evolution
...e of handling complex information, memory, storage, creation and manipulation of resources. This is believed to be caused by their diet, including meat, reduced amount of cellulose replaced by meat and also usage of tools to do some of the molar’s job. Homo erectus are one of our most famous ancestors ranging 1.5 to 1 m.y.a and they are well known by examining the Peking man and others. They had reduced jaw and larger brain size and the first specimen was found in Asia and Europe. They had a longer more robust skull and a thickening along the saggital crest. Most of these features are believed to have appeared due to technology, such as tool and controlled fire. Fire would have been a major technological breakthrough and could have potentially influenced hominid biological evolution. For example, as a result of cooking, food items became more tender, thus, chewing stresses were reduced, perhaps leading to selection for reduced size of dentition. The advantages of controlled fire were also warmth, hardening of the end of a spear, aiding production of stone tools, chase predators out of caves, light source during the night. Archiac Homo sapiens, are much like the H. erectus, however had spread into Europe about 1 m.y.a and developed into a unique form, the classic Neanderthals. They were powerful hunters who dominated Europe for more than 100,000 years. Neanderthals had similar brain size to that of H. erectus and their posture and size were very human like. However, Neanderthals had to compete for food and territory with fast-spreading modern humans, who are believed to have been more adept at finding resources and cooperating strategically. Other factors such as changing climates, which was colder in Europe also may have played a role in the theory of their extinction. Modern Homo sapiens (anatomically modern humans) or even well known as H. sapiens sapiens is what scientists believe to be our most recent ancestors. Their features were somewhat similar to those of the Neanderthals and identical to the modern human beings. One of the largest difference was the shape of the head. It was higher, shorter and rounder and the frontal regions appears to be more filled out, rising more vertically above the brows, and a human brain size and features. This population is believed to have used tools, fire, very cultured, they had various art forms ( in caves) and had the human potential for intelligence, their only effective weapon to survive! Processes of Evolution Evolution is the complexity of processes by which living organisms were established on earth and have been expanded and modified through theorized changes in form and function. Human evolution is the biological and cultural development of the Homo sapiens species, from their Hominid ancestors. The roots of all of our evolutionary thinking goes back to Darwin’s theory of evolution. Darwin saw evolution as the gradual unfolding of new varieties of life, from previous forms, over long periods of time. These long term effects can come about only by the accumulation of many small genetic changes occurring every generation and the affect of natural selection. We understand how the process of evolution works by studying short term events between generations in various organisms, including humans. From modern genetic perspective evolution is defined as a change in allele frequencies from one generation to the next. Allele frequencies are indicators of the genetic makeup of an interbreeding group of individuals known as population. Allele frequency change, can be examined by looking at physical traits that is inherited, such as blood type. However the question that still remains is how do allele frequencies change or in other words what causes evolution? Evolutionary change is seen as a two stage process. The first stage is the production and redistribution of variation. The second stage is the process where by natural selection acts on the accumulated genetic variations. In addition there are factors of gene flow, genetic drift and recombination function to redistribute variation within individuals (recombination), within populations (genetic drift) and between populations (gene flow). Natural selection is the central determining factor influencing the long term direction of evolutionary change. How natural selection works can be best explained as how successful individuals are in leaving offspring to succeeding generations. Some examples of the mechanics of evolutionary change produced by natural selection are: (1. A triat must be inherited to have importance in natural selection, 2. Natural selection can not occur without variation in inherited characteristics(it can only work with variations that exists), 3. Fitness is a relative measure that will change as environment changes, (Darwin, Natural selection Law)). Natural selection was just one of Darwin’s many evolutionary theories. The term Darwinism arrives from Darwin’s theories on: common decendents, multiplications of species, gradualism, sexual selection. Sexual selection has been an important attribute in human evolution. The long term effect of sexual selection (male competition for mates), is to increase the frequency of those traits that lead to greater success in acquiring mates. In primates males competition for females is prominent. In these species, sexual