Broke My Crayon (el 20/11/14 a las 4:43 am)
If i had a nickel for every time 15 year old me fapped to dem
TheTrekkie42 (el 10/12/14 a las 6:42 am)
This was me in Chemistry. History was my thing.
MegaMicky1995 (el 13/12/14 a las 11:36 pm)
That boob grab
99.9999% of Youtube: YES, YES YESSSSSSSSSSSSSSSSS
bassisku (el 16/12/14 a las 12:58 am)
For all of you people thinking there is only 7 million people in the world
you're dead wrong. There has been countless of studies that have shown that
there is in fact more than 7 billion. Billion is a thousand millions.
The word homo, the name of the biological genus to which humans belong, is
Latin for "human". It was chosen originally by Carolus Linnaeus in his
classification system. The word "human" is from the Latin humanus, the
adjectival form of homo. The Latin "homo" derives from the Indo-European
root *dhghem, or "earth". Linnaeus and other scientists of his time
also considered the great apes to be the closest relatives of humans based
on morphological and anatomical similarities.
The possibility of linking humans with earlier apes by descent became clear
only after 1859 with the publication of Charles Darwin's On the Origin of
Species, in which he argued for the idea of the evolution of new species
from earlier ones. Darwin's book did not address the question of human
evolution, saying only that "Light will be thrown on the origin of man and
The first debates about the nature of human evolution arose between Thomas
Huxley and Richard Owen. Huxley argued for human evolution from apes by
illustrating many of the similarities and differences between humans and
apes, and did so particularly in his 1863 book Evidence as to Man's Place
in Nature. However, many of Darwin's early supporters (such as Alfred
Russel Wallace and Charles Lyell) did not initially agree that the origin
of the mental capacities and the moral sensibilities of humans could be
explained by natural selection, though this later changed. Darwin applied
the theory of evolution and sexual selection to humans when he published
The Descent of Man in 1871.
A major problem at that time was the lack of fossil intermediaries. Despite
the 1891 discovery by Eugène Dubois of what is now called Homo erectus at
Trinil, Java, it was only in the 1920s when such fossils were discovered in
Africa, that intermediate species began to accumulate. In 1925, Raymond
Dart described Australopithecus africanus. The type specimen was the Taung
Child, an Australopithecine infant which was discovered in a cave. The
child's remains were a remarkably well-preserved tiny skull and an
endocranial cast of the brain.
Although the brain was small (410 cm3), its shape was rounded, unlike that
of chimpanzees and gorillas, and more like a modern human brain. Also, the
specimen showed short canine teeth, and the position of the foramen magnum
was evidence of bipedal locomotion. All of these traits convinced Dart that
the Taung baby was a bipedal human ancestor, a transitional form between
apes and humans.
The East African fossils
Louis Leakey examining skulls from Olduvai Gorge, Tanzania.
During the 1960s and 1970s, hundreds of fossils were found, particularly in
East Africa in the regions of the Olduvai gorge and Lake Turkana. The
driving force in the East African researches was the Leakey family, with
Louis Leakey and his wife Mary Leakey, and later their son Richard and
daughter in-law Meave being among the most successful fossil hunters and
palaeoanthropologists. From the fossil beds of Olduvai and Lake Turkana
they amassed fossils of australopithecines, early Homo and even Homo
These finds cemented Africa as the cradle of humankind. In the 1980s,
Ethiopia emerged as the new hot spot of palaeoanthropology as "Lucy", the
most complete fossil member of the species Australopithecus afarensis, was
found by Donald Johanson in Hadar in the desertic Middle Awash region of
northern Ethiopia. This area would be the location of many new hominin
fossils, particularly those uncovered by the teams of Tim White in the
1990s, such as Ardipithecus ramidus.
The genetic revolution
The genetic revolution in studies of human evolution started when Vincent
Sarich and Allan Wilson measured the strength of immunological
cross-reactions of blood serum albumin between pairs of creatures,
including humans and African apes (chimpanzees and gorillas). The
strength of the reaction could be expressed numerically as an immunological
distance, which was in turn proportional to the number of amino acid
differences between homologous proteins in different species. By
constructing a calibration curve of the ID of species' pairs with known
divergence times in the fossil record, the data could be used as a
molecular clock to estimate the times of divergence of pairs with poorer or
unknown fossil records.
In their seminal 1967 paper in Science, Sarich and Wilson estimated the
divergence time of humans and apes as four to five million years ago,
at a time when standard interpretations of the fossil record gave this
divergence as at least 10 to as much as 30 million years. Subsequent fossil
discoveries, notably Lucy, and reinterpretation of older fossil materials,
notably Ramapithecus, showed the younger estimates to be correct and
validated the albumin method. Application of the molecular clock principle
revolutionized the study of molecular evolution.
The quest for the earliest hominin
In the 1990s, several teams of paleoanthropologists were working throughout
Africa looking for evidence of the earliest divergence of the Hominin
lineage from the great apes. In 1994, Meave Leakey discovered
Australopithecus anamensis. The find was overshadowed by Tim White's 1995
discovery of Ardipithecus ramidus, which pushed back the fossil record to
4.2 million years ago.
