The Berkeley Evolution Site

Students and teachers who explore the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are organized into different learning paths for example "What does T. rex look like?"

Charles Darwin's theory of natural selection explains how in time, creatures more adaptable to changing environments thrive, and those that are not extinct. Science is all about this process of evolution.

What is Evolution?

The term "evolution" has a variety of nonscientific meanings. For instance "progress" or "descent with modification." Scientifically, it refers to a process of changing the characteristics of organisms (or species) over time. In biological terms this change is due to natural selection and genetic drift.

Evolution is a central tenet of modern biology. It is an accepted theory that has withstood the test of time and a multitude of scientific experiments. It does not address God's presence or spiritual beliefs like other theories in science, like the Copernican or germ theory of diseases.

Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change, in a step-like way, over time. This was known as the "Ladder of Nature" or scala Naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.

Darwin presented his theory of evolution in his book On the Origin of Species published in the early 1800s. It states that all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the current view of evolution that is supported by a variety of lines of research in science that include molecular genetics.


Scientists aren't sure the evolution of organisms, but they are confident that natural selection and genetic drift are responsible for the development of life. People with desirable traits are more likely to live and reproduce, and they transmit their genes to the next generation. Over time this leads to gradual changes to the gene pool that gradually create new species and types.

Certain scientists use the term"evolution" to refer to large-scale change, such as the evolution of one species from an ancestral one. Other scientists, such as population geneticists, define the term "evolution" more broadly by referring an overall variation in the frequency of alleles over generations. Both definitions are accurate and acceptable, however some scientists believe that allele-frequency definitions omit important features of evolution.

Origins of Life

The most important step in evolution is the appearance of life. The emergence of life occurs when living systems begin to develop at a microscopic scale, for instance within cells.

The origin of life is an important subject in a variety of fields that include biology and chemistry. The question of how living organisms began is of particular importance in science because it is a major challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."

The notion that life could arise from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's experiments proved that the development of living organisms was not possible through the natural process.

Many scientists believe it is possible to go from living to nonliving substances. The conditions necessary for the creation of life are difficult to replicate in a laboratory. Researchers who are interested in the origins and development of life are also eager to know the physical properties of the early Earth as well as other planets.

Additionally, the evolution of life is dependent on a sequence of very complex chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading of long information-rich molecules (DNA or RNA) into proteins that carry out a function as well as the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg problem of how life began: The emergence of DNA/RNA and proteins-based cell machinery is vital for the onset of life, but without the development of life the chemistry that makes it possible isn't working.

Research in the area of abiogenesis requires collaboration between scientists from many different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.

Evolutionary Changes

The term "evolution" is typically used to describe the accumulated changes in genetic characteristics of an entire population over time. These changes could result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.

This mechanism also increases the number of genes that offer an advantage for survival in a species, resulting in an overall change in the appearance of the group. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction and the flow of genes.

While mutation and reshuffling of genes occur in all organisms, the process by which beneficial mutations become more common is referred to as natural selection. As previously mentioned, those who possess the desirable characteristic have a higher reproduction rate than those who do not. Over many generations, this variation in the number of offspring produced can result in gradual changes in the average number of beneficial characteristics in a particular population.

One good example is the increase in the size of the beaks on different species of finches on the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new environment. These changes in form and shape can aid in the creation of new organisms.

The majority of the changes that take place are the result of a single mutation, but occasionally several will happen simultaneously. The majority of these changes could be harmful or neutral however, a few can have a beneficial impact on survival and reproduce with increasing frequency over time. Natural selection is a process that can produce the accumulating change over time that eventually leads to the creation of a new species.

Some people confuse the idea of evolution with the notion that traits inherited can be altered through conscious choice or use and abuse, a notion known as soft inheritance. This is a misunderstanding of the nature of evolution and of the actual biological processes that cause it. It is more accurate to say that the process of evolution is a two-step, separate process, which involves the forces of natural selection as well as mutation.

Origins of Humans

Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species that includes gorillas and chimpanzees. Our predecessors walked on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In fact, we are most closely connected to chimpanzees belonging to the Pan Genus which includes bonobos and pygmy-chimpanzees. The last common human ancestor as well as chimpanzees lived between 8 and 6 million years ago.

Humans have developed a range of traits over time including bipedalism, the use of fire and advanced tools. 무료 에볼루션 's only within the last 100,000 years that we have developed the majority of our key characteristics. These include language, a large brain, the ability to construct and use complex tools, and the ability to adapt to cultural differences.

Evolution happens when genetic changes allow individuals in a group to better adapt to their surroundings. This adaptation is triggered by natural selection, a process whereby certain traits are more desirable than others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is how all species evolve and is the foundation of the theory of evolution.

Scientists call it the "law of Natural Selection." The law says that species that have a common ancestor are more likely to develop similar characteristics over time. This is because those traits make it easier for them to live and reproduce in their environment.

All organisms possess a DNA molecule that contains the information needed to control their growth. The structure of DNA is made of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases found in each strand determines the phenotype, the appearance and behavior of an individual. Different mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction cause variation in a group.

Fossils from the first human species, Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. While there are some differences between them, these fossils all support the idea that modern humans first came into existence in Africa. The evidence from fossils and genetics suggests that early humans left Africa and moved to Asia and Europe.