Timeline of human evolution

Last updated
Haeckel's Paleontological Tree of Vertebrates (c. 1879). The evolutionary history of species has been described as a "tree" with many branches arising from a single trunk. While Haeckel's tree is outdated, it illustrates clearly the principles that more complex and accurate modern reconstructions can obscure. Age-of-Man-wiki.jpg
Haeckel's Paleontological Tree of Vertebrates (c. 1879). The evolutionary history of species has been described as a "tree" with many branches arising from a single trunk. While Haeckel's tree is outdated, it illustrates clearly the principles that more complex and accurate modern reconstructions can obscure.

The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens , throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period.


It includes brief explanations of the various taxonomic ranks in the human lineage. The timeline reflects the mainstream views in modern taxonomy, based on the principle of phylogenetic nomenclature; in cases of open questions with no clear consensus, the main competing possibilities are briefly outlined.

Overview of taxonomic ranks

A tabular overview of the taxonomic ranking of Homo sapiens (with age estimates for each rank) is shown below.

RankNameCommon nameMillions of years ago (commencement)
Life 4,200
Archaea 3,700
Domain Eukaryota Eukaryotes2,100
Podiata Excludes Plants and their relatives1,540
Obazoa Excludes Amoebozoa (Amoebas)
Opisthokonts Holozoa + Holomycota (Cristidicoidea and Fungi)1,300
Holozoa Excludes Holomycota1,100
Filozoa Choanozoa + Filasterea
Choanozoa Choanoflagellates + Animals900
Kingdom Animalia Animals610
Subkingdom Eumetazoa Excludes Porifera (Sponges)
Parahoxozoa Excludes Ctenophora (Comb Jellies)
Bilateria Triploblasts / Worms560
Deuterostomes Division from Protostomes
Phylum Chordata Chordates (Vertebrates and closely related invertebrates)530
Olfactores Excludes cephalochordates (Lancelets)
Subphylum Vertebrata Fish / Vertebrates505
Infraphylum Gnathostomata Jawed fish460
Teleostomi Bony fish420
Sarcopterygii Lobe finned fish
Superclass Tetrapoda Tetrapods (animals with four limbs)395
Amniota Amniotes (fully terrestrial tetrapods whose eggs are "equipped with an amnion")340
Synapsida Proto-Mammals308
Therapsid Limbs beneath the body and other mammalian traits280
Class Mammalia Mammals220
Subclass Theria Mammals that give birth to live young (i.e., non-egg-laying)160
Infraclass Eutheria Placental mammals (i.e., non-marsupials)125
Magnorder Boreoeutheria Supraprimates, (most) hoofed mammals, (most) carnivorous mammals, cetaceans, and bats124–101
Superorder Euarchontoglires Supraprimates: primates, colugos, tree shrews, rodents, and rabbits100
Grandorder Euarchonta Primates, colugos, and tree shrews 99–80
Mirorder Primatomorpha Primates and colugos79.6
Order Primates Primates / Plesiadapiformes 66
Suborder Haplorrhini "Dry-nosed" (literally, "simple-nosed") primates: tarsiers and monkeys (incl. apes)63
Infraorder Simiiformes monkeys (incl. apes)40
Parvorder Catarrhini "Downward-nosed" primates: apes and old-world monkeys30
Superfamily Hominoidea Apes: great apes and lesser apes (gibbons)22-20
Family Hominidae Great apes: humans, chimpanzees, gorillas and orangutans—the hominids 20–15
Subfamily Homininae Humans, chimpanzees, and gorillas (the African apes) [1] 14–12
Tribe Hominini Includes both Homo, Pan (chimpanzees), but not Gorilla.10–8
Subtribe Hominina Genus Homo and close human relatives and ancestors after splitting from Pan—the hominins 8–4 [2]
(Genus) Ardipithecus s.l. 6-4
(Genus) Australopithecus 3
Genus Homo (H. habilis) Humans2.5
(Species) H. erectus s.l.
(Species) H. heidelbergensis s.l.
Species Homo sapiens s.s. Anatomically modern humans 0.8–0.3 [3]


Unicellular life

4.3-4.1  Ga
The earliest life appears, possibly as protocells. Their genetic material was probably composed of RNA, capable of both self replication and enzymatic activity; their membranes were composed of lipids. The genes were separate strands, translated into proteins and often exchanged between the protocells.
4.0-3.8 Ga Prokaryotic cells appear; their genetic materials are composed of the more stable DNA and they use proteins for various reasons, primarily for aiding DNA to replicate itself by proteinaceous enzymes (RNA now acts as an intermediary in this central dogma of genetic information flow of cellular life); genes are now linked in sequences so all information passes to offsprings. They had cell walls & outer membranes and were probably initially thermophiles.
3.5 GaThis marks the first appearance of cyanobacteria and their method of oxygenic photosynthesis and therefore the first occurrence of atmospheric oxygen on Earth.

For another billion years, prokaryotes would continue to diversify undisturbed.

2.5-2.2 GaFirst organisms to use oxygen. By 2400 Ma, in what is referred to as the Great Oxidation Event, (GOE), most of the pre-oxygen anaerobic forms of life were wiped out by the oxygen producers.
2.2-1.8 GaOrigin of the eukaryotes: organisms with nuclei, endomembrane systems (including mitochondria) and complex cytoskeletons; they spliced mRNA between transcription and translation (splicing also occurs in prokaryotes, but it is only of non-coding RNAs). The evolution of eukaryotes, and possibly sex, is thought to be related to the GOE, as it probably pressured two or three lineages of prokaryotes (including an aerobe one, which later became mitochondria) to depend on each other, leading to endosymbiosis. Early eukaryotes lost their cell walls and outer membranes.
1.2 Ga Sexual reproduction evolves (mitosis and meiosis) by this time at least, leading to faster evolution [4] where genes are mixed in every generation enabling greater variation for subsequent selection.
1.2-0.8 Ga
Choanoflagellate Cronoflagelado2.svg

The Holozoa lineage of eukaryotes evolves many features for making cell colonies, and finally leads to the ancestor of animals (metazoans) and choanoflagellates. [5] [6]

Proterospongia (members of the Choanoflagellata) are the best living examples of what the ancestor of all animals may have looked like. They live in colonies, and show a primitive level of cellular specialization for different tasks.


