Evolution of the Human Brain - Essay Example

Evolution of the Human Brain Lecturer’s Due Introduction According to Darwin’s theory of natural selection, individuals withadaptive traits produce more offspring; therefore, species evolve with time (Rosenzweig, 1999). The natural selection process leads to the development of new genes that give adaptive characteristics, which also include behavioural traits. Additionally, Darwin’s theory of evolution explains that animals have evolved in order to blend into the dynamic environment for survival. Evolution has led to the increased number of different organisms in the planet. Over the years, the individual brain has evolved and developed to more complex organ than it was millions of years ago. The discussion below aims at describing some aspects about the human brain and its development by comparing it to other animals. Comparison between the human brain and other species All vertebrates have the same major segments of the brain. The primary difference among these animals lies on quantity and mass. The vertebrae brain weight constitutes to 0.69 power of the total body weight (encephalisation quotient) (Rosenzweig, 1999). Some animals have large brains while others possess small ones relative to their body weight, which means their brain size differs from what is expected. When fully grown, the human brain weighs about three pounds and stores every memory and generates both feelings and thoughts. Humans have larger brains based on their body weight predictions. More than any other organ, the human brain differentiates people from other animals. Although the human brain is among the largest based on its size, animals such as elephants, whales and dolphins have bigger ones. Then what makes the human brain unique? Sharks possess a stalk-like olfactory bulb, which is the most prominent part of its brain. The unique feature rises as a result of the animal’s sensitivity to smell. The Great white shark can pick the scent of the tiniest drop of blood in the water. However, the cerebrum is quite small compared to that of other animals. In contrast, people have a large percentage of their brain dedicate to vision. Chimpanzees have a brain that looks a lot like a human brain and they are part of the primate species. Both brains have an enlarged planum temporale on the left side and a large planum parietale on the right. Conversely, the human brain is greater than that of other primates. It has an enlarged angular gyrus. The gyrus creates an outline of different object and links it to the name of the object. Dolphins hold the largest brains among other animals. They possess an extended neo-cortex compared to human beings. The neo-cortex is the wrinkled part of the brain, which enables complex thinking. However, the human brain has more layers, which makes it more efficient. The different sizes in particular parts of the brain, in a range of species sometimes relates to the distinctive forms of behavioural adaptation. That is why sharks, which have a strong sense of smell, have elongated olfactory bulb. While, on the other hand, people have large brains due to increased capacity for intelligence and memory storage. Additionally, the brain possesses a large number of genes expresses in it compared to other primates such as the chimpanzees. Different psychological aspects make the human mind different from other vertebrates, besides having an exclusive size. These features include humour; no other creature can create, express and appreciate humour. The second feature involves the capability of the human brain to understand certain attributes such as beauty. Man can see the beauty in different things such as art, music and fashion. Thirdly, the human brain features the self-conscious trait. Self- consciousness gives an individual the ability to know his or her position in the society. A person can either be a critic, spectator or participant. He or she can evaluate what role suits him or her best. Finally, human beings differ from other species because of love. The mind of a person can think of love in which people share their dreams, hopes, goals and experiences with people they share emotional feelings. On the other hand, other animals form lifelong relationships with the aim of reproduction. Evolution of the human brain The human brain cell, brain molecules, synapses and neurotransmitters are almost similar to those of other animals. Therefore, insects, reptiles, fish, and other mammals share the same brain building blocks as human beings (Rosenzweig, 1999). In the beginning, brains were very simple. However, the hominid brain has grown from four hundred grams 3-4 million years ago to the present mass of 1.4 kilograms. More than the development in brain size; the human brain has grown more complex and intelligent than in the past. According to neuroscience results, more intelligent animals such as human beings, dolphins and apes possess exceptionally convoluted brains contrast to the smooth brains of less intellectual animals. As babies develop in the womb, they have smooth brains until they reach the age of six months where convolutions start developing. In the past several hundred years, the human thought has greatly changed in three ways. Firstly, the Copernican Revolution that makes human beings aware of other planets orbiting the sun. Secondly, the Darwinian Revolution, which states that by the outstanding process of evolution organism have grown differently with varying shapes, sizes and behaviour. Finally, evolution has enabled people to understand more about DNA. Primates own a large cortex relative to the overall brain size. Its enlargement