The Berkeley Evolution Site
The Berkeley site has resources that can assist students and teachers learn about and teach evolution. The materials are arranged in various learning paths that can be used in a variety of ways like "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that in time, creatures better able to adapt biologically to changing environments survive and those that don't become extinct. Science is concerned with this process of evolution.
What is Evolution?
The term "evolution" could have many nonscientific meanings. For instance, it can mean "progress" and "descent with modifications." Scientifically it refers to a process of change in the characteristics of living organisms (or species) over time. 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 theory that has been confirmed through thousands of scientific tests. Evolution doesn't deal with spiritual beliefs or God's presence like other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a step-wise manner, as time passes. This was referred to as the "Ladder of Nature", or scala Naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
Darwin published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms share the same ancestry, which can be traced through fossils and other evidence. This is the current view on evolution, which is supported in many areas of science which include molecular biology.
Scientists do not know how organisms have evolved however they are certain that natural selection and genetic drift is the primary reason for the evolution of life. People with advantages are more likely to survive and reproduce. They transmit their genes on to the next generation. As time passes this leads to an accumulation of changes to the gene pool, which eventually lead to new species and forms.
Some scientists use the term evolution in reference to large-scale changes, such the evolution of one species from an ancestral one. Other scientists, like population geneticists, define evolution more broadly by referring to a net change in the frequency of alleles across generations. Both definitions are valid and palatable, but certain scientists argue that allele frequency definitions omit important features of evolutionary process.
Origins of Life
A key step in evolution is the development of life. This occurs when living systems begin to evolve at the micro level, within cells, for instance.
The origins of life is a topic in many disciplines such as geology, chemistry, biology and chemistry. The origin of life is a topic of great interest in science because 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 objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a popular belief prior to Louis Pasteur's experiments proved that the creation of living organisms was not achievable through an organic process.
바카라 에볼루션 believe it is possible to go from nonliving substances to living. However, the conditions that are required are extremely difficult to reproduce in a laboratory. Researchers who are interested in the evolution and origins 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 are not predicted by basic physical laws. These include the transformation of long information-rich molecules (DNA or RNA) into proteins that carry out some function, and the replication of these intricate molecules to produce new DNA or RNA sequences. These chemical reactions are comparable to the chicken-and-egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is required for the beginning of life. Although, without life, the chemistry that is required to make it possible appears to be working.
Abiogenesis research requires collaboration between researchers from different fields. This includes prebiotic chemists, the astrobiologists, the planet scientists geophysicists and geologists.
Evolutionary Changes
The term "evolution" today is used to describe cumulative changes in genetic characteristics over time. These changes could result from adaptation to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This is a process that increases the frequency of genes in a species that offer an advantage in survival over others which results in an ongoing change in the appearance of a group. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and also gene flow between populations.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo changes and reshuffles in their genes. This happens because, as we've mentioned earlier those who have the advantageous trait are likely 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 cause a gradual change in the average number of beneficial characteristics in the group.
A good example of this is the growth of beak size on various species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new environment. These changes in shape and form could also aid in the creation of new species.
The majority of changes are caused by a single mutation, but sometimes several occur at the same time. The majority of these changes could be harmful or neutral, but a small number could have a positive impact on the survival of the species and reproduce, increasing their frequency over time. This is the process of natural selection, and it is able to, over time, produce the accumulating changes that eventually lead to an entirely new species.
Many people think that evolution is a form of soft inheritance, which is the idea that traits inherited from parents can be changed by deliberate choice or misuse. This is a misinterpretation of the nature of evolution, and of the actual biological processes that cause it. A more accurate description of evolution is that it is a two-step procedure that involves the distinct and often antagonistic forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a species of mammal species which includes gorillas and chimpanzees. Our ancestors walked on two legs, as evidenced by the oldest fossils. Genetic and biological similarities show that we have an intimate relationship with chimpanzees. In fact we are the closest with chimpanzees in the Pan genus that includes pygmy and bonobos and pygmy-chimpanzees. 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 number 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 the majority of the traits that distinguish us from other species have emerged. They include language, a large brain, the capacity to build and use sophisticated tools, and a the ability to adapt to cultural differences.
Evolution is when genetic changes allow members of an organization to better adapt to their environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. Those with the better adaptations are more likely to pass their genes to the next generation. This is the way all species evolve, and the basis for the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that share an ancestor will tend to develop similar characteristics in the course of time. This is because those characteristics make it easier for them to survive and reproduce in their environments.
All organisms possess a DNA molecule that contains the information needed to control their growth. The DNA molecule is composed of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases in each strand determines the phenotype, the characteristic appearance and behavior of a person. Variations in changes and reshuffling of genetic material (known as alleles) during sexual reproduction cause variation in a population.
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences the fossils all support the notion that modern humans first appeared in Africa. The genetic and fossil evidence suggests that the first humans left Africa and migrated to Asia and Europe.