly globalized and interconnected.[126]

Humans are one of the most adaptable species, despite having a low or narrow tolerance for many of the earth's extreme environments.[134] Currently the species is present in all eight biogeographical realms, although their presence in the Antarctic realm is very limited to research stations and annually there is a population decline in the winter months of this realm. Humans established nation-states in the other seven realms, such as for example South Africa, India, Russia, Australia, Fiji, United States and Brazil (each located in a different biogeographical realm).

By using advanced tools and clothing, humans have been able to extend their tolerance to a wide variety of temperatures, humidities, and altitudes.[134][135] As a result, humans are a cosmopolitan species found in almost all regions of the world, including tropical rainforest, arid desert, extremely cold arctic regions, and heavily polluted cities; in comparison, most other species are confined to a few geographical areas by their limited adaptability.[136] The human population is not, however, uniformly distributed on the Earth's surface, because the population density varies from one region to another, and large stretches of surface are almost completely uninhabited, like Antarctica and vast swathes of the ocean.[134][137] Most humans (61%) live in Asia; the remainder live in the Americas (14%), Africa (14%), Europe (11%), and Oceania (0.5%).[138]

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