Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Homo is the genus which emerged in the otherwise extinct Australopithecus genus that encompasses the extant species Homo sapiens, plus several extinct species classified as either ancestral to or related to modern humans, most notably Homo erectus and Homo neanderthalensis. The genus is taken to emerge with the appearance of Homo habilis, just over two million years ago. Genus Homo, together with the genus Paranthropus is sister to A. africanus in the genus Australopithecus, which itself had split from the lineage of Pan, the chimpanzees. Homo erectus appeared about two million years ago and, in several early migrations, it spread throughout Africa and Eurasia, it was the first human species to live in a hunter-gatherer society and to control fire. An adaptive and successful species, Homo erectus persisted for more than a million years, diverged into new species by around 500,000 years ago. Homo sapiens emerges close to 300,000 to 200,000 years ago, most in Africa, Homo neanderthalensis emerged at around the same time in Europe and Western Asia.
H. sapiens dispersed from Africa in several waves, from as early as 250,000 years ago, by 130,000 years ago, the so-called Southern Dispersal beginning about 70,000 years ago leading to the lasting colonisation of Eurasia and Oceania by 50,000 years ago. Both in Africa and Eurasia, H. sapiens interbred with archaic humans. Separate archaic human species are thought to have survived until around 40,000 years ago, with possible late survival of hybrid species as late as 12,000 years ago. See Homininae for an overview of taxonomy; the Latin noun homō means "human being" or "man" in the generic sense of "human being, mankind". The binomial name Homo sapiens was coined by Carl Linnaeus. Names for other species of the genus were introduced beginning in the second half of the 19th century. Today, the genus Homo has not been properly defined. Since the early human fossil record began to emerge from the earth, the boundaries and definitions of the genus Homo have been poorly defined and in flux; because there was no reason to think it would have any additional members, Carl Linnaeus did not bother to define Homo when he first created it for humans in the 18th century.
The discovery of Neanderthal brought the first addition. The genus Homo was given its taxonomic name to suggest that its member species can be classified as human. And, over the decades of the 20th century, fossil finds of pre-human and early human species from late Miocene and early Pliocene times produced a rich mix for debating classifications. There is continuing debate on delineating Homo from Australopithecus—or, delineating Homo from Pan, as one body of scientists argue that the two species of chimpanzee should be classed with genus Homo rather than Pan. So, classifying the fossils of Homo coincides with evidence of: 1) competent human bipedalism in Homo habilis inherited from the earlier Australopithecus of more than four million years ago, as demonstrated by the Laetoli footprints. From the late-19th to mid-20th centuries, a number of new taxonomic names including new generic names were proposed for early human fossils. Many such names are now dubbed as "synonyms" with Homo, including Pithecanthropus,Protanthropus,Sinanthropus,Cyphanthropus,Africanthropus,Telanthropus,Atlanthropus, Tchadanthropus.
Classifying the genus Homo into species and subspecies is subject to incomplete information and remains poorly done. This has led to using common names in scientific papers to avoid trinomial names or the ambiguity of classifying groups as incertae sedis —for example, H. neanderthalensis vs. H. sapiens neanderthalensis, or H. georgicus vs. H. erectus georgicus. Some extinct species in the genus Homo are only discovered and do not as yet have consensus binomial names. Since the beginning of the Holocene, it is that Homo sapiens has been the only extant species of Homo. John Edward Gray was an early advocate of classifying taxa by designating families. Wood and Richmond proposed that Hominini be designated as a tribe that comprised all species of early humans and pre-humans ancestral to humans back to after the chimpanzee-human last common ancestor. Designations alternative to Hominina existed, or were offered: Australopithecinae and Preanthropinae. See Hominini and Chimpanzee–human last common ancestor for the separation of Australopithecina and Panina.
Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, Australopithecus afarensis, have been proposed as the direct ancestor of the Homo lineage. These species have morphological features that align them with Homo
Sahelanthropus tchadensis is an extinct species of the Hominini and is the ancestor to Orrorin, dated to about 7 million years ago, during the Miocene epoch very close to the time of the chimpanzee–human divergence. Few specimens other than the partial skull, nicknamed Toumaï, are known. Existing fossils include a small cranium named Toumaï, five pieces of jaw, some teeth, making up a head that has a mixture of derived and primitive features; the braincase, being only 320 cm3 to 380 cm3 in volume, is similar to that of extant chimpanzees and is notably less than the approximate human volume of 1350 cm3. The teeth, brow ridges, facial structure differ markedly from those found in Homo sapiens. Cranial features show a flatter face, u-shaped dental arcade, small canines, an anterior foramen magnum, heavy brow ridges. No postcranial remains have been recovered; the only known skull suffered a large amount of distortion during the time of fossilisation and discovery, as the cranium is dorsoventrally flattened, the right side is depressed.
