The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are organized into optional learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection states that over time creatures that are more able to adapt to changing environments survive and those that are not extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The term "evolution" could be used to refer to a variety of nonscientific meanings. For instance it could refer to "progress" and "descent with modifications." It is a scientific term that is used to describe the process of changing traits over time in organisms or species. In terms of biology, this change is based on natural selection and genetic drift.
Evolution is one of the fundamental tenets of modern biology. It is a concept that has been tested and proven by thousands of scientific tests. Evolution does not deal with God's presence or spiritual beliefs in the same way as other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change, in a gradual manner, over time. They referred to this as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms share common ancestors that can be traced by fossils and other evidence. This is the current view on evolution, and is supported by a variety of disciplines which include molecular biology.
Scientists don't know how organisms have evolved but they are sure that natural selection and genetic drift is responsible for the development of life. People with traits that are advantageous are more likely to live and reproduce, and these individuals transmit their genes to the next generation. In time, this results in an accumulation of changes to the gene pool that gradually lead to new species and forms.
Some scientists employ the term"evolution" in reference to large-scale changes, like the development of one species from an ancestral one. Certain scientists, including population geneticists, define the term "evolution" in a broader sense by using the term "net change" to refer to the change in allele frequency over generations. Both definitions are valid and acceptable, however some scientists believe that allele-frequency definitions omit important features of evolution.
Origins of Life
A key step in evolution is the emergence of life. This occurs when living systems begin to evolve at the micro level - within cells, for example.
The origins of life are an important issue in a variety of fields, including biology and chemical. The question of how living things got their start is of particular importance in science because it is an enormous challenge to the theory of evolution. It is often referred to as "the mystery of life" or "abiogenesis."
Traditionally, the belief that life can arise from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the emergence of life to be a result of the natural process.
Many scientists believe that it is possible to go from nonliving materials to living. The conditions needed 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.
The growth of life is dependent on a number of complex chemical reactions which are not predicted by the basic physical laws. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that perform functions as well as the replication of these complex molecules to create new DNA or sequences of RNA. These chemical reactions can be compared with a chicken-and egg problem which is the development and emergence of DNA/RNA, a protein-based cell machinery, is essential for the onset life. Although, without life, the chemistry needed to enable it appears to be working.
Abiogenesis research requires collaboration with researchers from different disciplines. This includes prebiotic chemists, the astrobiologists, the planet scientists geophysicists, geologists, and geophysicists.
Evolutionary Changes
Today, the word evolution is used to describe cumulative changes in genetic characteristics 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 natural selection.
The latter is a mechanism that increases the frequency of genes in a species which confer a survival advantage over others, resulting in an ongoing change in the appearance of a population. The specific mechanisms responsible for these evolutionary changes include mutation and reshuffling of genes in sexual reproduction, and also gene flow between populations.
While reshuffling and mutations of genes happen in all organisms, the process by which beneficial mutations are more frequent is referred to as natural selection. This happens because, as we've mentioned earlier, those individuals with the advantageous trait are likely to have a higher fertility rate than those without it. This difference in the number of offspring born over a number of generations could cause a gradual change in the average number advantageous traits within the group.
This is evident in the evolution of various beak shapes on finches from the Galapagos Islands. They have developed these beaks in order that they can eat more easily in their new habitat. These changes in form and shape can aid in the creation of new organisms.
Most of the changes that take place are the result of one mutation, however occasionally, multiple mutations occur at once. The majority of these changes are neither harmful nor even detrimental to the organism, however a small portion of them could be beneficial to the longevity and reproduction of the species, thus increasing their frequency in the population over time. This is the mechanism of natural selection, and it can, over time, produce the cumulative changes that eventually result in the creation of a new species.
Many people mistakenly associate evolution with the concept of soft inheritance that is the belief that traits inherited from parents can be altered by conscious choice or by abuse. This is a misinterpretation of the nature of evolution, and of the actual biological processes that trigger it. A more accurate description of evolution is that it involves a two-step process, which involves the separate and often conflicting forces of mutation and natural selection.
Origins of Humans
Humans of today (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, walkers with two legs. Genetic and biological similarities show that we have a close relationship with Chimpanzees. In fact, our closest relatives are chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years ago.
In the course of time, humans have developed a range of characteristics, including bipedalism as well as the use of fire. They also invented advanced tools. However, it is only in the last 100,000 years or so that most of the essential characteristics that differentiate us from other species have emerged. These include a large brain that is complex human ability to build and use tools, and the diversity of our culture.
Evolution occurs when genetic changes allow members of an organization to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain traits are preferred over others. The better adaptable 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 refer to it as the "law of natural selection." The law states that species that have a common ancestor, tend to develop similar characteristics over time. It is because these traits make it easier to live and reproduce in their environment.
All organisms possess the DNA molecule, which contains the information needed to control their growth. 에볼루션 무료체험 is composed of base pair that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each string determines the phenotype or the characteristic appearance and behavior of a person. A variety of changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a group.
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite a few variations in their appearance, all support the hypothesis that modern humans' ancestors originated in Africa. Evidence from fossils and genetics suggest that early humans migrated out of Africa into Asia and then Europe.