The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to assist them in understanding and teaching evolution. The materials are arranged 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 on natural selection explains how creatures that are better equipped to adapt biologically to a changing environments over time, and those who do not become extinct. Science is about this process of evolution.
What is Evolution?
The word evolution has many nonscientific meanings, such as "progress" or "descent with modification." It is an academic term that refers to the process of change of characteristics over time in organisms or species. In terms of biology, this change is caused by natural selection and genetic drift.
Evolution is a fundamental tenet in modern biology. It is a concept that has been tested and proven by a myriad of scientific tests. Evolution does not deal with the existence of God or religious beliefs like other scientific theories such as the Copernican or germ theory of diseases.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change in a step-like manner, as time passes. They called this the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
Darwin revealed his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It claims that different species of organisms have an ancestry that can be determined through fossils and other evidence. This is the current understanding of evolution, and is supported by numerous lines of scientific research, including molecular genetics.
While scientists do not know exactly how organisms evolved however they are sure that the evolution of life on earth is the result of natural selection and genetic drift. People with advantages are more likely to survive and reproduce. They then pass their genes on to the next generation. Over time the gene pool slowly changes and develops into new species.
Some scientists also employ the term evolution to refer to large-scale evolutionary changes such as the creation of an entirely new species from an ancestral species. Others, like population geneticists, define the term "evolution" more broadly by referring to the net change in allele frequencies over generations. Both definitions are valid and reliable however, some scientists claim that the allele-frequency definition is missing essential aspects of the evolution process.
Origins of Life
The emergence of life is a crucial stage in evolution. This happens when living systems begin to develop at a micro-level - within individual cells, for instance.
The origins of life are an important issue in many disciplines, including biology and the field of chemistry. The nature of life is an area of interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
Traditionally, the idea that life could emerge from nonliving objects is known as spontaneous generation, or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's research showed that it was impossible for the emergence of life to happen through the natural process.
Many scientists still believe it is possible to make the transition from nonliving substances to life. The conditions necessary for the creation of life are difficult to reproduce in a lab. Researchers studying the nature of life are also interested in determining the physical properties of early Earth and other planets.
Additionally, the evolution of life depends on an intricate sequence of chemical reactions that cannot be predicted from the fundamental physical laws on their own. 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 produce new DNA or RNA sequences. These chemical reactions can be compared with a chicken-and egg problem: the emergence and development of DNA/RNA, a protein-based cell machinery, is necessary for the onset life. Although without life, the chemistry that is required to enable it appears to be working.
Abiogenesis research requires collaboration among scientists from different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
Today, the word evolution is used to describe the general changes in genetic traits over time. These changes may be the result of the adaptation to environmental pressures as described in Darwinism.
This latter mechanism increases the frequency of genes that confer the advantage of survival for a species, resulting in an overall change in the appearance of an entire group. 에볼루션사이트 are triggered by mutations, reshuffling of genes during sexual reproduction, and the flow of genes.
While reshuffling and mutation of genes occur in all living organisms, the process by which beneficial mutations become more common is referred to as natural selection. This happens because, as mentioned above, those individuals with the advantageous trait are likely to have a higher fertility rate than those without it. Over the course of several generations, this difference in the numbers of offspring born can result in gradual changes in the average amount of desirable traits in a population.
This is evident in the evolution of different beak shapes for finches from the Galapagos Islands. They have developed these beaks so that they can access food more easily in their new habitat. These changes in the shape and form of organisms could also help create new species.
The majority of changes are caused by a single mutation, however sometimes multiple occur at once. Most of these changes are not harmful or even harmful to the organism, however a small portion of them could have a positive impact on the longevity and reproduction of the species, thus increasing the frequency of these changes in the population over time. Natural selection is a mechanism that causes the accumulating change over time that eventually leads to the creation of a new species.
Some people think that evolution is a form of soft inheritance, which is the idea that inherited traits can be altered by deliberate choice or misuse. This is a misunderstanding of the biological processes that lead up to evolution. It is more accurate to say that the process of evolution is a two-step independent 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 mammal species that includes chimpanzees and gorillas. Our ancestral ancestors were walking on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we share a close relationship with Chimpanzees. In fact our closest relatives are the chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor shared between modern humans and chimpanzees was 8 to 6 million years old.
Humans have evolved a wide range of traits over time including bipedalism, the use of fire and advanced tools. It is only in the past 100,000 years or so that the majority of the essential traits that distinguish us from other species have been developed. They include a huge, complex brain human ability to build and use tools, and cultural diversity.
The process of evolution occurs when genetic changes allow members of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process whereby certain traits are more desirable than others. The more adjusted are more likely to pass on their genes to the next generation. This is how all species evolve, and it is the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species which share an ancestor will tend to develop similar traits in the course of time. This is because these characteristics make it easier for them to live and reproduce in their environment.
All organisms have a DNA molecule that contains the information needed to control their growth and development. The DNA molecule is made up of base pairs arranged spirally around sugar molecules and phosphate molecules. The sequence of bases within each string determines the phenotype or the appearance and behavior of an individual. Variations in a population can be caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite some differences in their appearance, all support the hypothesis that modern humans' ancestors originated in Africa. The fossil and genetic evidence suggests that the first humans left Africa and moved to Asia and Europe.