The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The re sources are organized into various learning paths that can be used in a variety of ways for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that over time, animals that are more able to adapt to changing environments survive and those that do not become extinct. This process of evolution in biology is the main focus of science.
What is Evolution?
The term "evolution" could be used to refer to a variety of nonscientific meanings. For example it could mean "progress" and "descent with modifications." It is an academic term that refers to the process of change of characteristics in a species or species. This change is based in biological terms on natural drift and selection.
Evolution is a key principle in the field of biology today. It is an established theory that has stood the test of time and a multitude of scientific studies. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, the evolution theory does not address questions of religion 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 gradual manner, as time passes. They called this 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 published in the early 1800s. It asserts that all species of organisms share common ancestors that can be traced by fossils and other evidence. This is the modern view of evolution, which is supported by a variety of lines of scientific research, including molecular genetics.
Scientists do not know how organisms have evolved however they are certain that natural selection and genetic drift are the reason for the development of life. People with desirable traits are more likely to survive and reproduce, and these individuals transmit their genes to the next generation. Over time the gene pool slowly changes and evolves into new species.
Some scientists use the term"evolution" in reference to large-scale changes, such the development of a species from an ancestral one. Other scientists, such as population geneticists, define it more broadly by referring to an overall change in allele frequencies over generations. Both definitions are acceptable and precise however, some scientists claim that the definition of allele frequency is lacking crucial aspects of the evolutionary process.
Origins of Life
The emergence of life is a key step in the process of evolution. The beginning of life takes place when living systems begin to develop at a micro level, like within cells.
The origins of life are an issue in a variety of disciplines such as biology, chemistry and geology. The origin of life is a subject of great interest in science because it challenges the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life could emerge from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a popular view before Louis Pasteur's experiments proved that it was impossible for the development of life to occur by an entirely natural process.
Many scientists still believe it is possible to go from nonliving substances to living. However, the conditions that are required are extremely difficult to replicate in a laboratory. Researchers interested in the evolution and origins of life are also eager to learn about the physical characteristics of the early Earth as well as other planets.
Additionally, the evolution of life depends on an intricate sequence of chemical reactions that can't be predicted from the fundamental physical laws on their own. These include the reading and re-reading of complex molecules, like DNA or RNA, in order to make proteins that perform a particular function. These chemical reactions are often compared with the chicken-and-egg issue of how life came into existence: The emergence of DNA/RNA and protein-based cell machinery is essential for the beginning of life, but without the appearance of life the chemical process that allows it does not appear to work.
Research in the area of abiogenesis requires cooperation among scientists from various fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is commonly used today to describe the accumulated changes in genetic characteristics of an entire population over time. These changes can result from adaptation to environmental pressures, as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This is a method that increases the frequency of genes in a species that confer an advantage in survival over other species, resulting in an ongoing change in the overall appearance of a group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes.
While reshuffling and mutation of genes happen in all organisms The process through which beneficial mutations are more prevalent is referred to as natural selection. As previously mentioned, those who possess the desirable trait have a higher reproductive rate than those who don't. This differential in the number of offspring born over many generations can cause a gradual change in the number of advantageous traits in a group.
An excellent example is the growth of the size of the beaks on different species of finches on the Galapagos Islands, which have evolved different shaped beaks to allow them to more easily access food in their new home. These changes in shape and form could also help create new organisms.
Most of the changes that occur are the result of a single mutation, but occasionally, multiple mutations occur simultaneously. The majority of these changes could be harmful or neutral, but a small number could have a positive impact on survival and reproduce with increasing frequency as time passes. This is the way of natural selection and it could be a time-consuming process that produces the cumulative changes that eventually lead to a new species.
Some people mistakenly associate evolution with the concept of soft inheritance which is the notion that inherited traits can be altered by deliberate choice or misuse. This is a misunderstanding of the biological processes that lead up 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 and mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a group of mammal species which includes gorillas and chimpanzees. Our ancestors walked on two legs, as evidenced by the first fossils. Genetic and biological similarities suggest that we have the same ancestry with chimpanzees. In reality we are the closest with chimpanzees in the Pan Genus that includes pygmy and bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees lived between 8 and 6 million years ago.
Over time, humans have developed a variety of characteristics, including bipedalism and the use fire. They also created advanced tools. It's only within the last 100,000 years that we've developed the majority of our important traits. These include a large brain that is sophisticated and the capacity of humans to construct and use tools, and the diversity of our culture.
Evolution occurs when genetic changes allow members of a population to better adapt to their environment. This adaptation is driven by natural selection, which is a process by which certain traits are preferred over others. The ones who are better adaptable are more likely to pass their genes on to the next generation. This is the process that evolves all species and is the foundation of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species that have a common ancestor, tend to develop similar traits over time. This is because the characteristics make it easier for them to live and reproduce in their environments.
Every organism has an molecule called DNA that holds the information needed to control their growth. The DNA structure is made of base pairs which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each strand determines the phenotype, the distinctive appearance and behavior of a person. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite a few differences in their appearance, all support the theory that modern humans' ancestors originated in Africa. Genetic and fossil evidence also suggest that early humans came from Africa into Asia and then Europe.