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Line 1: − {{Dablink|This article is about the timeline of human evolution. For a timeline of general evolution see [[Timeline of evolution]].}}+ − {{Dablink|See also [[Human evolution]] for more details on this topic.}}+ − + − The '''timeline of human evolution''' outlines the major events in the development of [[human]] [[species]], and the [[evolution]] of humans' [[ancestor]]s. It includes a brief explanation of some [[animal]]s, [[species]] or [[genus|genera]], which are possible ancestors of ''[[Homo sapiens sapiens]]''. It does not address the [[origin of life]], which is addressed by [[abiogenesis]], but presents a possible line of descendants that led to humans. This timeline is based on studies from [[paleontology]], [[developmental biology]], [[Morphology (biology)|morphology]] and from [[anatomical]] and [[Genetics|genetic]] data. The study of human evolution is a major component of [[anthropology]].+ − + − ==Homo sapiens taxonomy==+ − The [[cladistic]] line of descent ([[taxonomic rank]]) of ''[[homo sapiens sapiens]]'' (modern humans) is as follows:<br />+ − <blockquote> − [[Domain (biology)|domain]]: [[eukaryote]]s (2.100.000.000 years ago)<br /> − [[Kingdom (biology)|kingdom]]: [[Animals|animalia]] (590.000.000 years ago)<br /> − [[phylum]]: [[Chordate|chordata]] (530.000.000 years ago)<br /> − [[subphylum]]: [[Vertebrate|vertebrata]] (505.000.000 years ago)<br /> − [[Class (biology)|class]]: [[mammal|mammalia]] (220.000.000 years ago)<br /> − [[subclass]]: [[Theria|theriiformes]]<br /> − [[infraclass]]: [[eutheria]] (125.000.000 years ago)<br /> − [[magnorder]]: [[boreoeutheria]]<br /> − [[superorder]]: [[euarchontoglires]] ([[supraprimates]]) (100.000.000 years ago)<br /> − [[Order (biology)|order]]: [[primate]]s (75.000.000 years ago)<br /> − [[suborder]]: [[haplorrhini]] ([[tarsiers]], [[monkeys]], [[apes]], "dry-nosed" primates) (40.000.000 years ago)<br /> − [[infraorder]]: [[Simian|simiiformes]] (simians, "higher" primates)<br /> − [[parvorder]]: [[catarrhini]] ("narrow nosed" primates) (30.000.000 years ago)<br /> − [[superfamily]]: [[Ape|hominoidea]] (25.000.000 years ago)<br /> − [[Family (biology)|family]]: [[hominidae]] ([[great apes]]) (15.000.000 years ago)<br /> − [[subfamily]]: [[homininae]] (4.500.000 years ago)<br /> − [[Tribe (biology)|tribe]]: [[hominini]]<br /> − [[subtribe]]: [[hominina]] (3.000.000 years ago)<br /> − − [[species]]: [[homo sapiens]] (195.000 years ago)<br /> − [[sub-species]]: [[Anatomically modern humans|homo sapiens sapiens]] (12.000 years ago){{fact|date=February 2010}}<br /> − </blockquote> − − ==Timeline== − === First living beings === − {| class="wikitable" − |- − ! Date − ! Event − |- valign="top" − | align="RIGHT" nowrap | 4000 [[Megaannum|Ma]]<br>(million<br>years ago) − |The earliest life appears. − − {{See|Origin of life}} − − |- valign="TOP" − | align="RIGHT" nowrap | 3900 Ma − |[[Cell (biology)|Cell]]s resembling [[prokaryote]]s appear. − − {{See|Cell (biology)#Origins of cells}} − |- valign="TOP" − | align="RIGHT" nowrap | 2500 Ma − | First organisms to utilize [[oxygen]]. − |- valign="TOP" − | align="RIGHT" nowrap | 2100 Ma − |More complex cells appear: the [[eukaryote]]s. − − {{See|Eukaryote#Origin and evolution}} − |- valign="TOP" − | align="RIGHT" nowrap | 1200 Ma − | [[Evolution of sexual reproduction|Sexual reproduction]] evolves, leading to faster evolution.<ref>"'Experiments with sex have been very hard to conduct,' Goddard said. 'In an experiment, one needs to hold all else constant, apart from the aspect of interest. This means that no higher organisms can be used, since they have to have sex to reproduce and therefore provide no asexual control.'<br />Goddard and colleagues instead turned to a single-celled organism, yeast, to test the idea that sex allows populations to adapt to new conditions more rapidly than asexual populations.<cite></cite>" [http://news.nationalgeographic.com/news/2005/03/0330_050330_sexevolution.html Sex Speeds Up Evolution, Study Finds] (URL accessed on January 9, 2005)</ref> − |- valign="TOP" − | align="RIGHT" nowrap | 900 Ma − | [[Image:Cronoflagelado2.jpg|thumb|100px|[[Choanoflagellate]]]] − The [[choanoflagellate]]s may look similar to the [[ancestors]] of the entire [[animal]] [[kingdom (biology)|kingdom]], and in particular they may be the direct ancestors of [[Sponge]]s.