The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to help them understand and teach evolution. The resources are organized into 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 explains how over time creatures that are more able to adapt to changing environments do better than those that don't become extinct. This process of evolution is the main focus of science.
What is Evolution?
The word evolution has many nonscientific meanings, including "progress" or "descent with modification." It is a scientific term that refers to the process of change of characteristics in a species or species. This change is based in biological terms on natural selection and drift.
Evolution is an important tenet in the field of biology today. It is a concept that has been tested and verified by a myriad of scientific tests. In contrast to other theories in science like the Copernican theory or the germ theory of disease, evolution does not address issues of spiritual belief or God's existence.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner over time. This was referred to as 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 published in the early 1800s. It states that all species of organisms share an ancestry that can be determined through fossils and other evidence. This is the current view of evolution that is supported by many research lines in science that include molecular genetics.
While scientists don't know exactly how organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to live and reproduce, and these individuals pass their genes on to the next generation. In time this leads to gradual changes to the gene pool which gradually result in new species and forms.
Some scientists employ the term"evolution" to refer to large-scale changes, like the development of one species from an ancestral one. Others, like population geneticists, define the term "evolution" more broadly by referring an overall change in allele frequencies over generations. Both definitions are valid and acceptable, but some scientists argue that allele-frequency definitions omit important features of evolution.
Origins of Life
The emergence of life is a key step in evolution. The beginning of life takes place when living systems start to develop at a micro level, such as within cells.
The origins of life are one of the major topics in various disciplines, including biology, chemistry and geology. The nature of life is an area of great interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life can emerge from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the emergence of life to be a result of a purely natural process.
Many scientists believe that it is possible to transition from nonliving substances to living. The conditions required to make life are not easy to replicate in a laboratory. Researchers interested in the evolution and origins of life are also eager to learn about the physical characteristics of the early Earth as well as other planets.
In addition, the development of life depends on an intricate sequence of chemical reactions that cannot be predicted from basic physical laws alone. These include the reading and the replication of complex molecules, such as DNA or RNA, to create proteins that perform a particular function. These chemical reactions can be compared with the chicken-and-egg problem: the emergence and development of DNA/RNA, protein-based cell machinery, is essential to begin the process of becoming a living organism. Although without life, the chemistry required to create it appears to be working.
Abiogenesis research requires collaboration among scientists from various fields. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
Today, the word evolution is used to describe the gradual changes in genetic traits over time. These changes may be the result of adapting to environmental pressures, as described in Darwinism.
This latter mechanism increases the frequency of genes that offer a survival advantage in a species, resulting in an overall change in the appearance of an entire group. The specific mechanisms that cause these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, and gene flow between populations.
While mutation and reshuffling of genes happen in all organisms, the process by which beneficial mutations become more common is known as natural selection. This happens because, as we've mentioned earlier those with the beneficial trait tend to have a higher reproduction rate than those with it. This differential in the number of offspring born over a long period of time can result in a gradual shift in the number of advantageous characteristics in the group.
One good example is the growing beak size on various species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new home. These changes in the form and shape of living organisms may also aid in the creation of new species.
Most of the changes that occur are caused by one mutation, however occasionally several will happen simultaneously. Most of these changes can be neutral or even harmful, but a small number can have a beneficial impact on survival and reproduce with increasing frequency as time passes. 에볼루션사이트 is a process that causes the accumulating change over time that leads to a new species.
Many people confuse the concept of evolution with the notion that traits inherited can be changed through conscious choice or use and abuse, a concept called soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that lead to it. It is more accurate to say that evolution is a two-step independent process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes gorillas, chimpanzees, and bonobos. The earliest human fossils prove that our ancestors were bipeds - walking on two legs. Biological and genetic similarities indicate that we have the same ancestry with the chimpanzees. In actual fact we are the closest with chimpanzees in the Pan Genus that includes pygmy and bonobos and pygmy chimpanzees. 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 characteristics, including bipedalism and 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 characteristics that differentiate us from other species have developed. These include a large brain that is complex, the ability of humans to construct and use tools, and cultural variety.
The process of evolution occurs when genetic changes enable members of an organization to better adapt to the environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The better adjusted are more likely to pass on their genes to the next generation. This is how all species evolve and is the foundation of the theory of evolution.
Scientists call it the "law of Natural Selection." The law states that species which have an ancestor in common will tend to develop similar traits in the course of time. This is because the characteristics make it easier for them to live and reproduce in their environments.
All organisms possess an molecule called DNA that holds the information needed to guide their growth. The structure of DNA is composed of base pairs that are arranged in a spiral around sugar and phosphate 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 mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus, as well as Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite some differences in their appearance, all support the theory of the origins of modern humans in Africa. The fossil and genetic evidence suggests that the first humans left Africa and migrated to Asia and Europe.