The Berkeley Evolution Site
The Berkeley site has resources that can help students and educators understand and teach evolution. The resources are organized into a variety of learning paths like "What did T. rex taste like?"
Charles Darwin's theory on natural selection describes how species that are better equipped to adapt biologically to changing environments over time, and those who do not end up becoming extinct. Science is about this process of biological evolutionary change.
What is Evolution?
The word evolution has many nonscientific meanings, such as "progress" or "descent with modification." Scientifically it refers to a process of changing the characteristics of living organisms (or species) over time. The reason for this change is biological terms on natural drift and selection.
Evolution is one of the fundamental tenets of modern biology. It is a theory that has been verified through thousands of scientific tests. Unlike many other scientific theories, such as the Copernican theory or the germ theory of disease, evolution does not address issues of religion or the existence of God.
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, over time. They referred to this as the "Ladder of Nature" or the 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 which was written in the early 1800s. It states that all species of organisms share an ancestry that can be traced using fossils and other evidence. This is the current perspective on evolution, which is supported in a wide range of disciplines, including molecular biology.
While scientists do not know the exact mechanism by which organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. People with advantages are more likely to survive and reproduce. They pass on their genes to the next generation. As time passes this leads to an accumulation of changes to the gene pool, which eventually result in new species and types.
Certain scientists use the term evolution in reference to large-scale changes, such the evolution of an animal from an ancestral one. Other scientists, such as population geneticists, define evolution more broadly, referring to an overall change in the frequency of alleles across generations. Both definitions are acceptable and accurate, although some scientists argue that the definition of allele frequency is lacking important features of the evolutionary process.
Origins of Life
The emergence of life is an essential step in evolution. This happens when living systems begin to evolve at the micro level - within individual cells, for instance.
The origin of life is an important topic in a variety of areas such as biology and chemistry. The question of how living things got their start is of particular importance in science since it poses an enormous challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
The idea that life could emerge from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". It was a popular belief before Louis Pasteur's experiments proved that the emergence of living organisms was not possible through the natural process.
Many scientists still believe that it is possible to go from nonliving materials to living. The conditions necessary to create life are difficult to reproduce in a lab. This is why researchers investigating the nature of life are also keen to understand the physical properties of the early Earth and other planets.
The growth of life is dependent on a variety of complex chemical reactions, which are not predicted by simple physical laws. These include the reading and replication of complex molecules, like DNA or RNA, in order to make proteins that perform a specific function. These chemical reactions are often compared to the chicken-and-egg problem of how life began in the first place. The emergence of DNA/RNA and proteins-based cell machinery is vital to the birth of life, however, without the emergence of life the chemical reaction that is the basis for it does not appear to work.
Abiogenesis research requires collaboration among scientists from different fields. This includes prebiotic chemists planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is commonly used to describe the cumulative changes in the genetic characteristics of a population over time. These changes can be the result of adaptation to environmental pressures as described in Darwinism.
This is a method that increases the frequency of genes that confer an advantage in survival over other species and causes a gradual change in the overall appearance of a particular population. The specific mechanisms behind these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, as well as gene flow between populations.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles of their genes. This happens because, as noted above those who have the advantageous trait are likely to have a higher reproductive rate than those without it. This variation in the number of offspring that are produced over many generations can cause a gradual change in the average number advantageous traits in the group.
A good example of this is the growing the size of the beaks on different species of finches found on the Galapagos Islands, which have evolved different shaped beaks to allow them to more easily access food in their new home. These changes in form and shape can aid in the creation of new organisms.
The majority of changes are caused by a single mutation, although sometimes multiple occur at once. Most of these changes are neither harmful nor even detrimental to the organism, but a small percentage can have an advantageous impact on the survival of the organism and its reproduction, thereby increasing the frequency of these changes in the population over time. Natural selection is a mechanism that causes the accumulating change over time that leads to 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 misunderstanding of the biological processes that lead to evolution. It is more accurate to say that evolution is a two-step independent process that involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees and gorillas and bonobos. The earliest human fossils prove that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we share the same ancestry with chimpanzees. In fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor of modern humans and chimpanzees was 8 to 6 million years old.
Humans have evolved a variety of characteristics over time including bipedalism, the use of fire, and the development of advanced tools. However, 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. These include a big brain that is complex human ability to construct and use tools, and cultural variety.
The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. This adaptation is driven by natural selection, which is a process by which certain traits are favored over other traits. The ones with the best adaptations are more likely to pass on their genes to the next generation. 에볼루션 슬롯 is how all species evolve and forms the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that have a common ancestor are likely to develop similar traits in the course of time. It is because these traits make it easier to survive and reproduce within their environment.
Every organism has the DNA molecule, which contains the information necessary to direct their growth. The DNA structure is composed of base pairs which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in mutations and reshufflings of the genetic material (known as alleles) during reproduction causes variation in a population.
Fossils from the early human species Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. Despite some differences the fossils all support the notion that modern humans first appeared in Africa. The fossil evidence and genetic evidence suggest that early humans moved out of Africa into Asia and then Europe.