<ref>"Proterospongia is a rare freshwater protist, a colonial member of the Choanoflagellata." "Proterospongia itself is not the ancestor of sponges. However, it serves as a useful model for what the ancestor of sponges and other metazoans may have been like." http://www.ucmp.berkeley.edu/protista/proterospongia.html Berkeley University</ref> − [[Proterospongia]] (members of the Choanoflagellata) are the best living examples of what the ancestor of all [[animal]]s may have looked like. − − They live in [[colony (biology)|colonies]], and show a primitive level of [[cell (biology)|cellular]] specialization for different tasks. − |- valign="TOP" − | align="RIGHT" nowrap | 600 Ma − |It is thought that the earliest multicellular animal was a [[sea sponge|sponge]]-like creature. − [[Sponge]]s are among the simplest of animals, with partially differentiated [[Biological tissue|tissue]]s. − − Sponges (Porifera) are the phylogenetically oldest [[animal]] [[phylum]] extant today. − |- valign="TOP" − | align="RIGHT" nowrap | 580 Ma − |The movement of all animals may have started with [[cnidarians]]. Almost all cnidarians possess [[nerves]] and [[muscle]]s and, because they are the simplest [[animal]]s to possess it, their direct [[ancestor]]s were very likely the first animals to use nerves and muscles together. Cnidarians are also the first animals with an actual [[body]] of definite form and shape. They have [[symmetry (biology)#Radial symmetry|radial symmetry]]. The first [[Eye|eyes]] evolved at this time. − |- valign="TOP" − | align="RIGHT" nowrap | 550 Ma − | [[Image:FlatwormZICA.png|thumb|200px|[[Flatworm]]]] Flatworms are the earliest animals to have a [[brain]], and the simplest animals alive to have [[symmetry (biology)#Bilateral symmetry|bilateral symmetry]]. They are also the simplest animals with organs that form from three [[germ layer]]s. − |- valign="TOP" − | align="RIGHT" nowrap | 540 Ma − |[[Acorn worm]]s are considered more highly specialised and advanced than other similarly shaped [[worm]]-like creatures. They have a [[circulatory system]] with a [[heart]] that also functions as a [[kidney]]. Acorn worms have a [[gill]]-like structure used for [[breath]]ing, a structure similar to that of [[Prehistoric fish|primitive fish]]. Acorn worms are thus sometimes said to be a link between [[vertebrate]]s and [[invertebrate]]s{{Citation needed|date=September 2009}}. − |} − − === [[Chordates]] === − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 530 Ma − |[[Image:Pikaia3ZICA.png|thumb|200px|[[Pikaia]]]] One of the earliest known ancestor of the [[chordate]]s is [[Pikaia]].<ref>"It is possible that Pikaia, until now the cynosure of Cambrianchordates, is peripheral to the line-age leading to the vertebrates." http://creation.com/images/pdfs/tj/j18_1/j18_1_10-11.pdf</ref> It is the first known [[animal]] with a [[notochord]]. Pikaia is believed to be the ancestor of all chordates and [[vertebrate]]s.<ref> "Obviously vertebrates must have had ancestors living in the Cambrian, but they were assumed to be invertebrate forerunners of the true vertebrates — protochordates. Pikaia has been heavily promoted as the oldest fossil protochordate." [[Richard Dawkins]] [[2004]] [[The Ancestor's Tale]] Page 289, ISBN 0618005838</ref> − − The [[Lancelet]], still living today, retains some characteristics of the primitive [[chordate]]s. It resembles [[Pikaia]] − − Other earliest known chordate-like fossils is from a [[conodonts]] an "eel-shaped animal of 4-20 cm (1½-8 in) long" with a pair of huge eyes at the head end and a complex basket of teeth. − |- valign="TOP" − | align="RIGHT" nowrap | 505 Ma − |[[Image:Agnata.png|thumb|200px|[[Agnatha]]]] − − The first [[vertebrate]]s appear: the [[ostracoderm]]s, jawless fish related to present-day [[lamprey]]s and [[hagfish]]es. ''[[Haikouichthys]]'' and ''[[Myllokunmingia]]'' are examples of these jawless fish, or [[Agnatha]]. (See also [[prehistoric fish]]). They were jawless and their internal skeletons were cartilaginous. They lacked the paired (pectoral and pelvic) [[fins]] of more advanced [[fish]]. They were the Precursors to the [[Osteichthyes]] (bony fish). <ref>These first vertebrates lacked jaws, like the living hagfish and lampreys. Jawed vertebrates appeared 100 million years later, in the Silurian. http://www.ucmp.berkeley.edu/vertebrates/vertintro.html Berkeley University</ref> − |- valign="TOP" − | align="RIGHT" nowrap | 480 Ma − |[[Image:PlacodermiZICA.png|thumb|200px|A [[Placoderm]]]] − The [[Placodermi]] were [[prehistoric fish]]es. Placoderms were the first of the jawed fishes, their jaws evolving from the first of their gill arches <ref>"<cite>Bones of first gill arch became upper and lower jaws.</cite>" [http://www.uhh.hawaii.edu/~ronald/392/Homol-Gill-Jaw.JPG (Image)] (URL accessed on November 16, 2006)</ref>. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked. − |- valign="TOP" − | align="RIGHT" nowrap | 400 Ma − |First ''[[Coelacanth]]'' appears; this order of animals had been thought to have no extant members until living specimens were discovered in 1938. It is often referred to as a [[living fossil]]. − |- valign="TOP" − | align="RIGHT" nowrap | 375 Ma − | ''[[Tiktaalik]]'' is a genus of [[Sarcopterygii|sarcopterygian]] (lobe-finned) fishes from the late Devonian with many tetrapod-like features. It shows a clear link between [[Panderichthys]] and [[Acanthostega]]. − |} − − === [[Tetrapod|Tetrapodes]] === − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 365 Ma − |[[Image:PanderichthysZICA.png|thumb|200px|[[Panderichthys]]]] − Some fresh water lobe-finned [[fish]] ([[Sarcopterygii]]) develop legs and give rise to the [[Tetrapoda]]. − − The first tetrapods [[evolution|evolved]] in shallow and [[swamp]]y [[freshwater]] [[habitat (ecology)|habitats]]. − − Primitive tetrapods developed from a [[lobe-finned fish]] (an "osteolepid [[sarcopterygii|Sarcopterygian]]"), with a two-lobed [[brain]] in a flattened skull, a wide mouth and a short snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed adaptations of fins with fleshy bases and [[bone]]s. The "living fossil" [[coelacanth]] is a related [[lobe-finned fish]] without these shallow-water adaptations. These fishes used their fins as [[paddle]]s in shallow-water habitats choked with plants and [[detritus]]. The universal tetrapod characteristics of front [[Limb (anatomy)|limb]]s that bend backward at the [[Elbow-joint|elbow]] and hind limbs that bend forward at the [[knee]] can plausibly be traced to early tetrapods living in shallow water.<ref>"Lungfish are believed to be the closest living relatives of the tetrapods, and share a number of important characteristics with them. Among these characters are tooth enamel, separation of pulmonary blood flow from body blood flow, arrangement of the skull bones, and the presence of four similarly sized limbs with the same position and structure as the four tetrapod legs." http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html Berkeley University</ref> − − [[Panderichthys]] is a 90-130 cm (35-50 in) long [[fish]] from the Late [[Devonian period]]. It has a large [[tetrapod]]-like [[head]]. Panderichthys exhibits features transitional between lobe-finned fishes and early tetrapods. − − [[Lungfish]]es retain some characteristics of the early [[Tetrapoda]]s. One example is the [[Queensland Lungfish]]. − |- valign="TOP" − | align="RIGHT" nowrap | 315 Ma − |[[Image:Acanthostega2 ZICA.png|thumb|200px|[[Acanthostega]]]] − [[Image:PleaisaidesZICA.png|thumb|200px|[[Ichthyostega]]]] − [[Acanthostega]] is an extinct [[amphibian]], among the first animals to have recognizable [[Limb (anatomy)|limb]]s. It is a candidate for being one of the first [[vertebrate]]s to be capable of coming onto land. It lacked [[wrist]]s, and was generally poorly adapted for life on land. The limbs could not support the animal's weight. [[Acanthostega]] had both [[lungs]] and [[gills]], also indicating it was a link between lobe-finned fish and terrestrial vertebrates. − − [[Ichthyostega]] is an early [[tetrapod]]. Being one of the first animals with legs, arms, and finger bones, Ichthyostega is seen as a [[Hybrid (biology)|hybrid]] between a [[fish]] and an [[amphibia]]n. [[Ichthyostega]]' had legs but its [[Limb (anatomy)|limb]]s probably weren't used for [[walking]], they may have spent very brief periods out of water and would have used their legs to paw their way through the [[mud]].<ref> "the ancestor that amphibians share with reptiles and ourselves? " " These possibly transitional fossils have been much studied, among − them Acanthostega, which seems to have been wholly aquatic, and Ichthyostega" [[Richard Dawkins]] [[2004]] [[The Ancestor's Tale]] page 250, ISBN 0618005838</ref> − − [[Amphibian|Amphibia]] were the first four-legged animals to develop [[lungs]]. − − [[Amphibian]]s living today still retain many characteristics of the early [[tetrapods]]. − |- valign="TOP" − | align="RIGHT" nowrap | 300 Ma − |[[Image:HylonomusZICA.png|thumb|200px|[[Hylonomus]]]] − From amphibians came the first reptiles: [[Hylonomus]] is the earliest known [[reptile]]. It was 20 cm (8 in) long (including the tail) and probably would have looked rather similar to modern [[lizard]]s. It had small sharp teeth and probably ate [[millipede]]s and early [[insect]]s. It is a precursor of later [[Amniote]]s and [[mammal-like reptiles]]. − − Evolution of the amniotic egg gives rise to the Amniota, [[reptile]]s that can reproduce on land and lay eggs on dry land. They did not need to return to water for reproduction. This adaptation gave them the capability to colonize the uplands for the first time. − − Reptiles have advanced nervous system, compared