Human Origins The Origins of Bipedalism Essays

Human Origins The Origins of Bipedalism Essays Human Origins The Origins of Bipedalism Paper Human Origins The Origins of Bipedalism Paper Essay Topic: Sociology Upright walking is far more complicated than many people think. It requires a number of highly specialized adaptations that have taken millions of years to evolve. It is part of what defines the human race, because there is no other organism on the planet that shares this group of skills. An understanding of the origins of bipedalism is therefore the key to answering many questions about human nature. To understand the evolution of bipedal locomotion, one must first look to our non-upright past. Although we know very little about the common ancestor of apes and hominids, we can still gain some idea about how it might have moved. Similarities in the bone structure of ape and human wrists, arms and shoulders lead some scientists to believe that our common ancestor was most likely a knuckle walker.i From this conclusion, we can examine the morphological distinctions between the two forms of locomotion by comparing humans and knuckle walking apes. One major morphological difference between apes and humans is the bicondylar angle of the femur. The human femur is angled inward about 10Â °. In gorillas, the angle is only about 1Â °. This greater bicondylar angle is specially adapted for bipedalism. It allows humans to keep their center of gravity more directly over the legs while walking. The lack of this angle in gorillas is due to the fact that their weight can shift to their arms and back to their legs while walking.ii The morphology of the foot has also changed to accommodate bipedal walking. The foot of an ape has a large gap between the last toe and the other four and is relatively flat on the bottom. Humans have gained a reinforced heel and an arch to absorb shock. The toes have become aligned to point forward, allowing for a smoother ending to the propulsive phase of the stride.iii Other adaptations for bipedalism pertain to the location and function of muscles. The gluteus maximus in apes is located at the side of the hip, in order to pull the thigh outward. In humans, it is at the back of the illium, pulling the thigh back during the propulsive phase while walking and running.iv Skeletal changes that have occurred due to bipedalism include the flaring out of the illium, the s-shaped curvature of the vertebral column, and the repositioning of the foramen magnum. The iliac blades are shorter and wider, forming a basin that cups and protects the organs. Additionally, they can better support the direct pressure of upright posture. The s-shaped spine centers the weight of the upper body over the pelvis. This is in place of a quadrupeds straighter spine. The foramen magnum is repositioned from the back of the skull to the base of the skull. This change allows humans to look forward while upright.v All of these changes occurred over the course of many millions of years. We understand how they occurred, but there are many different theories that attempt to explain why. Some of the most compelling come from Peter Wheeler, C. Owen Lovejoy, and Kevin Hunt. Wheelers thermoregulatory theory proposes that bipedalism originated because an upright stance allows the body to cool more effectively than that of a quadruped. The theory is based on the idea that at noon, in an open area such as the seashore or the savannah grasslands of Africa, an upright individual would be exposed to more wind and less sun than a quadruped. The wind would facilitate cooling through sweat evaporation, allowing the individual to be much more efficient. This would allow upright individuals to exploit the midday niche while facing little competition from quadrupeds, who are more susceptible to overheating.vi Lovejoys behavioral model for bipedalism centers on the theme of a family. Instead of both parents taking care of their offspring and getting food for the family, bipedalism would allow one parent to travel long distances while carrying food. The other parent would be left to take care of the offspring, increasing the chance of survival. The larger area that can be exploited by a bipedal individual allows for more available food for that individuals family. This also increases the survival rate of their offspring, essentially selecting for bipedalism.vii Lovejoy backs his theory up by connecting it to human sexual behavior. He claims that the monogamous mating structure of this model accounts for the elimination of any sort of mating season in humans. Mating seasons exist so that mating can coincide with a time when energy and resources are not needed for offspring. Since bipedalism allows families access to more resources, copulation can occur at any time.viii Hunts postural feeding hypothesis suggests that bipedalism originated in quadruped feeding activities. Essentially, the terrestrial quadrupeds that could stand up were able to get the most food. His hypothesis is backed up by studies of chimpanzee behavior. According to Hunt, Eighty per cent of chimpanzee bipedalism was during feeding.ix Hunt claims that retained morphological aspects of arm hanging helped the early quadrupeds reach for food. He explains evidence that these traits, including long arms and fingers, were present in australopithecines.x Although these theories all seem to be solid and well based, they each contain at least one implausible aspect. Wheelers thermoregulatory theory does not apply to enough geographical situations. This limitedness only becomes worse when the areas he proposes are considered rationally. For example, even the African savannah had tall vegetation. Bipedal hominids that walked by some dense shrubs or even tall grass would be blocked from the wind. Additionally, the bipedal advantage only lasts for a few hours in the middle of the day. The benefits do not last long enough to really affect the efficiency of an individual. It is therefore unlikely that the thermoregulatory theory was entirely responsible for bipedalism. Lovejoys theory is the most probable of the three. His claims make a lot of sense because of how he ties in other aspects of human development to bipedalism. The only problem that isnt addressed in his article is how women developed bipedalism. According to his theory, males went out to provision for the family while females stayed behind and took care of the babies. Hunts theory makes interesting points, but it conflicts with more sound evidence that early hominids and apes evolved from a knuckle-walking quadruped. It is also much more vague than the other theories. Many other theories exist that attempt to explain the shift from quadrupedal locomotion to bipedalism. Each offers compelling evidence to support its claims. Additionally, each is flawed in one way or another. Without new evidence, we may never know the true origin of our most unique characteristic.

