EARLY HOMINID EVOLUTION:

http://www.wsu.edu/gened/learn-modules/top_longfor/timeline/01_notes_definitions.html

Sahelanthropus tchadensis (7 mya) fossils of six and perhaps as many as nine individuals oldest hominid may have been the time (before or after?) when the hominids are thought to have diverged from chimpanzees often referred to as the “great divergence” The chief issue is determining where S. tachadensis stands in relation to the “great divergence” of the chimpanzee and hominid lines.  Is it from before or after? Probably arose soon after the divergence of the chimpanzee and human lineages

Orrorin Tugenensis (6 mya) means “original man” in Tugen represented by only a few fragments of bone thirteen fossils belonging to at least five individuals may be a direct line of descent to modern humans if correct, then all of the australopithecine species would represent a different branch of hominids, rather than human ancestors the human line would presumably stretch from an as yet undiscovered species at the point of divergence through Orrorin tugenensis, and from thence through several as yet undiscovered species to the earliest Homo species The human line would presumably stretch from an as yet undiscovered species at the point of divergence through Orrorin tugenensis, and from thence through Kenyanthropus platyops (?) and several as yet undiscovered species to the earliest Homo species who lived three million years ago or shortly thereafter

Ardipithecus ramidus (4.4 million years ago) much more widely accepted by the scientific community as a hominid than previous species lacks almost all of the advanced specializations of modern chimps such as knuckle-walking and brachiation may have walked upright What is all the talk in headlines about Ar. ramidus refuting the idea of a missing link? Although it is true that no-one claims humans evolved from chimps, there is still a general perception that the last common ancestor of humans and chimps was, if not a chimp, at least somewhat chimp-like (hence the idea of a 'missing link' between chimps and humans). This ramidus skeleton disproves that, according to the discoverers. As we consider modern humans, H. erectus, H. habilis, australopithecines and ramidus, their skeletons become less and less like modern humans, but they are not becoming more and more chimp-like. Au. ramidus lacks almost all of the advanced specializations of modern chimps such as knuckle-walking and brachiation. The hands and feet of ramidus, and possibly our common ancestor with chimps, seem to have been relatively unspecialized, and in some ways more similar to our hands and feet than to those of chimps

Australopithecus anamensis (4.2 to 3.9 million years ago) direct evidence of bi-pedalism somewhat earlier than 4 million years ago these early hominids had developed upright walking prior to the disappearance of woodlands and forests in eastern Africa thickened enamel on teeth suggesting a diet of hard-to-chew foods is also a trait characteristic of all later hominids Our hominid ancestors acquired the ability to walk upright in a forest environment, not out on the savanna or in bush country Nevertheless, one aspect of the earlier hypothesis holds up.  When conditions in Africa did became drier and the forest retreated, bipedal hominid species had the physical “equipment” to move out and colonize the new environments.

Three million years ago was a critical period in the development of the hominid species, and ultimately, of human beings http://www.wsu.edu/gened/learn-modules/top_longfor/timeline/01_notes_definitions.html

Australopithecus afarensis (3.6 to 2.9 mya) “Lucy” Finding Lucy (4:33) fragments of 320 individuals of have been discovered the earliest species for which we have reliable brain and body size estimates, thanks to a rich fossil record for the species probably inhabited the savannas and open woodlands where they likely found fruits, seeds, and roots Most scientists consider this evidence that afarensis was still partially adapted to climbing in trees, others consider it evolutionary baggage.

"Lucy" in comparison with a modern human female knee and pelvic bone structure of were very humanlike, leaving no doubt that A. afarensis walked upright Fossil evidence of bipedalism (3:06) Latoli footprints (3:20) "Lucy" in comparison with a modern human female

Kenyanthropus platyops (3.5 to 3.3 million years ago) small ear holes and advanced traits like a relatively flat face and small molars may put it in the direct line to modern humans humans may have emerged from a completely different line descending from O. tugenensis and/or K. platyops, as the Leakeys believe many anthropologists will continue to withhold judgement on its validity and significance Claimed that this fossil is so severely distorted that it cannot be reliably identified, and that it may merely be a Kenyan version of Australopithecus afarensis For example, if this find is what its discoverers claim it is, then east Africa was home to more than one species of early hominid three million years ago), and the hominid family tree has more branches than anticipated

Australopithecus africanus (3 to 2 million years ago) pelvis is more human than apelike shape of the jaw is like that of humans, and the size of the canine teeth is further reduced compared to afarensis

not regarded as being in the ancestral line to modern humans Paranthropus aethiopicus, robustus and boisei (2.7 to 1.4 million years ago) evolved “along side” early human species and undoubtedly interacted with them not regarded as being in the ancestral line to modern humans small brained (400-550 cc) compared to human species “chewing” specialization in contrast to our ancestors, that evolved as omnivores with a taste for meat massive grinding teeth and jaws

