Advantages of Bipedalism - Assignment Example

Anthropology 130g . Questions A) If a creature is bipedal then certain adaptations seen in the knee joint, especially in the valgus angle. In thefeet the hallux ( big toe) will be completely abducted. . As well as in the limbs there are indicators found in the cranium with a fully inferior foramen magnum, the opening in the base of the skull through which the spinal cord passes (Wren , 2006) .There are also differences in the pelvis with a broadening of the sacrum in order to better support the contents of the abdomen. Advantages of bipedalism include the fact that the hands are free to carry things, to use weapons and tools and so on, or to allow for easier climbing. The creature also has its eye line elevated, so it can see further, above low growing plants, which is an advantage when seeking food, hunting or even avoiding enemies. On the other hand the eyes are further form the ground so further from tracks and low growing berries or other food sources, ye t at the same time leaves the hands free to forage. According to the University of Austin (2007) bipedal adaptation allows the body to cool more efficiently in hot temperatures, a process referred to as known as thermoregulation. Adopting a tall upright posture means that less of the creature’s surface area is exposed directly to the sun’s heat. At the same time a greater surface area is exposed to cool, moving air. This would however be a disadvantage in a cooler climate if clothing was not used. This rising up does however make the creature more visible to prey. Nor does it necessarily make the creature able to run faster, especially over uneven ground as he is somewhat less stable than if on all fours. . B) According to the Columbia Encyclopedia entry Australopithecus anamensis, or whom many specimens have been found over a wide area, was bipedal , but may not have always been fully comfortable being so, as they were also adapted to be tree climbers. They mention similarities to chimpanzees and gorillas, both of whom are capable of bipedalism , but who also walk on all fours. Some of the species found are though in very fragmented pieces. According to the New World Encyclopedia entry ( 2008) the pelvis structure and feet of the specimens found are almost indistinguishable if compared comparison to modern humans, although other parts of their bodies were very different, with very long arms. Australopithecus afarensis left behind the earliest known bipedal footprints in Laetoli, preserved by the erupting lava of a volcano in what is now northern Tanzania (Zaitsev et al , 2011) 2) a) Orrorin tugenensis. This creature has had fossils found in Kenya which show evidence from built up femurs , which are evidence of early bipedalism , although this was not their only means of mobilisation ( Smithsonian , 2014) b) Sahelanthropus tchadensis combines features of the great apes and of humans. Although full skeletons have not been found, there are cranial specimens a spinal cord opening ) foramen magnum) directly underneath the skull.It is found no further forward in any other hominid creatures or apes except modern humans. In the non-bipedal apes this opening is further back. ( Smithsonian , 2014). c) Ardipithecus kadabba . There is relatively little fossil evidence of this species , but a hallux ( big toe) found is broad and strong , and so capable of the push off needed for bipedal mobilisation. This is however quite minimal evidence and no pelvic or leg bones have been found to back it up ( Smithsonian, 2014) . d) Ardipithecus ramidus . This specimen has foot bones which seem to be from a half-way point between bipedalism and tree climbing . It lived in wooded areas, which goes against the usual theory that bipedalism evolved in the open savannahs of Africa ( Smithsonian , 2014) B)The arguments put forward are based mainly on Orrorins relatively thick-enamelled molars, which Pickord and Senut saw as being different from the thinner -enamelled molars found in Ardipithecus, but at the same time they lacked the enlarged teeth of Australopithecus ( Hawks, 2008) . Hawks does no t necessarily agree with their views as they take no account of possible reversal i.e. that creatures with larger teeth might eventually have off spring with somewhat smaller dentition. 3) A.Early Pliocene. According to Ungar and Teaford ( undated) the thin enamel found on dentition from this period in African specimens suggests a diet which is harder and more abrasive as compared with their ancestors. O’Neil ( 2012) sees this creature as a transitional one. These creatures were large boned and robust. As found by Robert Broom in 1938 ( cited by O’Neill A. afarensis, is from the Afar region of Ethiopia, and A. africanus from the far south of Africa. B) Middle Pliocene . Jacobs (2000) describes how the climate had changed, becoming much drier. This meant fewer plants and so those species which were entirely vegetarian tended to fail, or else migrated into areas of Eurasia. Jacobs describes how during this period the brain case became bigger and bipedalism developed. Leakey et al place A. afarensis in this period, so these are large boned and bipedal . C) Late Pliocene A. robustus, found in Eastern Africa , is often given its own name Paranthropus ( Smithsonian 2014) this very robust species was known to have had a very varied diet, which aided its survival. They had large cheek muscles and massive teeth and were able to grind foods which other species might find too fibrous. 4) a) What features distinguish Homo erectus from a) Homo habilis,. These two species co-exisited (Naveeen , 2011) H.erectus was taller and more robustly built. It is closer on the evolutionary tree to humans than H.habilis. It was also more intelligent, and had larger teeth. It stood in a more erect posture. b) Homo georgicus (Dmanisi) is distinguished by where it was found in Georgia,and it has the smallest cranium of any non-African hominids except h. floresiensis (Talking Stone, undated) . It is therefore further away on the evolutionary tree than homo erectus. ( c) Homo erectus, as compared to Homo sapiens of which it is an ancestor , had heavier brow ridges and less of a barrel shaped rib cage. They had an occipital torus or bulge as did Neanderthals and more orthognatic faces, that is with upper jaw which are in a vertical relationship with the rest of the face. Their brain cases sit rather lower than in homo sapiens and they have a sagittal keel (Jermain et al, 2008). 