to [[amphibians]]. They have twelve pairs of cranial nerves. − |} − === Mammals === − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 256 Ma − | [[Image:Phtinosuchus1ZICA.png|thumb|200px|[[Phthinosuchus]], an early [[Therapsid]]]] Shortly after the appearance of the first [[reptile]]s, two branches split off. One branch is the [[Diapsid]]s, from which come the modern [[reptile]]s. The other branch is [[Synapsid|Synapsida]], which had [[temporal fenestra]], a pair of holes in their skulls behind the eyes, which were used to increase the space for jaw muscles. − − The earliest '''mammal-like reptiles''' are the [[pelycosaur]]s. The pelycosaurs were the first animals to have temporal fenestra. Pelycosaurs are not [[Therapsid]]s but soon they gave rise to them. The Therapsida were the direct ancestor of [[mammals]]. − − The therapsids have temporal fenestrae larger and more mammal-like than pelycosaurs, their teeth show more serial differentiation; and later forms had evolved a [[secondary palate]]. A secondary palate enables the animal to eat and breathe at the same time and is a sign of a more active, perhaps warm-blooded, way of life. <ref>"In many respects, the pelycosaurs are intermediate between the reptiles and mammals" http://www.ucmp.berkeley.edu/synapsids/pelycosaurs.html Berkeley University</ref> − |- valign="TOP" − | align="RIGHT" nowrap | 220 Ma − |One sub-group of therapsids, the [[cynodont]]s evolved more mammal-like characteristics. − The jaws of cynodonts resemble modern mammal jaws. It is very likely this group of animals contains a species which is the direct ancestor of all modern mammals.<ref> "Tlvinaxodon, like any fossil, should be thought of as a cousin of our ancestor, not the ancestor itself. It was a member of a group of mammal-like reptiles called the cynodonts. The cynodonts were so mammal-like, it is tempting to call them mammals. But who cares what we call them? They are almost perfect intermediates." [[Richard Dawkins]] [[2004]] [[The Ancestor's Tale]] page 211, ISBN 0618005838</ref> − |- valign="TOP" − | align="RIGHT" nowrap | 220 Ma − |[[Image:RepenomamusuZICA.png|right|thumb|200px|''[[Repenomamus]]'']] − From [[Eucynodontia]] ([[cynodonts]]) came the first [[mammal]]s. Most early mammals were small and shrew-like animals that fed on insects. Although there is no evidence in the fossil record, it is likely that these animals had a constant body temperature, milk glands for their young. The [[neocortex]] region of the [[brain]] first evolved in mammals and thus is unique to them. − |- valign="TOP" − | align="RIGHT" nowrap | 125 Ma − |[[Image:Eomaia23423.jpg|right|thumb|200px|''[[Eomaia|Eomaia scansoria]]'']] − ''[[Eomaia|Eomaia scansoria]]'', a eutherian mammal, leads to the formation of modern placental mammals. It looks like modern dormouse, climbing small shrubs in [[Liaoning]], [[China]]. − |- valign="TOP" − | align="RIGHT" nowrap | 100 Ma − | Common [[genetics|genetic]] [[ancestor]] of [[Mouse|mice]] and humans (base of the clade [[Euarchontoglires]]). − |} − − ===Primates === − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 65–85 Ma − |[[Image:PlesiadapisZICA.png|right|thumb|200px|''[[Carpolestes simpsoni]]'']] − [[Image:PlesiadapisNewZICA.png|right|thumb|200px|A ''[[Plesiadapis]]'' without [[fur]].]] − A group of small, nocturnal and arboreal, insect-eating mammals called the [[Euarchonta]] begins a speciation that will lead to the [[primate]], [[treeshrew]] and [[flying lemur]] [[order (biology)|orders]]. The [[Primatomorpha]] is a subdivision of Euarchonta that includes the primates and the proto-primate [[Plesiadapiformes]]. One of the early proto-primates is ''[[Plesiadapis]]''. ''Plesiadapis'' still had claws and the eyes located on each side of the head. Because of this they were faster on the ground than on the top of the trees, but they began to spend long times on lower branches of trees, feeding on [[fruit]]s and [[leaf|leaves]]. The [[Plesiadapiformes]] very likely contain the species which is the ancestor of all primates.