In 2000, Martin Pickford and Brigitte Senut discovered in the Tugen Hills
of Kenya a 6-million-year-old bipedal hominin which they named Orrorin
tugenensis. And in 2001, a team led by Michel Brunet discovered the skull
of Sahelanthropus tchadensis which was dated as 7.2 million years ago, and
which Brunet argued was a bipedal, and therefore a hominid.
Map with arrows emanating from Africa, across Eurasia, to Australia and the
A model of human migration, based from divergence of the mitochondrial DNA
(which indicates the matrilineage). Timescale (kya) indicated by
Trellis of intermingling populations for the last two million years.
A "trellis" (as Wolpoff called it) that emphasizes back-and-forth gene flow
among geographic regions.
Different models for the beginning of the present human species.
See also: Early human migrations, Recent African origin of modern humans
and Multiregional hypothesis
Anthropologists in the 1980s were divided regarding some details of
reproductive barriers and migratory dispersals of the Homo genus.
Subsequently, genetics has been used to investigate and resolve these
issues. According to the Sahara pump theory evidence suggests that genus
Homo have migrated out of Africa at least three times (e.g. Homo erectus,
Homo heidelbergensis and Homo sapiens).
The Out-of-Africa model proposed that modern H. sapiens speciated in Africa
recently (approx. 200,000 years ago) and the subsequent migration through
Eurasia resulted in nearly complete replacement of other Homo species. This
model has been developed by Chris Stringer and Peter Andrews. In
contrast, the multiregional hypothesis proposed that Homo genus contained
only a single interconnected population as it does today (not separate
species), and that its evolution took place worldwide continuously over the
last couple million years. This model was proposed in 1988 by Milford H.
Progress in DNA sequencing, specifically mitochondrial DNA (mtDNA) and then
Y-chromosome DNA advanced the understanding of human origins.
Sequencing mtDNA and Y-DNA sampled from a wide range of indigenous
populations revealed ancestral information relating to both male and female
genetic heritage. Aligned in genetic tree differences were interpreted
as supportive of a recent single origin. Analyses have shown a greater
diversity of DNA patterns throughout Africa, consistent with the idea that
Africa is the ancestral home of mitochondrial Eve and Y-chromosomal
Out of Africa has gained support from research using female mitochondrial
DNA (mtDNA) and the male Y chromosome. After analysing genealogy trees
constructed using 133 types of mtDNA, researchers concluded that all were
descended from a female African progenitor, dubbed Mitochondrial Eve. Out
of Africa is also supported by the fact that mitochondrial genetic
diversity is highest among African populations.
A broad study of African genetic diversity, headed by Sarah Tishkoff, found
the San people had the greatest genetic diversity among the 113 distinct
populations sampled, making them one of 14 "ancestral population clusters".
The research also located the origin of modern human migration in
south-western Africa, near the coastal border of Namibia and Angola.
The fossil evidence was insufficient for Richard Leakey to resolve this
debate. Studies of haplogroups in Y-chromosomal DNA and mitochondrial
DNA have largely supported a recent African origin. Evidence from
autosomal DNA also predominantly supports a Recent African origin. However
evidence for archaic admixture in modern humans had been suggested by some
Recent sequencing of Neanderthal and Denisovan genomes shows that
some admixture occurred. Modern humans outside Africa have 2-4% Neanderthal
alleles in their genome, and some Melanesians have an additional 4-6% of
Denisovan alleles. These new results do not contradict the Out of Africa
model, except in its strictest interpretation. After recovery from a
genetic bottleneck that might be due to the Toba supervolcano catastrophe,
a fairly small group left Africa and briefly interbred with Neanderthals,
probably in the middle-east or even North Africa before their departure.
Their still predominantly African descendants spread to populate the world.
A fraction in turn interbred with Denisovans, probably in south-east Asia,
before populating Melanesia. HLA haplotypes of Neanderthal and Denisova
origin have been identified in modern Eurasian and Oceanian populations.
There are still differing theories on whether there was a single exodus or
several. A multiple dispersal model involves the Southern Dispersal
theory, which has gained support in recent years from genetic,
linguistic and archaeological evidence. In this theory, there was a coastal
dispersal of modern humans from the Horn of Africa around 70,000 years ago.
This group helped to populate Southeast Asia and Oceania, explaining the
discovery of early human sites in these areas much earlier than those in
A second wave of humans may have dispersed across the Sinai peninsula into
Asia, resulting in the bulk of human population for Eurasia. This second
group possibly possessed a more sophisticated tool technology and was less
dependent on coastal food sources than the original group. Much of the
evidence for the first group's expansion would have been destroyed by the
rising sea levels at the end of each glacial maximum. The multiple
dispersal model is contradicted by studies indicating that the populations
of Eurasia and the populations of Southeast Asia and Oceania are all
descended from the same mitochondrial DNA lineages, which support a single
migration out of Africa that gave rise to all non-African populations.
The hominoids are descendants of a common ancestor.
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humans and chimpanzees.
The most significant of these adaptations are bipedalism, increased brain
size, lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of
ongoing debate. Other significant morphological changes included the
evolution of a power and precision grip, a change first occurring in H.