selection produce dimorphism with regard to a number of traits most noticeably is body size. These amazing, random, and hereditary developments are the steps to human evolution. Order Primates Humans are members of the order Primates which consists of about 180 species (there are 17 different orders of mammals which diverged 80-65 million years ago). Primates are a relatively old order of mammals. Most of the synapomorphies of this order are associated with an arboreal way of life: flexible digits, forward facing eyes, vision as a primary sense. These traits may have played a role in the evolution of brain size in the lineage leading to humans. Humans are a member of the family Hominidae which is believed to have diverged about 5 million year ago from the other members of the Hominoidea. Order primates originally divided into the Prosimii and the Anthropoidea. Anthropoidea generally had larger brain size relative to their weight and generally larger body size than the Prosimii. They also had special dentition, increased parental care and more mutual grooming. Anthropoidea, then separated into two groups: the new world monkeys, such as the spidermonkey and the old world monkeys, apes and humans. Eventually this branched off into the hominoidea family which only included apes and humans. Homnoidea has three sub-families: teo of which are the great apes species (gorillas, chimpanzees and orangutans) and the hominidae (H. sapiens). The old world monkeys were quadripedal, however they adapted to life on the ground like the baboon and spend much time sleeping, feeding and grooming. They had physical features that were different compared to the new world monkeys. The new world monkeys were smaller in size and had broader nose. The hominoidea generally had a larger body size, absence of the tale, shortened trunk, more complex behavior, more complex brain and increased period of infancy development and dependency. This is where scientists believe that human separated from apes. They had developing reduced canine, typical primate teeth and more details in the skull structure. And eventually through millions of years we evolved both physically and mentally as we are now capable of writing, reading, thinking, and cultural innovation. Now that we understand that we are part of the hominoidea, we can identify our similarities and differences by observing our closest relatives, the great apes. Besides the fact that our DNA is different, clearly it’s the behavioral attributes that most dramatically sets humans apart. Humans are bipedal, live in permanent bisexual social groups with the males often bounded to one or more females (realistically not true in today’s society), capable of complex learning, and thinking symbolically and use of language as means of communication. One of the attributes that separates us from other primates is our ability to assume, understand motifs and be able to be sneaky and lie! Observing a chimpanzees behavior, it is much less complicating than humans, chimpanzees only react to what they see, their means of communication is visual. They are capable of communicating amongst themselves but their behavior is not as complex as the human species. It is clear that the hominoidea family branched off and each evolved in their separate ways. Controversies Some of the social controversies surrounding evolution are Darwin’s evolutionary theory and it’s interference with the bible. Also in a feminist perspective, the image of the male as the gatherer ,and the most controversial, Neanderthal’s relations to the modern humans. Creationists say that human ancestors were not apes. They were always humans, evolutionary theory is a myth which states God created everything as we see it today. People that believe in creationism say that if man descended from ape-like creatures, then humans should be like them. Yet humans have very different DNA. The number of vertebrae in our backbone is different. Human cranial capacity is totally different. They believe that ancient humans moved into difficult climatic areas and, for a time, lived in "stone-age cultures" until they had opportunity to build cities, plant, and become caught up in animal agriculture. The theory of evolution is the most reasonable theory today. Creationists don't have any historical proof. The creationist theory is only written and the evolutionary theory is actual living proof that humans did evolve from apes and why the environmental adaptations have made humans the dominant creatures on earth. Since behavior doesn't fossilize, much of the conclusions on early human behavior is speculative. Researchers must rely considerably on their imaginations in creating early hominid behavioral evolution. In such an atmosphere bias often emerges. Among the most controversial topics in anthropology is the debate concerning origins of early hominid gender role differences. Did early hominid males have different behavioral adaptations from their female companions? Did one sex dominate the other? According to “man, the hunter” theory, the hunting of large animals by males was the central stimulus of hominid behavioral evolution. In this scenario increased intelligence accompanied by the development of tools, language, bipedalism was the males doing. While the males were leading the hominid evolution, the females remained at ho...