800–650 Ma
Dickinsonia costata from the Ediacaran biota, 635-542 Ma, a possible early member of Animalia. DickinsoniaCostata.jpg
Dickinsonia costata from the Ediacaran biota, 635–542 Ma, a possible early member of Animalia.

Urmetazoan: The first fossils that might represent animals appear in the 665-million-year-old rocks of the Trezona Formation of South Australia. These fossils are interpreted as being early sponges. [7] Multicellular animals may have existed from 800 Ma. Separation from the Porifera (sponges) lineage. Eumetazoa/Diploblast: separation from the Ctenophora ("comb jellies") lineage. Planulozoa/ParaHoxozoa: separation from the Placozoa and Cnidaria lineages. All diploblasts possess epithelia, nerves, muscles and connective tissue and mouths, and except for placozoans, have some form of symmetry, with their ancestors probably having radial symmetry like that of cnidarians. Diploblasts separated their early embryonic cells into two germ layers (ecto- and endoderm). Photoreceptive eye-spots evolve.

650-600 Ma
Proporus sp., a xenacoelomorph. Proporus sp.png
Proporus sp., a xenacoelomorph.

Urbilaterian: the last common ancestor of xenacoelomorphs, protostomes (including the arthropod [insect, crustacean, spider], mollusc [squid, snail, clam] and annelid [earthworm] lineages) and the deuterostomes (including the vertebrate [human] lineage) (the last two are more related to each other and called Nephrozoa). Xenacoelomorphs all have a gonopore to expel gametes but nephrozoans merged it with their anus. Earliest development of bilateral symmetry, mesoderm, head (anterior cephalization) and various gut muscles (and thus peristalsis) and, in the Nephrozoa, nephridia (kidney precursors), coelom (or maybe pseudocoelom), distinct mouth and anus (evolution of through-gut), and possibly even nerve cords and blood vessels. [8] Reproductive tissue probably concentrates into a pair of gonads connecting just before the posterior orifice. "Cup-eyes" and balance organs evolve (the function of hearing added later as the more complex inner ear evolves in vertebrates). The nephrozoan through-gut had a wider portion in the front, called the pharynx. The integument or skin consists of an epithelial layer (epidermis) and a connective layer.

600-540 Ma
A sea cucumber (Actinopyga echinites), displaying its feeding tentacles and tube feet. Actinopyga echinites1.jpg
A sea cucumber ( Actinopyga echinites ), displaying its feeding tentacles and tube feet.

Most known animal phyla appeared in the fossil record as marine species during the Ediacaran-Cambrian explosion , probably caused by long scale oxygenation since around 585 Ma (sometimes called the Neoproterozoic Oxygenation Event or NOE) and also an influx of oceanic minerals. Deuterostomes, the last common ancestor of the Chordata [human] lineage, Hemichordata (acorn worms and graptolites) and Echinodermata (starfish, sea urchins, sea cucumbers, etc.), probably had both ventral and dorsal nerve cords like modern acorn worms.

An archaic survivor from this stage is the acorn worm, sporting an open circulatory system (with less branched blood vessels) with a heart that also functions as a kidney. Acorn worms have a plexus concentrated into both dorsal and ventral nerve cords. The dorsal cord reaches into the proboscis, and is partially separated from the epidermis in that region. This part of the dorsal nerve cord is often hollow, and may well be homologous with the brain of vertebrates. [9] Deuterostomes also evolved pharyngeal slits, which were probably used for filter feeding like in hemi- and proto-chordates.


540-520 Ma
Pikaia Pikaia BW.jpg

The increased amount of oxygen causes many eukaryotes, including most animals, to become obligate aerobes.

The Chordata ancestor gave rise to the lancelets (Amphioxii) and Olfactores. Ancestral chordates evolved a post-anal tail, notochord, and endostyle (precursor of thyroid). The pharyngeal slits (or gills) are now supported by connective tissue and used for filter feeding and possibly breathing. [10] Other, earlier chordate predecessors include Myllokunmingia fengjiaoa, [11] Haikouella lanceolata , [12] and Haikouichthys ercaicunensis. [13] They probably lost their ventral nerve cord and evolved a special region of the dorsal one, called the brain, with glia becoming permanently associated with neurons. They probably evolved the first blood cells (probably early leukocytes, indicating advanced innate immunity), which they made around the pharynx and gut. [14] All chordates except tunicates sport an intricate, closed circulatory system, with highly branched blood vessels.

Olfactores, last common ancestor of tunicates and vertebrates in which olfaction (smell) evolved. Since lancelets lack a heart, it possibly emerged in this ancestor (previously the blood vessels themselves were contractile) though it could've been lost in lancelets after evolving in early deuterostomes (hemichordates and echinoderms have hearts).

