The Berkeley Evolution Site
The Berkeley site has resources that can help students and educators learn about and teach evolution. The materials are organized into a variety of learning paths such as "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how animals that are better equipped to adapt biologically to changing environments survive longer and those that don't become extinct. This process of evolution in biology is what science is all about.
What is Evolution?
The term "evolution" can have a variety of meanings that are not scientific. For example, it can mean "progress" and "descent with modifications." Scientifically it refers to a process of changes in the traits of living things (or species) over time. In terms of biology this change is due to natural selection and genetic drift.
Evolution is a fundamental tenet in the field of biology today. It is a concept that has been tested and confirmed by thousands of scientific tests. Contrary to other theories of science like the Copernican theory or the germ theory of disease, the evolution theory does not address issues 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 way, over time. 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. 에볼루션 슬롯 states that all species of organisms share a common ancestry which can be traced through fossils and other evidence. This is the current understanding of evolution, and is supported by a variety of research lines in science, including molecular genetics.
While scientists do not know exactly how organisms developed, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. People with traits that are advantageous are more likely to survive and reproduce, and they pass their genes on to the next generation. Over time the gene pool gradually changes and develops into new species.
Some scientists also use the term evolution to describe large-scale evolutionary changes such as the creation of the new species from an ancestral species. 에볼루션 바카라 체험 , such as population geneticists, define evolution more broadly by referring the net change in allele frequencies over generations. Both definitions are acceptable and accurate however some scientists believe that the definition of allele frequency is lacking important features of the evolutionary process.
Origins of Life
The development of life is a key step in evolution. The emergence of life happens when living systems begin to evolve at a micro level, like within individual cells.
The origin of life is an issue in a variety of disciplines, including biology, chemistry, and geology. The origin of life is a subject of interest in science, as it is a challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the notion that life could emerge from nonliving objects is known as spontaneous generation, or "spontaneous evolution." This was a popular view before Louis Pasteur's experiments proved that it was impossible for the creation of life to occur by an entirely natural process.
Many scientists still believe that it is possible to make the transition from nonliving substances to life. The conditions necessary to create life are difficult to replicate in a laboratory. Researchers interested in the evolution and origins of life are also keen to understand the physical properties of the early Earth as well as other planets.
The development of life is dependent on a number of complex chemical reactions which are not predicted by simple physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that perform functions as well as the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions are often compared with the chicken-and-egg issue of how life first appeared in the first place. The development of DNA/RNA as well as protein-based cell machinery is essential to the birth of life, however, without the development of life the chemical process that allows it isn't working.
Abiogenesis research requires collaboration among scientists from different fields. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" is commonly used today to describe the cumulative changes in the genetic traits of populations over time. These changes can result from the response to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This latter mechanism increases the frequency of genes that confer a survival advantage in a species, resulting in an overall change in the appearance of an entire group. These changes in evolutionary patterns are caused by mutations, reshuffling of 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. This is because, as mentioned above, those individuals with the beneficial trait tend to have a higher reproductive rate than those who do not have it. This differential in the number of offspring produced over a long period of time can result in a gradual shift in the average number of beneficial characteristics in a group.
An excellent example is the growing beak size on different species of finches found on the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new home. These changes in the form and shape of organisms could also be a catalyst for the creation of new species.
The majority of changes are caused by one mutation, although sometimes multiple occur at once. Most of these changes can be harmful or neutral, but a small number can have a beneficial impact on survival and reproduction, increasing their frequency over time. This is the process of natural selection and it can, over time, produce the cumulative changes that eventually result in an entirely new species.
Many people confuse evolution with the idea of soft inheritance that is the belief that inherited traits can be altered by deliberate choice or misuse. This is a misinterpretation 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 which involves the separate and often conflicting forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a group of mammals that also includes gorillas, chimpanzees, and bonobos. The earliest human fossils indicate that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we have the same ancestry with Chimpanzees. In actual fact, our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was born between 8 and 6 million years ago.
Humans have evolved a wide range of characteristics over time including bipedalism, the use of fire and advanced tools. It is only within the last 100,000 years that we have developed the majority of our key traits. They include a huge brain that is complex, the ability of humans to build 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 environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The more adapted are more likely to pass on their genes to the next generation. This is the process that evolves all species and forms the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states species that have a common ancestor are likely to develop similar traits as time passes. This is because those traits allow them to live and reproduce in their environment.
All organisms have a DNA molecule that contains the information needed to direct their growth and development. The DNA molecule consists of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in a population can be caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. Although there are some differences, these fossils all support the hypothesis that modern humans first came into existence in Africa. The fossil and genetic evidence suggests that early humans left Africa and moved to Asia and Europe.