The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The resources are organized into a variety of learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory on natural selection describes how species who are better able to adapt to changes in their environments survive longer and those who do not end up becoming extinct. This process of evolution is the basis of science.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, including "progress" or "descent with modification." It is a scientific term that is used to describe the process of changing characteristics over time in organisms or species. This change is based in biological terms on natural drift and selection.
Evolution is an important concept in the field of biology today. It is an accepted theory that has withstood the tests of time and thousands of scientific tests. 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 religious belief or God's existence.
Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a stepped-like 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 published his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It claims that different species of organisms have an ancestry that can be proven through fossils and other lines of evidence. This is the modern view on evolution, and is supported in a wide range of disciplines which include molecular biology.
Scientists aren't sure the evolution of organisms but they are sure that natural selection and genetic drift is the primary reason for the development of life. People with traits that are advantageous are more likely to survive and reproduce, and they transmit their genes to the next generation. Over time the gene pool gradually changes and develops into new species.
Certain scientists also use the term"evolution" to refer to large-scale evolutionary changes, such as the formation of the new species from an ancestral species. Other scientists, such as population geneticists, define it more broadly by referring to an overall variation in the frequency of alleles over generations. Both definitions are accurate and palatable, but some scientists argue that allele-frequency definitions miss important aspects of the evolution.
Origins of Life
The birth of life is a key step in evolution. The emergence of life happens when living systems start to develop at a microscopic level, like within individual cells.
The origin of life is an important topic in many areas such as biology and the field of chemistry. The question of how living things got their start has a special place in science due to it being an enormous challenge to the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
The notion that life could be born from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's tests proved that the development of living organisms was not possible by an organic process.
Many scientists believe it is possible to transition from nonliving substances to living ones. The conditions necessary to make life are not easy to replicate in a laboratory. Researchers who are interested in the origins and evolution of life are also keen to understand the physical properties of the early Earth as well as other planets.
The life-cycle of a living organism is dependent on a number of complex chemical reactions, which cannot be predicted by basic physical laws. These include the reading and re-reading of complex molecules, such as DNA or RNA, to produce proteins that perform a specific function. These chemical reactions are comparable to the chicken-and-egg problem: the emergence and development of DNA/RNA, protein-based cell machinery, is necessary to begin the process of becoming a living organism. However, without life, the chemistry that is required to enable it does appear to work.
Abiogenesis research requires collaboration with scientists from various disciplines. This includes prebiotic chemists, astrobiologists, planetary scientists geophysicists, geologists, and geophysicists.
Evolutionary Changes
The term "evolution" is commonly used today to refer to the accumulated changes in the genetic traits of populations over time. These changes could be the result of adapting to environmental pressures, as described in Darwinism.
This is a process that increases the frequency of genes in a species that offer an advantage in survival over other species, resulting in gradual changes in the appearance of a population. The specific mechanisms that cause these evolutionary changes include mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations.
While reshuffling and mutation of genes occur in all organisms, the process by which beneficial mutations become more common is referred to as natural selection. As mentioned above, those who have the advantageous characteristic have a higher reproduction rate than those who do not. This variation in the number of offspring produced over a number of generations could cause a gradual change in the number of advantageous traits in the group.
One good example is the growth of beak size on various species of finches on the Galapagos Islands, which have developed beaks with different shapes to allow them to more easily access food in their new environment. These changes in the shape and form of organisms can also be a catalyst for the creation of new species.
The majority of changes are caused by a single mutation, however sometimes multiple occur simultaneously. Most of these changes are neutral or even harmful to the organism but a small percentage can have a positive impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a process that can produce the accumulating changes over time that lead to a new species.
Many people confuse the concept of evolution with the notion that inherited characteristics can be changed through conscious choice or use and abuse, a notion known as soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that trigger it. It is more precise 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 mammals that also includes gorillas, chimpanzees, and bonobos. The earliest human fossils show that our ancestors were bipeds - walking on two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In actual fact we are the closest with chimpanzees in the Pan genus which includes bonobos and pygmy chimpanzees. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
Over time, humans have developed a range of characteristics, Evolutionkr such as bipedalism as well as the use of fire. They also developed advanced tools. It's only within the last 100,000 years that we've developed the majority of our important traits. These include language, large brain, the ability to construct and use sophisticated tools, and a cultural diversity.
The process of evolution occurs when genetic changes allow members of a population to better adapt to their surroundings. Natural selection is the process that drives this change. Certain traits are preferred over others. The ones who are better adaptable are more likely to pass on their genes to the next generation. This is the way that all species evolve and forms the basis of the theory of evolution.
Scientists call it the "law of natural selection." The law states that species that share an ancestor will tend to develop similar traits as time passes. This is because the traits make it easier for them to live and reproduce in their natural environment.
All organisms have a DNA molecule that contains the information needed to control their growth and development. The structure of DNA is made of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each string determines the phenotype or the distinctive appearance and behavior of a person. Variations in changes and reshuffling of genetic material (known as alleles) during sexual reproduction can cause variations in a population.
Fossils from the first human species, Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. Although there are some differences they all support the idea that modern humans first appeared in Africa. Genetic and fossil evidence also suggest that early humans came out of Africa into Asia and then Europe.