Bipedal Hominid and Quadrupedal Apes: Muscle and Skeletons

Bipedal Hominid and Quadrupedal Apes Muscle and SkeletonsDifferences mingled with the hip build and musculature of two- animal backsideed hominian and quadrupedal apes.Ilium kindsreduced height, relative wideness (it is historic in bipedal posture, because the encumbrance of the ashes does non concentrate onto the spinal cord only).Orientation of blade (the bender and the medio lateral pass penchant of the iliac blades help the Glutei medius and minimi to act as abductors and they mountain overly assist in support of the trunk. This curved execute similarly helps in balancing the swiftness body during locomotion, because the external and internal oblique muscles conquer to the iliac crown).Acetabular margin and the well-developed anterior inferior iliac spurring (AIIS) reflects the bipedal locomotion. Rectus femoris takes its origin here, that extends the tholepin at the knee. Rectus femoris is in truth important in some of the leaping and clinging prosimians , as the galagos and lemurs, because Rectus femoris is a leaping muscle in them. Neverthe slight, in apes, on that point is no king-size AIIS. AIIS is alike a place for the iliofemoral ligament in worldly concern that prevents the hip knock from overextending.ApesThere is no S-shaped curve visible at the iliac visor and the eyeshade projects laterally. Therefore, the iliac fossa orients anteriorly and the gluteal heighten projects hindquartersly. This penchant keeps the trunk in an upright position during sitting or squatting. In case if they want to bye bipedally, the Glutei medius and minumi muscles medially rotate the flexed thigh at the hip plot of ground in homophile beingss they abduct the extended thigh.The persistent iliac wind is an adaptation to climbing. Latissimus dorsi origins from here and inserts into the humerus. Because this is one of the most important climbing-muscles, the longer the iliac crest is, the better aid is in climbing.The otic bug out and the iliac tuberosity atomic number 18 polisheder in apes. It is primarily because of the fact that their weight does not focus on their pelvic domain and lower limbs (hind limbs).IschiumHumansIschial tuberosity is an attachment for the hamstring muscles (Biceps femoris, Semitendinosus, Semimembranosus and adductor magnus hamstring part). At a superior pressure during the bipedal posture, the posterior part of the sacrum elevates, and pulls upwards the ischial tuberosity. The ischial tuberosity which is located just below the spacious sciatic notch reflects the bipedalism.ApesLong ischium.The ischial tuberosity is wider in apes than it is in pieces and it does not look so pulled-up in apes. The ischial tuberosity lacks the facets for the hamstring and adductor muscles.PubisHumansPubic crest and pubic tubercle atomic number 18 important in bipedal locomotion as well, because the pubic crest serves as an attachment for Rectus abdominis that supports the guts and pubic tu bercle is associated with the inguinal ligament, which helps in supporting the trunk.The iliopubic eminence is the divider of the Anterior Superior Iliac grit (ASIS) and the AIIS. Here takes place the iliopsoas muscle that helps in flexing the hip and supporting the upper body on the hip enounce.ApesApes lack all these tender characteristics at the pubis they do not build a pubic crest nor tubercle, and because their pelvis orient differently, their ilipsoas groove and iliopubic eminence argon missing.The pubic symphysis in apes are usually fuses together, while it only rarely happens in humans. cotyloid cavityHumansThe orientation of the acetabulum is inferior-lateral-anterior. The superior margin of acetabulum moldiness cope with the biggest weight/pressure, it developed a very thick cartilage, so did the cutting edge of the femur. This is called laubrum. Very strong, Z-shaped, ligaments are present here. The depth of the acetabulum can tell us a lot some the mobility of the hip colligation. If the acetabulum is shallow, it reflects to a greater extent flexibility. The acetabulum in humans is shallow compared to many of the African apes ( scarcely chimpanzees), solely it is deep compared to the orang-utans.ApesThe ligaments are weaker than in humans.Sacrum, coccyxHumansThe human sacrum contains five fused vertebrae averagely. However, it can be varied between cardinal and six. The coccyx stands from four fused vertebrae, usually.The sacrum in humans is wider than in apes and it is not so long as an ape sacrum. This unique shape is very distinctive regarding to bipedalism. The wider sacrum mover more distance between the sacroiliac joint, which helps in transferring the weight and the pressure from pubic symphysis. A wider distance at this joint also means a larger birth-canal.ApesIn apes and monkeys the number of the fused vertebrae of the sacrum and coccyx may vary from species to species.The shape of the sacrum is not so wide and more elongated. It let ons that they do not support so ample weight on their pelvic region as do the humans.FemurHumansThe human femur is longer than that of an ape.The lateral condyle in humans is more prominent.The bicondylar surface is larger in humans than in apes. It is because of the centre of gravity of the body.Apes median(a) condyle is larger in apes.More flexibility at the hip joint.B, Actions of muscles at the knee and mortise joint joints during bipedal locomotion. Observed features in ancestral hominid fossils.Extensors of the leg at the knee jointTensor fasciae lataeQuadriceps femoris muscles (Rectus femoris, Vasti lateralis, medialis, intermedius)flexors of the leg at the knee jointSartoriusGracilis (also can assist in medial rotation)Hamstring muscles (Biceps femoris it is also the lateral rotator of the knee joint, Semimembranosus, Semitendenosus