The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The resources are organized into optional learning paths, such as "What does T. rex look like?"
Charles Darwin's theory on natural selection describes how species that are better equipped to adapt to changes in their environment survive over time and those that do not disappear. Science is about this process of evolutionary change.
What is Evolution?
The word evolution can have a variety of meanings that are not scientific. For instance, it can mean "progress" and "descent with modifications." It is an academic term that is used to describe the process of changing characteristics in a species or species. The reason for this change is biological terms on natural selection and drift.
Evolution is a central tenet of modern biology. It is a theory that has been verified by a myriad of scientific tests. Contrary to other theories of science, such as the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of religion or God's existence.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change in a step-wise manner, as time passes. This was called 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. It states that all species of organisms share a common ancestry which can be traced through fossils and other evidence. This is the current view of evolution, and is supported by many research lines in science, including molecular genetics.
Scientists don't know how organisms have evolved, but they are confident that natural selection and genetic drift is the primary reason for the evolution of life. People with traits that are advantageous are more likely to survive and reproduce, and these individuals pass their genes on to the next generation. In time this leads to a gradual accumulation of changes in the gene pool, which eventually create new species and types.
Some scientists also employ the term"evolution" to describe large-scale evolutionary changes like the creation of a new species from an ancestral species. Others, like population geneticists, define the term "evolution" more broadly by referring an overall change in allele frequencies over generations. Both definitions are valid and acceptable, but some scientists believe that allele-frequency definitions miss important aspects of the evolution.
Origins of Life
The birth of life is a key stage in evolution. This happens when living systems begin to develop at the micro level, within individual cells, for example.
The origin of life is an important issue in many fields that include biology and the field of chemistry. The question of how living things started has a special place in science because it is a major challenge to the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
The notion that life could arise from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". This was a common belief prior to Louis Pasteur's tests showed that the development of living organisms was not achievable through an organic process.
Many scientists still believe that it is possible to go from nonliving materials to living. The conditions required for the creation of life are difficult to reproduce in a lab. Researchers interested in the evolution and origins of life are also keen 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, that are not predicted by the basic physical laws. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out some function, and the replication of these complex molecules to create new DNA or sequences of RNA. These chemical reactions are comparable to the chicken-and-egg issue: the emergence and development of DNA/RNA, a protein-based cell machinery, is essential for the onset life. Although without life, the chemistry that is required to make it possible is working.
Research in the area of abiogenesis requires collaboration among scientists from a variety of fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is used to describe general changes in genetic traits over time. These changes could result from adaptation to environmental pressures as discussed in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
에볼루션게이밍 is a method that increases the frequency of genes in a species that offer an advantage in survival over others and causes a gradual change in the overall appearance of a population. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction, and the flow of genes.
While reshuffling and mutation of genes are common in all organisms, the process by which beneficial mutations become more common is known as natural selection. As previously mentioned, those with the beneficial characteristic have a higher reproduction rate than those who don't. Over the course of many generations, this difference in the numbers of offspring born could result in gradual changes in the average number of advantageous traits within a group of.
This can be seen in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have created these beaks to ensure that they can eat more easily in their new environment. These changes in the form and shape of organisms could also help create new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur simultaneously. Most of these changes are not harmful or even detrimental to the organism, however a small portion of them could have a positive impact on survival and reproduction, thus increasing the frequency of these changes in the population over time. This is the process of natural selection and it can, over time, produce the cumulative changes that ultimately lead to the creation of a new species.
Some people mistakenly associate evolution with the concept of soft inheritance which is the notion that traits inherited from parents can be changed by conscious choice or abuse. This is a misinterpretation of the nature of evolution and of the actual biological processes that cause it. A more accurate description is that evolution is a two-step process involving the independent, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a group of mammal species that includes chimpanzees as well as gorillas. The earliest human fossils prove that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In fact our closest relatives are the chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
Humans have evolved a wide range of traits over time, including bipedalism, the use of fire and advanced tools. It is only in the last 100,000 years or so that the majority of the essential traits that distinguish us from other species have emerged. These include a large brain that is sophisticated human ability to create 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 preferred over other traits. The more adjusted are more likely to pass their genes on to the next generation. This is the way that all species evolve and forms the foundation of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which have an ancestor in common will tend to develop similar characteristics over time. This is because these traits help them to reproduce and survive within their environment.
All organisms have a DNA molecule, which is the source of information that helps direct their growth and development. The DNA structure is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction can cause variations in a population.
Fossils of the first human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Despite some differences, these fossils all support the notion 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.