The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The materials are organized into a variety of learning paths like "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how animals who are better equipped to adapt biologically to changing environment survive over time and those that don't end up becoming extinct. This process of evolution in biology is the main focus of science.
What is Evolution?
The word evolution can have a variety of meanings that are not scientific. For example it could refer to "progress" and "descent with modifications." Scientifically it refers to a change in the characteristics of living organisms (or species) over time. The reason for this change is biological terms on natural drift and selection.
Evolution is a central tenet of modern biology. It is a theory that has been confirmed by a myriad of scientific tests. Evolution doesn't deal with the existence of God or religious beliefs, unlike many other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a gradual manner over time. This was known as the "Ladder of Nature" or scala Naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin presented his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It states that all species of organisms have the same ancestry, which can be proven through fossils and other lines of evidence. This is the modern view of evolution that is supported by a variety of research lines in science which includes molecular genetics.
Scientists aren't sure the evolution of organisms but they are sure that natural selection and genetic drift is the primary reason for the evolution of life. Individuals with advantageous characteristics are more likely to survive and reproduce. They pass on their genes on to the next generation. Over time the gene pool slowly changes and develops into new species.
Certain scientists use the term"evolution" in reference to large-scale changes, such the development of one species from an ancestral one. Other scientists, like population geneticists, define it more broadly by referring to an overall change in the frequency of alleles across generations. Both definitions are valid and acceptable, but some scientists argue that allele-frequency definitions omit important features of evolutionary process.
Origins of Life
A key step in evolution is the emergence of life. This occurs when living systems begin to evolve at the micro level, within cells, for example.
The origin of life is an important subject in many fields, including biology and chemistry. The question of how living organisms began has a special place in science since it poses an enormous challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
Traditionally, the belief that life can emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the creation of life to happen through the natural process.
Many scientists still believe it is possible to transition from nonliving materials to living. The conditions needed to create life are difficult to reproduce in a lab. sell is why scientists studying the origins of life are also keen to understand the physical properties of early Earth and other planets.
The life-cycle of a living organism is dependent on a number of complex chemical reactions, that are not predicted by the basic physical laws. These include the reading and re-reading of complex molecules, such as DNA or RNA, to create proteins that perform a specific function. These chemical reactions can be compared with the chicken-and-egg problem: the emergence and development of DNA/RNA, protein-based cell machinery, is essential to begin the process of becoming a living organism. Although, without life, the chemistry needed to make it possible does appear to work.
Research in the field of abiogenesis requires cooperation among scientists from a variety of disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes may be the result of the adaptation to environmental pressures as described 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. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction, and the flow of genes.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles of their genes. As mentioned above, those who possess the desirable characteristic have a higher reproduction rate than those that do not. This differential in the number of offspring that are produced over a long period of time can result in a gradual change in the average number advantageous traits within a group.
A good example of this is the growing beak size on various species of finches on the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new habitat. These changes in shape and form can aid in the creation of new organisms.
The majority of the changes that occur are caused by a single mutation, but sometimes, several changes occur at once. Most of these changes are neither harmful nor even harmful to the organism, but a small percentage can have a positive impact on survival and reproduction, thus increasing the frequency of these changes in the population over time. Natural selection is a mechanism that can produce the accumulating change over time that leads to the creation of a new species.
Many people mistakenly associate evolution with the concept of soft inheritance that is the belief that inherited traits can be changed by conscious choice or by abuse. This is a misinterpretation of the biological processes that lead to the process of evolution. A more accurate description of evolution is that it involves a two-step process, involving the independent, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, 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 show that we have an intimate relationship with Chimpanzees. In actual fact, we are most closely connected to chimpanzees belonging to the Pan genus that includes pygmy and pygmy chimpanzees and bonobos. The last common ancestor of humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a wide range of traits over time, including bipedalism, the use of fire, and the development of advanced tools. But it's only in the last 100,000 years or so that the majority of the important traits that distinguish us from other species have emerged. They include a huge brain that is sophisticated human ability to create and use tools, and cultural diversity.
Evolution occurs when genetic changes allow members of the group to better adapt to the environment. Natural selection is the mechanism that triggers this adaptation. Certain traits are preferred over others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is the way that all species evolve and is the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species which have an ancestor in common will tend to develop similar traits as time passes. This is because these traits allow them to live and reproduce in their environments.
Every living thing has a DNA molecule, which is the source of information that helps guide their growth and development. The DNA molecule is composed of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases found in each string determines the phenotype or the distinctive appearance and behavior of an individual. Variations in a population can be caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite a few differences in their appearance, all support the idea of the origins of modern humans in Africa. The fossil and genetic evidence suggests that early humans left Africa and moved to Asia and Europe.