520-480 Ma
Agnatha Agnata.png

The first vertebrates ("fish") appear: the ostracoderms. Haikouichthys and Myllokunmingia are examples of these jawless fish, or Agnatha; the jawless Cyclostomata diverge at this stage. They were jawless, had seven pairs of pharyngeal arches like their descendants today, and their endoskeletons were cartilaginous (then only consisting of the chondro cranium/braincase and vertebrae). The connective tissue below the epidermis differentiates into the dermis and hypodermis. [15] They depended on gills for respiration and evolved the unique sense of taste (the remaining sense of the skin now called "touch"), endothelia, camera eyes and inner ears (capable of hearing and balancing; each consists of a lagena, an otolithic organ and two semicircular canals) as well as livers, thyroids, kidneys and two-chambered hearts (one atrium and one ventricle). They had a tail fin but lacked the paired (pectoral and pelvic) fins of more advanced fish. Brain divided into three parts (further division created distinct regions based on function). The pineal gland of the brain penetrates to the level of the skin on the head, making it seem like a third eye. They evolved the first erythrocytes and thrombocytes. [16]

460-430 Ma
A placoderm Coccosteus BW.jpg
A placoderm

The Placodermi were the first jawed fishes (Gnathostomata); their jaws evolved from the first gill/pharyngeal arch and they largely replaced their endoskeletal cartilage with bone and evolved pectoral and pelvic fins. Bones of the first gill arch became the upper and lower jaw, while those from the second arch became the hyomandibula, ceratohyal and basihyal; this closed two of the seven pairs of gills. The gap between the first and second arches just below the braincase (fused with upper jaw) created a pair of spiracles, which opened in the skin and led to the pharynx (water passed through them and left through gills). Placoderms had competition with the previous dominant animals, the cephalopods and sea scorpions, and rose to dominance themselves. A lineage of them probably evolved into the bony and cartilaginous fish, after evolving scales, teeth (which allowed the transition to full carnivory), stomachs, spleens, thymuses, myelin sheaths, hemoglobin and advanced, adaptive immunity (the latter two occurred independently in the lampreys and hagfish). Jawed fish also have a third, lateral semicircular canal and their otoliths are divided between a saccule and utricle.

430-410 Ma
Coelacanth caught in 1974 Latimeria Chalumnae - Coelacanth - NHMW.jpg
Coelacanth caught in 1974
Bony fish split their jaws into several bones and evolve lungs, fin bones, two pairs of rib bones, and opercular bones, and diverge into the actinopterygii (with ray fins) and the sarcopterygii (with fleshy, lower fins); [17] the latter transitioned from marine to freshwater habitats. Jawed fish also possess dorsal and anal fins.


390 Ma
Panderichthys Panderichthys BW.jpg

Some freshwater lobe-finned fish (sarcopterygii) develop limbs and give rise to the Tetrapodomorpha. These fish evolved in shallow and swampy freshwater habitats, where they evolved large eyes and spiracles.

Primitive tetrapods ("fishapods") developed from tetrapodomorphs with a two-lobed brain in a flattened skull, a wide mouth and a medium snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed adaptations of fins with fleshy bases and bones. (The "living fossil" coelacanth is a related lobe-finned fish without these shallow-water adaptations.) Tetrapod fishes used their fins as paddles in shallow-water habitats choked with plants and detritus. The universal tetrapod characteristics of front limbs that bend backward at the elbow and hind limbs that bend forward at the knee can plausibly be traced to early tetrapods living in shallow water. [18]

Panderichthys is a 90–130 cm (35–50 in) long fish from the Late Devonian period (380 Mya). It has a large tetrapod-like head. Panderichthys exhibits features transitional between lobe-finned fishes and early tetrapods.

Trackway impressions made by something that resembles Ichthyostega's limbs were formed 390 Ma in Polish marine tidal sediments. This suggests tetrapod evolution is older than the dated fossils of Panderichthys through to Ichthyostega.

375-350 Ma
Tiktaalik Tiktaalik BW.jpg

Tiktaalik is a genus of sarcopterygian (lobe-finned) fishes from the late Devonian with many tetrapod-like features. It shows a clear link between Panderichthys and Acanthostega.

Acanthostega Acanthostega BW.jpg
Ichthyostega Ichthyostega BW.jpg

Acanthostega is an extinct tetrapod, among the first animals to have recognizable limbs. It is a candidate for being one of the first vertebrates to be capable of coming onto land. It lacked wrists, 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. The dorsal pair of ribs form a rib cage to support the lungs, while the ventral pair disappears.

Ichthyostega is another extinct tetrapod. Being one of the first animals with only two pairs of limbs (also unique since they end in digits and have bones), Ichthyostega is seen as an intermediate between a fish and an amphibian. Ichthyostega had limbs but these probably were not used for walking. They may have spent very brief periods out of water and would have used their limbs to paw their way through the mud. [19] They both had more than five digits (eight or seven) at the end of each of their limbs, and their bodies were scaleless (except their bellies, where they remained as gastralia). Many evolutionary changes occurred at this stage: eyelids and tear glands evolved to keep the eyes wet out of water and the eyes became connected to the pharynx for draining the liquid; the hyomandibula (now called columella) shrank into the spiracle, which now also connected to the inner ear at one side and the pharynx at another, becoming the Eustachian tube (columella assisted in hearing); an early eardrum (a patch of connective tissue) evolved on the end of each tube (called the otic notch); and the ceratohyal and basihyal merged into the hyoid. These "fishapods" had more ossified and stronger bones to support themselves on land (especially skull and limb bones). Jaw bones fuse together while gill and opercular bones disappear.

350-330 Ma
Pederpes Pederpes22small.jpg

Pederpes from around 350 Ma indicates that the standard number of 5 digits evolved at the Early Carboniferous, when modern tetrapods (or "amphibians") split in two directions (one leading to the extant amphibians and the other to amniotes). At this stage, our ancestors evolved vomeronasal organs, salivary glands, tongues, parathyroid glands, three-chambered hearts (with two atria and one ventricle) and bladders, and completely removed their gills by adulthood. The glottis evolves to prevent food going into the respiratory tract. Lungs and thin, moist skin allowed them to breathe; water was also needed to give birth to shell-less eggs and for early development. Dorsal, anal and tail fins all disappeared.

Lissamphibia (extant amphibians) retain many features of early amphibians but they have only four digits (caecilians have none).