Sahelanthropus tchadensis may have walked on two legs. However, because no postcranial remains have been discovered, it is not known definitively whether Sahelanthropus was indeed bipedal, although claims for an anteriorly placed foramen magnum suggests that this may have been the case. Upon examination of the foramen magnum in the primary study, the lead author speculated that a bipedal gait "would not be unreasonable" based on basicranial morphology similar to more recent hominins; some palaeontologists have disputed this interpretation, stating that the basicranium, as well as dentition and facial features, do not represent adaptations unique to the hominin clade, nor indicative of bipedalism. Further, according to recent information, what might be a femur of a hominid was discovered near the cranium—but which has not been published nor accounted for. Fifteen years after the discovery of the fossil, the anthropologist Roberto Macchiarelli—professor at the University of Poitiers and the Museum of Natural History of Paris—suspects Michel Brunet and his laboratory in Poitiers of blocking information about a femur found close to the skull.
That the laboratory would have delayed identification may question the bipedalism of Toumaï. The fossils were discovered in the Djurab Desert of Chad by a team of four led by a Frenchman, Alain Beauvilain, three Chadians, Adoum Mahamat, Djimdoumalbaye Ahounta, Gongdibé Fanoné, members of the Mission paleoanthropologique Franco-tchadienne led by Michel Brunet. All known material of Sahelanthropus was found between July 2001 and March 2002 at three sites: TM 247, TM 266, which yielded most of the material, including a cranium and a femur, TM 292; the discoverers claimed that S. tchadensis is the oldest-known human ancestor after the split of the human line from that of chimpanzees. The bones were found far from most previous hominin fossil finds, which are from Eastern and Southern Africa. However, an Australopithecus bahrelghazali mandible was found in Chad by Mamelbaye Tomalta and Alain Beauvilain, Michel Brunet and Aladji H. E. Moutaye as early as 1995. With the sexual dimorphism known to have existed in early hominins, the difference between Ardipithecus and Sahelanthropus may not be large enough to warrant a separate species for the latter.
Sahelanthropus may represent a common ancestor of humans and chimpanzees, though no consensus has been reached yet by the scientific community. The original placement of this species as a human ancestor but not a chimpanzee ancestor would complicate the picture of human phylogeny. In particular, if Toumaï is indeed a direct human ancestor its facial features bring into doubt the status of Australopithecus whose thickened brow ridges were reported to be similar to those of some fossil hominins, where the brow ridge morphology of Sahelanthropus differs from that observed in all australopithecines, most fossil hominins and extant humans. Another possibility is that Toumaï is related to both humans and chimpanzees, but is the ancestor of neither. Brigitte Senut and Martin Pickford, the discoverers of Orrorin tugenensis, suggested that the features of S. tchadensis are consistent with a female proto-gorilla. If this claim is upheld the find would lose none of its significance, because at present few chimpanzee or gorilla ancestors have been found anywhere in Africa.
