ANTH 1020: Physical Anthropology
Coursework:
Research Paper on Bipedalism and Brain Size
By: Jonathen Green
April 21, 2018
Physical Anthropology
Salt Lake Community College
Teresa Potter
Bipedalism is the ability to habitually walk on two legs. It is one of the key distinguishing characteristics of humans and our immediate ancestors, the hominins. The word “hominin” is a term that describes the members of the evolutionary lineage that also include our own species, Homo sapiens as well as all of our extinct bipedal relatives. (Guest, 2017; Jurmain et al. 2013)
Based on fossil evidence from the fossils of two very primitive pre-australopithecines, Australopithecus ardipithecus and Australopithecus sahelanthropus, scientists believe that bipedalism probably appeared between 7 and 4.4 million years ago (mya). (Guest, 2017)
The pelvis and the foot, show key anatomical changes that show that ardipithecus was a competent biped.” (Jurmain et al. 2013)
However, these primates were not exclusively bipedal but based on the shapes of the foot bones, the femur and the pelvis, their fossilized remains show that they spent a great deal of time on the ground, but also in the trees. (Guest, 2017)
Their foot acted like a prop to help them with walking, but they probably were not able to run bipedally. Their foot also had a divergent front toe that was best for grasping branches and moving on all fours along the tops of tree branches. (Jurmain et al. 2013)
Fossilized hominid footprints from Laetoli, Tanzania, as well as many fossilized bones show that the australopiths who lived 4.2 million years ago were clearly bipedal. So although bipedalism first appeared in the pre-australopithecines up to 7 mya, by 4 mya it was clearly the primary means of locomotion for the Australopiths. (Jurmain et al. 2013)
To tell that a fossil was bipedal, we have to look for changes in their skeletons. These changes include a shorter and broader pelvis the extends around to the side. This pelvis helps us to stabilize our weight transmission from our lower-backs to the hips when we stand in a bipedal posture. The foot also is different. To support walking, it has to act like a prop where we first land on our heal and then propel ourselves forward by pushing off of our inline big toe. Our legs must be longer and have changes so that we can fully extend our knee and keep our center of gravity directly under our bodies. (Jurmain et al. 2013)
We find evidence of bipedalism in several east African sites such as the Middle Awash River Valley site in North-Eastern Ethiopia and the Laetoli site in Tanzania but also as fare north-west as the central African nation of Chad and its Toros-Menalla site. (Guest 2017; Jurmain et al. 2013)
According to our textbook, “the single most important defining characteristics for the entire course of hominin evolution is bipedalism.” (Jurmain et al. 2013)
Bipedalism is one of the key distinguishing characteristics of humans and our immediate ancestors. As pre-australopithecus adapted to a cooling environment that had less forest and more savannah grasslands, using bipedalism to move from the trees to the ground had evolutionary advantages. (Guest, 2017)
Bipedal locomotion was a tremendous advantage. It freed the hands for carrying objects, especially our infants, and also for gathering and carrying food, and later tools. It gave us a wider view of the surrounding countryside and let us see greater distances over open spaces so that we could more easily spot predators. It let us reach food in higher up places on trees and on bushes, and it even helped our bodies stay cooler in the hot African sun by exposing less of our body mass to direct sunlight. It is an extremely efficient means for us to cover long distances which would later become very helpful for hunting. (Guest, 2017; Jurmain et al. 2013)
Bipedalism allowed us to use a specialized form of locomotion to adapt to our environment. We were able to use it to respond to climate changes and then exploit resources in more varied habitats including forests, intermittent woodlands, open grasslands, and lake shores. (Guest 2017, Jurmain et al. 2013)
Our brains, are also a major distinguishing characteristics. All primates have an expand and more complex brain than other animals. Our brains are especially complex in the visual and the associative areas of the brain’s neocortex where information about three-dimensional images from overlapping fields of vision is sent to, and the processed in, both hemispheres of the brain at the same time. In the Neocortex, the information about different sensations can be compared and combined to help us interpret the world around us. (Jurmain et al. 2013)
To make guesses about the intelligence of our ancestors, scientists measure the cranial capacity and the shape of their skulls which we can use to tell us how large and complex their brains were, and therefore may be a good indicator of their intelligence. (Jurmain et al. 2013)
However, it a common misperception that bigger is better, but bigger brains don’t necessarily indicated greater cognitive abilities. For example, elephants have much larger brains than humans. Therefore, a better measure of our cognitive abilities is actually the size of our brain when compared with the rest of the body. This measurement is called relative brain size. Species that have a high relative brain size, such as primates, usually live in complex social groups, have a generalized diet, range over long distances and they have a long period of maturation. It is more likely that the complexity of the human brain is because of a combination of factors, such as surface area and increased density from folds in the cerebral cortex. Primitive brains are smooth and advanced brains are convoluted. (Shumaker et al. 2003)
Language and the ability to communicate, one of the greatest markers of culture, also has a relationship with our brains. It has been suggested by linguists that the human brain is actually hard-wired with the underlying framework and the structure that is required to organize language. But is also likely that different languages can actually change and shape our individual ways of thinking. We use language to establish different ways of classifying our reality and perceiving our world. (Guest, 2017) Language, like our brain, is flexible and fluid, and it allows us to respond to changes in our surrounding environment and our culture so that we can describe and analyze our world. (Guest, 2017)
Although evidence of Oldowan tools at australopithecus sites show significantly increased mental capacity, it was with Homo habilis, nicknamed “the handy man”, who lived in Southern and Eastern Africa about 2.5 million years ago that we experienced a truly dramatic increase in our intelligence. Homo habilis had an increased cranial capacity, a greater mental capacity, and much increased tool use. (Guest, 2017) Homo habilis represents a key moment in our evolutionary history. This is the introduction of culture.