Bipedalism is the basic adaption of the Hominin line and is considered the
main cause behind a suite of skeletal changes shared by all bipedal
hominins. The earliest bipedal Hominin is considered to be either
Sahelanthropus or Orrorin, with Ardipithecus, a full bipedal, coming
somewhat later. The knuckle-walkers, the gorilla and chimpanzee, diverged
around the same time, and either Sahelanthropus or Orrorin may be our last
shared ancestor.
The early bipedals eventually evolved into the australopithecines and later
the genus Homo. There are several theories of the adaptation value of
bipedalism. It is possible that bipedalism was favored because it freed up
the hands for reaching and carrying food, saved energy during
locomotion, enabled long distance running and hunting, enhanced field
of vision and helped avoid hyperthermia by reducing the surface area
exposed to direct sun; all this mainly for thriving in the new grassland
type environment rather than the previous forest type. A new study
provides support for the hypothesis that walking on two legs, or
bipedalism, evolved because it used less energy than quadrupedal
Anatomically the evolution of bipedalism has been accompanied by a large
number of skeletal changes, not just to the legs and pelvis, but also to
the vertebral column, feet and ankles, and skull. The femur evolved
into a slightly more angular position to move the center of gravity toward
the geometric center of the body. The knee and ankle joints became
increasingly robust to better support increased weight. To support the
increased weight on each vertebra in the upright position, the human
vertebral column became S-shaped and the lumbar vertebrae became shorter
and wider. In the feet the big toe moved into alignment with the other toes
to help in forward locomotion. The arms and forearms shortened relative to
the legs making it easier to run. The foramen magnum migrated under the
skull and more anterior.
The most significant changes are in the pelvic region, where the long
downward facing iliac blade was shortened and became wide as a requirement
for keeping the center of gravity stable while walking; bipedal
hominids have a shorter but broad, bowl-like pelvis due to this. A drawback
is that the birth canal of these apes is smaller than regular
knuckle-walking apes, though there has been a widening of it in comparison
to that of australopithecine and modern humans, permitting the passage of
newborns due to the increase in cranial size but this is limited to the
upper portion, since further increase can hinder normal bipedal
The shortening of the pelvis and smaller birth canal evolved as a
requirement for bipedalism and had significant effects on the process of
human birth which is much more difficult in modern humans than in other
primates. During human birth, because of the variation in size of the
pelvic region, the fetal head must be in a transverse position (compared to
the mother) during entry into the birth canal and rotate about 90 degrees
upon exit. The smaller size of the birth canal became an obstacle when
the brain size began to increase in early humans, prompted a shorter
gestation period and the reason why humans give birth to immature
offspring, who are unable to walk much before 12 months and have greater
neoteny, compared to other primates, who are motile at a much earlier
age. The increased brain growth after birth and the increased
dependency of children on mothers had a big effect upon the female
reproductive cycle, and the more frequent appearance of
monogamous relationships in humans when compared with other hominids.
Delayed human sexual maturity also led to the evolution of menopause with
one explanation saying that elderly women could better pass on their genes
by taking care of their daughter's offspring, as compared to having more of
The human species developed a much larger brain than that of other primates
– typically 1,330 cm3 in modern humans, over twice the size of that of a
chimpanzee or gorilla. The pattern of encephalization started with Homo
habilis, which at approximately 600 cm3 had a brain slightly larger than
that of chimpanzees, and continued with Homo erectus (800–1,100 cm3),
reaching a maximum in Neanderthals with an average size of (1,200–1,900
cm3), larger even than Homo sapiens. The pattern of human postnatal brain
growth differs from that of other apes (heterochrony) and allows for
extended periods of social learning and language acquisition in juvenile
humans. However, the differences between the structure of human brains and
those of other apes may be even more significant than differences in
The increase in volume over time has affected areas within the brain
unequally – the temporal lobes, which contain centers for language
processing, have increased disproportionately, as has the prefrontal cortex
which has been related to complex decision-making and moderating social
behavior. Encephalization has been tied to an increasing emphasis on
meat in the diet, or with the development of cooking, and it
has been proposed that intelligence increased as a response to an increased
necessity for solving social problems as human society became more complex.
The human brain was able to expand because of the changes in the morphology
of smaller mandibles and mandible muscle attachments to the skull into
allowing more room for the brain to grow.
The increase in volume of the neocortex also included a rapid increase in
size of the cerebellum. Traditionally the cerebellum has been associated
with a paleocerebellum and archicerebellum as well as a neocerebellum. Its
function has also traditionally been associated with balance, fine motor
control but more recently speech and cognition. The great apes including
humans and its antecessors had a more pronounced development of the
cerebellum relative to the neocortex than other primates. It has been
suggested that because of its function of sensory-motor control and
assisting in learning complex muscular action sequences, the cerebellum may
have underpinned the evolution of human's technological adaptations
including the preadaptation of speech.