<ref> "Fossils that might help us reconstruct what Concestor 8 was like include the large group called plesiadapi-forms. They lived about the right time, and they have many of the qualities you would expect of the grand ancestor of all the primates" [[Richard Dawkins]] [[2004]] [[The Ancestor's Tale]] page 136, ISBN 0618005838</ref> − − One of the last [[Plesiadapiformes]] is ''[[Carpolestes simpsoni]]''. It had grasping digits but no forward facing eyes. − |- valign="TOP" − | align="RIGHT" nowrap | 47 Ma − |''[[Darwinius masillae]]'', a [[transitional form]] between the [[prosimian]]s ([[lemur]]s and other primitive primates) and the [[simian]]s ([[monkey]]s, [[ape]]s). It looked much like a [[lemur]] but had [[opposable thumb]]s. − |- valign="TOP" − | align="RIGHT" nowrap | 40 Ma − |[[Primate]]s diverge into suborders [[Strepsirrhini]] (wet-nosed primates) and [[Haplorrhini]] (dry nosed primates). Strepsirrhini contains most of the [[prosimian]]s; modern examples include the [[lemur]]s and [[loris]]es. The haplorrhines include the three living groups the prosimian [[tarsier]]s, the simian [[monkey]]s, and [[ape]]s. One of the earliest haplorrhines is ''[[Teilhardina asiatica]]'', a mouse-sized, diurnal creature with small eyes. The Haplorrhini metabolism lost the ability to make its own [[Vitamin C]]. This means that it and all its descendants had to include fruit in its diet, where Vitamin C could be obtained externally. − |- valign="TOP" − | align="RIGHT" nowrap | 30 Ma − |[[Image:Aegyptopithecus ZICA.png|right|thumb|200px|''[[Aegyptopithecus]]'']] − [[Haplorrhini]] splits into infraorders [[New World monkey|Platyrrhini]] and [[Catarrhini]]. Platyrrhines, New World monkeys, have prehensile tails and males are color blind. They may have migrated to South America on a raft of vegetation across the Atlantic ocean (circa 4,500 km, 2,800 mi). Catarrhines mostly stayed in [[Africa]] as the two continents drifted apart. One ancestor of catarrhines might be ''[[Aegyptopithecus]]''. − |- valign="TOP" − | align="RIGHT" nowrap | 25 Ma − |[[Image:ProconsulZICA.png|right|thumb|200px|''[[Proconsul (genus)|Proconsul]]'']] − [[Catarrhini]] splits into 2 superfamilies, [[Old World monkey]]s (Cercopithecoidea) and [[ape]]s ([[Hominoidea]]). Our [[Trichromat|trichromatic]] color vision had its genetic origins in this period. − − ''[[Proconsul (primate)|Proconsul]]'' was an early [[genus]] of catarrhine primates. They had a mixture of [[Old World monkey]] and [[ape]] characteristics. ''Proconsul'''s [[monkey]]-like features include thin [[tooth]] enamel, a light build with a narrow chest and short forelimbs, and an arboreal quadrupedal lifestyle. Its ape-like features are its lack of a [[tail]], ape-like [[Elbow-joint|elbow]]s, and a slightly larger brain relative to body size. − − ''[[Proconsul africanus]]'' is a possible ancestor of both great and lesser apes, and humans. − |} − − ===[[Hominidae]]=== − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 15 Ma − |[[Hominidae]] (great apes) speciate from the ancestors of the [[gibbon]] (lesser apes). − |- valign="TOP" − | align="RIGHT" nowrap | 13 Ma − |[[Homininae]] ancestors speciate from the ancestors of the [[orangutan]]<ref> Raauma, Ryan, Sternera, K., (2005) "Catarrhine primate divergence dates estimated from complete mitochondrial genomes", Journal of Human Evolution 48: 237-257 [http://www.nyu.edu/gsas/dept/anthro/programs/csho/Content/Facultycvandinfo/Disotell/RAUMM&DISS.pdf] − </ref>. − − ''[[Pierolapithecus|Pierolapithecus catalaunicus]]'' is believed to be a [[common ancestor]] of humans and the great apes or at least a species that brings us closer to a common ancestor than any previous [[fossil]] discovery. − − ''Pierolapithecus'' had special adaptations for tree climbing, just as humans and other great apes do: a wide, flat [[ribcage]], a stiff lower [[vertebral column|spine]], flexible wrists, and [[shoulder]] blades that lie along its back. − |- valign="TOP" − | align="RIGHT" nowrap | 10 Ma − |[[Hominini]] speciate from the ancestors of the [[gorilla]]s. − |- valign="TOP" − | align="RIGHT" nowrap | 7 Ma − |[[Image:SahelanthropustchadensisZICA.png|right|thumb|200px|''[[Sahelanthropus tchadensis]]'']] − [[Hominina]] speciate from the ancestors of the [[chimpanzee]]s. The [[latest common ancestor]] lived around the time of ''[[Sahelanthropus tchadensis]]'', ca. 7 Ma[http://www.talkorigins.org/faqs/homs/species.html#tchadensis]; S. tchadensis is sometimes claimed to be the last common ancestor of humans and chimpanzees, but this is disputed. The earliest known human ancestor post-dating the separation of the human and the chimpanzee lines is ''[[Orrorin tugenensis]]'' (Millennium Man, Kenya; ca. 6 Ma). − Both chimpanzees and humans have a [[larynx]] that repositions during the first two years of life to a spot between the [[pharynx]] and the lungs, indicating that the common ancestors have this feature, a precursor of speech. − |- valign="TOP" − | align="RIGHT" nowrap | 4.4 Ma − |[[Ardipithecus]] is a very early [[Hominini|hominin]] [[genus]] ([[subfamily]] [[Homininae]]). Two species are described in the literature: ''A. ramidus'', which lived about 4.4 million years ago<ref name=%26quot%3BNatGeo-News%26quot%3B%26gt%3B%7B%7Bcite web − | url = http://news.nationalgeographic.com/news/2001/07/0712_ethiopianbones.html − | title = Fossils From