Homo habilis (pronounced /?ho?mo? ?hæb?l?s/) ("handy man", "skillful person") is a species of the genus Homo, which lived from approximately 2.5 million to at least 1.6 million years ago at the beginning of the Pleistocene. The definition of this species is credited to both Mary and Louis Leakey, who found fossils in Tanzania, East Africa, between 1962 and 1964. Homo habilis is arguably the first species of the Homo genus to appear. In its appearance and morphology, H. habilis was the least similar to modern humans of all species to be placed in the genus Homo (except possibly Homo rudolfensis). Homo habilis was short and had disproportionately long arms compared to modern humans; however, it had a reduction in the protrusion in the face. It is thought to have descended from a species of australopithecine hominid. Its immediate ancestor may have been the more massive and ape-like Homo rudolfensis. Homo habilis had a cranial capacity slightly less than half of the size of modern humans. Despite the ape-like morphology of the bodies, H. habilis remains are often accompanied by primitive stone tools (e.g. Olduvai Gorge, Tanzania and Lake Turkana, Kenya).

Homo habilis has often been thought to be the ancestor of the lankier and more sophisticated Homo ergaster, which in turn gave rise to the more human-appearing species, Homo erectus. Debates continue over whether H. habilis is a direct human ancestor, and whether all of the known fossils are properly attributed to the species. However, in 2007, new findings suggest that the two species coexisted and may be separate lineages from a common ancestor instead of H. erectus being descended from H. habilis

Homo georgicus is a species of hominin that was suggested in 2002 to describe fossil skulls and jaws found in Dmanisi, Georgia in 1999 and 2001, which seem intermediate between Homo habilis and H. erectus. A partial skeleton was discovered in 2001. The fossils are about 1.8 million years old. The remains were first discovered in 1991 by Georgian scientist, David Lordkipanidze, accompanied by an international team which unearthed the hominin remains. Implements and animal bones were found alongside the ancient hominin remains.

At first, scientists thought they had found mandibles and skulls belonging to Homo ergaster, but size differences led them to consider erecting a new species, Homo georgicus, which would be the descendant of Homo habilis and ancestor of Asian Homo erectus.

Homo erectus (Latin: upright man) is an extinct species of the genus Homo, believed to have been the first hominin to leave Africa.

H. erectus originally migrated from Africa during the Early Pleistocene, possibly as a result of the operation of the Saharan pump, around 2.0 million years ago, and dispersed throughout most of the Old World. Fossilized remains 1.8 and 1.0 million years old have been found in Africa (e.g., Lake Turkana[1] and Olduvai Gorge), Europe (Georgia, Spain), Indonesia (e.g., Sangiran and Trinil), Vietnam, and China (e.g., Shaanxi).

Homo heidelbergensis ("Heidelberg Man") is an extinct species of the genus Homo which may be the direct ancestor of Homo neanderthalensis in Europe. The best evidence found for these hominins date between 600,000 and 400,000 years ago. H. heidelbergensis stone tool technology was considerably close to that of the Acheulean tools used by Homo erectus.

The Neanderthal (IPA: /ne??ænd?rt??l/, also with /ni?-/ and /-???l/), or Neandertal, is an extinct member of the Homo genus that is known from Pleistocene specimens found in Europe and parts of western and central Asia. Neanderthals are either classified as a subspecies of humans (Homo sapiens neanderthalensis) or as a separate species (Homo neanderthalensis). The first proto-Neanderthal traits appeared in Europe as early as 600,000–350,000 years ago. Proto-Neanderthal traits are occasionally grouped to another cladistic 'species', Homo heidelbergensis, or a migrant form, Homo rhodesiensis. By 130,000 years ago, complete Neanderthal characteristics had appeared. These characteristics then disappeared in Asia by 50,000 years ago and in Europe by 30,000 years ago. The youngest Neanderthal finds include Hyaena Den (UK), considered older than 30,000 years ago, while the Vindija (Croatia) Neanderthals have been re-dated to between 32,000 and 33,000 years ago. No definite specimens younger than 30,000 years ago have been found; however, evidence of fire by Neanderthals at Gibraltar indicate that they may have survived there until 24,000 years ago. Modern human skeletal remains with 'Neanderthal traits' were found in Lagar Velho (Portugal), dated to 24,500 years ago and interpreted as indications of extensively admixed populations.

Neanderthal stone tools provide further evidence for their presence where skeletal remains have not been found. The last traces of Mousterian culture, a type of stone tools associated with Neanderthals, were found in Gorham's Cave on the remote south-facing coast of Gibraltar. Other tool cultures sometimes associated with Neanderthal include Châtelperronian, Aurignacian, and Gravettian, with the latter extending to 22,000 years ago, the last indication of Neanderthal presence.

Neanderthal cranial capacity is often thought to have been as large or larger than modern humans, indicating that their brain size may have been the same or greater; however, a 1993 analysis of 118 hominid crania concluded that the cranial capacity of H.s. neandertal averaged 1412cc while that of fossil modern H.s. sapiens averaged 1487cc. They were almost exclusively carnivorous and apex predators. On average, the height of Neanderthals was comparable to contemporaneous Homo sapiens. Neanderthal males stood about 165–168 cm tall (about 5'5") and were heavily built with robust bone structure. They were much stronger, having particularly strong arms and hands. Females stood about 152–156 cm tall (about 5'1").

