The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to assist them in understanding and teaching evolution. The resources are arranged into different learning paths like "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how animals who are better able to adapt biologically to a changing environment survive over time and those that don't disappear. This process of biological evolution is the main focus of science.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, including "progress" or "descent with modification." Scientifically, it refers to a changes in the traits of organisms (or species) over time. In terms of biology the change is due to natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is an established theory that has stood up to the test of time and a multitude of scientific tests. Evolution does not deal with God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists, like 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. They called this the "Ladder of Nature" or scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin revealed his theory of evolution in his book On the Origin of Species, written in the early 1800s. It states that all species of organisms share an ancestry that can be traced through fossils and other evidence. This is the modern view of evolution, and is supported by a variety of research lines in science, including molecular genetics.
Scientists aren't sure how organisms have evolved but they are sure that natural selection and genetic drift are the primary reason for the development of life. People with desirable traits are more likely than others to live and reproduce. These individuals transmit their genes on to the next generation. Over time the gene pool gradually changes and develops into new species.
Certain scientists use the term"evolution" in reference to large-scale changes, such the development of an animal from an ancestral one. Others, like population geneticists, define it more broadly, referring to an overall change in allele frequencies over generations. Both definitions are valid and palatable, but some scientists believe that allele-frequency definitions omit important features of evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the development of life. This happens when living systems begin to develop at the micro level - within individual cells, for instance.
The origin of life is an important topic in many fields that include biology and the field of chemistry. The question of how living things got their start has a special place in science because it is a major challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
The idea that life could emerge from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a common belief prior to Louis Pasteur's tests proved that the creation of living organisms was not achievable through the natural process.
Many scientists believe it is possible to transition from living to nonliving substances. However, the conditions needed are extremely difficult to replicate in the 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 development of life is dependent on a number of complex chemical reactions, which are not predicted by the basic physical laws. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that carry out functions as well as the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions are often compared with the chicken-and-egg issue of how life first appeared with the development of DNA/RNA as well as proteins-based cell machinery is vital for the beginning of life, however, without the emergence of life the chemical reaction that is the basis for it isn't working.
Research in the field of abiogenesis requires collaboration among scientists from many different disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
Today, the word evolution is used to describe general changes in genetic traits over time. 에볼루션 무료체험 may be the result of the adaptation to environmental pressures as discussed in Darwinism.
The latter is a mechanism that increases the frequency of genes in a species which confer an advantage in survival over others, resulting in a gradual change in the overall appearance of a particular population. These changes in evolutionary patterns are caused by mutations, reshuffling genes in the process of sexual reproduction, and also by gene flow.
While reshuffling and mutations of genes happen in all living organisms and the process by which beneficial mutations are more prevalent is referred to as natural selection. This occurs because, as noted above those who have the advantageous trait are likely to have a higher reproductive rate than those with it. This variation in the number of offspring born over a number of generations could result in a gradual change in the average number of beneficial traits within the group.
A good example of this is the growth of beak size on various species of finches 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 one mutation, but sometimes several occur at once. The majority of these changes could be neutral or even harmful however, a small percentage could have a positive impact on the survival of the species and reproduce, increasing their frequency as time passes. Natural selection is a mechanism that could result in the accumulation of change over time that leads to the creation of a new species.
Some people think that evolution is a form of soft inheritance, which is the idea that inherited traits can be altered by conscious choice or by abuse. This is a misunderstanding of the biological processes that lead to the process of evolution. A more precise description is that evolution involves a two-step process, that involves the distinct and often conflicting forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species that includes chimpanzees and gorillas. Our predecessors 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 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 between 8 and 6 million years ago.
Humans have evolved a wide range of traits over time such as bipedalism, use of fire and advanced tools. It is only in the last 100,000 years or so that the majority of the characteristics that differentiate us from other species have developed. These include a big, complex brain, the ability of humans to build and use tools, and cultural diversity.
Evolution happens when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The ones who are better adapted are more likely to pass on their genes to the next generation. This is how all species evolve and is the basis for the theory of evolution.
Scientists call it the "law of Natural Selection." The law states that species which have a common ancestor are likely to acquire similar traits in the course of time. This is because these characteristics make it easier for them to live and reproduce in their environment.
All organisms have a DNA molecule that provides the information necessary to control their growth and development. The structure of DNA is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases in each strand determines the phenotype - the appearance and behavior of a person. Variations in a population can be 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 discovered in Africa, Asia, and Europe. These fossils, despite variations in their appearance, all support the theory that modern humans' ancestors originated in Africa. Evidence from fossils and genetics suggest that early humans moved out of Africa into Asia and then Europe.