Thus if S. tchadensis is an ancestral relative of the chimpanzees or gorillas it represents the earliest known member of their lineage. And S. tchadensis does indicate that the last common ancestor of humans and chimpanzees is unlikely to resemble extant chimpanzees, as had been supposed by some paleontologists. A further possibility, highlighted by research published in 2012, is that the human–chimpanzee split is earlier than thought, with a possible range of 7 to 13 million years ago, based on slower than thought changes between generations in human DNA. Indeed, some researchers consider suggestions that Sahelanthropus is too early to be a human ancestor to have evaporated. Sediment isotope analysis of cosmogenic atoms in the fossil yielded an age of about 7 million years. In this case, the fossils were found exposed in loose sand. In fact, Toumaï may have been reburied in the r
Timeline of human evolution
The timeline of human evolution outlines the major events in the development of the human species, Homo sapiens, the evolution of the human's ancestors. It includes brief explanations of some of the species and the higher ranks of taxa that are seen today as possible ancestors of modern humans; this timeline is based on studies from anthropology, developmental biology and from anatomical and genetic data. It does not address the origin of life; that discussion is provided by abiogenesis, but presents one possible line of evolutionary descent of species that led to humans. One of several possible lines of descent, or taxonomic ranking, of Homo sapiens is shown below. Palaeos Hominid Timeline Berkeley Evolution History of Animal Evolution Tree of Life Web Project – explore complete phylogenetic tree interactively Human Timeline – Smithsonian, National Museum of Natural History
The Stone Age was a broad prehistoric period during which stone was used to make implements with an edge, a point, or a percussion surface. The period lasted 3.4 million years and ended between 8700 BCE and 2000 BCE with the advent of metalworking. Stone Age artifacts include tools used by modern humans and by their predecessor species in the genus Homo, by the earlier contemporaneous genera Australopithecus and Paranthropus. Bone tools were used during this period as well but are preserved in the archaeological record; the Stone Age is further subdivided by the types of stone tools in use. The Stone Age is the first period in the three-age system of archaeology, which divides human technological prehistory into three periods: The Stone Age The Bronze Age The Iron Age The Stone Age is contemporaneous with the evolution of the genus Homo, the only exception being the early Stone Age, when species prior to Homo may have manufactured tools. According to the age and location of the current evidence, the cradle of the genus is the East African Rift System toward the north in Ethiopia, where it is bordered by grasslands.
The closest relative among the other living primates, the genus Pan, represents a branch that continued on in the deep forest, where the primates evolved. The rift served as a conduit for movement into southern Africa and north down the Nile into North Africa and through the continuation of the rift in the Levant to the vast grasslands of Asia. Starting from about 4 million years ago a single biome established itself from South Africa through the rift, North Africa, across Asia to modern China, called "transcontinental'savannahstan'" recently. Starting in the grasslands of the rift, Homo erectus, the predecessor of modern humans, found an ecological niche as a tool-maker and developed a dependence on it, becoming a "tool equipped savanna dweller"; the oldest indirect evidence found of stone tool use is fossilised animal bones with tool marks. Archaeological discoveries in Kenya in 2015, identifying the oldest known evidence of hominin use of tools to date, have indicated that Kenyanthropus platyops may have been the earliest tool-users known.
The oldest stone tools were excavated from the site of Lomekwi 3 in West Turkana, northwestern Kenya, date to 3.3 million years old. Prior to the discovery of these "Lomekwian" tools, the oldest known stone tools had been found at several sites at Gona, Ethiopia, on the sediments of the paleo-Awash River, which serve to date them. All the tools come from the Busidama Formation, which lies above a disconformity, or missing layer, which would have been from 2.9 to 2.7 mya. The oldest sites containing tools are dated to 2.6–2.55 mya. One of the most striking circumstances about these sites is that they are from the Late Pliocene, where previous to their discovery tools were thought to have evolved only in the Pleistocene. Excavators at the locality point out that: "...the earliest stone tool makers were skilled flintknappers.... The possible reasons behind this seeming abrupt transition from the absence of stone tools to the presence thereof include... gaps in the geological record."The species who made the Pliocene tools remains unknown.
Fragments of Australopithecus garhi, Australopithecus aethiopicus and Homo Homo habilis, have been found in sites near the age of the Gona tools. In July 2018, scientists reported the discovery in China of the oldest stone tools outside Africa, estimated at 2.12 million years old. Innovation of the technique of smelting ore began the Bronze Age; the first most significant metal manufactured was bronze, an alloy of copper and tin, each of, smelted separately. The transition from the Stone Age to the Bronze Age was a period during which modern people could smelt copper, but did not yet manufacture bronze, a time known as the Copper Age, or more technically the Chalcolithic, "copper-stone" age; the Chalcolithic by convention is the initial period of the Bronze Age. The Bronze Age was followed by the Iron Age; the transition out of the Stone Age occurred between 6000 BCE and 2500 BCE for much of humanity living in North Africa and Eurasia. The first evidence of human metallurgy dates to between the 5th and 6th millennium BCE in the archaeological sites of Majdanpek and Pločnik in modern-day Serbia, though not conventionally considered part of the Chalcolithic or "Copper Age", this provides the earliest known example of copper metallurgy.