they also medially rotate the knee joint when the leg is flexedgastrocnemiusPopliteus (weak flexor, but it is a medial rotator of the leg)PlantarisMuscles that act at the ankle (taloshinbonel) jointTibialis anterior (dorsiflexion)Extensor hallucis longus (dorsiflexion)Extensor digitorum longus (dorsiflexion)Peroneus tertius (dorsiflexion)Peroneus longus and brevis (plantar flexion)Gastrocnemius (plantar flexion)Soleus (plantar flexion)Plantaris (plantar flexion)Flexor digitorum longus (plantar flexor)Tibialis posterior (plantar flexor)Fossil recordsgenus Australopithecus afarensisThe shin and the fibula are quite interesting. We can observe adaptations to both woody and bipedal signs. This is called Mosaic syllable structure.The examined specimens AL 129-1b, AL 288-1aq and AL 333x-26). Ape- the like elements of a sudden border to the lateral condyle, in the first two specimens, in that location are features that general in the apes (under the epicedial there was the hollowed-out appearance) which means that the Tibialis posterior attached to the lateral side of the tibia instead of the posterior side. Other attachments such as semimembranosus and gracilis are also rather ape-like.Nevertheless, other A. afarensis specimens show bipedal characteristicsDistal articulation surface of the tibia (the tip off of the ankle joint and the tibia and fibula). But, yet again, there are ape-like features also on the distal part of fibula the guardianship of the articular facet, (orients distally rather than medially as in the juvenile humans), they have an anteriorly orientated peroneal groove on their fibulae while it faces laterally in newfangled humans. The A. afarensis Lucy (AL 288-1) also owns these mosaic morphological features the posteriorly oriented distal tibial angle shows similarities with the apes, while in other afarensis specimens the angle is lateral, which is a human feature. The carrying angle at the knee joint also shows more similarities to the young human specimens. This can reveal an individual arboreal habit of Lucy, and a more developed bipedalism in the other specime ns. humanity habilisThe H. habilis specimens do not cause so many arguments than the australopithecines. They have more human like features in their lower legs and less ape-like features. Although, they do not lack these features ( locomote anterior border of the tibia, in humans the insertion bailiwick of the Flexor digitorum longus is bigger than that of the tibialis posterior it is quite the opposite in the habilis. The attachments of other muscles soleus, popliteus show sort of a transition between apes and humans, etc.).The NeanderthalsThe fibula and the tibia are very ample, but bear the human characteristics.Q2, growth of the early hominid hoof itThe main characteristics of the human foot imply the forepart of the arches, the calcaneocuboid joint, the proportions of the major parts of the foot, the shape of the ankle-joint and the fact that the hallux cannot be opposed.The arches in foot are quite unique, the apes do not have arches (they have only one arch, the tran sverse arch). In humans, apart from the plantar aponeurosis, there are other ligaments that aid in having these arches the stick out ligament, the compact plantar ligament and the long plantar ligament. The length of the distal digits of the toes are ofttimes shorter in humans than in apes, however, the size of the big toe is slightly the same.The foot of Australopithecus afarensis, such as in the leg, shows mosaic morphology. It means that certain features are similar to the juvenile humans, while others share similarities with the apes.The human-like morphology the talus which also has both human and ape characteristics together with the tibia and fibula, shows a more human like joint at the talotibia. Although, the shape of the talus is rather ape-like. Other signs that reveal a more human appearance in the afarensis foot are the talar trochlear shape, the direction of the ankle joints axis and of the Flexor hallucis longuss groove which mention that the movements of the afarensis were very similar to those of the mod humans.The shape of the fifth metatarsals reveal a very similar cogency of dorsiflexion as it is present in modern humans. Their navicular bones in appearance are more ape-like, but the presence of the groove of the spring ligament proves that they might have similar arches than the modern humans have. The possibility of the bipedal locomotion can be traced down also by the human-like lateral cuneiform, although, its hook makes it look more ape like.Nevertheless, the ape-like curves of the phalanges suggest that they might be arboreal. The calcareous also have both human and ape like features, the medial cuneiform is rather ape like, so is the first metatarsals round head.The foot of genus Paranthropus robostus has some(prenominal) human-like characteristics. These features are the following the hallux in all prob efficiency was adducted unlike in the apes where the big toe is rather abducted, the plantar ligaments suggest similari ties to the human foot, the first metatarsal suggests that it bore more weight than the apes because of its stout appearance, but other features on the first metatarsal bone reveal ape-like features, too. According to the article of Susman and Brain (1988, mentioned in Aiello and Dean), it is very likely that the Paranthropus robostus was bipedal but in a different way than the modern humans.The foot of the Homo habilisThe biggest argument is caused by the tarsal bones of a young Homo habilis (OH 8 from Olduvai Gorge), because some researchers do not sound off that the human characteristics of this specimens foot bones are good enough to be classified as humans. The elements of the foot show the signs of the bipedalism even those agree with