The reduced degree of sexual dimorphism is visible primarily in the
reduction of the male canine tooth relative to other ape species (except
gibbons) and reduced brow ridges and general robustness of males. Another
important physiological change related to sexuality in humans was the
evolution of hidden estrus. Humans and bonobos are the only apes in which
the female is fertile year round and in which no special signals of
fertility are produced by the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the
distribution of body hair and subcutaneous fat, and in the overall size,
males being around 15% larger than females. These changes taken together
have been interpreted as a result of an increased emphasis on pair bonding
as a possible solution to the requirement for increased parental investment
due to the prolonged infancy of offspring.
A number of other changes have also characterized the evolution of humans,
among them an increased importance on vision rather than smell; a smaller
gut; loss of body hair; evolution of sweat glands; a change in the shape of
the dental arcade from being u-shaped to being parabolic; development of a
chin (found in Homo sapiens alone), development of styloid processes;
development of a descended larynx.
The evidence on which scientific accounts of human evolution is based comes
from many fields of natural science. The main sources of knowledge about
the evolutionary process has traditionally been the fossil record, but
since the development of genetics beginning in the 1970s, DNA analysis has
come to occupy a place of comparable importance. The studies of ontogeny,
phylogeny and especially evolutionary developmental biology of both
vertebrates and invertebrates offer considerable insight into the evolution
of all life, including how humans evolved. The specific study of the origin
and life of humans is anthropology, particularly paleoanthropology which
focuses on the study of human prehistory.
Evidence from molecular biology
Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genus Pan), gorillas (genus Gorilla), orangutans (genus
Pongo), and gibbons (four genera of the family Hylobatidae: Hylobates,
Hoolock, Nomascus, and Symphalangus). All except gibbons are hominids.
The closest living relatives of humans are bonobos and chimpanzees (both
genus Pan) and gorillas (genus Gorilla). With the sequencing of both
the human and chimpanzee genome, current estimates of the similarity
between their DNA sequences range between 95% and 99%. By using
the technique called the molecular clock which estimates the time required
for the number of divergent mutations to accumulate between two lineages,
the approximate date for the split between lineages can be calculated. The
gibbons (family Hylobatidae) and orangutans (genus Pongo) were the first
groups to split from the line leading to the humans, then gorillas followed
by the chimpanzees and bonobos. The splitting date between human and
chimpanzee lineages is placed around 4-8 million years ago during the late
Genetic evidence has also been employed to resolve the question of whether
there was any gene flow between early modern humans and Neanderthals, and
to enhance our understanding of the early human migration patterns and
splitting dates. By comparing the parts of the genome that are not under
natural selection and which therefore accumulate mutations at a fairly
steady rate, it is possible to reconstruct a genetic tree incorporating the
entire human species since the last shared ancestor.
Each time a certain mutation (Single-nucleotide polymorphism) appears in an
individual and is passed on to his or her descendants a haplogroup is
formed including all of the descendants of the individual who will also
carry that mutation. By comparing mitochondrial DNA which is inherited only
from the mother, geneticists have concluded that the last female common
ancestor whose genetic marker is found in all modern humans, the so-called
mitochondrial Eve, must have lived around 200,000 years ago.
Main articles: Human evolutionary genetics and Human genetic variation
Human evolutionary genetics studies how one human genome differs from the
other, the evolutionary past that gave rise to it, and its current effects.
Differences between genomes have anthropological, medical and forensic
implications and applications. Genetic data can provide important insight
into human evolution.
Evidence from the fossil record
Replica of fossil skull of Homo habilis. Fossil number KNM ER 1813, found
at Koobi Fora, Kenya.
Replica of fossil skull of Homo ergaster (African Homo erectus). Fossil
number Khm-Heu 3733 discovered in 1975 in Kenya.
There is little fossil evidence for the divergence of the gorilla,
chimpanzee and hominin lineages. The earliest fossils that have been
proposed as members of the hominin lineage are Sahelanthropus tchadensis
dating from 7 million years ago, Orrorin tugenensis dating from 5.7 million
years ago and Ardipithecus kadabba dating to 5.6 million years ago. Each of
these have been argued to be a bipedal ancestor of later hominins but, in
each case, the claims have been contested. It is also possible that one or
more of these species are ancestors of another branch of African apes, or
that they represent a shared ancestor between hominins and other apes.
The question of the relationship between these early fossil species and the
hominin lineage is still to be resolved. From these early species, the
australopithecines arose around 4 million years ago and diverged into
robust (also called Paranthropus) and gracile branches, one of which
(possibly A. garhi) probably went on to become ancestors of the genus Homo.
The australopithecine species that is best represented in the fossil record
is Australopithecus afarensis with more than one hundred fossil individuals
represented, found from Northern Ethiopia (such as the famous "Lucy"), to
Kenya, and South Africa. Fossils of robust australopithecines such as A.
robustus (or alternatively Paranthropus robustus) and A./P. boisei are
particularly abundant in South Africa at sites such as Kromdraai and
Swartkrans, and around Lake Turkana in Kenya.
