The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The resources 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 equipped to adapt to changes in their environments survive longer and those that do not disappear. This process of biological evolution is the basis of science.
What is Evolution?
The word evolution can be used to refer to a variety of nonscientific meanings. For instance, it can mean "progress" and "descent with modifications." Scientifically it refers to a change in the characteristics of organisms (or species) over time. In terms of biology this change is due to natural selection and genetic drift.
Evolution is a key concept in the field of biology today. 에볼루션 사이트 is a theory that has been tested and verified by thousands of scientific tests. It does not address the existence of God or religious beliefs like 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 traits were predetermined to change in a gradual 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 revealed his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms share a common ancestry, which can be traced through fossils and other evidence. This is the current understanding of evolution, and is supported by numerous lines of research in science that include molecular genetics.
Scientists aren't sure how organisms evolved, but they are confident that natural selection and genetic drift are the reason for the evolution of life. 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 this leads to an accumulation of changes to the gene pool that gradually lead to new species and forms.
Certain scientists also use the term"evolution" to refer to large-scale changes in evolutionary processes, such as the formation of a new species from an ancestral species. Other scientists, like population geneticists, define evolution more broadly, referring to a net variation in the frequency of alleles over generations. Both definitions are accurate and acceptable, however certain scientists argue that allele frequency definitions miss important aspects of the evolution.
Origins of Life
The most important step in evolution is the emergence of life. The beginning of life takes place when living systems start to develop at a micro level, such as within individual cells.
The origin of life is an important issue in a variety of areas that include biology and the field of chemistry. The nature of life is an area that is of immense interest to scientists, as it challenges the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could arise from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's experiments proved that the emergence of living organisms was not achievable through the natural process.
Many scientists still think it is possible to move from nonliving substances to living ones. However, the conditions that are required are extremely difficult to replicate in a laboratory. Researchers who are interested in the origins and evolution of life are also keen to learn about the physical characteristics of the early Earth as well as other planets.
The growth of life is dependent on a variety of complex chemical reactions, which are not predicted by basic physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that carry out functions as well as the replication of these intricate molecules to generate new DNA or RNA sequences. These chemical reactions can be compared with the chicken-and-egg problem: the emergence and development of DNA/RNA, the protein-based cell machinery, is essential for the beginning of life. However, without life, the chemistry required to create it is working.
Research in the field of abiogenesis requires cooperation 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 characteristics of an entire population over time. These changes could be the result of the adaptation to environmental pressures as discussed in Darwinism.
This process increases the frequency of genes that offer an advantage for survival in a species, resulting in an overall change in the appearance of an entire group. The specific mechanisms behind these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, and gene flow between populations.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo mutations and reshuffles of their genes. As noted above, individuals who have the advantageous trait have a higher reproductive rate than those who don't. Over many generations, this differential in the number of offspring born can result in a gradual shift in the average number of advantageous characteristics in a particular population.
This can be seen in the evolution of different beak shapes for finches from the Galapagos Islands. They have developed these beaks so they can get food more easily in their new environment. These changes in the shape and form of organisms could also help create new species.
The majority of changes are caused by a single mutation, but sometimes several occur at once. The majority of these changes could 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. Natural selection is a process 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 which is the notion that traits inherited from parents can be changed by conscious choice or by abuse. This is a misunderstanding of the biological processes that lead up to the process of evolution. It is more accurate to say that the process of evolution is a two-step, separate process, which involves the forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that also includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In reality our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor 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. It is only in the last 100,000 years or so that most of the important traits that distinguish us from other species have been developed. These include language, large brain, the ability to create and utilize complex tools, and the diversity of our culture.
The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the mechanism that drives this change. Certain traits are preferred over others. The ones with the best 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, tend to develop similar traits over time. This is because the traits make it easier for them to survive and reproduce in their environments.
Every organism has a DNA molecule, which provides the information necessary to guide their growth and development. The DNA molecule is composed of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in a population can be 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 differences in their appearance, all support the theory 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.