Ethiopia May Be Earliest Human Ancestor − | first = David | last = Perlman − | publisher = National Geographic News − | date = July 12, 2001 | accessdate = July 2009 − | quote = Another co-author is Tim D. White, a paleoanthropologist at UC-Berkeley who in 1994 discovered a pre-human fossil, named Ardipithecus ramidus, that was then the oldest known, at 4.4 million years. − }}</ref> during the early [[Pliocene]], and ''A. kadabba'', dated to approximately 5.6 million years ago<ref name=%26quot%3BAndThePaleobiology%26quot%3B%26gt%3B%7B%7Bcite journal |last=White |first=Tim D. |authorlink= |coauthors=Asfaw, Berhane; Beyene, Yonas; Haile-Selassie, Yohannes; Lovejoy, C. Owen; Suwa, Gen; WoldeGabriel, Giday|year=2009 |month= |title=''Ardipithecus ramidus'' and the Paleobiology of Early Hominids. |journal=[[Science (journal)|Science]] |volume=326 |issue=5949 |pages=75–86 |doi=10.1126/science.1175802 |url= |quote=|pmid=}}</ref> (late [[Miocene]]). ''A. ramidus'' had a small brain, measuring between 300 and 350 cm<sup>3</sup>. This is about the same size as modern [[bonobo]] and female [[common chimpanzee]] brain, but much smaller than the brain of australopithecines like Lucy (~400 to 550 cm<sup>3</sup>) and slightly over a fifth the size of the modern ''Homo sapiens'' brain. Ardipithecus was aboreal, meaning it lived largely in the forest where it competed with other forest animals for food, including the contemporary ancestor for the chimpanzees. Ardipithecus was likely [[bipedal]] as evidenced by its bowl shaped pelvis and centered [[foramen magnum]], though its feet were still adapted for grasping rather than walking for long distances. − − |- valign="TOP" − | align="RIGHT" nowrap | 3.6 Ma − | [[File:Australopithecus_afarensis.JPG|right|thumb|200px|''[[Australopithecus afarensis]]'']] Some ''[[Australopithecus afarensis]]'' left human-like footprints on volcanic ash in Laetoli, Kenya (Northern Tanzania) which provides strong evidence of full-time bipedalism. Australopithecus afarensis lived between 3.9 and 2.9 million years ago. It is thought that A. afarensis was ancestral to both the genus [[Australopithecus]] and the [[Homo (genus)|genus Homo]]. Compared to the modern and extinct great [[ape]]s, A. afarensis has reduced canines and molars, although they are still relatively larger than in modern humans. A. afarensis also has a relatively small brain size (~380-430cm³) and a prognathic (i.e. projecting anteriorly) face. Australopithecines have been found in Savannah environments and likely increased its diet to include meat from scavenging opportunities. An analysis of [[Australopithecus africanus]] lower [[Vertebrae|vertebrae]] suggests that females had changes to support bipedalism even while pregnant. − |- valign="TOP" − | align="RIGHT" nowrap | 3.5 Ma − | [[Kenyanthropus platyops]], a possible ancestor of ''Homo'', emerges from the ''Australopithecus'' genus. − |- valign="TOP" − | align="RIGHT" nowrap | 3 Ma − | The bipedal [[Australopithecus|australopithecines]] (a genus of the ''[[Hominina]]'' subtribe) evolve in the savannas of [[Africa]] being hunted by ''[[Dinofelis]]''. Loss of [[body hair]] takes place in the period 3-2 Ma, in parallel with the development of full [[bipedalism]]. − |} − − ===[[Homo (genus)|Homo]]=== − {| class="wikitable" − |- − ! Date − ! Event − |- valign="TOP" − | align="RIGHT" nowrap | 2.5 Ma − |[[Image:Homo_habilis.JPG|right|thumb|200px|''[[Homo habilis]]'']] − Appearance of ''[[Homo (genus)|Homo]]''. − ''[[Homo habilis]]'' is thought to be the ancestor of the lankier and more sophisticated ''[[Homo ergaster]]''. Lived side by side with ''[[Homo erectus]]'' until at least 1.44 Ma, making it highly unlikely that ''[[Homo erectus]]'' directly evolved out of ''[[Homo habilis]]''. First [[stone tool]]s, beginning of the [[Lower Paleolithic]]. − {{See|Homo rudolfensis}} − |- valign="TOP" − | align="RIGHT" nowrap | 1.8 Ma − |[[Image:Homo erectus.JPG|thumb|200px|A reconstruction of ''[[Homo erectus]]''. ]] − ''[[Homo erectus]]'' evolves in [[Africa]]. − ''Homo erectus'' would bear a striking resemblance to modern humans, but had a brain about 74 percent of the size of modern man. Its forehead is less sloping and the teeth are smaller. Other hominid designations such as [[Homo georgicus]], [[Homo ergaster]], [[Peking Man|Homo pekinensis]], [[Homo heidelbergensis]] are often put under the umbrella species name of Homo erectus<ref>NOVA: Becoming Human Part 2 http://video.pbs.org/video/1319997127/</ref>. Starting with Homo georgicus found in what is now the Republic of Georgia dated at 1.8 Ma, the pelvis and backbone grew more human-like and gave georgicus the ability [[early human migrations|cover very long