The earliest member of the genus Homo is Homo habilis which evolved around
2.3 million years ago. Homo habilis is the first species for which we have
positive evidence of the use of stone tools. They developed the oldowan
lithic technology, named after the Olduvai gorge in which the first
specimens were found. Some scientists consider Homo rudolfensis, a larger
bodied group of fossils with similar morphology to the original H. habilis
fossils, to be a separate species while others consider them to be part of
H. habilis—simply representing species internal variation, or perhaps even
sexual dimorphism. The brains of these early hominins were about the same
size as that of a chimpanzee, and their main adaptation was bipedalism as
an adaptation to terrestrial living.
During the next million years, a process of encephalization began and, with
the arrival of Homo erectus in the fossil record, cranial capacity had
doubled. Homo erectus were the first of the hominina to leave Africa, and
this species spread through Africa, Asia, and Europe between 1.3 to 1.8
million years ago. One population of H. erectus, also sometimes classified
as a separate species Homo ergaster, stayed in Africa and evolved into Homo
sapiens. It is believed that these species were the first to use fire and
The earliest transitional fossils between H. ergaster/erectus and Archaic
H. sapiens are from Africa, such as Homo rhodesiensis, but seemingly
transitional forms were also found at Dmanisi, Georgia. These descendants
of African H. erectus spread through Eurasia from ca. 500,000 years ago
evolving into H. antecessor, H. heidelbergensis and H. neanderthalensis.
The earliest fossils of anatomically modern humans are from the Middle
Paleolithic, about 200,000 years ago such as the Omo remains of Ethiopia;
later fossils from Skhul in Israel and Southern Europe begin around 90,000
As modern humans spread out from Africa, they encountered other hominins
such as Homo neanderthalensis and the so-called Denisovans, who may have
evolved from populations of Homo erectus that had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations
may have contributed genetic material to modern humans.
This migration out of Africa is estimated to have begun about 70,000 years
BP and modern humans subsequently spread globally, replacing earlier
hominins either through competition or hybridization. They inhabited
Eurasia and Oceania by 40,000 years BP, and the Americas by at least 14,500
For evolutionary history before primates, see Evolution of mammals,
Evolutionary history of life, and Timeline of human evolution.
Early evolution of primates
See also: Evolution of primates
Evolutionary history of the primates can be traced back 65 million
years. The oldest known primate-like mammal species, the
Plesiadapis, came from North America, but they were widespread in Eurasia
and Africa during the tropical conditions of the Paleocene and Eocene.
David Begun concluded that early primates flourished in Eurasia and
that a lineage leading to the African apes and humans, including
Dryopithecus, migrated south from Europe or Western Asia into Africa. The
surviving tropical population of primates, which is seen most completely in
the upper Eocene and lowermost Oligocene fossil beds of the Faiyum
depression southwest of Cairo, gave rise to all living species—lemurs of
Madagascar, lorises of Southeast Asia, galagos or "bush babies" of Africa,
and the anthropoids: platyrrhine or New World monkeys, catarrhines or Old
World monkeys, and the great apes, including humans.
The earliest known catarrhine is Kamoyapithecus from uppermost Oligocene at
Eragaleit in the northern Kenya Rift Valley, dated to 24 million years
ago. Its ancestry is thought to be species related to Aegyptopithecus,
Propliopithecus, and Parapithecus from the Fayum, at around 35 million
years ago. In 2010, Saadanius was described as a close relative of the
last common ancestor of the crown catarrhines, and tentatively dated to
29–28 million years ago, helping to fill an 11-million-year gap in the
Reconstructed tailless Proconsul skeleton
In the early Miocene, about 22 million years ago, the many kinds of
arboreally adapted primitive catarrhines from East Africa suggest a long
history of prior diversification. Fossils at 20 million years ago include
fragments attributed to Victoriapithecus, the earliest Old World Monkey.
Among the genera thought to be in the ape lineage leading up to 13 million
years ago are Proconsul, Rangwapithecus, Dendropithecus, Limnopithecus,
Nacholapithecus, Equatorius, Nyanzapithecus, Afropithecus, Heliopithecus,
and Kenyapithecus, all from East Africa.
The presence of other generalized non-cercopithecids of middle Miocene age
from sites far distant—Otavipithecus from cave deposits in Namibia, and
Pierolapithecus and Dryopithecus from France, Spain and Austria—is evidence
of a wide diversity of forms across Africa and the Mediterranean basin
during the relatively warm and equable climatic regimes of the early and
middle Miocene. The youngest of the Miocene hominoids, Oreopithecus, is
from coal beds in Italy that have been dated to 9 million years ago.
Molecular evidence indicates that the lineage of gibbons (family
Hylobatidae) diverged from Great Apes some 18-12 million years ago, and
that of orangutans (subfamily Ponginae) diverged from the other Great Apes
at about 12 million years; there are no fossils that clearly document the
ancestry of gibbons, which may have originated in a so-far-unknown South
East Asian hominoid population, but fossil proto-orangutans may be
represented by Sivapithecus from India and Griphopithecus from Turkey,
dated to around 10 million years ago.
