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The Berkeley Evolution Site Teachers and students who visit the Berkeley site will find resources to aid in understanding and teaching evolution. The materials are organized in various learning paths that can be used in a variety of ways like “What does T. rex look like?” Charles Darwin's theory of natural selection describes how species who are better equipped to adapt biologically to changing environment survive over time and those that do not disappear. 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.” Scientifically, it refers to a change in the characteristics of living things (or species) over time. In biological terms the change is based on natural selection and genetic drift. Evolution is a key tenet in modern biology. It is an established theory that has withstood the test of time and thousands of scientific studies. It does not address God's presence or spiritual beliefs in the same way as other theories in science, like the Copernican or germ theory of disease. Early evolutionists, like 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. They called this 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 asserts that all species of organisms share common ancestors that can be traced through fossils and other evidence. This is the current view on evolution, and is supported by a variety of disciplines which include molecular biology. Although scientists aren't able to determine exactly how organisms evolved, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. People with desirable traits are more likely than others to live and reproduce. They then pass their genes to the next generation. In time this leads to an accumulation of changes in the gene pool which gradually lead to new species and forms. Certain scientists also use the term”evolution” to refer to large-scale evolutionary changes like the creation of an entirely new species from an ancestral species. Some scientists, like population geneticists, define evolution in a broader sense by referring to the net change in the frequency of alleles across generations. Both definitions are acceptable and accurate however, some scientists claim that the allele-frequency definition omits essential aspects of the evolution process. Origins of Life A key step in evolution is the emergence of life. The emergence of life occurs when living systems begin to develop at a micro level, like within individual cells. The origins of life is an issue in a variety of disciplines, including biology, chemistry, and geology. The question of how living things got their start is of particular importance in science due to it being a major challenge to the theory of evolution. It is often referred to “the mystery” of life or “abiogenesis.” Traditionally, the idea that life can arise from nonliving things is called spontaneous generation or “spontaneous evolution.” This was a common belief before Louis Pasteur's research showed that it was impossible for the creation of life to be a result of an entirely natural process. Many scientists still think it is possible to move from nonliving to living substances. The conditions required to make life are not easy to replicate in a laboratory. This is why researchers studying the origins of life are also keen to understand the physical properties of early Earth and other planets. Additionally, the evolution of life depends on the sequence of extremely complex chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading and the replication of complex molecules, such as DNA or RNA, to create proteins that serve a specific function. These chemical reactions are often compared with the chicken-and-egg issue of how life began: The emergence of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, but without the emergence of life, the chemistry that makes it possible isn't working. Abiogenesis research requires collaboration between scientists from different fields. This includes prebiotic chemists planet scientists, astrobiologists geophysicists and geologists. Evolutionary Changes The word evolution is usually used to refer to 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. 에볼루션 바카라 사이트 is a mechanism that increases the frequency of genes which confer a survival advantage over others, resulting in an ongoing change in the appearance of a group. The specific mechanisms behind these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, and also gene flow between populations. While mutation and reshuffling of genes occur in all living things, the process by which beneficial mutations are more frequent is referred to as natural selection. This occurs because, as mentioned above those with the beneficial trait tend to have a higher fertility rate than those without it. This differential in the number of offspring born over many generations can result in a gradual shift in the average number advantageous traits in a group. This is evident in the evolution of various beak shapes for finches from the Galapagos Islands. They have developed these beaks so that they can eat more easily in their new environment. These changes in form and shape can also help create new organisms. Most of the changes that take place are the result of a single mutation, but occasionally, multiple mutations occur at once. The majority of these changes could be neutral or even harmful, but a small number could have a positive impact on survival and reproduce, increasing their frequency as time passes. This is the mechanism of natural selection, and it can eventually result in the gradual changes that ultimately lead to an entirely new species. Some people confuse the notion of evolution with the idea that traits inherited can be altered by conscious choice or by use and abuse, which is known as soft inheritance. This is a misinterpretation of the nature of evolution and of the actual biological processes that trigger it. A more accurate description is that evolution is a two-step procedure that involves the distinct and often conflicting forces of mutation and natural selection. Origins of Humans Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species which includes gorillas and chimpanzees. The earliest human fossils show that our ancestors were bipeds, walkers with two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact, our closest relatives are chimpanzees of the Pan genus. This includes pygmy and bonobos. The last common ancestor between modern humans and chimpanzees dated 8 to 6 million years old. As time has passed humans have developed a variety of characteristics, including bipedalism as well as the use of fire. They also invented advanced tools. It's only within the last 100,000 years that we've developed the majority of our essential characteristics. These include a large, complex brain human ability to construct and use tools, and cultural diversity. Evolution occurs when genetic changes enable members of the group to better adapt to the environment. This adaptation is driven by natural selection, a process whereby certain traits are more desirable than other traits. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is the way all species evolve and the basis for the theory of evolution. Scientists refer to it as the “law of natural selection.” The law states that species which have a common ancestor are likely to develop similar characteristics in the course of time. This is because these traits make it easier for them to live and reproduce in their environments. Every organism has a DNA molecule that contains the information needed to control their growth. The DNA molecule is made up of base pairs that are spirally arranged around phosphate molecules and sugar molecules. The sequence of bases in each strand determines the phenotype, the characteristic appearance and behavior of a person. Variations in changes and reshuffling of genetic material (known as alleles) during sexual reproduction cause variations in a population. Fossils of the first human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite differences in their appearance, all support the theory of the origins of modern humans in Africa. Evidence from fossils and genetics suggest that early humans moved out of Africa into Asia and then Europe.