330-300 Ma
Hylonomus Hylonomus BW.jpg

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 lizards. It had small sharp teeth and probably ate small millipedes and insects. It is a precursor of later amniotes (broadest sense of "reptile"). Alpha keratin first evolves here; it is used in the claws of modern amniotes, and hair in mammals, indicating claws and a different type of scales evolved in amniotes (complete loss of gills as well). [20]

Evolution of the amniotic egg gives rise to the amniotes, tetrapods that can reproduce on land and lay shelled eggs on dry land. They did not need to return to water for reproduction nor breathing. This adaptation and the desiccation-resistant scales gave them the capability to inhabit the uplands for the first time, albeit making them drink water through their mouths. At this stage, adrenal tissue may have concentrated into discrete glands.

Amniotes have advanced nervous systems, with twelve pairs of cranial nerves, unlike lower vertebrates. They also evolved true sternums but lost their eardrums and otic notches (hearing only by columella bone conduction).


300-260 MaShortly after the appearance of the first reptiles, two branches split off. One branch is the Sauropsida, from which come the modern reptiles and birds. The other branch is Synapsida from which come modern mammals. Both had temporal fenestrae, a pair of holes in their skulls behind the eyes, which were used to increase the space for jaw muscles. Synapsids had one opening on each side, while diapsids (a branch of Sauropsida) had two. An early, inefficient version of diaphragm may have evolved in synapsids.

The earliest "mammal-like reptiles" are the pelycosaurs. The pelycosaurs were the first animals to have temporal fenestrae. Pelycosaurs were not therapsids but their ancestors. The therapsids were, in turn, the ancestors of mammals.

The therapsids had temporal fenestrae larger and more mammal-like than pelycosaurs, their teeth showed more serial differentiation, their gait was semi-erect 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. [21] They had lost gastralia and, possibly, scales.

260-230 Ma
Cynognathus Cynognathus BW.jpg

One subgroup of therapsids, the cynodonts, lose pineal eye & lumbar ribs and very likely became warm-blooded. The lower respiratory tract forms intricate branches in the lung parenchyma, ending in highly vascularized alveoli. Erythrocytes and thrombocytes lose their nuclei while lymphatic systems and advanced immunity emerge. They may have also had thicker dermis like mammals today.

The jaws of cynodonts resembled modern mammal jaws; the anterior portion, the dentary, held differentiated teeth. This group of animals likely contains a species which is the ancestor of all modern mammals. Their temporal fenestrae merged with their orbits. Their hindlimbs became erect and their posterior bones of the jaw progressively shrunk to the region of the columella. [22]

230-170 Ma
Repenomamus Repenomamus BW.jpg

From Eucynodontia came the first mammals. Most early mammals were small shrew-like animals that fed on insects and had transitioned to nocturnality to avoid competition with the dominant archosaurs — this led to the loss of the vision of red and ultraviolet light (ancestral tetrachromacy of vertebrates reduced to dichromacy). Although there is no evidence in the fossil record, it is likely that these animals had a constant body temperature, hair and milk glands for their young (the glands stemmed from the milk line). The neocortex (part of the cerebrum) region of the brain evolves in Mammalia, at the reduction of the tectum (non-smell senses which were processed here became integrated into neocortex but smell became primary sense). Origin of the prostate gland and a pair of holes opening to the columella and nearby shrinking jaw bones; new eardrums stand in front of the columella and Eustachian tube. The skin becomes hairy, glandular (glands secreting sebum and sweat) and thermoregulatory. Teeth fully differentiate into incisors, canines, premolars and molars; mammals become diphyodont and possess developed diaphragms and males have internal penises. All mammals have four chambered hearts (with two atria and two ventricles) and lack cervical ribs (now mammals only have thoracic ribs).

Monotremes are an egg-laying group of mammals represented today by the platypus and echidna. Recent genome sequencing of the platypus indicates that its sex genes are closer to those of birds than to those of the therian (live birthing) mammals. Comparing this to other mammals, it can be inferred that the first mammals to gain sexual differentiation through the existence or lack of SRY gene (found in the y-Chromosome) evolved only in the therians. Early mammals and possibly their eucynodontian ancestors had epipubic bones, which serve to hold the pouch in modern marsupials (in both sexes).

170-120 Ma
Juramaia sinensis Juramaia NT.jpg
Juramaia sinensis

Evolution of live birth (viviparity), with early therians probably having pouches for keeping their undeveloped young like in modern marsupials. Nipples stemmed out of the therian milk lines. The posterior orifice separates into anal and urogenital openings; males possess an external penis.

Monotremes and therians independently detach the malleus and incus from the dentary (lower jaw) and combine them to the shrunken columella (now called stapes) in the tympanic cavity behind the eardrum (which is connected to the malleus and held by another bone detached from the dentary, the tympanic plus ectotympanic), and coil their lagena (cochlea) to advance their hearing, with therians further evolving an external pinna and erect forelimbs. Female placentalian mammals don’t have pouches and epipubic bones but instead have a developed placenta which penetrates the uterus walls (unlike marsupials), allowing a longer gestation; they also have separated urinary and genital openings. [23]

100-90 Ma Last common ancestor of rodents, rabbits, ungulates, carnivorans, bats, shrews and humans (base of the clade Boreoeutheria; males now have external testicles).


90–66 Ma
Plesiadapis Plesiadapis2.jpg
Carpolestes simpsoni CarpolestesCL.png
Carpolestes simpsoni

A group of small, nocturnal, arboreal, insect-eating mammals called Euarchonta begins a speciation that will lead to the orders of primates, treeshrews and flying lemurs. They reduced the number of mammaries to only two pairs (on the chest). Primatomorpha is a subdivision of Euarchonta including primates and their ancestral stem-primates Plesiadapiformes. An early stem-primate, Plesiadapis , still had claws and eyes on the side of the head, making it faster on the ground than in the trees, but it began to spend long times on lower branches, feeding on fruits and leaves.