A human being, also human or man is a member of a species of bipedal primates in the family Hominidae (taxonomically Homo sapiens — Latin: "wise human" or "knowing human"). DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago. Humans have a highly developed brain, capable of abstract reasoning, language, introspection and problem solving. This mental capability, combined with an erect body carriage that frees the forelimbs (arms) for manipulating objects, has allowed humans to make far greater use of tools than any other species. Humans are distributed worldwide, with large populations inhabiting every continent on Earth except Antarctica. The human population on Earth is greater than 6.7 billion, as of February, 2009. There is only one extant subspecies, Homo sapiens sapiens. As of 2008, humans are listed as a species of least concern for extinction by the International Union for Conservation of Nature. As of the present time, humans are a dominant form of biological life, in terms of their distribution and effect on the biosphere.

Like most higher primates, humans are social by nature. Humans are particularly adept at utilizing systems of communication — primarily spoken, gestural, and written language — for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans have established an extremely wide variety of traditions, rituals, ethics, values, social norms, and laws, which together form the basis of human society. Humans have a marked appreciation for beauty and aesthetics, which, combined with the desire for self-expression, has led to cultural innovations such as art, writing, literature and music.

Humans are notable for their desire to understand and influence the environment around them, seeking to explain and manipulate natural phenomena through philosophy, art, science, mythology and religion. This natural curiosity has led to the development of advanced tools and skills. Humans are the only species known to build fires, cook their food, and clothe themselves; as well as utilize numerous other technologies. Humans pass down their skills and knowledge to the next generations through education.

Australopithecus anamensis is a fossil species of Australopithecus. The first fossilized specimen of the species, though not recognized as such at the time, was a single arm bone found in Pliocene strata in the Kanapoi region of East Lake Turkana by a Harvard University research team in 1965. The specimen was tentatively assigned at the time to Australopithecus and dated about four million years old. Little additional information was uncovered until 1987, when Canadian archaeologist Allan Morton (with Harvard University's Koobi Fora Field School) discovered fragments of a specimen protruding from a partially eroded hillside east of Allia Bay, near Lake Turkana, Kenya. Six years later the London-born Kenyan paleoanthropologist Meave Leakey and archaeologist Alan Walker excavated the Allia Bay site and uncovered several additional fragments of the hominid, including one complete lower jaw bone which closely resembles that of a common chimpanzee (Pan troglodytes) but whose teeth are much more similar to those of a human. In 1995, Meave Leakey and her associates, taking note of differences between Australopithecus afarensis and the new finds, assigned them to a new species, A. anamensis, deriving its name from the Turkana word anam, meaning "lake". Leakey determined that this species was independent of any others. It does not represent an intermediate species of any type.

Trolls are made of "metamorphorical rock" (a play on metamorphic rock and metaphorical), which means that trolls take on some of the appearance and characteristics of certain stones and minerals, after which they are usually named.
The common troll is nocturnal. Their natural tendency to spend daylight hours dormant led to the stories of them turning to stone when hit by the sun. Though apparently unintelligent, this is due to heat negatively affecting the conductivity of their silicon brains, which operate in a similar fashion to computer circuits (in essence a trollish form of hyperthermia). In the coldness of the high mountain areas that they usually call home, they can, in certain respects, be quite clever. When sufficiently deep-frozen, they can perform exceptional mathematical feats, possibly involving quantum computing. Oddly, the silicon-based trolls are capable of freezing to death if exposed to sufficiently cold temperatures.

A. kadabba is dated to have lived between 5.8 million to 5.2 million years ago. The canine teeth show primitive features, shared with Sahelanthropus and Orrorin, that distinguish them from those of more recent hominins. It has been suggested that A. kadabba is the most recent common ancestor of Homo and Pan.[citation needed] Anthropologists Yohannes Haile-Selassie, Gen Suwa, and Tim D. White published an article suggesting that the presence of a "canine cutting complex" indicates a need for relocation in hominid evolutionary history. Since A. ramidus is lacking the canine cutting complex, the authors argue, it is reasonable to infer the canine cutting complex, which is present in modern day chimpanzees, is a primitive trait which was lost during hominin evolution. The specific name comes from the Afar word for "basal family ancestor".

Paranthropus boisei (originally called Zinjanthropus boisei and then Australopithecus boisei until recently) was an early hominin and described as the largest of the Paranthropus species. It lived from about 2.6 until about 1.2 million years ago during the Pliocene and Pleistocene epochs in Eastern Africa.

Paranthropus robustus was originally discovered in Southern Africa in 1938. The development of P. robustus, namely in cranial features, seemed to be aimed in the direction of a "heavy-chewing complex". Because of the definitive traits that are associated with this robust line of australopithecine, anthropologist Robert Broom erected the genus Paranthropus and placed this species into it.

Paranthropus robustus (considered for a time by the scientific community as Australopithecus robustus) is generally dated to have lived between 2.0 and 1.2 million years ago. P. robustus had large sagittal crests, jaws, jaw muscles, and post-canine teeth that were adapted to serve in the dry environment that they lived in.