The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are organized into a variety of learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection describes how species that are better equipped to adapt biologically to changing environments over time, and those that don't end up becoming extinct. Science is concerned with this process of biological evolution.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For example, it can mean "progress" and "descent with modifications." It is scientifically based and refers to the process of change of characteristics in a species or species. In terms of biology this change is due to natural selection and genetic drift.
Evolution is a key tenet in modern biology. It is a theory that has been proven by a myriad of scientific tests. Unlike many other scientific theories, such as the Copernican theory or the germ theory of disease, evolution does not address questions of religious belief or the existence of God.
Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a stepped-like 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.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It claims that different species of organisms have the same ancestry, which can be determined through fossils and other lines of evidence. This is the current view of evolution, which is supported in many areas of science that include molecular biology.
While scientists do not know the exact mechanism by which organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to survive and reproduce, and they transmit their genes to the next generation. As time passes, this results in an accumulation of changes to the gene pool which gradually lead to new species and forms.
Certain scientists use the term"evolution" in reference to large-scale changes, such the evolution of one species from an ancestral one. Other scientists, like population geneticists, define the term "evolution" more broadly by referring to an overall variation in the frequency of alleles over generations. Both definitions are acceptable and precise however some scientists believe that the allele-frequency definition omits important features of the evolutionary process.
Origins of Life
The most important step in evolution is the development of life. The emergence of life happens when living systems begin to develop at a micro scale, for instance within individual cells.
The origins of life are a topic in many disciplines, including biology, chemistry, and geology. 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."
Traditionally, the idea that life can arise from nonliving things is called spontaneous generation, or "spontaneous evolution." 에볼루션 게이밍 was a popular belief prior to Louis Pasteur's research showed that it was impossible for the emergence of life to occur by a purely natural process.
Many scientists still think it is possible to transition from nonliving substances to living ones. However, the conditions needed are extremely difficult to reproduce in labs. Researchers investigating the beginnings of life are also keen to understand the physical properties of the early Earth and other planets.
In addition, the development of life is an intricate sequence of chemical reactions that cannot be predicted from the fundamental physical laws on their own. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that perform functions as well as the replication of these intricate molecules to generate new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg issue of how life first appeared in the first place. The appearance of DNA/RNA and protein-based cell machinery is crucial for the beginning of life, but without the appearance of life the chemical process that allows it isn't working.
Abiogenesis research requires collaboration between scientists from various fields. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" is commonly used to describe the accumulated changes in the genetic characteristics of an entire population over time. These changes could result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This latter mechanism increases the frequency of genes that confer a survival advantage in an animal, resulting in an overall change in the appearance of the group. These evolutionary changes are caused by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes.
While reshuffling and mutations of genes are common in all organisms and the process by which beneficial mutations are more prevalent is referred to as natural selection. As previously mentioned, those who have the advantageous characteristic have a higher reproduction rate than those that do not. Over the course of many generations, this variation in the numbers of offspring born can result in gradual changes in the average amount of desirable traits within a group of.
This is evident in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have created these beaks to ensure that they can eat more easily in their new environment. These changes in the form and shape of living organisms may also be a catalyst for the creation of new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur simultaneously. The majority of these changes could be negative or even harmful however, a small percentage could have a positive impact on the survival of the species and reproduce and increase their frequency as time passes. Natural selection is a process that could result in the accumulation of changes over time that lead to the creation of a new species.
Some people mistakenly associate evolution with the concept of soft inheritance, which is the idea that traits inherited from parents can be changed through conscious choice or by abuse. This is a misinterpretation of the biological processes that lead to the process of evolution. It is more precise to say that evolution is a two-step, separate process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a group of mammals that also includes chimpanzees, gorillas, and bonobos. Our predecessors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact we are the closest related to the chimpanzees within the Pan genus that includes pygmy and bonobos and pygmy chimpanzees. The last common ancestor of humans and chimpanzees was 8 to 6 million years old.
Humans have developed a range of traits over time, including bipedalism, the use of fire, and the development of advanced tools. It's only in the last 100,000 years that we've developed the majority of our essential traits. These include language, a large brain, the ability to build and use sophisticated tools, and a cultural diversity.
The process of evolution occurs when genetic changes enable members of an organization to better adapt to their environment. This adaptation is triggered by natural selection, a process that determines certain traits are preferred over other traits. 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 forms the foundation of the theory of evolution.
Scientists refer to it as the "law of Natural Selection." The law states that species that have an ancestor in common will tend to develop similar traits over time. This is because those traits allow them to survive and reproduce in their environment.
Every organism has an molecule called DNA that holds the information necessary to direct their growth. The structure of DNA is composed of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the early 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 idea of modern humans' origins in Africa. Evidence from fossils and genetics suggest that early humans moved out of Africa into Asia and then Europe.