The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are arranged in optional learning paths for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how over time creatures that are more adaptable to changing environments survive and those that do not become extinct. This process of evolution is the basis of science.
What is Evolution?
The term "evolution" can have many nonscientific meanings, including "progress" or "descent with modification." Scientifically, it refers to a changing the characteristics of organisms (or species) over time. In biological terms, this change is caused by natural selection and genetic drift.
Evolution is the central tenet of modern biology. It is a theory that has been tested and confirmed by a myriad of scientific tests. Evolution does not deal with spiritual beliefs or God's presence in the same way as other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a step-like fashion over time. 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.
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 an ancestry that can be traced by fossils and other evidence. This is the modern view of evolution, and is supported by numerous lines of research in science which includes molecular genetics.
Scientists do not know how organisms have evolved however they are certain that natural selection and genetic drift are the reason for the development 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. As time passes this leads to a gradual accumulation of changes in the gene pool that gradually result in new species and forms.
에볼루션 코리아 use the term"evolution" to refer to large-scale changes, like the formation of one species from an ancestral one. Other scientists, like population geneticists, define it more broadly, referring to a net change in allele frequencies over generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The most important step in evolution is the appearance of life. The emergence of life occurs when living systems begin to develop at a microscopic scale, for instance within individual cells.
The origins of life are an important issue in a variety of disciplines, including biology and chemical. The origin of life is a subject of great 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 belief that life can emerge from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the emergence of life to be a result of an entirely natural process.
Many scientists still believe that it is possible to make the transition from nonliving materials to living. The conditions necessary for the creation of life are difficult to reproduce in a lab. Researchers investigating the beginnings of life are also interested in determining 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 basic physical laws. 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 sequences of RNA. These chemical reactions can be compared to a chicken-and egg problem that is the emergence and growth of DNA/RNA, protein-based cell machinery, is required to begin the process of becoming a living organism. But, without life, the chemistry needed to create it is working.
Abiogenesis research requires collaboration among scientists from various disciplines. This includes prebiotic chemists, planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is commonly used today to describe the accumulated changes in the genetic traits of an entire population over time. These changes can 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 latter mechanism increases the number of genes that offer a survival advantage in the species, leading to an overall change in the appearance of an entire group. The specific mechanisms behind these changes in evolutionary process include mutation, reshuffling of genes during sexual reproduction, and also gene flow between populations.
While reshuffling and mutation of genes occur in all organisms, the process by which beneficial mutations are more prevalent is referred to as natural selection. As noted above, individuals who have the advantageous trait have a higher reproductive rate than those who do not. This variation in the number of offspring that are produced over many generations can result in a gradual change in the average number of beneficial characteristics in a group.
This is evident in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order they can get food more quickly in their new home. These changes in shape and form can also help create new organisms.
Most of the changes that take place are caused by one mutation, but occasionally several will happen simultaneously. The majority of these changes could be neutral or even harmful however, a few could have a positive impact on survival and reproduction and increase their frequency as time passes. Natural selection is a process that can produce the accumulating change over time that leads to the creation of a new species.
Many people confuse the concept of evolution with the notion that inherited characteristics can be altered by conscious choice, or through use and abuse, which is called soft inheritance. This is a misinterpretation of the biological processes that lead up to the process of evolution. It is more precise to say that evolution is a two-step, separate 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 which includes chimpanzees as well as gorillas. The earliest human fossils indicate that our ancestors were bipeds - walkers on two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In fact we are the most closely connected to chimpanzees belonging to the Pan Genus, which includes bonobos and pygmy-chimpanzees. The last common ancestor between modern humans and chimpanzees dated 8 to 6 million years old.
In the course of time, humans have developed a number of characteristics, including bipedalism and the use fire. They also invented advanced tools. It is only in the past 100,000 years or so that most of the essential characteristics that differentiate us from other species have developed. These include language, a large brain, the capacity to construct and use complex tools, as well as the diversity of our culture.
Evolution occurs when genetic changes allow members of an organization to better adapt to their environment. Natural selection is the mechanism that drives this adaptation. Certain characteristics are more desirable than others. The ones who are better adapted are more likely to pass their genes on to the next generation. This is the process that evolves all species and is the foundation of the theory of evolution.
Scientists call it the "law of natural selection." The law states that species that share an ancestor will tend to develop similar characteristics over time. It is because these traits help them to survive and reproduce within their environment.
Every organism has an molecule called DNA that holds the information necessary to direct their growth. The DNA molecule is made up of base pairs that are spirally arranged around phosphate molecules and sugar molecules. The sequence of bases in each strand determines the phenotype, the characteristic appearance and behavior of a person. The variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite some variations in their appearance, all support the idea that modern humans' ancestors originated in Africa. The fossil evidence and genetic evidence suggest that early humans moved from Africa into Asia and then Europe.