The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are arranged in optional learning paths, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that in time, creatures more adaptable to changing environments do better than those that are not extinct. This process of evolution is what science is all about.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, such as "progress" or "descent with modification." Evolution KR is scientifically based and refers to the process of changing characteristics over time in organisms or species. This change is based in biological terms on natural selection and drift.
Evolution is a key principle in the field of biology today. It is a concept that has been confirmed through thousands of scientific tests. Unlike many other scientific theories, such as the Copernican theory or the germ theory of disease, evolution does not address issues of religion or God's existence.
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-wise manner, over time. This was known as 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 which was written in the early 1800s. It claims that different species of organisms have an ancestry that can be traced through fossils and other evidence. This is the modern view of evolution, and is supported by a variety of lines of research in science which includes molecular genetics.
Scientists don't know the evolution of organisms however they are certain that natural selection and genetic drift is responsible for the development of life. 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 a gradual accumulation of changes to the gene pool which gradually lead to new species and forms.
Certain scientists also use the term evolution to describe large-scale evolutionary changes, such as the formation of an entirely new species from an ancestral species. Certain scientists, such as population geneticists, define the term "evolution" in a more broad sense by talking about the net variation in the frequency of alleles over generations. Both definitions are valid and palatable, but certain scientists argue that allele frequency definitions miss important aspects of the evolutionary process.
Origins of Life
The emergence of life is an essential step in the process of evolution. The beginning of life takes place when living systems start to develop at a micro scale, for instance within cells.
The origins of life are an important subject in many areas such as biology and chemical. The origin of life is a topic of interest in science because it challenges the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could emerge from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a common belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible through an organic process.
Many scientists still believe it is possible to go from nonliving substances to life. The conditions needed to make life are not easy to replicate in a laboratory. Researchers 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.
Furthermore, the growth of life is the sequence of extremely complex chemical reactions that cannot be predicted from the fundamental physical laws alone. These include the reading and re-reading of complex molecules, like DNA or RNA, to create proteins that perform a specific function. These chemical reactions can be compared with the chicken-and-egg issue that is the emergence and growth of DNA/RNA, protein-based cell machinery, is required to begin the process of becoming a living organism. But without life, the chemistry that is required to make it possible appears to be working.
Research in the area of abiogenesis requires collaboration between scientists from various fields. This includes prebiotic chemists, astrobiologists, planetary scientists geophysicists and geologists.
Evolutionary Changes
Today, the word evolution is used to describe cumulative changes in genetic characteristics over time. These changes may result from adaptation to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This latter mechanism increases the number of genes that confer the advantage of survival for the species, leading to an overall change in the appearance of an entire group. The specific mechanisms responsible for these changes in evolutionary process include mutation and reshuffling of genes in sexual reproduction, and gene flow between populations.
While mutation and reshuffling of genes are common in all living organisms The process through which beneficial mutations are more frequent is referred to as natural selection. This is because, as mentioned above those who have the beneficial trait tend to have a higher reproduction rate than those without it. This differential in the number of offspring born over a long period of time can result in a gradual shift in the number of advantageous traits in a group.
An excellent example is the growing beak size on different species of finches in the Galapagos Islands, which have developed different beak shapes to allow them to more easily access food in their new habitat. 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 at the same time. Most of these changes are neither harmful nor even detrimental to the organism, however, a small proportion of them can have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. This is the mechanism of natural selection and it could eventually result in the accumulating changes that ultimately lead to a new species.
Many people think that evolution is a form of soft inheritance that is the belief that traits inherited from parents can be changed through deliberate choice or misuse. This is a misunderstanding of the biological processes that lead up to the process of evolution. A more accurate description of evolution is that it is a two-step procedure which involves the separate and often antagonistic forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a group of mammals that also includes gorillas, chimpanzees, and bonobos. The earliest human fossils prove that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality, we are most closely with chimpanzees in the Pan genus which includes bonobos and pygmy-chimpanzees. The last common ancestor of modern humans and chimpanzees lived between 8 and 6 million years ago.
In the course of time, humans have developed a variety of characteristics, such as bipedalism and the use of fire. They also developed advanced tools. It's only in the last 100,000 years that we have developed the majority of our essential traits. These include a big, complex brain, the ability of humans to construct and use tools, as well as cultural variety.
The process of evolution is when genetic changes allow members of the group to better adapt to the environment. Natural selection is the process that triggers this adaptation. Certain traits are preferred over others. The ones who are better adjusted are more likely to pass their genes on to the next generation. This is how all species evolve and the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which have a common ancestor, tend to develop similar traits over time. It is because these traits make it easier to reproduce and survive within their environment.
Every organism has a DNA molecule that provides the information necessary to control their growth and development. The DNA structure is made of base pairs arranged in a spiral around sugar and phosphate molecules. The sequence of bases in each strand determines the phenotype, the appearance and behavior of a person. The variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the early human species Homo erectus and Homo neanderthalensis have been found in Africa, Asia and Europe. Although there are some differences they all support the hypothesis that modern humans first appeared in Africa. Genetic and fossil evidence also suggest that early humans moved from Africa into Asia and then Europe.