Divergence of the human clade from other great apes
A reconstruction of a female Australopithecus afarensis (National Museum of
Species close to the last common ancestor of gorillas, chimpanzees and
humans may be represented by Nakalipithecus fossils found in Kenya and
Ouranopithecus found in Greece. Molecular evidence suggests that between 8
and 4 million years ago, first the gorillas, and then the chimpanzees
(genus Pan) split off from the line leading to the humans; human DNA is
approximately 98.4% identical to that of chimpanzees when comparing single
nucleotide polymorphisms (see human evolutionary genetics). The fossil
record of gorillas and chimpanzees is limited. Both poor preservation (rain
forest soils tend to be acidic and dissolve bone) and sampling bias
probably contribute to this problem.
Other hominins likely adapted to the drier environments outside the
equatorial belt, along with antelopes, hyenas, dogs, pigs, elephants, and
horses. The equatorial belt contracted after about 8 million years ago.
There is very little fossil evidence for the split of the hominin lineage
from the lineages of gorillas and chimpanzees. The earliest fossils that
have been argued to belong to the human lineage are Sahelanthropus
tchadensis (7 Ma) and Orrorin tugenensis (6 Ma), followed by Ardipithecus
(5.5–4.4 Ma), with species Ar. kadabba and Ar. ramidus;
The Australopithecus genus evolved in eastern Africa around 4 million years
ago before spreading throughout the continent and eventually becoming
extinct 2 million years ago. During this time period various forms of
australopiths existed, including Australopithecus anamensis, A. afarensis,
A. sediba, and A. africanus. There is still some debate amongst academics
whether certain African hominid species of this time, such as A. robustus
and A. boisei, constitute members of the same genus; if so, they would be
considered to be A. robust australopiths whilst the others would be
considered A. gracile australopiths. However, if these species do indeed
constitute their own genus, then they may be given their own name, the
Australopithecus (4–1.8 Ma), with species Au. anamensis, Au. afarensis, Au.
africanus, Au. bahrelghazali, Au. garhi, and Au. sediba;
Kenyanthropus (3–2.7 Ma), with species Kenyanthropus platyops;
Paranthropus (3–1.2 Ma), with species P. aethiopicus, P. boisei, and P.
One current view of the temporal and geographical distribution of hominid
populations Other interpretations differ mainly in the taxonomy and
geographical distribution of hominid species.
A reconstruction of Homo habilis
1. Gorilla 2. Australopithecus 3. Homo erectus 4. Neanderthal (La Chapelle
aux Saints) 5. Steinheim Skull 6. modern Homo sapiens. Notice the
decreasing prognathism and thickness of the brow ridge, and the increasing
size of the forehead.
Homo sapiens is the only extant species of its genus, Homo. While some
other, extinct Homo species might have been ancestors of Homo sapiens, many
were likely our "cousins", having speciated away from our ancestral
line. There is not yet a consensus as to which of these groups
should count as separate species and which as subspecies. In some cases
this is due to the dearth of fossils, in other cases it is due to the
slight differences used to classify species in the Homo genus. The
Sahara pump theory (describing an occasionally passable "wet" Sahara
Desert) provides one possible explanation of the early variation in the
Based on archaeological and paleontological evidence, it has been possible
to infer, to some extent, the ancient dietary practices of various Homo
species and to study the role of diet in physical and behavioral evolution
According to the Toba catastrophe theory to which some anthropologists and
archeologists subscribe, the supereruption of Lake Toba on Sumatra island
in Indonesia roughly 70,000 years ago had global consequences, killing
most humans then alive and creating a population bottleneck that affected
the genetic inheritance of all humans today.
H. habilis and H. gautengensis
Homo habilis lived from about 2.4 to 1.4 Ma. Homo habilis evolved in South
and East Africa in the late Pliocene or early Pleistocene, 2.5–2 Ma, when
it diverged from the australopithecines. Homo habilis had smaller molars
and larger brains than the australopithecines, and made tools from stone
and perhaps animal bones. One of the first known hominids, it was nicknamed
'handy man' by discoverer Louis Leakey due to its association with stone
tools. Some scientists have proposed moving this species out of Homo and
into Australopithecus due to the morphology of its skeleton being more
adapted to living on trees rather than to moving on two legs like Homo
It was considered to be the first species of the genus Homo until May 2010,
when a new species, Homo gautengensis was discovered in South Africa, that
most likely arose earlier than Homo habilis.
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6 Ma, whose
relation to Homo habilis is not yet clear.
Homo rudolfensis refers to a single, incomplete skull from Kenya.
Scientists have suggested that this was another Homo habilis, but this has
not been confirmed.
Homo georgicus, from Georgia, may be an intermediate form between Homo
habilis and Homo erectus, or a sub-species of Homo erectus.
H. ergaster and H. erectus
The first fossils of Homo erectus were discovered by Dutch physician Eugene
Dubois in 1891 on the Indonesian island of Java. He originally named the
material Pithecanthropus erectus based on its morphology, which he
considered to be intermediate between that of humans and apes. Homo
erectus lived from about 1.8 Ma to about 70,000 years ago (which would
indicate that they were probably wiped out by the Toba catastrophe;
however, Homo floresiensis survived it). Often the early phase, from 1.8 to
1.25 Ma, is considered to be a separate species, Homo ergaster, or it is
seen as a subspecies of Homo erectus, Homo erectus ergaster.
