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The Berkeley Evolution Site The Berkeley site offers resources that can assist students and teachers understand and teach evolution. The materials are organized in various learning paths that can be used in a variety of ways, such as “What does T. rex look like?” Charles Darwin's theory of natural selection states that over time creatures that are more adaptable to changing environments thrive, and those that are not extinct. This process of biological evolution is the main focus of science. What is Evolution? The term “evolution” has a variety of nonscientific meanings, including “progress” or “descent with modification.” It is scientifically based and is used to describe the process of change of traits over time in organisms or species. In biological terms, this change is based on natural selection and genetic drift. Evolution is a key principle in modern biology. It is an accepted theory that has stood the test of time and thousands of scientific tests. Unlike many other scientific theories like the Copernican theory or the germ theory of disease, the evolution theory does not address questions of spiritual belief or the existence of God. Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a step-like manner, as time passes. This was called the “Ladder of Nature” or scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology. Darwin presented his theory of evolution in his book On the Origin of Species, written in the early 1800s. It asserts that all species of organisms share an ancestry that can be traced using fossils and other evidence. This is the current perspective on evolution, which is supported in many areas of science, including molecular biology. Scientists aren't sure the evolution of organisms however they are certain that natural selection and genetic drift is responsible for the evolution of life. People with advantages are more likely than others to survive and reproduce. They pass on their genes on to the next generation. In time, this results in an accumulation of changes in the gene pool which gradually result in new species and types. Some scientists also use the term evolution to refer to large-scale changes in evolutionary processes like the creation of the new species from an ancestral species. Certain scientists, including population geneticists, define the term “evolution” in a broad sense, referring to the net change in allele frequency over generations. Both definitions are acceptable and accurate however, some scientists claim that the allele-frequency definition omits crucial aspects of the evolutionary process. Origins of Life The development of life is a key step in evolution. This occurs when living systems begin to develop at the micro level, within cells, for example. The origin of life is an important issue in many fields, including biology and chemistry. The nature of life is an area of great interest in science because it challenges the theory of evolution. It is often referred to “the mystery” of life or “abiogenesis.” Traditionally, the notion that life could emerge from nonliving things is called spontaneous generation or “spontaneous evolution.” This was a popular belief prior to Louis Pasteur's experiments showed that it was impossible for the development of life to be a result of a purely natural process. Many scientists still believe that it is possible to transition from nonliving substances to life. However, the conditions needed are extremely difficult to reproduce in a laboratory. This is why researchers studying the nature of life are also interested in determining the physical properties of the early Earth and other planets. Additionally, the evolution of life depends on a sequence of very complex chemical reactions that cannot be predicted from basic physical laws alone. These include the reading and re-reading of complex molecules, such as DNA or RNA, to produce proteins that perform a particular function. These chemical reactions can be compared to the chicken-and-egg issue: the emergence and development of DNA/RNA, the protein-based cell machinery, is necessary for the onset life. But, without life, the chemistry needed to make it possible does appear to work. Research in the field of abiogenesis requires collaboration between scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists. Evolutionary Changes The term “evolution” is typically used to describe the cumulative changes in the genetic characteristics of an entire population over time. These changes could be the result of adapting to environmental pressures, as explained in Darwinism. This process increases the number of genes that provide the advantage of survival for the species, leading to an overall change in the appearance of an entire group. The specific mechanisms responsible for these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, as well as gene flow between populations. While mutation and reshuffling of genes occur in all living things and the process by which beneficial mutations become more common is referred to as natural selection. As previously mentioned, those with the beneficial trait have a higher reproductive rate than those who do not. Over the course of many generations, this variation in the numbers of offspring born could result in gradual changes in the amount of desirable characteristics in a particular population. This can be seen in the evolution of different beak shapes on finches from the Galapagos Islands. 에볼루션사이트 have developed these beaks so they can get food more easily in their new environment. These changes in shape and form could aid in the creation of new organisms. The majority of the changes that take place are the result of a single mutation, but occasionally several will happen at once. Most of these changes can be harmful or neutral however, a few can have a beneficial impact on survival and reproduction, increasing their frequency over time. Natural selection is a process that causes the accumulating change over time that leads to the creation of a new species. Many people confuse the concept of evolution with the notion that inherited characteristics can be changed through conscious choice, or through use and abuse, a notion called soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. A more accurate description is that evolution is a two-step procedure which involves the separate and often conflicting forces of natural selection and mutation. Origins of Humans Humans of today (Homo sapiens) evolved from primates – a group of mammals that includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as evidenced by the oldest fossils. Genetic and biological similarities suggest that we share the same ancestry with chimpanzees. In fact our closest relatives are chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor between humans and chimpanzees was between 8 and 6 million years old. As time has passed, humans have developed a range of characteristics, such as bipedalism and the use of fire. They also developed advanced tools. But it's only in the last 100,000 years or so that the majority of the important characteristics that differentiate us from other species have been developed. These include a big brain that is complex human ability to build and use tools, and the diversity of our culture. Evolution happens when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is driven by natural selection, a process whereby certain traits are favored over others. The ones who are better adjusted are more likely to pass on their genes to the next generation. This is the way that all species evolve and is the foundation of the theory of evolution. Scientists refer to this as the “law of natural selection.” The law states that species which have a common ancestor are more likely to develop similar characteristics over time. This is because those characteristics make it easier for them to live and reproduce in their environments. Every organism has the DNA molecule, which contains the information needed to control their growth. The DNA molecule is composed of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases in each strand determines the phenotype, the appearance and behavior of an individual. The variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles). Fossils of the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite a few differences in their appearance all support the hypothesis of modern humans' origins in Africa. Genetic and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.