Sociology lesson1b human evoulutionPresentation Transcript
Homo The Genus Homo is were we find ourselves, this branch contains the most advanced primates to have ever lived. These species were the first to make stone tools and proliferate large areas, culminating in Our species which has become the dominant species on this planet. Highlighted are five major species within this genus.Homo habilis Homo rudolfensis Homo erectus Homo sapiens Homo neanderthanensis
Australopithecus The Australopithecines are around the oldest ancestors to the Homo lineage. Highlighted are four Australopithecus species. These species mark the possible beginnings of our kind.Australopithecus afarensis Australopithecus africanus Australopithecus garhiAustralopithecus anamensis
Paranthropus The genus Paranthropus is a dead end along the evolutionary tree toward Homo sapiens. These robust Hominids are very similar and lived at a similar time as the Australopithecines, leading many to rename them as Australopithecus Robustus. Highlighted are the three main Paranthropus speciesAustralopithecus Robustus Australopithecus Robustus robustusaethiopicus Australopithecus Robustus boisei
New Hominids This is a group of recently discovered hominids that do not immediately fall into one of the three main groups.Kenyanthropus platyops Sahelanthropus tchadensis Ardipithecus ramidus
H. habilisHomo habilis, or “handy man” is one of the oldest of the our genus. Itsfirst naming was in 1964, after its discovery in 1960, and it wasattributed to the earliest stone tools in Olduvai. With larger incisors,brain case, and shape and size of the hand, it was determined thatthis species had more in common with the genus Homo thanAustralopithecus. Dates from 2.2 to 1.8 million years ago.
H. rudolfensisHomo rudolfensis is a highly debate species. This is due to its ageand features that some say are more consistent withAustralopithecus. Discovered in 1972, its large brain size led to itsdesignation as a member of the genus Homo. Most of the debatesare based on the fact that there are no post cranial remains in orderto compare it with other specimens, namely if its large dentition arein correlation to a large body. It has been said that this may be alink from Australopithecus to Homo.
H. erectusFor many years only two species were attributed to the genus Homo other thanus, Neanderthals, and Homo erectus. There is a wide body of specimens thatare attributed to erectus from all over the world, including Africa, Asia, andEurope. Many call for a division of these based on geography, as there aresubtle difference between these populations. These designations would split theEuropean into heidelbergensis, the early African as ergaster, and leaving themost recent finds to be called erectus. Originally named in 1894, after the 1891discovery of a mineralized skullcap. Now linked to material from 1.9 millionyears ago up to .2 million years ago, this species is the most far ranging hominidspecies other than ourselves. Due to the time, and indeed the place, where wesee this species ends many believe H. erectus to be the direct ancestors of H.sapiens
H. neanderthanensisThe Neanderthals developed as a species about the same time as fullymodern humans. It is believe that this divergence happened about 700thousand years ago, from an African population, most likely descended fromH. erectus. Neanderthals had very few major difference from physicallymodern humans of the time. They were typically shorter and stockier that H.sapiens, and somewhat larger brains, suggesting that they moved out of Africaand into the colder European climate earlier than H. sapiens, leading todifferentiation due to climate shift. Neanderthals used this time alone to spreadacross much of the European continent unopposed for several hundredthousand years. Their down fall likely came from direct contact andcompetition with H. Sapiens. Genetic studies have shown that Neanderthalsdid not contribute to the modern gene pool.
H. sapiensFully modern humans arrived on the scenes about 200 to 250 thousand yearsago. They came out of Africa and began to spread across lands that had beenpreviously and currently occupied by Neanderthals. Fully modern humanstook over as the last of the Neanderthals and some late ranging populationsof H. erectus were forced into extinction. With out competition, fully modernhumans were able to proliferate across the landscape in ways no otherspecies has ever done. In a geologically short period of time, .1 million yearsor so, H. sapiens have become the dominant species on this planet. Thedifference that drove us to this point has been our use of technology,language, and culture. Beginning with the flint arrowhead, and ranging to thesuper computer, our species has been at the forefront of technology, leadingus to the top of the food chain.
A. afarensisQuite possibly the best know early hominid species, due to the extent of samplesattributed to the species as well as the nearly complete specimen of “Lucy”, whichis one of the most complete specimens of an early hominid. This species in one ofthe first to be shown to be an obligate biped, due to the arrangement of the bonesand the location of the foramen magnum. This species date from 3.9 million to 2.9million years ago, making this one of the most successful hominid species. Likeother early hominids, this species shows an ape-like face and dentition with amoderate sized brain case, and some advanced features as well. The famousLaetoli footprints are attributed to afarensis due to their proximity to afarensisspecimens as well as the approximate age of the footprints.
A. africanusFirst named in 1925, many disputed the find as a possible humanancestor, as many expected to find true hominids in Europe, not inAfrica, and appear to have a modern cranium with an ape-likemaxilla and jaw. This was the first specimen to be namedAustralopithecus, which means “walking man” in a combination ofLatin and Greek. Dates to approx. 2.9 to 2.4 million years ago.
A. anamensisDiscovered in 1965, this fossil hominid was not recognized as aseparate until more specimens were found in 1994. originally classifiedas a specimen of A. afarensis, it was reclassified in 1995 as a separatespecies due to differences in dentition form the typical afarensisspecimens. Dates to approx. 4.0 million years ago
A. garhiThis Australopithecine species was named in 1999, to much controversy.Dating from 2.5 to 2.0 million years ago. The lasting argument for this toremain a separate species is the fact that it come from East Africa, wherevery few fossils are found during this period.
A.R. aethiopicusThe oldest of the Robust Australopithecines, this species has the mostprominent cranial crest of all these robust species. Aethiopicus is dated toapprox. 2.5 million years ago. This is a much debated species as so fewspecimens are attributed to it, and many will say that is an early form ofother Robust Australopithecines.
A.R. boiseiDiscovered in 1959 in the Olduvai valley, boisei is the “youngest” or mostrecent evolution of the Robust Australopithecines, dating from approx.2.3 to 1.2 million years ago. This is one of the most successful robustspecies both by longevity and by the spread of the species. This appearsto be a highly specialized species with a very large mandible anddentition most likely used for hard foods such as nuts, berries and roots.A sudden change in environment may have caused their extiction.
A.R. robustusA.R. robustus was first discovered in 1938. Living at the same time and atthe same region as A. africanus, many have speculated that theseindividuals may have interbred. Many theorize that these competingspecies may have specialized and grown apart due to competition forfood and other resources. They are still considered by many to beseparate species, due to the large number of differential traits. Like allrobust australopithecines, robustus has a large and prominent crest atopthe skull that is used as muscle attachment for its enlarged mandible.
Sahelanthropus tchadensisLittle is known yet of this recent find, other that it was found in a layerof strata typical of the oldest hominid species. Yet unlike the oldesthominid fossils, tchadensis has many more modern features. Couldthis be the proverbial “missing link”?
Kenyanthropus platyopsDiscovered in 1998 on the shores of Lake Turkana, and first described in 2001,Kenyanthropus lived approx. 3.5 million years ago. This reconstructed skullshows a full range of traits that are both advanced and primitive, placing it in theline to be a possible human ancestor.
Ardipithecus ramidusOriginally placed with other Australopithecines, this hominid has recently beenplaced into a genus of it’s own due to features not seen in other Australopithecines.Living between 4.5 and 4.2 million years ago, this could end up being one of ourearliest ancestors. Mandible and post cranial skeleton fragments found.