Note the Rudna Glava mine in Serbia. Ötzi the Iceman, a mummy from about 3300 BCE carried with him a flint knife. In regions such as Sub-Saharan Africa, the Stone Age was followed directly by the Iron Age; the Middle East and southeastern Asian regions progressed past Stone Age technology around 6000 BCE. Europe, the rest of Asia became post-Stone Age societies by about 4000 BCE; the proto-Inca cultures of South America continued at a Stone Age level until around 2000 BCE, when gold and silver made their entrance. The Americas notably did not develop a widespread behavior of smelting Bronze or Iron after the Stone Age period, although the technology existed. Stone tool manufacture continued after the Stone Age ended in a given area. In Europe and North America, millstones were in use until well into the 20th century, still are in many parts of the world; the terms "Stone Age", "Bronze Age", "Iron Age" were never meant to suggest that advancement and time periods in prehistory are only measured by the type of tool material, rather than, for
Clothing is a collective term for items worn on the body. Clothing can be made of animal skin, or other thin sheets of materials put together; the wearing of clothing is restricted to human beings and is a feature of all human societies. The amount and type of clothing worn depend on body type and geographic considerations; some clothing can be gender-specific. Physically, clothing serves many purposes: it can serve as protection from the elements and can enhance safety during hazardous activities such as hiking and cooking, it protects the wearer from rough surfaces, rash-causing plants, insect bites, splinters and prickles by providing a barrier between the skin and the environment. Clothes can insulate against cold or hot conditions, they can provide a hygienic barrier, keeping infectious and toxic materials away from the body. Clothing provides protection from ultraviolet radiation. Wearing clothes is a social norm, being deprived of clothing in front of others may be embarrassing, or not wearing clothes in public such that genitals, breasts or buttocks are visible could be seen as indecent exposure.
There is no easy way to determine when clothing was first developed, but some information has been inferred by studying lice which estimates the introduction of clothing at 42,000–72,000 years ago. The most obvious function of clothing is to improve the comfort of the wearer, by protecting the wearer from the elements. In hot climates, clothing provides protection from sunburn or wind damage, while in cold climates its thermal insulation properties are more important. Shelter reduces the functional need for clothing. For example, hats and other outer layers are removed when entering a warm home if one is living or sleeping there. Clothing has seasonal and regional aspects, so that thinner materials and fewer layers of clothing are worn in warmer regions and seasons than in colder ones. Clothing performs a range of social and cultural functions, such as individual and gender differentiation, social status. In many societies, norms about clothing reflect standards of modesty, religion and social status.
Clothing may function as a form of adornment and an expression of personal taste or style. Clothing can be and has in the past been made from a wide variety of materials. Materials have ranged from leather and furs to woven materials, to elaborate and exotic natural and synthetic fabrics. Not all body coverings are regarded as clothing. Articles carried rather than worn, worn on a single part of the body and removed, worn purely for adornment, or those that serve a function other than protection, are considered accessories rather than clothing, except for shoes. Clothing protects against many things. Clothes protect people from the elements, including rain, snow and other weather, as well as from the sun. However, clothing, too sheer, small, etc. offers less protection. Appropriate clothes can reduce risk during activities such as work or sport; some clothing protects from specific hazards, such as insects, noxious chemicals, weather and contact with abrasive substances. Conversely, clothing may protect the environment from the clothing wearer: for instance doctors wear medical scrubs.
Humans have been ingenious in devising clothing solutions to environmental or other hazards: such as space suits, air conditioned clothing, diving suits, bee-keeper gear, motorcycle leathers, high-visibility clothing, other pieces of protective clothing. Meanwhile, the distinction between clothing and protective equipment is not always clear-cut, since clothes designed to be fashionable have protective value and clothes designed for function consider fashion in their design; the choice of clothes has social implications. They cover parts of the body that social norms require to be covered, act as a form of adornment, serve other social purposes. Someone who lacks the means to procure reasonable clothing due to poverty or affordability, or lack of inclination, is sometimes said to be scruffy, ragged, or shabby. Serious books on clothing and its functions appear from the 19th century as imperialists dealt with new environments such as India and the tropics; some scientific research into the multiple functions of clothing in the first half of the 20th century, with publications such as J.
C. Flügel's Psychology of Clothes in 1930, Newburgh's seminal Physiology of Heat Regulation and The Science of Clothing in 1949. By 1968, the field of environmental physiology had advanced and expanded but the science of clothing in relation to environmental physiology had changed little. There has since been considerable research, the knowledge base has grown but the main concepts remain unchanged, indeed Newburgh's book is still cited by contemporary authors, including those attempting to develop thermoregulatory models of clothing development. In most cultures, gender differentiation of clothing is considered appropriate; the differences are in styles and fabrics. In Western societies, skirts and high-heeled shoes are seen as women's clothing, while neckties are seen as men's clothing. Trousers were once seen as male clothing, but can nowadays be worn by both genders. Male clothes are more practical, but a wider range of clothing styles are available for females. Males are allowed to bare their chests in a greater variety of public places.