In the early Pleistocene, 1.5–1 Ma, in Africa some populations of Homo
habilis are thought to have evolved larger brains and made more elaborate
stone tools; these differences and others are sufficient for
anthropologists to classify them as a new species, Homo erectus. This
was made possible by the evolution of locking knees and a different
location of the foramen magnum (the hole in the skull where the spine
enters). They may have used fire to cook their meat.
See also: Control of fire by early humans
A famous example of Homo erectus is Peking Man; others were found in Asia
(notably in Indonesia), Africa, and Europe. Many paleoanthropologists now
use the term Homo ergaster for the non-Asian forms of this group, and
reserve Homo erectus only for those fossils that are found in Asia and meet
certain skeletal and dental requirements which differ slightly from H.
H. cepranensis and H. antecessor
These are proposed as species that may be intermediate between H. erectus
and H. heidelbergensis.
H. antecessor is known from fossils from Spain and England that are dated
1.2 Ma–500 ka.
H. cepranensis refers to a single skull cap from Italy, estimated to be
about 800,000 years old.
Reconstruction of Homo heidelbergensis which may be the direct ancestor of
both Homo neanderthalensis and Homo sapiens.
H. heidelbergensis (Heidelberg Man) lived from about 800,000 to about
300,000 years ago. Also proposed as Homo sapiens heidelbergensis or Homo
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most current
researchers place Rhodesian Man within the group of Homo heidelbergensis,
though other designations such as Archaic Homo sapiens and Homo sapiens
rhodesiensis have been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate between H. erectus and H. sapiens or one
of many evolutionary dead ends. The skull from Gawis, Ethiopia, is believed
to be 500,000–250,000 years old. Only summary details are known, and the
finders have not yet released a peer-reviewed study. Gawis man's facial
features suggest its being either an intermediate species or an example of
a "Bodo man" female.
Neanderthal and Denisovan
Main articles: Neanderthal and Denisovan
Dermoplastic reconstruction of a Neanderthal
H. neanderthalensis, alternatively designated as Homo sapiens
neanderthalensis, lived in Europe and Asia from 400,000 to about
30,000 years ago. Evidence from sequencing mitochondrial DNA indicated that
no significant gene flow occurred between H. neanderthalensis and H.
sapiens, and, therefore, the two were separate species that shared a common
ancestor about 660,000 years ago. However, the 2010
sequencing of the Neanderthal genome indicated that Neanderthals did indeed
interbreed with anatomically modern humans circa 45,000 to 80,000 years ago
(at the approximate time that modern humans migrated out from Africa, but
before they dispersed into Europe, Asia and elsewhere).
Nearly all modern non-African humans have 1% to 4% of their DNA derived
from Neanderthal DNA, and this finding is consistent with recent
studies indicating that the divergence of some human alleles dates to one
Ma, although the interpretation of these studies has been
questioned. Neanderthals and homo sapiens could have co-existed
in Europe for as long as 10,000 years, during which human populations
exploded vastly outnumbering Neanderthals, possibly outcompeting them by
sheer numerical strength.
In 2008, archaeologists working at the site of Denisova Cave in the Altai
Mountains of Siberia uncovered a small bone fragment from the fifth finger
of a juvenile member of Denisovans. Artifacts, including a bracelet,
excavated in the cave at the same level were carbon dated to around 40,000
BP. As DNA had survived in the fossil fragment due to the cool climate of
the Denisova Cave, both mtDNA and nuclear genomic DNA were
While the divergence point of the mtDNA was unexpectedly deep in time,
the full genomic sequence suggested the Denisovans belonged to the same
lineage as Neanderthals, with the two diverging shortly after their line
split from that lineage giving rise to modern humans. Modern humans are
known to have overlapped with Neanderthals in Europe for more than 10,000
years, and the discovery raises the possibility that Neanderthals, modern
humans and the Denisova hominin may have co-existed. The existence of this
distant branch creates a much more complex picture of humankind during the
Late Pleistocene than previously thought. Evidence has also been
found that as much as 6% of the genomes of some modern Melanesians derive
from Denisovans, indicating limited interbreeding in Southeast
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern
humans outside of Africa. HLA types from Denisovans and Neanderthal
represent more than half the HLA alleles of modern Eurasians,
indicating strong positive selection for these introgressed alleles.
Main article: Homo floresiensis
Restoration model of Homo floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamed hobbit for its small size, possibly a result of
insular dwarfism. H. floresiensis is intriguing both for its size and
its age, being an example of a recent species of the genus Homo that
exhibits derived traits not shared with modern humans. In other words, H.
floresiensis shares a common ancestor with modern humans, but split from
the modern human lineage and followed a distinct evolutionary path. The
main find was a skeleton believed to be a woman of about 30 years of age.
Found in 2003 it has been dated to approximately 18,000 years old. The
living woman was estimated to be one meter in height, with a brain volume
of just 380 cm3 (considered small for a chimpanzee and less than a third of
the H. sapiens average of 1400 cm3).
