The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are arranged into different learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection describes how species that are better equipped to adapt biologically to a changing environments over time, and those that don't disappear. This process of biological evolution is the main focus of science.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance, it can mean "progress" and "descent with modifications." Scientifically it refers to a process of changing the characteristics of organisms (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is an important concept in the field of biology today. It is a well-supported theory that has stood up to the test 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, evolution does not address issues 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 change in a step-like fashion over time. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this concept 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 asserts that all species of organisms share an ancestry that can be traced by fossils and other evidence. This is the current perspective on evolution, and is supported by a variety of areas of science, including molecular biology.
While scientists don't know exactly how organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to live and reproduce, and they transmit their genes to the next generation. In time this leads to an accumulation of changes in the gene pool, which eventually lead to new species and forms.
Certain scientists use the term"evolution" in reference to large-scale change, such as the evolution of an animal from an ancestral one. Certain scientists, such as population geneticists, define evolution in a more broad sense by talking about the net change in the frequency of alleles across generations. Both definitions are acceptable and precise however some scientists believe that the definition of allele frequency is lacking important features 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 a micro-level - within cells, for instance.
similar site of life are an issue in a variety of disciplines that include biology, chemistry, and geology. The question of how living organisms began is a major topic in science due to it being 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 matter was known as "spontaneous generation" or "spontaneous evolutionary". It was a popular belief before Louis Pasteur's experiments proved that the development of living organisms was not achievable through a natural process.
Many scientists still believe it is possible to transition from nonliving substances to life. The conditions required to create life are difficult to reproduce in a lab. Researchers who are interested in the origins and development of life are also keen to know the physical properties of the early Earth as well as other planets.
Additionally, the evolution of life depends on a sequence of very complex chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading and the replication of complex molecules, such as DNA or RNA, to produce proteins that perform a specific function. These chemical reactions are often compared to the chicken-and-egg issue of how life first appeared: The development of DNA/RNA as well as protein-based cell machinery is crucial for the onset of life, however, without the development of life, the chemistry that makes it possible isn't working.
Research in the area of abiogenesis requires cooperation among scientists from various disciplines. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists, geologists, and geophysicists.
Evolutionary Changes
The term "evolution" is used to describe the gradual changes in genetic traits over time. These changes could result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
The latter is a mechanism that increases the frequency of genes in a species which confer an advantage in survival over other species, resulting in a gradual change in the appearance of a group. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction and gene flow.
While reshuffling and mutation of genes happen in all living organisms, the process by which beneficial mutations are more prevalent is referred to as natural selection. As mentioned above, those who possess the desirable characteristic have a higher reproduction rate than those that do not. This difference in the number of offspring that are produced over many generations can result in a gradual change in the number of advantageous traits within the group.
An excellent example is the growth of the size of the beaks on different species of finches found on the Galapagos Islands, which have developed different beak shapes that allow them to easily access food in their new habitat. These changes in shape and form could aid in the creation of new organisms.
The majority of changes are caused by one mutation, however sometimes multiple occur at the same time. Most of these changes may be neutral or even harmful however, a few may have a positive effect on the survival of the species and reproduce and increase their frequency as time passes. similar site is a process that can produce the accumulating changes over time that lead to a new species.
Some people confuse the notion of evolution with the notion that inherited characteristics can be altered by conscious choice, or through use and abuse, a notion known as soft inheritance. This is a misinterpretation of the biological processes that lead to the process of evolution. It is more accurate to say that evolution is a two-step independent process, which involves the forces of natural selection as well as mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees and gorillas and bonobos. The earliest human fossils prove that our ancestors were bipeds, walking on two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In actual fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common human ancestor as well as chimpanzees was between 8 and 6 million years ago.
Humans have developed a range of traits over time such as bipedalism, use of fire and advanced tools. But it's only in the past 100,000 years or so that most of the traits that distinguish us from other species have emerged. These include a big brain that is sophisticated human ability to build and use tools, and cultural variety.
The process of evolution occurs when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is driven by natural selection, a process that determines certain traits are more desirable than other traits. The better adjusted are more likely to pass on their genes to the next generation. This is the way that all species evolve and forms the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that share a common ancestor tend to develop similar traits over time. This is because these traits allow them to live and reproduce in their environments.
Every living thing has DNA molecules, which contains the information needed to control their growth and development. The DNA molecule consists of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each string determines the phenotype or the characteristic appearance and behavior of a person. Variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences, these fossils all support the idea that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans came out of Africa into Asia and then Europe.