Culture, had a powerful effect on our ancestors and provide for many advantages. These advantages supported each other in a self-reinforcing system that we call biocultural evolution. By creating better tools, we were able to process meat more efficiently, which then allowed for much higher energy intake. This increase in energy supported an increase in cranial capacity and with it an increase in our mental functions. This the further supported the development of even more and improved technology and culture. (Guest 2017)
To become a cultural animal, a big brain, like that of an elephant a dolphin or a whale, isn’t enough. You must also have the anatomy to use tools, such as the ability to use your hands because you move bipedally. It can take hundreds of generations for natural selection to bring about a biological change, but major cultural changes can come about in a single lifetime, Even within minutes. (Stanford. 2001)
Bibliography
Jurmain, Robert., Kilgore, Lynn., Trevathan, Wenda., Barteling, Eric J., 2013. Essentials of Physical Anthropology. Tehth Edition. Boston, MA: Cengage Learning. Pages: 3-4, 124-125, 203, 206-207, 210, 214-215, 237-238.
Guest, Kenneth J. 2017. Cultural anthropology: a toolkit for a global age. Second edition. New York, NY: W. W. Norton & Company, Inc. Pages: 118, 121, 169-173.
Shumaker, Robert W., Beck, Benjamin B., 2003. Primates in Question. Smithsonian Institution. Pages 116-117.
Stanford, Craig. 2001. Got Culture? From Significant Others, 2001. Pg 109-119. Basic Books, a member of Perseus Books, L.L.C. Pages 1, 3-4.
By: Jonathen Green
April 21, 2018
Physical Anthropology
Salt Lake Community College
Teresa Potter
Bipedalism is the ability to habitually walk on two legs. It is one of the key distinguishing characteristics of humans and our immediate ancestors, the hominins. The word “hominin” is a term that describes the members of the evolutionary lineage that also include our own species, Homo sapiens as well as all of our extinct bipedal relatives. (Guest, 2017; Jurmain et al. 2013)
Based on fossil evidence from the fossils of two very primitive pre-australopithecines, Australopithecus ardipithecus and Australopithecus sahelanthropus, scientists believe that bipedalism probably appeared between 7 and 4.4 million years ago (mya). (Guest, 2017)
The pelvis and the foot, show key anatomical changes that show that ardipithecus was a competent biped.” (Jurmain et al. 2013)
However, these primates were not exclusively bipedal but based on the shapes of the foot bones, the femur and the pelvis, their fossilized remains show that they spent a great deal of time on the ground, but also in the trees. (Guest, 2017)
Their foot acted like a prop to help them with walking, but they probably were not able to run bipedally. Their foot also had a divergent front toe that was best for grasping branches and moving on all fours along the tops of tree branches. (Jurmain et al. 2013)
Fossilized hominid footprints from Laetoli, Tanzania, as well as many fossilized bones show that the australopiths who lived 4.2 million years ago were clearly bipedal. So although bipedalism first appeared in the pre-australopithecines up to 7 mya, by 4 mya it was clearly the primary means of locomotion for the Australopiths. (Jurmain et al. 2013)
To tell that a fossil was bipedal, we have to look for changes in their skeletons. These changes include a shorter and broader pelvis the extends around to the side. This pelvis helps us to stabilize our weight transmission from our lower-backs to the hips when we stand in a bipedal posture. The foot also is different. To support walking, it has to act like a prop where we first land on our heal and then propel ourselves forward by pushing off of our inline big toe. Our legs must be longer and have changes so that we can fully extend our knee and keep our center of gravity directly under our bodies. (Jurmain et al. 2013)
We find evidence of bipedalism in several east African sites such as the Middle Awash River Valley site in North-Eastern Ethiopia and the Laetoli site in Tanzania but also as fare north-west as the central African nation of Chad and its Toros-Menalla site. (Guest 2017; Jurmain et al. 2013)
According to our textbook, “the single most important defining characteristics for the entire course of hominin evolution is bipedalism.” (Jurmain et al. 2013)
Bipedalism is one of the key distinguishing characteristics of humans and our immediate ancestors. As pre-australopithecus adapted to a cooling environment that had less forest and more savannah grasslands, using bipedalism to move from the trees to the ground had evolutionary advantages. (Guest, 2017)
Bipedal locomotion was a tremendous advantage. It freed the hands for carrying objects, especially our infants, and also for gathering and carrying food, and later tools. It gave us a wider view of the surrounding countryside and let us see greater distances over open spaces so that we could more easily spot predators. It let us reach food in higher up places on trees and on bushes, and it even helped our bodies stay cooler in the hot African sun by exposing less of our body mass to direct sunlight. It is an extremely efficient means for us to cover long distances which would later become very helpful for hunting. (Guest, 2017; Jurmain et al. 2013)
