The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The resources are arranged into different learning paths like "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how creatures that are better equipped to adapt biologically to a changing environment survive over time and those that do not end up becoming extinct. This process of biological evolution is the basis of science.
What is Evolution?
The term "evolution" can have many nonscientific meanings, including "progress" or "descent with modification." Scientifically, it refers to a changes in the traits of living organisms (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is one of the fundamental tenets of modern biology. It is an accepted theory that has withstood the test of time and a multitude of scientific tests. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, evolution is not a discussion of religion or God's existence.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change, in a gradual manner, as time passes. They called this the "Ladder of Nature" or scala naturae. 에볼루션바카라사이트 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 different species of organisms share the same ancestry, which can be proven through fossils and other evidence. This is the modern view of evolution, which is supported in many disciplines which include molecular biology.
Scientists don't know the evolution of organisms but they are sure that natural selection and genetic drift is the reason for the evolution of life. People with desirable traits are more likely to live and reproduce, and these individuals pass their genes on to the next generation. Over time the gene pool gradually changes and develops into new species.
Some scientists also employ the term"evolution" to refer to large-scale evolutionary changes, such as the formation of a new species from an ancestral species. Other scientists, such as population geneticists, define evolution more broadly by referring to an overall variation in the frequency of alleles over generations. Both definitions are valid and reliable, although some scientists argue that the definition of allele frequency is lacking crucial aspects of the evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the appearance of life. This occurs when living systems begin to evolve at a micro-level - within cells, for example.
The origin of life is an important subject in a variety of disciplines, including biology and chemistry. The question of how living things got their start is of particular importance in science due to it being an important challenge to the theory of evolution. It is often described as "the mystery of life," or "abiogenesis."
Traditionally, the belief that life could emerge from nonliving things is called spontaneous generation or "spontaneous evolution." This was a popular view before Louis Pasteur's research showed that it was impossible for the emergence of life to happen through a purely natural process.
Many scientists still believe that it is possible to go from nonliving materials to living. The conditions necessary to create life are difficult to replicate in a laboratory. Researchers interested in the origins and evolution of life are also eager to understand the physical properties of the early Earth as well as other planets.
Furthermore, the growth of life is the sequence of extremely complex chemical reactions that can't be predicted from basic physical laws on their own. These include the reading and the replication of complex molecules, like DNA or RNA, in order to make proteins that perform a specific function. These chemical reactions are often compared to the chicken-and-egg problem of how life came into existence: The appearance of DNA/RNA and protein-based cell machinery is essential for the beginning of life, but without the development of life the chemistry that makes it possible isn't working.
Abiogenesis research requires collaboration between scientists from different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes could result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This latter mechanism increases the number of genes that provide a survival advantage in a species, resulting in an overall change in the appearance of an entire group. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction and the flow of genes.
While reshuffling and mutations of genes are common in all living organisms, the process by which beneficial mutations are more prevalent is referred to as natural selection. As mentioned above, those with the beneficial trait have a higher reproduction rate than those that do not. Over the course of many generations, this variation in the number of offspring produced can result in an inclination towards a shift in the average amount of desirable characteristics in a particular population.
This is evident in the evolution of different beak shapes on finches from the Galapagos Islands. They have developed these beaks so that they can eat more quickly in their new home. These changes in the form and shape of living organisms may also help create new species.
The majority of changes are caused by a single mutation, but sometimes several occur simultaneously. Most of these changes are neutral or even harmful to the organism, however, a small proportion of them can have a positive impact on survival and reproduction, thus increasing the frequency of these changes in the population over time. This is the mechanism of natural selection, and it can be a time-consuming process that produces the gradual changes that eventually result in an entirely new species.
Many people think that evolution is a form of soft inheritance that is the belief that traits inherited from parents can be altered by deliberate choice or misuse. This is a misinterpretation of the biological processes that lead up to evolution. It is more accurate to say that the process of evolution is a two-step, separate process that involves the forces of natural selection as well as mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a species of mammal species that includes gorillas and chimpanzees. Our predecessors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we have the same ancestry with Chimpanzees. In fact we are the closest with chimpanzees in the Pan genus, which includes bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a wide range of traits over time such as bipedalism, use of fire and advanced tools. But it's only in the last 100,000 years or so that most of the important traits that distinguish us from other species have been developed. These include a large brain that is sophisticated human ability to create and use tools, as well as cultural variety.
The process of evolution occurs when genetic changes allow individuals of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process that determines certain traits are favored over others. Those with the better adaptations are more likely to pass on their genes to the next generation. This is how all species evolve and the foundation for the theory of evolution.
Scientists call this the "law of natural selection." The law states species that share an ancestor will tend to develop similar characteristics as time passes. This is because these traits make it easier to survive and reproduce within their environment.
Every living thing has the DNA molecule, which contains the information needed to guide their growth. The DNA molecule is composed of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. 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 and Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite a few variations in their appearance, all support the idea of modern humans' origins in Africa. The evidence from fossils and genetics suggests that the first humans left Africa and migrated to Asia and Europe.