The Berkeley Evolution Site
The Berkeley site has resources that can help students and educators to understand and teach about evolution. The materials are organized in various learning paths that can be used in a variety of ways for example "What does T. rex look like?"
Charles Darwin's theory of natural selection states that in time, creatures more able to adapt to changing environments do better than those that are not extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, such as "progress" or "descent with modification." Scientifically, it refers to a process of changes in the traits of organisms (or species) over time. In terms of biology this change is based on natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a well-supported theory that has stood the tests of time and thousands of scientific studies. Unlike many other scientific theories such as the Copernican theory or the germ theory of disease, the evolution theory does not address issues of spiritual belief 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 the 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 claims that different species of organisms share an ancestry that can be determined through fossils and other evidence. This is the modern view of evolution, which is supported by many lines of research in science that include molecular genetics.
While scientists do not know the exact mechanism by which organisms evolved however they are sure that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to survive and reproduce, and these individuals pass their genes on to the next generation. Over time this leads to gradual changes in the gene pool that gradually lead to new species and types.
Some scientists employ the term evolution in reference to large-scale changes, such the evolution of an animal from an ancestral one. Certain scientists, such as population geneticists, define evolution in a more broad sense by using the term "net change" to refer to the variation in the frequency of alleles over generations. Both definitions are acceptable and precise however some scientists believe that the allele-frequency definition is missing important features of the evolutionary process.
Origins of Life
A key step in evolution is the appearance of life. The beginning of life takes place when living systems begin to evolve at a micro scale, for instance within individual cells.
The origin of life is one of the major topics in various disciplines that include biology, chemistry, and geology. The origin of life is an area that is of immense interest to scientists, as it challenges the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could emerge from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief before Louis Pasteur's tests showed that the emergence of living organisms was not achievable through a natural process.
Many scientists still think it is possible to move from nonliving to living substances. However, the conditions required are extremely difficult to replicate in the laboratory. Researchers interested in the origins and evolution of life are also eager to know the physical properties of the early Earth as well as other planets.
The life-cycle of a living organism is dependent on a number of complex chemical reactions, which cannot be predicted by simple physical laws. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that perform functions, and the replication of these complex molecules to create new DNA or RNA sequences. These chemical reactions can be compared to the chicken-and-egg problem that is the emergence and growth of DNA/RNA, protein-based cell machinery, is essential for the onset life. Although, without life, the chemistry that is required to enable it is working.
Research in the area of abiogenesis requires cooperation among scientists from many different disciplines. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists and geologists.
Evolutionary Changes
The term "evolution" is typically used to describe the accumulated changes in the genetic characteristics of a population 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 from natural selection.
This latter mechanism increases the number of genes that provide the advantage of survival for an animal, resulting in an overall change in the appearance of the group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction, and gene flow.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo mutations and reshuffles in their genes. As noted above, individuals with the beneficial trait have a higher reproductive rate than those that do not. Over the course of many generations, this difference in the number of offspring born can result in an inclination towards a shift in the number of beneficial traits within a group of.
One good example is the increase in beak size on various 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 form and shape can also help create new organisms.
The majority of changes are caused by a single mutation, however sometimes multiple occur at the same time. Most of these changes may be harmful or neutral however, a small percentage may have a positive effect on survival and reproduce, increasing their frequency over time. Natural selection is a mechanism that could result in the accumulation of change over time that leads to the creation of a new species.
Some people confuse the idea of evolution with the idea that traits inherited can be changed through conscious choice or by use and abuse, which is known as soft inheritance. This is a misinterpretation of the biological processes that lead to evolution. It is more accurate to say that the process of evolution is a two-step, separate process, which involves the forces of natural selection as well as mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees and gorillas and bonobos. mouse click the up coming internet site prove that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities show that we have an intimate relationship with chimpanzees. In actual fact we are the most closely with chimpanzees in the Pan genus that includes pygmy and bonobos and pygmy chimpanzees. The last common ancestor of humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a variety of traits throughout time such as bipedalism, use of fire, and the development of advanced tools. However, it is only in the last 100,000 years or so that most of the essential traits that distinguish us from other species have emerged. These include a large brain that is complex human ability to build and use tools, as well as cultural diversity.
Evolution occurs when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is triggered by natural selection, a process whereby certain traits are favored over other traits. The ones with the best 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 refer to it as the "law of Natural Selection." The law states species that share an ancestor will tend to develop similar traits in the course of time. This is because these traits allow them to survive and reproduce within their environment.
Every organism has a DNA molecule that contains the information necessary to direct their growth. The structure of DNA is composed of base pairs which 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. A variety of mutations and reshuffling of the genetic material (known as alleles) during reproduction causes variations in a population.
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Despite some differences they all support the hypothesis that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans migrated out of Africa into Asia and then Europe.