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The Berkeley Evolution Site The Berkeley site offers resources that can help students and teachers understand and teach evolution. The materials are arranged in different learning paths like “What does T. rex look like?” Charles Darwin's theory on natural selection describes how species that are better equipped to adapt to changes in their environment survive over time and those that do not disappear. This process of evolution is what science is all about. What is Evolution? The term “evolution” could have a variety of meanings that are not scientific. For instance it could mean “progress” and “descent with modifications.” Scientifically it is a term used to describe a changes in the traits of living organisms (or species) over time. In terms of biology this change is based on natural selection and genetic drift. Evolution is one of the fundamental tenets of modern biology. It is an accepted theory that has stood the test of time and a multitude of scientific experiments. Evolution doesn't deal with God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of disease. Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a stepped-like manner over time. This was known as the “Ladder of Nature”, or scala Naturae. Charles Lyell first used this term in 1833 in his Principles of Geology. In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the current view of evolution, which is supported by numerous research lines in science, including molecular genetics. While scientists don't know exactly how organisms developed but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. People with desirable traits are more likely to live and reproduce. They pass on their genes to the next generation. In time, this results in a gradual accumulation of changes to the gene pool which gradually result in new species and types. Some scientists also use the term evolution to refer to large-scale evolutionary changes, such as the formation of a new species from an ancestral species. Other scientists, like population geneticists, define it more broadly by referring to the net variation in the frequency of alleles over generations. Both definitions are valid and reliable however, some scientists claim that the allele-frequency definition is missing important features of the evolutionary process. Origins of Life A key step in evolution is the development of life. This occurs when living systems begin to evolve at a micro-level – within cells, for instance. The origins of life are an important topic in many fields, including biology and chemistry. click through the next site of how living things got their start is of particular importance in science due to it being an enormous challenge to the theory of evolution. It is often described as “the mystery of life” or “abiogenesis.” Traditionally, the belief that life can arise from nonliving objects is known as spontaneous generation or “spontaneous evolution.” This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the creation of life to happen through the natural process. Many scientists still think it is possible to go from nonliving substances to living ones. The conditions necessary to make life are not easy to replicate in a laboratory. Researchers studying the origins of life are also interested in determining the physical properties of the early Earth and other planets. Furthermore, the growth of life is dependent on an intricate sequence of chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading and re-reading of complex molecules, such as DNA or RNA, in order to make proteins that serve a specific function. These chemical reactions are often compared to the chicken-and-egg dilemma of how life came into existence with the emergence of DNA/RNA and protein-based cell machinery is essential for the beginning of life, however, without the development of life the chemical process that allows it isn't working. Research in the field of abiogenesis requires cooperation among scientists from various disciplines. This includes prebiotic chemists planet scientists, astrobiologists geophysicists, geologists, and geophysicists. Evolutionary Changes The term “evolution” today is used to describe cumulative changes in genetic characteristics over time. These changes can be the result of the adaptation to environmental pressures as discussed in Darwinism. This process increases the frequency of genes that provide the advantage of survival for an animal, resulting in an overall change in the appearance of an entire group. The specific mechanisms behind these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations. Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of genes. This is because, as noted above, those individuals with the advantageous trait are likely to have a higher fertility rate than those with it. Over the course of many generations, this variation in the numbers of offspring born could result in a gradual shift in the average number of beneficial traits within a group of. A good example of this is the increase in beak size on different species of finches on the Galapagos Islands, which have developed different beak shapes to enable them to more easily access food in their new environment. These changes in the form and shape of organisms can also aid in the creation of new species. The majority of the changes that take place are caused by one mutation, however occasionally, multiple mutations occur simultaneously. Most of these changes are neither harmful nor even harmful to the organism however a small portion of them could have an advantageous impact on the survival of the organism and its reproduction, thereby increasing the frequency of these changes in the population over time. Natural selection is a process that causes the accumulating change over time that eventually leads to a new species. Many people confuse evolution with the idea of soft inheritance that is the belief that traits inherited from parents can be changed by deliberate choice or misuse. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that cause it. A more accurate description of evolution is that it is a two-step procedure that involves the distinct and often antagonistic forces of mutation and natural selection. Origins of Humans Humans of today (Homo Sapiens) evolved from primates, a species of mammal species which includes chimpanzees as well as gorillas. click through the next site show that our ancestors were bipeds – walkers on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In actual fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor between humans and chimpanzees was 8 to 6 million years old. In the course of time humans have developed a range of traits, including bipedalism and the use of fire. They also developed advanced tools. It's only in the last 100,000 years that we have developed the majority of our essential traits. These include language, large brain, the ability to construct and use complex 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 that determines certain traits are favored over others. The better adapted are more likely to pass on their genes to the next generation. This is how all species evolve, and it is the foundation of the theory of evolution. Scientists refer to this as the “law of natural selection.” The law states species that have an ancestor in common will tend to acquire similar traits in the course of time. It is because these traits make it easier to reproduce and survive within their environment. Every organism has a DNA molecule that contains the information needed to control their growth. The DNA molecule consists of base pairs arranged spirally around sugar molecules and phosphate molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in a population can be caused by reshufflings and mutations of genetic material (known collectively as alleles). Fossils from the first human species, Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite some differences in their appearance, all support the hypothesis of modern humans' origins in Africa. The fossil evidence and genetic evidence suggest that early humans moved out of Africa into Asia and then Europe.