The Plesiadapiformes very likely contain the ancestor species of all primates. [24] They first appeared in the fossil record around 66 million years ago, soon after the Cretaceous–Paleogene extinction event that eliminated about three-quarters of plant and animal species on Earth, including most dinosaurs. [25] [26]

One of the last Plesiadapiformes is Carpolestes simpsoni , having grasping digits but not forward-facing eyes.

66-56 Ma Primates diverge into suborders Strepsirrhini (wet-nosed primates) and Haplorrhini (dry-nosed primates). Brain expands and cerebrum divides into 4 pairs of lobes. The postorbital bar evolves to separate the orbit from the temporal fossae as sight regains its position as the primary sense; eyes became forward-facing. Strepsirrhini contain most prosimians; modern examples include lemurs and lorises. The haplorrhines include the two living groups: prosimian tarsiers, and simian monkeys, including apes. The Haplorrhini metabolism lost the ability to produce vitamin C, forcing all descendants to include vitamin C-containing fruit in their diet. Early primates only had claws in their second digits; the rest were turned into nails.
50-35 Ma
Aegyptopithecus Aegyptopithecus NT.jpg

Simians split into infraorders Platyrrhini and Catarrhini. They fully transitioned to diurnality and lacked any claw and tapetum lucidum (which evolved many times in various vertebrates). They possibly evolved at least some of the paranasal sinuses, and transitioned from estrous cycle to menstrual cycle. The number of mammaries is now reduced to only one thoracic pair. Platyrrhines, New World monkeys, have prehensile tails and males are color blind. The individuals whose descendants would become Platyrrhini are conjectured to have migrated to South America either on a raft of vegetation or via a land bridge (the hypothesis now favored [27] ). Catarrhines mostly stayed in Africa as the two continents drifted apart. Possible early ancestors of catarrhines include Aegyptopithecus and Saadanius .

35-20 Ma
Proconsul Proconsul NT.jpg

Catarrhini splits into 2 superfamilies, Old World monkeys (Cercopithecoidea) and apes (Hominoidea). Human trichromatic color vision had its genetic origins in this period. Catarrhines lost the vomeronasal organ (or possibly reduced it to vestigial status).

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 elbows, and a slightly larger brain relative to body size.

Proconsul africanus is a possible ancestor of both great and lesser apes, including humans.


20-15 Ma Hominidae (great ape ancestors) speciate from the ancestors of the gibbon (lesser apes) between c. 20 to 16 Ma. They largely reduced their ancestral snout and lost the uricase enzyme (present in most organisms). [28]
16-12 Ma Homininae ancestors speciate from the ancestors of the orangutan between c. 18 to 14 Ma. [29]

Pierolapithecus catalaunicus is thought to be a common ancestor of humans and the other great apes, or at least a species that brings us closer to a common ancestor than any previous fossil discovery. It had the special adaptations for tree climbing as do present-day humans and other great apes: a wide, flat rib cage, a stiff lower spine, flexible wrists, and shoulder blades that lie along its back.

12 Ma Danuvius guggenmosi is the first-discovered Late Miocene great ape with preserved long bones, and greatly elucidates the anatomical structure and locomotion of contemporary apes. [30] It had adaptations for both hanging in trees (suspensory behavior) and walking on two legs (bipedalism)—whereas, among present-day hominids, humans are better adapted for the latter and the others for the former. Danuvius thus had a method of locomotion unlike any previously known ape called "extended limb clambering", walking directly along tree branches as well as using arms for suspending itself. The last common ancestor between humans and other apes possibly had a similar method of locomotion.
12-8 MaThe clade currently represented by humans and the genus Pan (chimpanzees and bonobos) splits from the ancestors of the gorillas between c. 12 to 8 Ma. [31]
8-6 Ma
Sahelanthropus tchadensis SahelanthropusCL.png
Sahelanthropus tchadensis

Hominini: The latest common ancestor of humans and chimpanzees is estimated to have lived between roughly 10 to 5 million years ago. 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 precondition for vocalized speech in humans. Speciation may have begun shortly after 10 Ma, but late admixture between the lineages may have taken place until after 5 Ma. Candidates of Hominina or Homininae species which lived in this time period include Ouranopithecus (c. 8 Ma), Graecopithecus (c. 7 Ma), Sahelanthropus tchadensis (c. 7 Ma), Orrorin tugenensis (c. 6 Ma).

Ardipithecus Ardi.jpg
Ardipithecus is, or may be, a very early hominin genus (tribe Hominini and subtribe Hominina). Two species are described in the literature: A. ramidus, which lived about 4.4 million years ago [32] during the early Pliocene, and A. kadabba, dated to approximately 5.6 million years ago [33] (late Miocene). A. ramidus had a small brain, measuring between 300 and 350 cm3. This is about the same size as the modern bonobo and female common chimpanzee brain; it is somewhat smaller than the brain of australopithecines like Lucy (400 to 550 cm3) and slightly over a fifth the size of the modern Homo sapiens brain.

Ardipithecus was arboreal, meaning it lived largely in the forest where it competed with other forest animals for food, no doubt including the contemporary ancestor of the chimpanzees. Ardipithecus was probably bipedal as evidenced by its bowl shaped pelvis, the angle of its foramen magnum and its thinner wrist bones, though its feet were still adapted for grasping rather than walking for long distances.

4-3.5 Ma
Reconstruction of "Lucy" Bienvenida al Museo de Lucy.jpg
Reconstruction of "Lucy"

A member of the Australopithecus afarensis left human-like footprints on volcanic ash in Laetoli, northern Tanzania, providing strong evidence of full-time bipedalism. Australopithecus afarensis lived between 3.9 and 2.9 million years ago, and is considered one of the earliest hominins—those species that developed and comprised the lineage of Homo and Homo's closest relatives after the split from the line of the chimpanzees.