this who do not think that this specimen deserves to be included into the Homo genus but, perhaps, in a expelly different way as it is seen in the modern humans. Another talus bone, the KNM-ER 813 from Koobi Fora, has less problems with its classifications, as it shows more similarities to the talus of the modern humans. The first metatarsal is the most robust, and the fifth metatarsal bone of the OH 8 is the second, while in apes the fifth metatarsal bone is the weakest. The size of the foot length of the OH 8 is also more similar to the structure of the human foot.The fossil record suggests that the opposability of the big toe of OH 8 is not present, but the adduction of it can be observed. The ability of grasping is also very likely, though.The foot of the NeanderthalsInterestingly, the evidences reveal that the opposability of the big toe might be somewhere between the modern humans and the existent apes. Others deny it, because of the more human characteristics in the tarsometatarsal joint, which can be varied on a great plate even in modern humans. Typical Neanderthal features are the short proximal phalanx of the big toe and the short neck of the talus.The attainable signs of the bipedalism in the fossil evide ncesApart from the bones of the foot other worn remains can reveal the erected body posture and the possible bipedal walking habits. A relative longer arm may be a sign of the arboreal purport-style, or partly arboreal living circumstances. Nevertheless, Lucy has relatively short fingers, not ape-like, long ones (JOHANSON-EDEY 1990) The shape of scapula and the orientation of the glenoid fossa also can help to answer this question. A small segment of an Australopithecus afarensis scapula suggests that its owner had a more ape-like in this question, than human like. In apes the glenoid fossa faces towards the cranium and this feature can be observed also in case of this fragment. A more complete scapula which derives from an A. africanus (Sts 7) can tell us more details about the possible functions of the pectoral girdle. This scapula looks very similar to the scapula fragment of the afarensis specimen (AL 288-1l), and they both bear more similarities to the pectoral girdle of t he apes, especially to the orang-utans. The ribcage has more ape-like characteristics in its appearance. The shape of the vertebral column, however, widens distally (the lumbar vertebrae are the widest) as it appears in humans, which is some other possible sign of the bipedal locomotion. The pelvic girdle shows more evidences for the mosaic morphology yet again. The iliac crest is rather human-like, although it is more elongated laterally and the acetabulum orients more anteriorly. by chance this is the reason why A. afarensis has a relatively very long femoral neck. The iliac blades direct interiorly, as well. The shape of the sacrum is very wide another human-like sign, however its posterior segment is not as curved anteriorly as it is in the modern humans.According to Johanson (JOHANSON-EDEY 1990), Lucys pelvis is adapted to the bipedal locomotion as well as to the possibility to give life to large-headed babies, as her pelvis is so wide.All these features make likely that the A. afarensis could walk bipedally, but in a more complicated way. The anteriorly approach acetabulum could result a very heavy bipedalism. On the femoral head, we can observe a stronger fovea than it is on the femoral head of the modern human.In quadrupeds the tibial tuberosity is more rounded and less sharp. The harshness of the tibial tuberosity is a more human (or bipedal) characteristic. This sharpness can be observed in Lucy, although her tibia looks more robust compared to the very tall juvenile, the Turkana boy (H. erectus).In proximal femur of the Australopithecines, there are about the same number of similarities to humans (the varied presence of the intertrochanteric line and the Obturator externus groove) than to chimpanzees (the small femoral head and the non-flaring greater trochanter) and the unique features (long femoral neck, compressed femoral neck-cross section), the more similarities to humans in the question of the distal femur (the high/very high bicondylar a ngle, the elliptical shaped lateral epicedial profile), and its own unique phenomena in the epiphysis shape and symmetry, but the femoral shafts more similarity to the chimpanzees gives us a very eclectic sentiment about the possible locomotion of the Australopithecines.As I wrote in the 1B question, the foot of the Australopithecines show very varied picture as well. It reveals both human and ape like features such as almost everything else in the Australopithecus skeleton. The more human like elements of the foot include the human-like ankle joint, the ability of a better dorsiflexion, the expanded base of the fifth metatarsal, the wide os tarsi fibulare and the presence of the longitudinal arch.On the other hand, there are several ape-like characteristics, like the shape of the phalanges, the tuberosity of the calcaneous has an oval orientation, also has a huge peroneal tubercle, the already mentioned ape-like shape of the hook of the lateral cuneiform bone, and the rounded he ad of the first metatarsal.Summarising, the mosaic morphology in the Australopithecines are very strongly present, they share similarities to the humans, as well as to the apes, but they also developed own features. It is very likely that they were adapted to the bipedal locomotion, but not in a modern human way.The essay has been written by using the following books as a guide-lineAiello and Dean, 2006 An Introduction To Human Evolutionary Anatomy, reprinted in 2006, Elsevier Academic Press, LondonThe materials during the Demo-sessionsAndJOHANSON-EDEY, 1990 Lucy The Beginnings of Humankind, Penguin Books, London, 1990.