Science Daily. robustus and Au. Culturally-driven evolution can defy the expectations of natural selection: while human populations experience some pressure that drives a selection for producing children at younger ages, the advent of effective contraception, higher education, and changing social norms have driven the observed selection in the opposite direction. [32][163][164][165][166], Some anthropologists and archaeologists subscribe to the Toba catastrophe theory, which posits that the supereruption of Lake Toba on Sumatran island in Indonesia some 70,000 years ago caused global consequences,[167] killing the majority of humans and creating a population bottleneck that affected the genetic inheritance of all humans today. [85], There is evidence from mitochondrial DNA that modern humans have passed through at least one genetic bottleneck, in which genome diversity was drastically reduced. [208], However, there is an ongoing debate over whether H. floresiensis is indeed a separate species. The closest living relatives of humans are bonobos and chimpanzees (both genus Pan) and gorillas (genus Gorilla). The earliest humans developed out of australopithecine ancestors after about 3 million years ago, most likely in Eastern Africa, most likely in the area of the Kenyan Rift Valley, where the oldest known stone tools were found. [note 4][26] The Florisbad Skull from Florisbad, South Africa, dated to about 259,000 years ago, has also been classified as early Homo sapiens. Each phase (H. habilis, H. ergaster, H. neanderthalensis) started at a higher level than the previous one, but after each phase started, further development was slow. took place before modern humans entered Europe. [49] These findings might give some support to the claim that modern humans from Africa arrived at southern China about 100,000 years ago (Zhiren Cave, Zhirendong, Chongzuo City: 100,000 years ago;[note 9] and the Liujiang hominid (Liujiang County): controversially dated at 139,000–111,000 years ago [54]). This migration has been proposed as being related to the operation of the Saharan pump, around 1.9 million years ago. Humans are primates. [218] Paleontology has yet to explain the expansion of this organ over millions of years despite being extremely demanding in terms of energy consumption. "Out of Africa" is also supported by the fact that mitochondrial genetic diversity is highest among African populations. During human birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position (compared to the mother) during entry into the birth canal and rotate about 90 degrees upon exit. [93][3][4][5] In fact, genomic research has shown that hybridization between substantially diverged lineages is the rule, not the exception, in human evolution. 500,000 years ago, evolving into H. antecessor, H. heidelbergensis and H. neanderthalensis. This migration and origin theory is usually referred to as the "recent single-origin hypothesis" or "out of Africa" theory. Within Africa, Homo sapiens dispersed around the time of its speciation, roughly 300,000 years ago. [96] The Denisovan EPAS1 gene has also been found in Tibetan populations. [86], "Out of Africa" has thus gained much support from research using female mitochondrial DNA and the male Y chromosome. The studies of ontogeny, phylogeny and especially evolutionary developmental biology of both vertebrates and invertebrates offer considerable insight into the evolution of all life, including how humans evolved. Another important physiological change related to sexuality in humans was the evolution of hidden estrus. A 2017 study of the ancient DNA of Tianyuan Man found that the individual is related to modern Asian and Native American populations. HLA haplotypes from Denisovans and Neanderthal represent more than half the HLA alleles of modern Eurasians,[96] indicating strong positive selection for these introgressed alleles. Contemporary Europeans have Neanderthal ancestry, but it seems likely that substantial interbreeding with Neanderthals ceased before 47,000 years ago, i.e. The Ainu were found to represent a more basal branch than the modern farming populations of East Asia, suggesting an ancient (pre-Neolithic) connection with northeast Siberians. [119], The hypothesis of interbreeding, also known as hybridization, admixture or hybrid-origin theory, has been discussed ever since the discovery of Neanderthal remains in the 19th century. Apes remained in trees for their primary food source. Many advanced traits -- including complex symbolic expression, art, and elaborate cultural diversity -- emerged mainly during the past 100,000 years. This initial migration was followed by other archaic humans including H. heidelbergensis, which lived around 500,000 years ago and was the likely ancestor of both Denisovans and Neanderthals. The main find was a skeleton believed to be a woman of about 30 years of age. It has been suggested that the changes were mainly social and behavioural, including increased empathic abilities,[43][44] increases in size of social groups,[45][46][47] and increased behavioural plasticity. Scientists classify each species with a unique, two-part scientific name. Populations of modern humans and Neanderthal overlapped in various regions such as the Iberian peninsula and the Middle East. Approaching the Science of Human Origins from Religious Perspectives, Religious Perspectives on the Science of Human Origins, Submit Your Response to "What Does It Mean To Be Human? Archaeological evidence suggests humans, whether Neanderthal or Cro-Magnon, reached sites in Arctic Russia by 40,000 years ago. [38], The increase in volume of the neocortex also included a rapid increase in size of the cerebellum. [35], The ancestors of the modern Khoi-San expanded to Southern Africa before 150,000 years ago, possibly as early as before 260,000 years ago,[note 5] so that by the beginning of the MIS 5 "megadrought", 130,000 years ago, there were two ancestral population clusters in Africa, bearers of mt-DNA haplogroup L0 in southern Africa, ancestral to the Khoi-San, and bearers of haplogroup L1-6 in central/eastern Africa, ancestral to everyone else. The field involves an understanding of the similarities and differences between humans and other species in their genes, body form, physiology, and behavior. Investigating how early humans evolved and lived helps us answer these questions. Early human migrations are the earliest migrations and expansions of archaic and modern humans across continents and are believed to have begun approximately 2 million years ago with the early expansions of hominins out of Africa of Homo erectus. Other important human characteristics -- such as a large and complex brain, the ability to make and use tools, and the capacity for language -- developed more recently. In the feet the big toe moved into alignment with the other toes to help in forward locomotion.

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