The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The resources are organized into various learning paths that can be used in a variety of ways like "What does T. rex look like?"
Charles Darwin's theory of natural selection states that over time, animals that are more adaptable to changing environments survive and those that do not become extinct. Science is all about this process of biological evolution.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, such as "progress" or "descent with modification." It is scientifically based and is used to describe the process of changing characteristics in a species or species. In terms of biology this change is due to natural selection and genetic drift.
Evolution is the central tenet of modern biology. It is a concept that has been verified by thousands of scientific tests. Unlike many other scientific theories such as the Copernican theory or the germ theory of disease, the evolution theory does not address questions of religious belief or the existence of God.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change in a step-wise way, over time. This was referred to as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
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 have common ancestors that can be traced through fossils and other evidence. This is the current view of evolution, which is supported in a wide range of areas of science, including molecular biology.
While scientists don't know exactly how organisms evolved however they are sure that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to live and reproduce, and these individuals transmit their genes to the next generation. Over time the gene pool gradually changes and evolves into new species.
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 it more broadly by referring to the net variation in the frequency of alleles over generations. Both definitions are acceptable and precise, although some scientists argue that the allele-frequency definition is missing important features of the evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. The beginning of life takes place when living systems begin to develop at a micro level, such as within individual cells.
The origins of life is one of the major topics in various disciplines that include geology, chemistry, biology and chemistry. The question of how living organisms began is a major topic in science since it poses a major challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
Traditionally, the idea that life can emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the emergence of life to happen through an entirely natural process.
Many scientists still think it is possible to transition from nonliving substances to living ones. However, the conditions that are required are extremely difficult to replicate in the laboratory. Researchers 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 life-cycle of a living organism is dependent on a variety of complex chemical reactions, that are not predicted by 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 can be compared to a chicken-and egg problem which is the development and emergence of DNA/RNA, protein-based cell machinery, is essential for the beginning of life. However without life, the chemistry needed to make it possible appears to be working.
Research in the area of abiogenesis requires collaboration among scientists from many different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is used to describe the gradual changes in genetic traits over time. These changes can result from the response to environmental pressures as discussed in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This mechanism also increases the frequency of genes that confer a survival advantage in an animal, resulting in an overall change in the appearance of an entire group. The specific mechanisms behind these changes in evolutionary process include mutation or reshuffling genes during sexual reproduction, as well as gene flow between populations.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles of genes. This happens because, as noted above those with the advantageous trait are likely to have a higher reproduction rate than those without it. Over the course of many generations, this variation in the numbers of offspring produced can result in an inclination towards a shift in the number of advantageous traits in a population.
A good example of this is the increase in the size of the beaks on different species of finches in the Galapagos Islands, which have developed beaks with different shapes to allow them to more easily access food in their new home. These changes in form and shape can also help create new organisms.
무료에볼루션 of changes are caused by a single mutation, however sometimes multiple occur simultaneously. The majority of these changes could be negative or even harmful however, a small percentage can have a beneficial impact on survival and reproduce and increase their frequency as time passes. Natural selection is a mechanism that could result in the accumulation of changes over time that lead to the creation of a new species.
Some people confuse evolution with the idea of soft inheritance, which is the idea 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. It is more accurate to say that the process of evolution is a two-step independent process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a group of mammal species that includes chimpanzees and gorillas. The earliest human fossils prove that our ancestors were bipeds. They were walkers with two legs. Biological and genetic similarities indicate that we have the same ancestry with Chimpanzees. In reality we are the most closely with chimpanzees in 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 evolved a wide range of traits over time, including bipedalism, the use of fire and advanced tools. But it's only in the past 100,000 years or so that most of the essential characteristics that differentiate us from other species have been developed. They include language, a large brain, the ability to construct and use sophisticated tools, and a the ability to adapt to cultural differences.
Evolution happens when genetic changes allow individuals of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process whereby certain traits are favored over other traits. Those with the better adaptations are more likely to pass their genes to the next generation. This is the process that evolves all species and is the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which have a common ancestor are likely to acquire similar traits over time. This is because these traits help them to survive and reproduce within their environment.
Every organism has a DNA molecule that contains the information needed to guide their growth. The DNA molecule consists of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. Variations in a population can be caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the first human species, Homo erectus, as well as Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite some differences in their appearance, all support the idea of modern humans' origins in Africa. Genetic and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.