It is thought that A. afarensis was ancestral to both the genus Australopithecus and the genus Homo . Compared to the modern and extinct great apes, A. afarensis had reduced canines and molars, although they were still relatively larger than in modern humans. A. afarensis also has a relatively small brain size (380–430 cm³) and a prognathic (anterior-projecting) face.

Australopithecines have been found in savannah environments; they probably developed their diet to include scavenged meat. Analyses of Australopithecus africanus lower vertebrae suggests that these bones changed in females to support bipedalism even during pregnancy.

3.5–3.0 Ma Kenyanthropus platyops , a possible ancestor of Homo, emerges from the Australopithecus. Stone tools are deliberately constructed. [34]
3 MaThe bipedal australopithecines (a genus of the subtribe Hominina) evolve in the savannas of Africa being hunted by Megantereon . Loss of body hair occurs from 3 to 2 Ma, in parallel with the development of full bipedalism and slight enlargement of the brain. [35]


2.5–2.0 Ma

Early Homo appears in East Africa, speciating from australopithecine ancestors. The Lower Paleolithic is defined by the beginning of use of stone tools. Australopithecus garhi was using stone tools at about 2.5 Ma. Homo habilis is the oldest species given the designation Homo, by Leakey et al in 1964. H. habilis is intermediate between Australopithecus afarensis and H. erectus , and there have been suggestions to re-classify it within genus Australopithecus, as Australopithecus habilis.

Stone tools found at the Shangchen site in China and dated to 2.12 million years ago are considered the earliest known evidence of hominins outside Africa, surpassing Dmanisi in Georgia by 300,000 years. [36]

1.9–0.8 Ma
Reconstruction of a female H. erectus Homo.erectus.adult.female.smithsonian.timevanson.flickr.jpg
Reconstruction of a female H. erectus

Homo erectus derives from early Homo or late Australopithecus.

Homo habilis , although significantly different of anatomy and physiology, is thought to be the ancestor of Homo ergaster , or African Homo erectus; but it is also known to have coexisted with H. erectus for almost half a million years (until about 1.5 Ma). From its earliest appearance at about 1.9 Ma, H. erectus is distributed in East Africa and Southwest Asia ( Homo georgicus ). H. erectus is the first known species to develop control of fire, by about 1.5 Ma.

H. erectus later migrates throughout Eurasia, reaching Southeast Asia by 0.7 Ma. It is described in a number of subspecies. [37] Early humans were social and initially scavenged, before becoming active hunters. The need to communicate and hunt prey efficiently in a new, fluctuating environment (where the locations of resources need to be memorized and told) may have driven the expansion of the brain from 2 to 0.8 Ma.

Evolution of dark skin at about 1.2 Ma. [38]

Homo antecessor may be a common ancestor of humans and Neanderthals. [39] [40] At present estimate, humans have approximately 20,000–25,000 genes and share 99% of their DNA with the now extinct Neanderthal [41] and 95–99% of their DNA with their closest living evolutionary relative, the chimpanzees. [42] [43] The human variant of the FOXP2 gene (linked to the control of speech) has been found to be identical in Neanderthals. [44]

0.8–0.3 Ma
Reconstruction of Homo heidelbergensis Homo heidelbergensis - forensic facial reconstruction-crop.png
Reconstruction of Homo heidelbergensis

Divergence of Neanderthal and Denisovan lineages from a common ancestor. [45] Homo heidelbergensis (in Africa also known as Homo rhodesiensis ) had long been thought to be a likely candidate for the last common ancestor of the Neanderthal and modern human lineages. However, genetic evidence from the Sima de los Huesos fossils published in 2016 seems to suggest that H. heidelbergensis in its entirety should be included in the Neanderthal lineage, as "pre-Neanderthal" or "early Neanderthal", while the divergence time between the Neanderthal and modern lineages has been pushed back to before the emergence of H. heidelbergensis, to about 600,000 to 800,000 years ago, the approximate age of Homo antecessor . [46] [47] Brain expansion (enlargement) between 0.8 and 0.2 Ma may have occurred due to the extinction of most African megafauna (which made humans feed from smaller prey and plants, which required greater intelligence due to greater speed of the former and uncertainty about whether the latter were poisonous or not), extreme climate variability after Mid-Pleistocene Transition (which intensified the situation, and resulted in frequent migrations), and in general selection for more social life (and intelligence) for greater chance of survival, reproductivity, and care for mothers. Solidified footprints dated to about 350 ka and associated with H. heidelbergensis were found in southern Italy in 2003. [48]

H. sapiens lost the brow ridges from their hominid ancestors as well as the snout completely, though their noses evolve to be protruding (possibly from the time of H. erectus). By 200 ka, humans had stopped their brain expansion.

Homo sapiens

300–130 ka
Reconstruction of early Homo sapiens from Jebel Irhoud, Morocco c. 315 000 years BP Homo sapiens sapiens (Fundort Jebel Irhoud Marokko).jpg
Reconstruction of early Homo sapiens from Jebel Irhoud, Morocco c.315 000 years BP

Neanderthals and Denisovans emerge from the northern Homo heidelbergensis lineage around 500-450 ka while Sapients emerge from the southern lineage around 350-300 ka. [49]

Fossils attributed to H. sapiens, along with stone tools, dated to approximately 300,000 years ago, found at Jebel Irhoud, Morocco [50] yield the earliest fossil evidence for anatomically modern Homo sapiens . Modern human presence in East Africa (Gademotta), at 276 kya. [51] In July 2019, anthropologists reported the discovery of 210,000 year old remains of a H. sapiens in Apidima Cave, Peloponnese, Greece. [52] [53] [54]

Patrilineal and matrilineal most recent common ancestors (MRCAs) of living humans roughly between 200 and 100 kya [55] [56] with some estimates on the patrilineal MRCA somewhat higher, ranging up to 250 to 500 kya. [57]

160,000 years ago, Homo sapiens idaltu in the Awash River Valley (near present-day Herto village, Ethiopia) practiced excarnation. [58]

130–80 ka Marine Isotope Stage 5 (Eemian).

