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The Berkeley Evolution Site Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The resources are arranged into different learning paths, such as “What did T. rex taste like?” Charles Darwin's theory on natural selection explains how animals who are better equipped to adapt to changes in their environments over time, and those that do not become extinct. This process of evolution is the basis of science. What is Evolution? The word evolution can be used to refer to a variety of nonscientific meanings. For instance it could refer to “progress” and “descent with modifications.” Scientifically it is a term used to describe a changing the characteristics of organisms (or species) over time. In biological terms the change is based on natural selection and genetic drift. Evolution is a fundamental principle in modern biology. It is a theory that has been proven by thousands of scientific tests. It does not address spiritual beliefs or God's presence, unlike many other scientific theories such as the Copernican or germ theory of diseases. Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a stepped-like manner over time. They referred to this as the “Ladder of Nature” or the scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology. In 에볼루션 게이밍 , Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It claims that different species of organisms share the same ancestry, which can be determined through fossils and other lines of evidence. This is the current perspective on evolution, which is supported in a wide range of scientific fields, including molecular biology. While scientists do not know exactly how organisms developed but they are certain that the evolution of life on earth is the result of natural selection and genetic drift. Individuals with advantageous characteristics are more likely to survive and reproduce. They then pass their genes on to the next generation. In time this leads to an accumulation of changes in the gene pool, which eventually lead to new species and types. Some scientists employ the term evolution in reference to large-scale changes, such the development of a species from an ancestral one. Other scientists, such as population geneticists, define it more broadly by referring to the net change in allele frequencies over generations. Both definitions are accurate and palatable, but certain scientists argue that allele frequency definitions do not include important aspects of evolution. Origins of Life The most important step in evolution is the emergence of life. This happens when living systems begin to evolve at the micro level, within cells, for instance. The origins of life are an important issue in a variety of areas that include biology and the field of chemistry. The question of how living things got their start is a major topic in science due to it being an important challenge to the theory of evolution. It is often referred to “the mystery” of life or “abiogenesis.” Traditionally, the belief that life can emerge from nonliving objects is known as spontaneous generation, or “spontaneous evolution.” This was a popular belief prior to Louis Pasteur's experiments showed that it was impossible for the creation of life to happen through an entirely natural process. Many scientists believe it is possible to go from nonliving substances to living ones. The conditions needed to make life are not easy to replicate in a laboratory. This is why researchers studying the beginnings of life are also interested in understanding the physical properties of the early Earth and other planets. The growth of life is dependent on a number of complex chemical reactions which cannot be predicted by basic physical laws. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that perform a function, and the replication of these intricate molecules to generate new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg dilemma of how life came into existence in the first place. The emergence of DNA/RNA and protein-based cell machinery is essential for the beginning of life, however, without the development of life the chemistry that makes it possible does not appear to work. Abiogenesis research requires collaboration with researchers from different fields. This includes prebiotic scientists, astrobiologists and planetary scientists. Evolutionary Changes The word evolution is usually used today to describe the accumulated changes in the genetic traits of a population over time. These changes can be the result of the adaptation to environmental pressures as explained in Darwinism. The latter is a mechanism that increases the frequency of genes in a species that confer a survival advantage over others and causes a gradual change in the overall appearance of a group. The specific mechanisms responsible for these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, and gene flow between populations. While reshuffling and mutation of genes occur in all organisms and the process by which beneficial mutations become more common is known as natural selection. This happens because, as noted above those with the beneficial trait tend to have a higher reproductive rate than those with it. This difference in the number of offspring that are produced over a long period of time can cause a gradual change in the number of advantageous characteristics in a group. A good example of this is the growth of the size of the beaks on different species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new environment. These changes in the form and shape of organisms could also aid in the creation of new species. The majority of changes are caused by one mutation, however sometimes multiple occur simultaneously. Most of these changes may be neutral or even harmful, but a small number can have a beneficial impact on survival and reproduce with increasing frequency as time passes. Natural selection is a process that can produce the accumulating changes over time that lead to a new species. Some people confuse evolution with the idea of soft inheritance which is the notion that inherited traits can be changed by conscious choice or by abuse. This is a misinterpretation of the biological processes that lead to evolution. A more accurate description is that evolution is a two-step procedure that involves the distinct and often antagonistic forces of natural selection and mutation. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species which includes chimpanzees and gorillas. The earliest human fossils show that our ancestors were bipeds – walkers on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality our closest relatives are the chimpanzees from the Pan genus. This includes pygmy and bonobos. The last common ancestor between modern humans and chimpanzees was between 8 and 6 million years old. As time has passed humans have developed a variety of traits, including bipedalism as well as the use of fire. They also developed advanced tools. However, it is only in the last 100,000 years or so that the majority of the important traits that distinguish us from other species have been developed. These include language, a large brain, the ability to build and use complex tools, as well as cultural diversity. Evolution happens when genetic changes allow members of a population to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain characteristics are more desirable than others. The ones who are better adaptable are more likely to pass on their genes to the next generation. This is how all species evolve and forms the basis of the theory of evolution. Scientists call it the “law of Natural Selection.” The law states species that have an ancestor in common will tend to acquire similar traits over time. It is because these traits help them to live and reproduce in their environment. Every living thing has the DNA molecule, which contains the information needed to control their growth. The DNA structure is made of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Different mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction can cause variations in a population. Fossils from the early human species Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. While there are some differences between them, these fossils all support the hypothesis that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans came out of Africa into Asia and then Europe.