Members of the Genus Homo most important characteristic of the genus Homo is larger brain size compared to other hominids the association of cultural artifacts and tools H. rudolfensis Homo habilis Heidelbergensis Neandertalensis

two current theories Parallel Evolution Theory several dispersed populations of Homo evolved into Homo sapiens at roughly the same time

Radiation theory modern human beings arose in Africa about 200,000 years ago and migrated out of Africa called the “Out of Africa” theory more recent theory based on genetic evidence

Homo rudolfensis (2.3 to 1.9 million years ago) oldest, fairly complete human skull yet discovered mix of characteristics makes this individual a good candidate for a transitional species between the australopithecines and the genus Homo

Homo habilis (2.3 to 1.6 million years ago) "handy man", was so called because of evidence of tools found with its remains the bulge of Broca's area, essential for speech, is visible in one H. habilis brain cast, indicating that the species may have been capable of rudimentary speech Habilis has been a controversial species. Originally, some scientists did not accept its validity, believing that all habilis specimens should be assigned to either the australopithecines or Homo erectus. H. habilis is now fully accepted as a species, but it is widely thought that the 'habilis' specimens have too wide a range of variation for a single species, and that some of the specimens should be placed in one or more other species. One suggested species which is accepted by many scientists is Homo rudolfensis, which would contain fossils such as ER 1470.

Homo ergaster (2 million to 1.5 mya) the most complete skeleton on any early hominid species male 11 to 13 years of age first Homo species to have roughly the same body proportions as modern humans

Homo erectus (1.8 to 0.3 million years ago) the most long-lived species in the genus Homo may have been the first to leave Africa remains are dispersed across three continents larger brained individuals exhibit a 50% increase in brain size over earlier hominids For the lay person interested in the subject of human evolution, rather than sort through the positions in the classification wars, it is probably more instructive to leaf through one of the lavishly illustrated books on human evolution (e.g., From Lucy to Language, by Donald Johanson and Blake Edgar [Simon & Shuster, revised edition, 2006].  Many Homo erectus remains have been found in eastern and southern Asia.  Stone tools dating to 2.25 million years ago have been found at Renzi cave in central China, upsetting all the conventional time lines. (This date is contested, of course.) Individual specimens of Homo erectus vary widely but trends are visible over time. These artist's reconstructions of three faces from skulls show variations over a period of about a million years

probably the first species to use and control fire decrease in sexual dimorphism a mutation slowed down the growth of the fetal brain   this also slowed our whole maturation process modern humans have the longest juvenile stage of any life form This shift in the size ratio of the sexes and the slowing of our maturational process may be among the most important milestones in human development.

Homo heidelbergensis (600,000 to 200,000 years ago) more robust and muscular than modern humans evidence that it hunted and butchered the large mammals of the period—elk, bison, horses, rhinos, and even mammoths at least estimated 28 individuals 5,000 bones found

Homo neanderthalensis (250,000 to 30,000 years ago) scientists long believed they were a closely related sub-species of modern humans and for a time classified as Homo sapiens neandertalensis modern human DNA differed more than expected from the Neanderthal DNA http://www.pbs.org/wgbh/nova/teachers/evolution/homo-sapiens-vs-neanderthals.html (4:58) average Neanderthal brain was slightly larger than that of modern humans, but this is probably correlated with larger body size in gender

arm and leg bones are approximately twice as thick as ours, suggesting both their immense strength and the rugged conditions of their existence for about 70,000 years, Neanderthals roamed Earth with modern Homo sapiens The left arm is completely withered from an early injury or disease. The fact that the individual with an injury this severe survived into a relatively advanced age implies the existence of a complex social life in which other group members would have shared food and other life-supporting tasks

H. floresiensis compared to modern human Homo floresienses (95,000 to 13,000 years ago) the Little People of Flores has been described as one of the most spectacular discoveries in paleoanthropology in half a century—and the most extreme human ever discovered scientists theorize that a group of H. erectus somehow found their way across this barrier and colonized the island.  Over time, the usual “island effects” by which large animals tend to become smaller and small ones larger affected this isolated population may be dwarf sub-species of Homo erectus http://www.pbs.org/wgbh/nova/evolution/little-people-flores.html (11:42) H. floresiensis compared to modern human

Homo sapiens (sapiens) (200,000 years ago to present) hunting elaborate tools cave art symbolic artifacts ceremonial practice