Lesson Plan Step #8 Assessment and Follow-Up

Lesson Plan Step #8 Assessment and Follow-Up In this series about lesson plans, were breaking down the 8 steps you need to take to create an effective lesson plan for the elementary classroom. The final step in a successful lesson plan for  teachers is Learning Goals, which coming  after defining the following steps:   ObjectiveAnticipatory SetDirect InstructionGuided Practice  ClosureIndependent PracticeRequired Materials and Equipment An  8-step lesson plan is not complete without the final step of Assessment. This is where you assess the final outcome of the lesson and to what extent the learning objectives were achieved. This is also your chance to adjust the overall lesson plan to overcome any unexpected challenges that may have arisen, preparing you for the next time you teach this lesson. Its also important to make note of the most successful aspects of your lesson plan, to ensure that you continue to capitalize on strengths and continue to push forward in those areas.   How to Assess Learning Goals Learning goals can be assessed in a variety of ways, including through quizzes, tests, independently performed worksheets, cooperative learning activities, hands-on experiments, oral discussion, question-and-answer sessions, writing assignments, presentations, or other concrete means. However, its important to remember that you may have students who better display their mastery of a topic or skill through non-traditional assessment methods, so try to think about creative ways you can assist those students in demonstrating mastery. Most importantly, teachers need to ensure that the Assessment activity is directly and explicitly tied to the stated learning objectives  you developed in step one of the lesson plan. In the learning objective section, you specified what students would accomplish and how well they would have to be able to perform a task in order to consider the lesson satisfactorily accomplished. The goals also had to fit within your district or state educational standards for the grade level. Follow-Up: Using the Results of the Assessment Once the students have completed the given assessment activity, you must take some time to reflect on the results. If the learning objectives were not adequately achieved, you will need to revisit the lesson in a different manner, revising the approach to learning. Either you will need to teach the lesson again or youll need to clear up areas that confused several of the students. Whether or not most students showed understanding of the material, based on the assessment, you should note how well students learned different parts of the lesson. This will allow you to modify the lesson plan in the future, clarifying or spending more time on areas where the assessments showed the students were weakest. Student performance on one lesson tends to inform performance on future lessons, giving you insight into where you should take your students next. If the assessment showed the students fully grasped the topic, you may want to proceed immediately to more advanced lessons. If understanding was moderate, you may want to take it slower and reinforce the takeaways. This may require teaching the entire lesson again, or, just portions of the lesson. Assessing different aspects of the lesson in greater detail can guide this decision.   Examples of Types of Assessments Quiz: a short series of questions with right and wrong answers that may not count towards a grade.Test: a longer or more in-depth series of questions that probes for more understanding of the topic and may count towards a grade.Class discussion: rather than a quiz or test that is scored, a discussion helps identify understanding. Its important to make sure all students are able to demonstrate mastery here, so that no one is lost in the shuffle.  Hands-on experiment: Where the subject matter is appropriate, the students apply the lesson to an experiment and record the outcomes.Worksheet: Students fill out a worksheet, especially for math or vocabulary lessons, but it also could be developed for many topics.Cooperative Learning activities: Students work in a group to solve a problem or have a structured discussion.Illustrations or Graphic Organizers: These can include Venn diagrams, K-W-L (Know, Want to Know, Learned) charts, flow charts, pie charts, concept maps, character traits, c ause/effect diagrams, spider web, cloud chart,T-chart, Y-chart, semantic feature analysis,fact/opinion chart, star chart, cycle chart, and other appropriate graphic  organizers. Often the subject will determine which works best as an assessment tool. Edited by Stacy Jagodowski