The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of re sources to help them understand and teach evolution. The materials are organized into optional learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains that over time creatures that are better able to adapt biologically to changing environments thrive, and those that don't become extinct. This process of evolution is the basis of science.
What is Evolution?
The word evolution has many nonscientific meanings, such as "progress" or "descent with modification." It is a scientific term that is used to describe the process of change of characteristics in a species or species. In terms of biology this change is due to natural selection and genetic drift.
Evolution is a key tenet in modern biology. It is an accepted theory that has stood up to the test of time and thousands of scientific tests. In contrast to other theories in science like 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 Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change, in a gradual manner, as time passes. This was referred to 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 published in the early 1800s. It asserts that all species of organisms share an ancestry that can be traced using fossils and other evidence. This is the current view of evolution, which is supported in a wide range of disciplines which include molecular biology.
Scientists don't know the evolution of organisms but they are sure that natural selection and genetic drift is responsible for the development of life. People with desirable traits are more likely than others to live and reproduce. They pass on their genes to the next generation. As time passes, this results in gradual changes in the gene pool which gradually lead to new species and forms.
Certain scientists use the term"evolution" to refer to large-scale change, such as the development of one species from an ancestral one. Other scientists, such as population geneticists, define evolution more broadly, referring to the net change in allele frequencies over generations. Both definitions are correct and palatable, but some scientists believe that allele-frequency definitions do not include important aspects of evolution.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. This occurs when living systems begin to evolve at the micro level, within individual cells, for instance.
The origins of life are an important topic in a variety of areas such as biology and the field of chemistry. The question of how living organisms began is a major topic in science due to it being an important challenge to the theory of evolution. It is often called "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". This was a common belief prior to Louis Pasteur's tests showed that the development of living organisms was not possible through a natural process.
Many scientists believe it is possible to move from nonliving substances to living ones. The conditions needed to make life are not easy to replicate in a laboratory. This is why researchers studying the beginnings of life are also interested in understanding the physical properties of early Earth and other planets.
The growth of life is dependent on a number of complex chemical reactions that are not predicted by basic physical laws. These include the reading and replication of complex molecules, such as DNA or RNA, to produce proteins that perform a specific function. These chemical reactions can be compared to the chicken-and-egg issue that is the emergence and growth of DNA/RNA, a protein-based cell machinery, is essential for the onset life. Although, without life, the chemistry needed to make it possible appears to be working.
Research in the area of abiogenesis requires collaboration among scientists from a variety of fields. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists and geologists.
Evolutionary Changes
The word evolution is usually used today to describe the accumulated changes in the genetic characteristics of populations over time. These changes can result from the response to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
The latter is a mechanism that increases the frequency of genes in a species which confer an advantage in survival over others which results in an ongoing change in the overall appearance of a group. The specific mechanisms that cause these evolutionary changes include mutation and reshuffling of genes in sexual reproduction, as well as gene flow between populations.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles in their genes. This is because, as we've mentioned earlier those who have the beneficial trait tend to have a higher reproduction rate than those without it. This difference in the number of offspring produced over a number of generations could result in a gradual shift in the number of advantageous traits within a group.
This can be seen in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order that they can access food more easily 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 may be harmful or neutral however, a few can have a beneficial impact on the survival of the species and reproduce and increase their frequency as time passes. Natural selection is a process that causes the accumulating changes over time that lead to a new species.
Some people think that evolution is a form of soft inheritance which is the notion that inherited traits can be altered by conscious choice or by abuse. This is a misunderstanding of the biological processes that lead to evolution. A more accurate description is that evolution is a two-step procedure involving the independent, and often competing, forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a species of mammal species which includes chimpanzees and gorillas. Our predecessors walked on two legs, as shown by the oldest fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality we are the closest connected to chimpanzees belonging to the Pan Genus which includes bonobos and pygmy-chimpanzees. The last common ancestor between humans and chimpanzees was 8 to 6 million years old.
Humans have evolved a variety of characteristics over time such as bipedalism, use of fire, and the development of advanced tools. It's only within the last 100,000 years that we have developed the majority of our essential traits. They include language, a large brain, the ability to build and use complex tools, as well as the diversity of our culture.
Evolution occurs when genetic changes allow members of an organization 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 their genes to the next generation. This is the way that all species evolve, and it is the foundation 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 in the course of time. This is because those traits make it easier for them to survive and reproduce in their environments.
Every living thing has an molecule called DNA that holds the information needed to guide their growth. The DNA structure is composed of base pairs which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in a population can be caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite some differences in their appearance all support the idea of modern humans' origins in Africa. Genetic and fossil evidence also suggest that early humans moved out of Africa into Asia and then Europe.