The Berkeley Evolution Site
The Berkeley site offers resources that can assist students and teachers learn about and teach evolution. The materials are organized into a variety of learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how over time creatures that are more adaptable to changing environments thrive, and those that do not become extinct. This process of biological evolution is the basis of science.
What is Evolution?
The word evolution can have a variety of meanings that are not scientific. For instance it could mean "progress" and "descent with modifications." It is an academic term that is used to describe the process of change of characteristics in a species or species. In terms of biology the change is caused by natural selection and genetic drift.
Evolution is a key principle in modern biology. It is an established theory that has stood the test of time and thousands of scientific studies. In contrast to other theories in science like the Copernican theory or the germ theory of disease, the evolution theory does not address issues of religion or the existence of God.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner 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.
Darwin presented his theory of evolution in his book On the Origin of Species published in the early 1800s. It claims that different species of organisms share an ancestry that can be traced through fossils and other evidence. This is the current view of evolution, which is supported by many research lines in science which includes molecular genetics.
While scientists don't know exactly how organisms developed but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous characteristics are more likely than others to live and reproduce. These individuals transmit their genes to the next generation. Over time, this results in an accumulation of changes to the gene pool, which eventually lead to new species and types.
Some scientists also use the term"evolution" to describe large-scale evolutionary changes like the creation of a new species from an ancestral species. Certain scientists, such as population geneticists define evolution in a more broad sense by using the term "net change" to refer to the change in allele frequency over generations. Both definitions are acceptable and precise however some scientists believe that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The emergence of life is a key step in the process of evolution. The emergence of life happens when living systems begin to develop at a micro level, such as within individual cells.
The origin of life is an important topic in a variety of fields, including biology and the field of chemistry. The question of how living things started has a special place in science because it is an enormous challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could be born from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's tests proved that the development of living organisms was not possible through an organic process.
Many scientists still believe it is possible to make the transition from nonliving substances to living. However, 에볼루션 needed are extremely difficult to replicate in labs. This is why scientists investigating the nature of life are also interested in understanding the physical properties of the early Earth and other planets.
Furthermore, the growth of life depends on an intricate sequence of chemical reactions that cannot be predicted based on basic physical laws on their own. These include the transformation of long information-rich molecules (DNA or RNA) into proteins that perform some function, and the replication of these complex molecules to generate new DNA or sequences of RNA. These chemical reactions are often compared to the chicken-and-egg issue of how life began with the appearance of DNA/RNA and protein-based cell machinery is crucial for the beginning of life, however, without the emergence of life, the chemical reaction that is the basis for it is not working.
Abiogenesis research requires collaboration among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
Today, the word evolution is used to describe the general changes in genetic traits over time. These changes can result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This latter mechanism increases the frequency of genes that offer an advantage for survival in the species, leading to an overall change in the appearance of an entire group. The specific mechanisms responsible for these changes in evolutionary process include 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 of their genes. As previously mentioned, those who have the advantageous trait have a higher reproduction rate than those who don't. This differential in the number of offspring born over a number of generations could result in a gradual shift in the average number advantageous traits in the group.
A good example of this is the growth of beak size on various species of finches found on the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new home. These changes in the form and shape of living organisms may also help create new species.
Most of the changes that take place are the result of one mutation, but occasionally several will happen simultaneously. The majority of these changes are not harmful or even harmful to the organism, but a small percentage can be beneficial to survival and reproduction, thus increasing the frequency of these changes in the population over time. Natural selection is a process that can produce the accumulating change over time that leads to a new species.
Some people confuse the idea of evolution with the idea that inherited characteristics can be altered through conscious choice or use and abuse, a concept called soft inheritance. This is a misunderstanding of the biological processes that lead to the process of evolution. It is more precise to say that evolution is a two-step, independent process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees, gorillas, and bonobos. Our predecessors walked on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality we are the closest related to the chimpanzees within the Pan genus that includes pygmy and bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
Humans have developed a range of traits throughout time including bipedalism, the use of fire, and the development of advanced tools. It's only within the last 100,000 years that we have developed the majority of our key characteristics. They include a huge, complex brain human ability to create and use tools, as well as the diversity of our culture.
Evolution occurs when genetic changes allow members of the group to better adapt to their environment. This adaptation is triggered by natural selection, which is a process by which certain traits are favored over other traits. The ones who are better adaptable are more likely to pass their genes on 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 that species which have a common ancestor, tend to develop similar characteristics over time. This is because these traits help them to survive and reproduce within their environment.
All organisms possess an molecule called DNA that holds the information needed to guide their growth. The DNA structure is composed of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite some differences in their appearance all support the idea that modern humans' ancestors originated in Africa. The evidence from fossils and genetics suggests that the first humans left Africa and moved to Asia and Europe.