distances]] in order to follow herds of other animals. This is the oldest fossil of a hominid found (so far) outside of Africa. [[Control of fire by early humans]] is achieved 1.5 Ma by Homo ergaster. Homo ergaster reaches a height of around 1.9 metres (6.2 ft). Evolution of [[dark skin]], which is linked to the loss of body hair in human ancestors, is complete by 1.2 Ma. Homo pekinensis first appears in Asia around 700 Ka but according to the "[[Recent_African_origin_of_modern_humans|recently out of africa]]" theory could not be a human ancestor, but rather, is just a cousin offshoot species from Homo ergaster. Homo heidelbergensis was a very large hominid that had [[Boxgrove Quarry|a more advanced complement of cutting tools]] and may have hunted big game such as horses. − |- valign="TOP" − | align="RIGHT" nowrap | 516 [[Annum#Multiples of an "annum"|ka]] − | ''[[Homo antecessor]]'' is the common genetic ancestor of humans and Neanderthal.<ref>Green, R. E., Krause, J, Ptak, S. E., Briggs, A. W., Ronan, M. T., Simons, J. F., et al. (2006) Analysis of one million base pairs of Neanderthal DNA. Nature, 16, 330–336. http://www.nature.com/nature/journal/v444/n7117/abs/nature05336.html</ref> At present estimate, humans have approximately 20,000–25,000 [[gene]]s and share 99% of their [[DNA]] with the now [[extinct]] [[Neanderthal]] <ref>"<cite>Rubin also said analysis so far suggests human and Neanderthal DNA are some 99.5 percent to nearly 99.9 percent identical.</cite>" [http://www.cnn.com/2006/TECH/science/11/15/neanderthal.ap/index.html Neanderthal bone gives DNA clues] (URL accessed on November 16, 2006)</ref> and 95-99% of their [[DNA]] with their closest [[living]] evolutionary relative, the [[chimpanzee]]s<ref>"<cite>The conclusion is the old saw that we share 98.5% of our DNA sequence with chimpanzee is probably in error. For this sample, a better estimate would be that 95% of the base pairs are exactly shared between chimpanzee and human DNA.</cite>" {{cite journal|doi=10.1073/pnas.172510699|title=Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels|author=Britten, R.J. |journal = PNAS |year=2002|volume=99|pages=13633|pmid=12368483}}</ref><ref>"<cite>...of the three billion letters that make up the human genome, only 15 million--less than 1 percent--have changed in the six million years or so since the human and chimp lineages diverged.</cite>" {{cite|title=What makes us human?|author=Pollard, K.S.|journal = Scientific American|year=2009|volume=300-5|pages=44–49.}}</ref>. The human variant of the [[FOXP2]] gene (linked to the control of speech) has been found to be identical in Neanderthal<ref name=%26quot%3Bpmid17949978%26quot%3B%26gt%3B%7B%7Bcite journal | author = Krause J, Lalueza-Fox C, Orlando L, Enard W, Green RE, Burbano HA, Hublin JJ, Hänni C, Fortea J, de la Rasilla M, Bertranpetit J, Rosas A, [[Svante Pääbo|Pääbo S]] | title = The derived FOXP2 variant of modern humans was shared with Neandertals | journal = Curr. Biol. | volume = 17 | issue = 21 | pages = 1908–12 | year = 2007 | month = November | pmid = 17949978 | doi = 10.1016/j.cub.2007.10.008 | url = | laysummary = http://www.nytimes.com/2007/10/19/science/19speech-web.html?ref=world | laysource = [[New York Times]] | laydate= 2007-10-19 }}</ref>. It can therefore be deduced that Homo antecessor would also have had the human FOXP2 gene. − |- valign="TOP" − | align="RIGHT" nowrap | 355 ka − | − Three 1.5 m (5 ft) tall ''[[Homo heidelbergensis]]'' [[Petrosomatoglyph#Footprints_in_Italy|left footprints in powdery volcanic ash solidified in Italy]]. ''Homo heidelbergensis'' is the common ancestor of both ''[[Neanderthal|Homo neanderthalensis]]'' and ''[[Homo sapiens]]''. It is morphologically very similar to ''[[Homo erectus]]'' but ''Homo heidelbergensis'' had a larger brain-case, about 93% the size of that of ''Homo sapiens''. The species was tall, 1.8 m (6 ft) on average, and more muscular than modern humans. Beginning of the [[Middle Paleolithic]]. − |- valign="TOP" − | align="RIGHT" nowrap | 195 ka − |[[Image:Human.svg|thumb|200px|''Homo sapiens sapiens'' ([[Pioneer plaque]])]] − [[Omo remains|Omo1]], [[Omo remains|Omo2]] (Ethiopia, Omo river) are the earliest fossil evidence for [[archaic Homo sapiens|archaic ''Homo sapiens'']], evolved from ''[[Homo heidelbergensis]]''. − |- valign="TOP" − | align="RIGHT" nowrap | 160 ka − | ''Homo sapiens'' (''[[Homo sapiens idaltu]]'') in Ethiopia, Awash River, Herto village, practice mortuary rituals and butcher hippos. − |- valign="TOP" − | align="RIGHT" nowrap | 150 ka − | [[Mitochondrial Eve]] is a woman that lived in [[East Africa]]. She is the statistically expected most recent female ancestor common to all [[mitochondrial]] lineages in humans alive today. Note that there is no evidence of any characteristic or genetic drift that significantly differentiated her from the contemporary social group she lived with at the time. Her ancestors were homo sapiens and her mother had the same mtDNA. − |- valign="TOP" − | align="RIGHT" nowrap | 70 ka − | Appearance of mitochondrial haplogroup [[Haplogroup L2 (mtDNA)|L2]]. [[Behavioral modernity]]. − |- valign="TOP" − | align="RIGHT" nowrap | 60 ka − | [[Y-chromosomal Adam]] lives in Africa. He is the [[most recent common ancestor]] from whom all male human Y chromosomes are descended. Appearance of mitochondrial haplogroups [[Haplogroup M (mtDNA)|M]] and [[Haplogroup N (mtDNA)|N]], which participate in the [[Recent African Origin|migration out of Africa]]. − |- valign="TOP" − | align="RIGHT" nowrap | 50 ka − | [[Early human migration|Migration]] to [[Paleolithic South Asia|South Asia]]. [[Haplogroup CT (Y-DNA)|M168]] mutation (carried by all non-African males). Beginning of the [[Upper Paleolithic]]. mt-haplogroups [[Haplogroup U (mtDNA)|U]], [[Haplogroup K (mtDNA)|K]]. − |- valign="TOP" − | align="RIGHT" nowrap | 40 ka − | Migration to [[Prehistory of Australia|Australia]] and [[Paleolithic Europe|Europe]] ([[Cro-Magnon]]). − |- valign="TOP" − | align="RIGHT" nowrap | 25 ka − | [[Neanderthal extinction hypotheses|Neanderthals die out]]. Y-Haplogroup [[Haplogroup R2 (Y-DNA)|R2]]; mt-haplogroups [[Haplogroup J (mtDNA)|J]], [[Haplogroup X (mtDNA)|X]]. − |- valign="TOP" − | align="RIGHT" nowrap | [[10th millennium BC|12 ka]] − | Beginning of the [[Mesolithic]] / [[Holocene]]. Y-Haplogroup [[Haplogroup R1a (Y-DNA)|R1a]]; mt-haplogroups [[Haplogroup V (mtDNA)|V]], [[Haplogroup T (mtDNA)|T]]. Evolution of [[light skin]] in Europeans ([[SLC24A5]]). ''[[Homo floresiensis]]'' dies out, leaving ''Homo sapiens'' as the only living species of the genus ''[[Homo (genus)|Homo]]''. − |} − − ==See also== − *[[Graphical timeline of our universe]] − *[[History of Earth]] − *[[Natural history]] − *[[History of the world]] − *[[Predictions for human evolution]] − *[[Evolutionary history of life]] − *[[Human evolution]] − *[[Human taxonomy]] − *[[Homo (genus)]] − *[[Most recent common ancestor]] − *[[List of human evolution fossils]] − *[[Prehistoric amphibian]] − *[[Prehistoric fish]] − *[[Prehistoric reptile]] − * ''[[The Ancestor's Tale]]'' by [[Richard Dawkins]] with a timeline comprising 40 rendezvous points − *[[Timeline of evolution]] - an explanation of the evolution of a wide variety of animals living today − *[[Y-DNA haplogroups by ethnic groups]] − − ==References== − {{Reflist|2}} − − ==External links== − *[http://www.palaeos.com Palaeos] − *[http://www.ucmp.berkeley.edu berkeley Evolution] − * [http://tolweb.org/Life_on_Earth/1 Tree of Life Web Project] - explore complete phylogenetic tree interactively − *[http://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml History of Animal Evolution] − − {{Human Evolution}} − − {{evolution}} − − <!-- Categorization --> − − {{DEFAULTSORT:Timeline Of Human Evolution}} − [[Category:Biology timelines|Evolution, human]] − [[Category:Evolution]] − [[Category:Human evolution]] − − [[ca:Línia temporal de l'evolució humana]] − [[fr:Origine évolutive de l'Homme]] − [[pt:Linha do tempo da evolução humana]] − [[ta:படிவளர்ச்சி காலக்கோடு]] − [[zh:人類演化歷程]]
Homosexuality Research (view source)
Revision as of 17:05, February 12, 2010
, 17:05, February 12, 2010Reverted edits by HappyBirthdayDarwin (Talk) to last version by Jpatt
{{Homosexuality}}
{{Homosexuality}}
There has been a tremendous amount of '''homosexuality research''' since the the latter part of the 20th century in regards to the causes and effects and homosexuality. Below are some resources in regards to research on homosexuality:
There has been a tremendous amount of '''homosexuality research''' since the the latter part of the 20th century in regards to the causes and effects and homosexuality. Below are some resources in regards to research on homosexuality:
==Homosexuality Research in Regards to the Causes of Homosexuality==
Below is some research on homosexuality in regards to the causes of homosexuality:
[[Image:Age-of-Man-wiki.jpg|thumb|portait|Evolutionary tree]]
*[[Causes of Homosexuality]]
*[[Religious Upbringing and Culture Affects Rates of Homosexuality]]
*[[Sexual Abuse Being a Contributing Factor for Homosexuality]]
*[[Homosexuality and Choice]]
*[[Homosexuality and Genetics]]
[[genus]]: [[Homo (genus)|homo]] (2.500.000 years ago)<br />
==Homosexuality Research in Regards to the Effects of Homosexuality on an Individual==
==Homosexuality Research in Regards to the Effects of Homosexuality on an Individual==