The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are arranged in various learning paths that can be used in a variety of ways, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how creatures that are better equipped to adapt biologically to changing environments over time, and those who do not become extinct. This process of evolution in biology is what science is all about.
What is Evolution?
The word evolution can be used to refer to a variety of nonscientific meanings. For instance it could mean "progress" and "descent with modifications." It is a scientific term that is used to describe 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 the central tenet of modern biology. It is an accepted theory that has stood up to the test of time and a multitude of scientific experiments. In contrast to other theories in science, such as 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, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a step-wise manner, over time. They called this 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 published in the early 1800s. It claims that different species of organisms have an ancestry that can be traced through fossils and other lines of evidence. This is the current understanding of evolution, and is supported by a variety of lines of research in science that include molecular genetics.
Scientists aren't sure the evolution of organisms however they are certain that natural selection and genetic drift is responsible for the evolution of life. People with advantages are more likely than others to survive and reproduce. These individuals then pass their genes to the next generation. As time passes the gene pool gradually changes and evolves into new species.
Certain scientists use the term"evolution" to refer to large-scale change, such as the development of one species from an ancestral one. Other scientists, like population geneticists, define evolution more broadly by referring a net variation in the frequency of alleles over generations. Both definitions are valid and acceptable, however some scientists believe that allele-frequency definitions miss important aspects of the evolutionary process.
Origins of Life
The development of life is a crucial step in evolution. The emergence of life happens when living systems start to develop at a micro level, such as within cells.
The origins of life are one of the major topics in various disciplines such as biology, chemistry and geology. The question of how living things started is a major topic in science since it poses a major challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life can arise 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 creation of life to happen through the natural process.
Many scientists believe it is possible to move from nonliving to living substances. However, the conditions required are extremely difficult to replicate in the laboratory. Researchers interested in the origins and evolution of life are also eager to know the physical properties of the early Earth as well as other planets.
The growth of life is dependent on a number of complex chemical reactions, which are not predicted by simple physical laws. This includes the conversion 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 are often compared to the chicken-and-egg issue of how life first appeared in the first place. The appearance of DNA/RNA and proteins-based cell machinery is vital for the onset of life, however, without the emergence of life the chemical reaction that is the basis for it isn't working.
Abiogenesis research requires collaboration with scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes may be the result of the adaptation to environmental pressures as explained in Darwinism.
This is a process that increases the frequency of those genes in a species that offer an advantage in survival over other species which results in gradual changes in the overall appearance of a group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of genes. This occurs because, as we've mentioned earlier those with the beneficial trait tend to have a higher reproduction rate than those who do not have it. Over the course of many generations, this variation in the numbers of offspring born can result in an inclination towards a shift in the average number of advantageous traits in a population.
This can be seen in the evolution of different beak shapes for finches from the Galapagos Islands. They have developed these beaks in order that they can access food more easily in their new habitat. These changes in shape and form can aid in the creation of new organisms.
The majority of changes are caused by a single mutation, however sometimes multiple occur at once. The majority of these changes are not harmful or even harmful to the organism, however, a small proportion of them can have an advantageous impact on the longevity and reproduction of the species, thus increasing their frequency in the population over time. Natural selection is a process that causes the accumulating changes over time that lead to the creation of a new species.
Many people think that evolution is a form of soft inheritance which is the notion that inherited traits can be altered by conscious choice or abuse. This is a misinterpretation of the biological processes that lead to the process of evolution. It is more accurate to say that evolution is a two-step independent process that involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a species of mammal species that includes chimpanzees and gorillas. The earliest human fossils show that our ancestors were bipeds - walkers on two legs. Genetic and biological similarities suggest that we have the same ancestry with the chimpanzees. In fact our closest relatives are the chimpanzees from the Pan genus. This includes pygmy and bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years old.
Over time humans have developed a range of characteristics, such as bipedalism and the use fire. They also created advanced tools. It is only within the last 100,000 years that we have developed the majority of our key characteristics. These include a large brain that is complex, the ability of humans to construct and use tools, as well as cultural diversity.
The process of evolution is when genetic changes allow members of an organization to better adapt to their environment. Natural selection is the process that drives this change. Certain traits are preferred over others. The more adapted are more likely to pass their genes on to the next generation. This is how all species evolve and is the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that share an ancestor will tend to develop similar traits as time passes. It is because these traits make it easier to live and reproduce in their environment.
Every organism has DNA molecules, which is the source of information that helps guide their growth and development. The DNA structure is made of base pairs arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in a population can be caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite differences in their appearance all support the theory of the origins of modern humans in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.