appears to have evolved due to the prolonged brain development resulting to disproportional large cortex. Scientists believe that a number of factors might have led to the rapid growth of the human brain. These factors include innovation, use of tools and social relationships. Additionally, sexual selection contributed to the enlargement of the human brain. In today’s Homo sapiens, the foetus brain grows dramatically in both complexity and size. Regulator genes control the whole development process. Each regulator affects other regulators; therefore, a slight change would lead to dramatic effects. Factors such as nutrition and hormones influence brain growth and a change in the environment could cause a shift in the development process. At six weeks after conception, the foetal brain starts taking shape. Three months later, the surface of the brain remains smooth without any convolutes. During the sixth month, the brain’s cerebrum starts developing wrinkles, which increase the surface area and brain capacity. The human brain enables people to handle complex tasks such as language interpretation, innovation, use of technology and symbolic thoughts. Among other factors that led to the progression of the human brain, dreams contributed to the gradual change in the human brain. Scientific studies show that dreams vary with people and that people react diversely to dreams. Scientists consider dreams as highly subjective and unique to every individual. Some people cannot recall their dreams, which makes them erroneously assume they do not dream. While, on the other hand, some people vividly remember their dreams. Secondly, some people acquire total control over their dreams, through inserting conscious control. On the other hand, some people experience dreams and do not have the ability to wake themselves. Furthermore, like human beings, other mammals such as cats also dream. For example, cats often flinch and display set counter-threat behaviour towards invisible objects. The condition displayed by cats refers to random eye movement (REM). It is a stage of sleep in which the brain is still hyperactive and conscious. In Darwin’s theory of natural selection, the evolution of dreams among different people led to the survival of some. Scientists consider dreams as a virtual representation of the real events that occur. Imagining something gives a person the ability to prepare him or her for the actual event. In REM, a number of species exhibit different characteristics. Some people act out on their dreams while others stay calm. People who act out on their dreams put themselves in greater danger. In relation to natural selection, these people did not survive, which led to predominant removal from the current inhabitants. Individuals with the physical inhibition trait during dreaming have a greater advantage because it proves that they can deal with the threat both in the dream and in reality (Franklin, 2005). Conclusively, the advancement of dreams in the human mind led to the development of various behavioural traits, which led to the survival of a section of the human population. The impacts of evolution on the human brain The expansion of the Hominid brain since the Homo erectus led to severe negative impacts on infancy, female locomotion and birth. To achieve its future size, the human brain needs to be large enough before birth; therefore, the infants’ head is a tight fit in the birth canal. The situation leads to complications during birth. Secondly, in order to minimise the birth complication problem, the female pelvis consequentially increased in size to accommodate the birth canal. The adaptation process led to non-optimal pelvic condition, which inhibits women from participating in some sports involving the lower part of the body (Skoyles, 1999). Progressive evolution Evolution progressively continues even today to both human beings and other species. With the change in the environment and climate, creatures need to adapt in order to stay alive. Recent studies show that the basal metabolic rate ratio is almost equal to the encephalisation quotient. The observable fact directly implies that the size of the brain is closely related to the amount of metabolic energy used. There is a huge encephalisation gap between human beings and other primates. The enlargement of the human brain differs from that of other primates. As stated before, the neo-cortex of a human being is larger than that of other primates due to factors such as increased intelligence. However, scientist also conceptualise the fact that metabolism also contributes to the differences between the brains. In conclusion, the human brain has greatly evolved throughout the years. Evolution greatly affected the increase in size of the human brain. People differ from other organisms with the brain and its functions as a major distinction factor. Additionally, Charles Darwin’s theory of natural selection supported by the dream phenomenon shows that the adaptation for survival also contributed to the development of the human brain. Progressive researches indicate that the brain still evolves to date with its link to metabolism being the main topic of study. Reference List Franklin, M. S., & Zyphur, M. J. (2005). The Role of Dreams in the Evolution of the Human Mind. Evolutionary Psychology, 3, 59-78. Rosenzweig, M. R., Leiman, A. L., & Breedlove, S. M. (1999). Biological psychology: an introduction to behavioral, cognitive, and clinical neuroscience (2nd ed.). Sunderland, Mass.: Sinauer Associates. Skoyles, J. R. (1999) Human evolution expanded brains to increase capacity not IQ. Psycoloquy: 10(002) brain expertise (1) Read More