4) a) Over time home erectus developed a larger brain. This required more energy, and so a diverse diet, including animal protein was needed. In East Africa it is known that they were able to use advanced tool making techniques to make hand axes, and in Georgia they used chopping tools. . b) In Asia homo erectus is thought to have been able to make rafts in order to travel across oceans ( Evidence, undated) . c) Homo heidelbergensis, who lived in Europe and possibly in China in colder climates, so their bodies were shorter and stouter. They were able to control fire in hearths and would gather together in groups to hunt animals with spears ( Smithsonian , 2014) d) When homo sapiens first reached Europe they also had relatively high foreheads, smaller faces than Neanderthals and pointed chins.They were successful hunters , and this led in time to the extinction of several of the larger species such as mammoths. They used personal ornaments, bone tools and colourants, just like more modern people( Phys.Org. 2013) 5) A) In 2012 Pablos et al reported new fossil finds at Gran Dolina ,Spain. They are several foot bones. They are similar to those found elsewhere which date from the Middle Pleistocene age. Some of the bones are similar to those of modern humans , but others are not. The claim made by the finders is that this is an as yet unknown species Homo antecessor, ancestor of both Neanderthal and homo sapiens ( Rose 1997). B) At Sima del Elfante the fossils found are the earliest evidence to date of humans in western Europe. The fragments of a jawbone and teeth found have been dated 1.1–1.2 million years ago ( Encyclopaedia Britannica , 2014) 28 skeletons of Middle Pleistocene hominins were found by a group led Dr Juan-Luis Arsuaga . Homo heidelbergensis is believed to have lived from 300,000 to 600,000 years ago. .There is evidence of funeral rituals at the site, suggesting that these people may have hand some belief in an afterlife ( Modern Human Origins, 2014). C) According to the web page ‘Homo heidelbergensis’(undated) that species is an ancestor of both Neanderthals and modern humans. They had compact body shapes adapted to cold climates as did Neanderthals and both are heavy boned. Neanderthals emerged about 200,000 years ago. Remains have been found all over Europe. They were very and made and used a diverse set of tools. They could control fire, made themselves shelters and clothing. They were omnivores and hunted animals. At times they made objects which were simply symbolic or ornamental. They held funerals and even decorated graves. The last Neanderthals lived about 28,000 ago in Europe ( Smithsonian, 2014) 6) A) Homo sapiens idaltu was found at Herta in Ethiopia and has been dated at 160,000 years ago. Its cranial capacity is bigger than that of homo sapiens, but other wise is very close to modern humans. Although it is often said that these three form a lineage , homo sapiens is so close to modern humans, it could possibly be a side branch on the primate tree. Homo rhodesinesis was very robust with large brow ridges ( Bradshaw Foundation , undated) so much broader and heavier in the face than homo sapiens. It has been hypothesized that it is an ancestor of homo sapiens idulta , and so of modern man, but they are so like modern man they could be a side branch, especially when one considers that the oldest homo sapiens sapiens species were also found in Ethiopia ( Brown and Siegel , 2005). B) According to Brown and Siegel ( 2005) the oldest modern human skeletons were found in Ethiopia. They are dated as being from 195,000 years old. The ancestors of homo sapiens , homo erectus, migrated out of Africa possibly 1.5 million years ago ( BBC World Service , undated). Because the fossil record is as yet incomplete it is impossible to be exact as to when homo sapiens sapiens actually left Africa, but a possible date is less than 50,000 years ago ( Quintana –Murci et al, 1999). In the Upper Paleolithic period many of the activities we associate with the modern age came into place- early music making, tool making and use ( Essay Web, 2008). They made jewellery and produced art, by carving into soft stone. C) Homo floresiensis is the most recently discovered early human species, dated at from 95,000 and 17,000 years ago. The name comes from where it was found on the Island of Flores, Indonesia. They are very small, only about 3 feet 6 inches, with very small brains, yet they were capable of using stone tools to hunt large prey, and to deal with predators. It is possible that they could control fire. They were shocking because it was thought that, isolated on a small island, they gradually dwarfed, almost the opposite of evolution as it is usually considered to progress. There is however another possibility , that their ancestors were already tiny when they landed on the island ( Smithsonian , 2014). There are various ideas as to where they fit in the primate ancestral family tree. One idea is that they are a genetic mutation of modern humans because of disease. Others think they evolved from homo erectus, but yet others believe they evolved from some other early primate. References BBC World Service, The story of Africa: Early History, undated, 20th April 2014, Bradshaw Foundation, Homo rhodesiensis, undated, 20th April 2014, Brown,F. and Siegel, L.,The oldest homo sapiens, 2005, 21st April 2014, Columbia Encyclopedia, Australopithecus, 2013, 20th April 2014 Encyclopaedia Britannica , Sima del Elefante , 2014, 21st April 2014 Essay Web, The Paleolithic Age, 20008 , 21st April 2014 Evidence, Tracing Fossil Finds : a hominid timeline, Undated Hawks, J. , The Orrorin identity, 2014, 21st April 2014 Homo heidelbergensis , undated, 20th April 2014 Jacobs, J., Paleoanthropology in the 1990s, 2009, 20th April 2014 Jermain, R., Kilgore. L., and Trevathan,W, Introduction to Physical Anthropology. 2009-2010 ed. 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