In taxonomy, Homo sapiens is the only extant human species. The name was introduced in 1758 by Carl Linnaeus. Extinct species of the genus Homo include Homo erectus, extant during 1.9 to 0.4 million years ago, a number of other species. The age of speciation of H. sapiens out of ancestral H. erectus is estimated to have been 350,000 years ago. Sustained archaic admixture is known to have taken place both in Africa and in Eurasia, between about 100,000 and 30,000 years ago; the term anatomically modern humans is used to distinguish H. sapiens having an anatomy consistent with the range of phenotypes seen in contemporary humans from varieties of extinct archaic humans. This is useful for times and regions where anatomically modern and archaic humans co-existed, for example, in Paleolithic Europe; the binomial name Homo sapiens was coined by Linnaeus, 1758. The Latin noun homō means "human being", while the participle sapiēns means "discerning, sensible"; the species was thought to have emerged from a predecessor within the genus Homo around 300,000 to 200,000 years ago.
A problem with the morphological classification of "anatomically modern" was that it would not have included certain extant populations. For this reason, a lineage-based definition of H. sapiens has been suggested, in which H. sapiens would by definition refer to the modern human lineage following the split from the Neanderthal lineage. Such a cladistic definition would extend the age of H. sapiens to over 500,000 years. Extant human populations have been divided into subspecies, but since around the 1980s all extant groups have tended to be subsumed into a single species, H. sapiens, avoiding division into subspecies altogether. Some sources show Neanderthals as a subspecies; the discovered specimens of the H. rhodesiensis species have been classified by some as a subspecies, although it remains more common to treat these last two as separate species within the genus Homo rather than as subspecies within H. sapiens. The subspecies name H. sapiens sapiens is sometimes used informally instead of "modern humans" or "anatomically modern humans".
It has no formal authority associated with it. By the early 2000s, it had become common to use H. s. sapiens for the ancestral population of all contemporary humans, as such it is equivalent to the binomial H. sapiens in the more restrictive sense. The speciation of H. sapiens out of archaic human varieties derived from H. erectus is estimated as having taken place over 350,000 years ago, as the Khoisan split from other populations is dated between 260,000 and 350,000 years ago. An alternative suggestion defines H. sapiens cladistically as including the lineage of modern humans since the split from the lineage of Neanderthals 500,000 to 800,000 years ago. The time of divergence between archaic H. sapiens and ancestors of Neanderthals and Denisovans caused by a genetic bottleneck of the latter was dated at 744,000 years ago, combined with repeated early admixture events and Denisovans diverging from Neanderthals 300 generations after their split from H. sapiens, as calculated by Rogers et al..
The derivation of a comparatively homogeneous single species of H. sapiens from more diverse varieties of archaic humans was debated in terms of two competing models during the 1980s: "recent African origin" postulated the emergence of H. sapiens from a single source population in Africa, which expanded and led to the extinction of all other human varieties, while the "multiregional evolution" model postulated the survival of regional forms of archaic humans converging into the modern human varieties by the mechanism of clinal variation, via genetic drift, gene flow and selection throughout the Pleistocene. Since the 2000s, the availability of data from archaeogenetics and population genetics has led to the emergence of a much more detailed picture, intermediate between the two competing scenarios outlined above: The recent Out-of-Africa expansion accounts for the predominant part of modern human ancestry, while there were significant admixture events with regional archaic humans. Since the 1970s, the Omo remains, dated to some 195,000 years ago, have been taken as the conventional cut-off point for the emergence of "anatomically modern humans".
Since the 2000s, the discovery of older remains with comparable characteristics, the discovery of ongoing hybridization between "modern" and "archaic" populations after the time of the Omo remains, have opened up a renewed debate on the "age of H. sapiens", in journalistic publications cast into terms of "H. sapiens may be older than thought". H. s. idaltu, dated to 160,000 years ago, has been postulated as an extinct subspecies of H. sapiens in 2003. H. Neanderthalensis, which became extinct about 40,000 years ago, has been classified as a subspecies, H. s. neanderthalensis. H. heidelbergensis, dated 600,000 to 300,000 years ago, has long been thought to be a 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