Modern human presence in Southern Africa and West Africa. [59] Appearance of mitochondrial haplogroup (mt-haplogroup) L2.

80–50 ka MIS 4, beginning of the Upper Paleolithic.

Early evidence for behavioral modernity. [60] Appearance of mt-haplogroups M and N. Southern Dispersal migration out of Africa, Proto-Australoid peopling of Oceania. [61] Archaic admixture from Neanderthals in Eurasia, [62] [63] from Denisovans in Oceania with trace amounts in Eastern Eurasia, [64] and from an unspecified African lineage of archaic humans in Sub-Saharan Africa as well as an interbred species of Neanderthals and Denisovans in Asia and Oceania. [65] [66] [67] [68]

50–25 ka
Reconstruction of Oase 2 (c. 40 ka) Homo sapiens sapiens, Oase, Rumanien (Daniela Hitzemann).jpg
Reconstruction of Oase 2 (c. 40 ka)

Behavioral modernity develops by this time or earlier, according to the "great leap forward" theory. [69] Extinction of Homo floresiensis . [70] M168 mutation (carried by all non-African males). Appearance of mt-haplogroups U and K. Peopling of Europe, peopling of the North Asian Mammoth steppe. Paleolithic art. Extinction of Neanderthals and other archaic human variants (with possible survival of hybrid populations in Asia and Africa.) Appearance of Y-Haplogroup R2; mt-haplogroups J and X.

after 25 ka
Reconstruction of a Neolithic farmer from Europe, Science Museum in Trento Homo sapiens - Neolithic - reconstruction - MUSE.jpg
Reconstruction of a Neolithic farmer from Europe, Science Museum in Trento

Last Glacial Maximum; Epipaleolithic / Mesolithic / Holocene. Peopling of the Americas. Appearance of: Y-Haplogroup R1a; mt-haplogroups V and T. Various recent divergence associated with environmental pressures, e.g. light skin in Europeans and East Asians (KITLG, ASIP), after 30 ka; [71] Inuit adaptation to high-fat diet and cold climate, 20 ka. [72]

Extinction of late surviving archaic humans at the beginning of the Holocene (12 ka). Accelerated divergence due to selection pressures in populations participating in the Neolithic Revolution after 12 ka, e.g. East Asian types of ADH1B associated with rice domestication, [73] or lactase persistence. [74] [75] A slight decrease in brain size occurred a few thousand years ago.

See also

Related Research Articles

<span class="mw-page-title-main">Human evolution</span> Evolutionary process leading to anatomically modern humans

Human evolution is the evolutionary process within the history of primates that led to the emergence of Homo sapiens as a distinct species of the hominid family, which includes all the great apes. This process involved the gradual development of traits such as human bipedalism, dexterity and complex language, as well as interbreeding with other hominins, indicating that human evolution was not linear but weblike. The study of human evolution involves several scientific disciplines, including physical and evolutionary anthropology, paleontology, and genetics.

<span class="mw-page-title-main">Homininae</span> Subfamily of mammals

Homininae, also called "African hominids" or "African apes", is a subfamily of Hominidae. It includes two tribes, with their extant as well as extinct species: 1) the tribe Hominini ―and 2) the tribe Gorillini (gorillas). Alternatively, the genus Pan is sometimes considered to belong to its own third tribe, Panini. Homininae comprises all hominids that arose after orangutans split from the line of great apes. The Homininae cladogram has three main branches, which lead to gorillas, and to humans and chimpanzees via the tribe Hominini and subtribes Hominina and Panina. There are two living species of Panina and two living species of gorillas, but only one extant human species. Traces of extinct Homo species, including Homo floresiensis have been found with dates as recent as 40,000 years ago. Organisms in this subfamily are described as hominine or hominines.

<span class="mw-page-title-main">Early modern human</span> Old Stone Age Homo sapiens

Early modern human (EMH) or anatomically modern human (AMH) are terms used to distinguish Homo sapiens that are anatomically consistent with the range of phenotypes seen in contemporary humans, from extinct archaic human species. This distinction is useful especially for times and regions where anatomically modern and archaic humans co-existed, for example, in Paleolithic Europe. Among the oldest known remains of Homo sapiens are those found at the Omo-Kibish I archaeological site in south-western Ethiopia, dating to about 233,000 to 196,000 years ago, the Florisbad site in South Africa, dating to about 259,000 years ago, and the Jebel Irhoud site in Morocco, dated about 315,000 years ago.

<i>Homo</i> Genus of hominins that includes humans and their closest extinct relatives

Homo is the genus that emerged from the genus Australopithecus and encompasses the extant species Homo sapiens and several extinct species classified as either ancestral to or closely related to modern humans, including Homo erectus and Homo neanderthalensis. The oldest member of the genus is Homo habilis, with records of just over 2 million years ago. Homo, together with the genus Paranthropus, is probably sister to Australopithecus africanus, which itself had split from the lineage of Pan, the chimpanzees.

<span class="mw-page-title-main">Neanderthal extinction</span> Prehistoric event

Neanderthals became extinct around 40,000 years ago. Hypotheses on the causes of the extinction include violence, transmission of diseases from modern humans which Neanderthals had no immunity to, competitive replacement, extinction by interbreeding with early modern human populations, natural catastrophes, climate change and inbreeding depression. It is likely that multiple factors caused the demise of an already low population.