However, there is an ongoing debate over whether H. floresiensis is indeed
a separate species. Some scientists hold that H. floresiensis was a
modern H. sapiens with pathological dwarfism. This hypothesis is
supported in part, because some modern humans who live on Flores, the
island where the skeleton was found, are pygmies. This, coupled with
pathological dwarfism, could possibly create a hobbit-like human. The other
major attack on H. floresiensis is that it was found with tools only
associated with H. sapiens.
The hypothesis of pathological dwarfism, however, fails to explain
additional anatomical features that are unlike those of modern humans
(diseased or not) but much like those of ancient members of our genus.
Aside from cranial features, these features include the form of bones in
the wrist, forearm, shoulder, knees, and feet. Additionally, this
hypothesis fails to explain the find of multiple examples of individuals
with these same characteristics, indicating they were common to a large
population, and not limited to one individual.
Main article: Archaic Homo sapiens
H. sapiens (the adjective sapiens is Latin for "wise" or "intelligent")
have lived from about 250,000 years ago to the present. Between 400,000
years ago and the second interglacial period in the Middle Pleistocene,
around 250,000 years ago, the trend in skull expansion and the elaboration
of stone tool technologies developed, providing evidence for a transition
from H. erectus to H. sapiens. The direct evidence suggests there was a
migration of H. erectus out of Africa, then a further speciation of H.
sapiens from H. erectus in Africa. A subsequent migration within and out of
Africa eventually replaced the earlier dispersed H. erectus. This migration
and origin theory is usually referred to as the recent single origin or Out
of Africa theory. Current evidence does not preclude some multiregional
evolution or some admixture of the migrant H. sapiens with existing Homo
populations. This is a hotly debated area of paleoanthropology.
Current research has established that humans are genetically highly
homogenous; that is, the DNA of individuals is more alike than usual for
most species, which may have resulted from their relatively recent
evolution or the possibility of a population bottleneck resulting from
cataclysmic natural events such as the Toba catastrophe.
Distinctive genetic characteristics have arisen, however, primarily as the
result of small groups of people moving into new environmental
circumstances. These adapted traits are a very small component of the Homo
sapiens genome, but include various characteristics such as skin color and
nose form, in addition to internal characteristics such as the ability to
breathe more efficiently at high altitudes.
H. sapiens idaltu, from Ethiopia, is an extinct sub-species from about
160,000 years ago.
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Comparative table of Homo species
Species Lived when Ma Lived where Adult height Adult mass Cranial capacity
(cm³) Fossil record Discovery / publication of name
Denisova hominin 0.04 Russia 1 site 2010
H. antecessor 1.2 – 0.8 Spain 175 cm (5 ft 9 in) 90 kg (200 lb) 1,000 2
H. cepranensis 0.9 – 0.35 Italy 1,000 1 skull cap 1994/2003
H. erectus 1.9 – 0.2 Africa, Eurasia (Java, China, India, Caucasus) 180 cm
(5 ft 11 in) 60 kg (130 lb) 850 (early) – 1,100 (late) Many 1891/1892
H. ergaster 1.9 – 1.4 Eastern and Southern Africa 700–850 Many 1975
H. floresiensis 0.10 – 0.012 Indonesia 100 cm (3 ft 3 in) 25 kg (55 lb) 400
7 individuals 2003/2004
H. gautengensis >2 – 0.6 South Africa 100 cm (3 ft 3 in) 1 individual
H. habilis 2.2 – 1.4 Africa 150 cm (4 ft 11 in) 33–55 kg (73–121 lb)
510–660 Many 1960/1964
H. heidelbergensis 0.6 – 0.35 Europe, Africa, China 180 cm (5 ft 11 in) 90
kg (200 lb) 1,100–1,400 Many 1908
H. neanderthalensis 0.35 – 0.04 Europe, Western Asia 170 cm (5 ft 7 in)
55–70 kg (121–154 lb) (heavily built) 1,200–1,900 Many (1829)/1864
H. rhodesiensis 0.3 – 0.12 Zambia 1,300 Very few 1921
H. rudolfensis 1.9 Kenya 700 2 sites 1972/1986
Red Deer Cave people 0.0145–0.0115 China Very few 2012
H. sapiens idaltu 0.16 – 0.15 Ethiopia 1,450 3 craniums 1997/2003
(modern humans) 0.2 – present Worldwide 150 - 190 cm (4 ft 7 in - 6 ft 3
in) 50–100 kg (110–220 lb) 950–1,800 Still living —/1758
Mafaman (el 01/02/15 a las 11:59 am)
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Alexis Leyva (el 26/11/14 a las 4:13 pm)
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Aravind Mani (el 01/02/15 a las 9:38 pm)
This is what you must do:-
1) Look at the clock.
2) 26 (for example) minutes until the lesson ends.
3) Draw 26 in nice bubble letters and decorate it.
4) Do this for a few minutes.
5) When you are done, look at the clock again.
6) Repeat from step 2 until the lesson ends.
Use themes. Make one stripy. Make one spotty. Have a binary themed one.
Good luck. Stay awake. 😉
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Victor Perez (el 18/02/15 a las 3:08 am)
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diceMEass (el 04/03/15 a las 6:24 pm)
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