The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are organized into optional learning paths, such as "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 environments survive longer and those who do not end up becoming extinct. Science is all about the process of biological evolutionary change.
What is Evolution?
The word evolution has many nonscientific meanings, including "progress" or "descent with modification." It is a scientific term that refers to the process of changing characteristics in a species or species. The reason for this change is biological terms on natural drift and selection.
Evolution is a central tenet of modern biology. It is an established theory that has stood up to the tests of time and thousands of scientific experiments. Unlike many other scientific theories like the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of spiritual belief or God's existence.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a step-like fashion over time. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
Darwin presented his theory of evolution in his book On the Origin of Species, written in the early 1800s. It asserts that different species of organisms share a common ancestry, which can be determined through fossils and other lines of evidence. This is the modern view of evolution, which is supported in a wide range of areas of science which include molecular biology.
Scientists aren't sure the evolution of organisms, but they are confident that natural selection and genetic drift are the primary reason for the evolution of life. People with traits that are advantageous are more likely to survive and reproduce, and they transmit their genes to the next generation. Over time, this results in an accumulation of changes to the gene pool which gradually lead to new species and types.
Some scientists also employ the term"evolution" to describe large-scale evolutionary changes, such as the formation of a new species from an ancestral species. Certain scientists, such as population geneticists define evolution in a broader sense by using the term "net change" to refer to the change in the frequency of alleles across generations. Both definitions are correct and acceptable, 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 emergence of life. This happens when living systems begin to develop at the micro level, within cells, for example.
The origin of life is a topic in many disciplines such as geology, chemistry, biology and chemistry. The question of how living things got their start is of particular importance in science due to it being an enormous challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
The idea that life could be born from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief before Louis Pasteur's experiments proved that the emergence of living organisms was not achievable through a natural process.
Many scientists still believe it is possible to transition from nonliving materials to living. The conditions required to create life are difficult to reproduce in a lab. Researchers who are interested in the evolution and origins of life are also keen to learn about the physical characteristics of the early Earth as well as other planets.
The development of life is also dependent on a series 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 are often compared to the chicken-and-egg issue of how life came into existence with the emergence of DNA/RNA and protein-based cell machinery is essential to the birth of life, however, without the development of life the chemical reaction that is the basis for it is not working.
Research in the area of abiogenesis requires cooperation among scientists from various disciplines. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists, geologists, and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes may be the result of adaptation to environmental pressures as discussed in Darwinism.
This latter mechanism increases the number of genes that offer a survival advantage in a species, resulting in an overall change in the appearance of a group. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction, and gene flow.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo mutations and reshuffles of their genes. As noted above, individuals who have the advantageous trait have a higher reproduction rate than those who don't. Over the course of many generations, this differential in the numbers of offspring born can result in a gradual shift in the average number of advantageous traits in a population.
This is evident in the evolution of different beak shapes for finches from the Galapagos Islands. They have created these beaks to ensure that they can eat more easily in their new environment. These changes in the shape and appearance of organisms can also be a catalyst for the creation of new species.
The majority of changes are caused by one mutation, but sometimes several occur simultaneously. Most of these changes can be neutral or even harmful however, a few can have a beneficial impact on the survival of the species and reproduce, increasing their frequency as time passes. This is the mechanism of natural selection and it can be a time-consuming process that produces the gradual changes that eventually lead to an entirely 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 abuse. This is a misinterpretation of the biological processes that lead to the process of evolution. A more accurate description is that evolution is a two-step procedure which involves the separate, and often competing, forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a group of mammals that includes chimpanzees, gorillas, and bonobos. Our ancestors walked on two legs, as evidenced by the earliest fossils. Biological and genetic similarities indicate that we have a close relationship with chimpanzees. In reality our closest relatives are chimpanzees of the Pan genus. This includes pygmy and bonobos. The last common ancestor between modern humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a variety of traits over time including bipedalism, the use of fire and advanced tools. It's only in the last 100,000 years that we've developed the majority of our key characteristics. They include language, a large brain, the ability to build and use sophisticated tools, and a the ability to adapt to cultural differences.
Evolution is when genetic changes allow members of the group to better adapt to the environment. Natural selection is the process that drives this adaptation. Certain traits are preferred over others. The more adapted are more likely to pass on their genes to the next generation. 에볼루션 is the way all species evolve and the foundation for the theory of evolution.
Scientists call it the "law of Natural Selection." The law states that species which share a common ancestor tend to develop similar characteristics over time. This is because these traits make it easier to live and reproduce in their environment.
All organisms possess the DNA molecule, which contains the information necessary to direct 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 phenotype or the individual's unique appearance and behavior. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite some differences in their appearance all support the hypothesis that modern humans' ancestors originated in Africa. Genetic and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.