walletrod3

The Berkeley Evolution Site The Berkeley site contains resources that can help students and teachers learn about and teach evolution. The materials are arranged in optional learning paths for example “What does T. rex look like?” Charles Darwin's theory of natural selection explains that in time, creatures better able to adapt biologically to changing environments survive and those that do not become extinct. This process of evolution in biology is what science is all about. What is Evolution? The term “evolution” has a variety of nonscientific meanings, such as “progress” or “descent with modification.” It is scientifically based and is used to describe the process of changing characteristics in a species or species. This change is based in biological terms on natural selection and drift. Evolution is a key tenet in the field of biology today. It is an accepted theory that has stood the test of time and a multitude of scientific studies. In contrast to other theories in science, such as 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, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a gradual manner, over time. They called this the “Ladder of Nature” or the scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833. Darwin published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms have a common ancestry, which can be proven through fossils and other evidence. This is the current understanding of evolution that is supported by numerous lines of scientific research, including molecular genetics. Although scientists aren't able to determine the exact mechanism by which organisms evolved 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 than others to live and reproduce. They then pass their genes to the next generation. In time this leads to gradual changes in the gene pool, which eventually create new species and forms. Some scientists employ the term”evolution” in reference to large-scale change, such as the evolution of one species from an ancestral one. Certain scientists, including population geneticists, define the term “evolution” in a broader sense by talking about the net change in allele frequency over generations. Both definitions are correct and acceptable, however certain scientists argue that allele frequency definitions miss important aspects of the evolutionary process. Origins of Life The birth of life is a crucial step in the process of evolution. This occurs when living systems begin to develop at the micro level – within cells, for example. The origins of life are an important topic in many disciplines that include biology and the field of chemistry. evolutionkr.kr of life is a topic that is of immense interest to scientists, as it challenges the theory of evolution. It is often called “the mystery of life,” or “abiogenesis.” Traditionally, the belief that life could emerge from nonliving things is known as spontaneous generation, or “spontaneous evolution.” This was a common belief before Louis Pasteur's experiments showed that it was impossible for the emergence of life to occur by a purely natural process. Many scientists still think it is possible to move from nonliving substances to living ones. However, the conditions that are required are extremely difficult to replicate in a laboratory. Researchers interested in the evolution and origins of life are also keen to know the physical properties of the early Earth as well as other planets. The development of life is also dependent on a series of complex chemical reactions, which are not predicted by the basic physical laws. These include the reading and re-reading of complex molecules, such as DNA or RNA, in order to make proteins that perform a specific function. These chemical reactions are often compared with the chicken-and-egg dilemma of how life began with the appearance of DNA/RNA and protein-based cell machinery is essential to the birth of life, however, without the development of life, the chemistry that makes it possible is not working. Research in the field of abiogenesis requires collaboration among scientists from various fields. This includes prebiotic scientists, astrobiologists and planet scientists. Evolutionary Changes The word evolution is usually used today to refer to the accumulated changes in the genetic traits of populations over time. These changes can result from adaptation to environmental pressures as discussed in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection. This latter mechanism increases the number of genes that offer the advantage of survival for a species, resulting in an overall change in the appearance of a group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes. While mutation and reshuffling of genes are common in all living organisms The process through which beneficial mutations are more frequent is known as natural selection. This happens because, as mentioned above those with the advantageous trait are likely to have a higher reproductive rate than those who do not have it. This variation in the number of offspring that are produced over a long period of time can cause a gradual change in the average number of beneficial traits in the group. An excellent example is the growth of beak size on various species of finches in the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new environment. These changes in shape and form can also aid in the creation of new species. The majority of the changes that occur are the result of one mutation, however occasionally, multiple mutations occur at once. Most of these changes can be harmful or neutral however, a few could have a positive impact on survival and reproduce and increase their frequency as time passes. This is the mechanism of natural selection, and it can, over time, produce the gradual changes that eventually lead to an entirely new species. Some people confuse evolution with the idea of soft inheritance that is the belief that inherited traits can be changed through deliberate choice or misuse. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that lead to it. A more accurate description is that evolution is a two-step process that involves the distinct, and often competing, forces of mutation and natural selection. Origins of Humans Humans today (Homo sapiens) evolved from primates – a species of mammals that includes chimpanzees, gorillas, and bonobos. The earliest human fossils indicate that our ancestors were bipeds, walkers with two legs. Biological and genetic similarities indicate that we share an intimate relationship with chimpanzees. In actual fact, our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years ago. As time has passed humans have developed a range of traits, 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 key traits. These include language, large brain, the capacity to build and use complex tools, as well as cultural diversity. The process of evolution occurs when genetic changes allow individuals of a population to better adapt to their surroundings. Natural selection is the mechanism that drives this adaptation. Certain characteristics are more desirable than others. The more adaptable are more likely to pass on their genes to the next generation. This is the way that all species evolve, and it is the basis of the theory of evolution. Scientists refer to this as the “law of natural selection.” The law states that species that have an ancestor in common will tend to develop similar traits as time passes. This is because the traits allow them to live and reproduce in their environment. Every living thing has a DNA molecule, which contains the information needed to guide their growth and development. The DNA structure is made of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype which is the person's distinctive appearance and behavior. The variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles). Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite differences in their appearance, all support the hypothesis that modern humans' ancestors originated in Africa. The evidence from fossils and genetics suggests that early humans left Africa and moved to Asia and Europe.