The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find resources to aid 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 that over time, animals that are more able to adapt to changing environments thrive, and those that are not extinct. This process of biological evolution is what science is all about.
What is Evolution?
The word evolution can be used to refer to a variety of nonscientific meanings. For example, it can mean "progress" and "descent with modifications." It is a scientific term that is used to describe the process of change of characteristics in a species or species. The reason for this change is biological terms on natural drift and selection.
Evolution is an important tenet in modern biology. It is a theory that has been proven by a myriad of scientific tests. Contrary to other theories of science like the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of religious belief or the existence of God.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical traits were predetermined to change in a step-like manner, 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.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms have common ancestors that can be traced through fossils and other evidence. This is the modern view on evolution, and is supported in a wide range of disciplines which include molecular biology.
Scientists do not know how organisms have evolved but they are sure that natural selection and genetic drift are responsible for the evolution of life. Individuals with advantageous characteristics are more likely to live and reproduce. These individuals transmit their genes on to the next generation. Over time the gene pool slowly changes and develops into new species.
Certain scientists also use the term"evolution" to describe large-scale evolutionary changes like the creation of an entirely new species from an ancestral species. Certain scientists, including population geneticists, define evolution in a broad sense, talking about the net change in the frequency of alleles across generations. Both definitions are acceptable and accurate however some scientists believe that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the development of life. This occurs when living systems begin to evolve at the micro level - within individual cells, for instance.
The origin of life is an important issue in a variety of areas such as biology and chemistry. The question of how living things got their start has a special place in science because it is an enormous challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the belief that life could emerge from nonliving things 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 emergence of life to occur by the natural process.
Many scientists still believe that it is possible to make the transition from nonliving materials to living. However, the conditions needed are extremely difficult to replicate in a laboratory. This is why scientists investigating the nature of life are also interested in understanding the physical properties of the early Earth and other planets.
The development of life is dependent on a variety of complex chemical reactions, that are not predicted by simple physical laws. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that perform a function and the replication of these complex molecules to produce new DNA or sequences of RNA. These chemical reactions are often compared to the chicken-and-egg issue of how life first appeared with the appearance of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, however, without the development of life the chemical reaction that is the basis for it does not appear to work.
Research in the area of abiogenesis requires cooperation among scientists from many different fields. This includes prebiotic chemists the astrobiologists, the planet 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 an entire population over time. These changes can be the result of adaptation to environmental pressures as explained in Darwinism.
This process increases the frequency of genes that provide a survival advantage in an animal, resulting in an overall change in the appearance of the group. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and gene flow between populations.
While reshuffling and mutations of genes occur in all living things The process through which beneficial mutations are more frequent is known as natural selection. As previously mentioned, those with the beneficial trait have a higher reproductive rate than those that do not. This difference in the number of offspring that are produced over a number of generations could result in a gradual shift in the average number advantageous characteristics in the group.
This is evident in the evolution of various 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 the shape and appearance of organisms can also help create new species.
The majority of changes are caused by a single mutation, but sometimes several occur simultaneously. The majority of these changes could be negative or even harmful however, a few could have a positive impact on survival and reproduction with increasing frequency as time passes. This is the mechanism of natural selection, and it can eventually result in the accumulating changes that eventually lead to a new species.
Some people confuse the notion of evolution with the notion that inherited characteristics can be altered through conscious choice or by use and abuse, a concept known as soft inheritance. This is a misunderstanding of the biological processes that lead to the process of evolution. A more precise description is that evolution is a two-step procedure which involves the separate, and often competing, forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species which includes chimpanzees and gorillas. Our predecessors walked on two legs, as evidenced by the oldest fossils. Genetic and biological similarities show that we share an intimate relationship with Chimpanzees. In fact our closest relatives are the chimpanzees of the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago.
As time has passed humans have developed a variety of traits, including bipedalism and the use fire. They also invented advanced tools. It is only within the last 100,000 years that we've developed the majority of our important characteristics. These include a large brain that is complex 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 group to better adapt to the environment. Natural selection is the process that drives this change. Certain characteristics 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 the process that evolves all species and is the basis of the theory of evolution.
Scientists refer to it as the "law of Natural Selection." The law states that species that have an ancestor in common will tend to acquire similar traits as time passes. It is because these traits make it easier to live and reproduce in their environment.
Every living thing has DNA molecules, which is the source of information that helps guide their growth and development. The DNA structure is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases found in each strand determines the phenotype - the appearance and behavior of an individual. Variations in mutations and reshuffling of the genetic material (known as alleles) during sexual reproduction can cause variation in a population.
Fossils from the earliest human species Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. Although there are some differences they all support the notion that modern humans first came into existence in Africa. Genetic and fossil evidence also suggest that early humans moved out of Africa into Asia and then Europe.