<span class="mw-page-title-main">Paleogenetics</span>

Paleogenetics is the study of the past through the examination of preserved genetic material from the remains of ancient organisms. Emile Zuckerkandl and Linus Pauling introduced the term in 1963, long before the sequencing of DNA, in reference to the possible reconstruction of the corresponding polypeptide sequences of past organisms. The first sequence of ancient DNA, isolated from a museum specimen of the extinct quagga, was published in 1984 by a team led by Allan Wilson.

Human taxonomy is the classification of the human species within zoological taxonomy. The systematic genus, Homo, is designed to include both anatomically modern humans and extinct varieties of archaic humans. Current humans have been designated as subspecies Homo sapiens sapiens, differentiated, according to some, from the direct ancestor, Homo sapiens idaltu.

<span class="mw-page-title-main">Archaic humans</span> Extinct relatives of modern humans

A number of varieties of Homo are grouped into the broad category of archaic humans in the period that precedes and is contemporary to the emergence of the earliest early modern humans around 300 ka. Among the earliest remains of H. sapiens are Omo-Kibish I from southern Ethiopia, the remains from Jebel Irhoud in Morocco and Florisbad in South Africa (259 ka). The term typically includes H. antecessor, H. bodoensis, Denisovans (H. denisova), H. heidelbergensis (600–200 ka), Neanderthals, and H. rhodesiensis (300–125 ka).

Human evolutionary genetics studies how one human genome differs from another human genome, the evolutionary past that gave rise to the human genome, and its current effects. Differences between genomes have anthropological, medical, historical and forensic implications and applications. Genetic data can provide important insights into human evolution.

The Neanderthal genome project is an effort of a group of scientists to sequence the Neanderthal genome, founded in July 2006.

<span class="mw-page-title-main">Early human migrations</span> Spread of humans from Africa through the world

Early human migrations are the earliest migrations and expansions of archaic and modern humans across continents. They are believed to have begun approximately 2 million years ago with the early expansions out of Africa by Homo erectus. 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 Denisovans and Neanderthals as well as modern humans. Early hominids had likely crossed land bridges that have now sunk.

<span class="mw-page-title-main">Evolution of the brain</span> Overview of the evolution of the brain

There is much to be discovered about the evolution of the brain and the principles that govern it. While much has been discovered, not everything currently known is well understood. The evolution of the brain has appeared to exhibit diverging adaptations within taxonomic classes such as Mammalia and more vastly diverse adaptations across other taxonomic classes. Brain to body size scales allometrically. This means as body size changes, so do other physiological, anatomical, and biochemical constructs connecting the brain to the body. Small bodied mammals have relatively large brains compared to their bodies whereas large mammals have a smaller brain to body ratios. If brain weight is plotted against body weight for primates, the regression line of the sample points can indicate the brain power of a primate species. Lemurs for example fall below this line which means that for a primate of equivalent size, we would expect a larger brain size. Humans lie well above the line indicating that humans are more encephalized than lemurs. In fact, humans are more encephalized compared to all other primates. This means that human brains have exhibited a larger evolutionary increase in its complexity relative to its size. Some of these evolutionary changes have been found to be linked to multiple genetic factors, such as proteins and other organelles.

The chimpanzee–human last common ancestor (CHLCA) is the last common ancestor shared by the extant Homo (human) and Pan genera of Hominini. Estimates of the divergence date vary widely from thirteen to five million years ago.

<span class="mw-page-title-main">Recent African origin of modern humans</span> "Out of Africa" theory of the early migration of humans

In paleoanthropology, the recent African origin of modern humans or the "Out of Africa" theory (OOA) is the most widely accepted model of the geographic origin and early migration of anatomically modern humans. It follows the early expansions of hominins out of Africa, accomplished by Homo erectus and then Homo neanderthalensis.

The multiregional hypothesis, multiregional evolution (MRE), or polycentric hypothesis, is a scientific model that provides an alternative explanation to the more widely accepted "Out of Africa" model of monogenesis for the pattern of human evolution.

<span class="mw-page-title-main">Denisovan</span> Asian archaic human

The Denisovans or Denisova hominins(di-NEE-sə-və) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. Denisovans are known from few physical remains; consequently, most of what is known about them comes from DNA evidence. No formal species name has been established pending more complete fossil material.

<span class="mw-page-title-main">Neanderthal</span> Extinct Eurasian species or subspecies of archaic humans

Neanderthals, also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. The reasons for Neanderthal extinction are disputed. Theories for their extinction include demographic factors such as small population size and inbreeding, competitive replacement, interbreeding and assimilation with modern humans, climate change, disease, or a combination of these factors.

<span class="mw-page-title-main">Molecular paleontology</span>

Molecular paleontology refers to the recovery and analysis of DNA, proteins, carbohydrates, or lipids, and their diagenetic products from ancient human, animal, and plant remains. The field of molecular paleontology has yielded important insights into evolutionary events, species' diasporas, the discovery and characterization of extinct species. loo In shallow time, advancements in the field of molecular paleontology have allowed scientists to pursue evolutionary questions on a genetic level rather than relying on phenotypic variation alone. By applying molecular analytical techniques to DNA in Recent animal remains, one can quantify the level of relatedness between any two organisms for which DNA has been recovered. Using various biotechnological techniques such as DNA isolation, amplification, and sequencing scientists have been able to gain expanded new insights into the divergence and evolutionary history of countless recently extinct organisms. In February 2021, scientists reported, for the first time, the sequencing of DNA from animal remains, a mammoth in this instance, over a million years old, the oldest DNA sequenced to date.

Genetic studies on Neanderthal ancient DNA became possible in the late 1990s. The Neanderthal genome project, established in 2006, presented the first fully sequenced Neanderthal genome in 2013.


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