Bipedalism allowed us to use a specialized form of locomotion to adapt to our environment. We were able to use it to respond to climate changes and then exploit resources in more varied habitats including forests, intermittent woodlands, open grasslands, and lake shores. (Guest 2017, Jurmain et al. 2013)
Our brains, are also a major distinguishing characteristics. All primates have an expand and more complex brain than other animals. Our brains are especially complex in the visual and the associative areas of the brain’s neocortex where information about three-dimensional images from overlapping fields of vision is sent to, and the processed in, both hemispheres of the brain at the same time. In the Neocortex, the information about different sensations can be compared and combined to help us interpret the world around us. (Jurmain et al. 2013)
To make guesses about the intelligence of our ancestors, scientists measure the cranial capacity and the shape of their skulls which we can use to tell us how large and complex their brains were, and therefore may be a good indicator of their intelligence. (Jurmain et al. 2013)
However, it a common misperception that bigger is better, but bigger brains don’t necessarily indicated greater cognitive abilities. For example, elephants have much larger brains than humans. Therefore, a better measure of our cognitive abilities is actually the size of our brain when compared with the rest of the body. This measurement is called relative brain size. Species that have a high relative brain size, such as primates, usually live in complex social groups, have a generalized diet, range over long distances and they have a long period of maturation. It is more likely that the complexity of the human brain is because of a combination of factors, such as surface area and increased density from folds in the cerebral cortex. Primitive brains are smooth and advanced brains are convoluted. (Shumaker et al. 2003)
Language and the ability to communicate, one of the greatest markers of culture, also has a relationship with our brains. It has been suggested by linguists that the human brain is actually hard-wired with the underlying framework and the structure that is required to organize language. But is also likely that different languages can actually change and shape our individual ways of thinking. We use language to establish different ways of classifying our reality and perceiving our world. (Guest, 2017) Language, like our brain, is flexible and fluid, and it allows us to respond to changes in our surrounding environment and our culture so that we can describe and analyze our world. (Guest, 2017)
Although evidence of Oldowan tools at australopithecus sites show significantly increased mental capacity, it was with Homo habilis, nicknamed “the handy man”, who lived in Southern and Eastern Africa about 2.5 million years ago that we experienced a truly dramatic increase in our intelligence. Homo habilis had an increased cranial capacity, a greater mental capacity, and much increased tool use. (Guest, 2017) Homo habilis represents a key moment in our evolutionary history. This is the introduction of culture.
Culture, had a powerful effect on our ancestors and provide for many advantages. These advantages supported each other in a self-reinforcing system that we call biocultural evolution. By creating better tools, we were able to process meat more efficiently, which then allowed for much higher energy intake. This increase in energy supported an increase in cranial capacity and with it an increase in our mental functions. This the further supported the development of even more and improved technology and culture. (Guest 2017)
To become a cultural animal, a big brain, like that of an elephant a dolphin or a whale, isn’t enough. You must also have the anatomy to use tools, such as the ability to use your hands because you move bipedally. It can take hundreds of generations for natural selection to bring about a biological change, but major cultural changes can come about in a single lifetime, Even within minutes. (Stanford. 2001)
Bibliography
Jurmain, Robert., Kilgore, Lynn., Trevathan, Wenda., Barteling, Eric J., 2013. Essentials of Physical Anthropology. Tehth Edition. Boston, MA: Cengage Learning. Pages: 3-4, 124-125, 203, 206-207, 210, 214-215, 237-238.
Guest, Kenneth J. 2017. Cultural anthropology: a toolkit for a global age. Second edition. New York, NY: W. W. Norton & Company, Inc. Pages: 118, 121, 169-173.
Shumaker, Robert W., Beck, Benjamin B., 2003. Primates in Question. Smithsonian Institution. Pages 116-117.
Stanford, Craig. 2001. Got Culture? From Significant Others, 2001. Pg 109-119. Basic Books, a member of Perseus Books, L.L.C. Pages 1, 3-4.