The Berkeley Evolution Site
The Berkeley site offers resources that can assist students and teachers understand and teach evolution. The resources are organized into various learning paths that can be used in a variety of ways like "What does T. rex look like?"
Charles Darwin's theory on natural selection explains how creatures who are better equipped to adapt biologically to changing environments survive longer and those that don't become extinct. Science is about the process of biological evolutionary change.
What is Evolution?
The word evolution has many nonscientific meanings. For instance "progress" or "descent with modification." It is an academic term that refers to the process of change of traits over time in organisms or species. The reason for this change is biological terms on natural drift and selection.
Evolution is a key concept in modern biology. It is a theory that has been tested and confirmed by thousands of scientific tests. In contrast to other theories in science like the Copernican theory or the germ theory of disease, evolution is not a discussion of religion or God's existence.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a stepped-like manner over time. They called this the "Ladder of Nature" or scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
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 the same ancestry, which can be traced through fossils and other evidence. This is the modern view on evolution, and is supported in many areas of science which include molecular biology.
Scientists aren't sure how organisms evolved, but they are confident that natural selection and genetic drift is responsible for the evolution of life. Individuals with advantageous characteristics are more likely than others to survive and reproduce. They transmit their genes to the next generation. Over time, the gene pool gradually changes and develops into new species.
Some scientists also employ the term evolution to refer to large-scale evolutionary changes, such as the formation of a new species from an ancestral species. Others, like population geneticists, define it more broadly by referring to a net variation in the frequency of alleles over generations. Both definitions are valid and palatable, but some scientists believe that allele-frequency definitions miss important aspects of the evolutionary process.
Origins of Life
A key step in evolution is the emergence of life. Evolution KR occurs when living systems begin to evolve at a micro-level - within cells, for example.
The origins of life are an important issue in many fields such as biology and chemistry. The nature of life is a topic that is of immense interest to scientists because it is a challenge to the theory of evolution. It is often described as "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 prior to Louis Pasteur's tests proved that the development of living organisms was not possible through the natural process.
Many scientists still believe that it is possible to make the transition from nonliving substances to life. The conditions required to create life are difficult to reproduce in a lab. Researchers interested in the origins and evolution of life are also keen to know the physical properties of the early Earth as well as other planets.
In addition, the development of life depends on the sequence of extremely complex chemical reactions that can't be predicted based on basic physical laws on their own. These include the transformation of long information-rich molecules (DNA or RNA) into proteins that carry out a function, and the replication of these intricate molecules to generate new DNA or RNA sequences. These chemical reactions are often compared with the chicken-and-egg problem of how life came into existence: The appearance of DNA/RNA and protein-based cell machinery is essential to the birth of life, but without the appearance of life, the chemistry that makes it possible is not working.
Abiogenesis research requires collaboration among researchers from different fields. This includes prebiotic chemists planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes can be the result of adaptation to environmental pressures as discussed in Darwinism.
This is a method that increases the frequency of those genes in a species which confer a survival advantage over others and causes a gradual change in the overall appearance of a population. The specific mechanisms responsible for these changes in evolutionary process 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 frequent. All organisms undergo changes and reshuffles of genes. As noted above, individuals who have the advantageous trait have a higher reproduction rate than those that do not. Over many generations, this variation in the numbers of offspring produced can result in a gradual shift in the amount of desirable traits in a population.
An excellent example is the increase in the size of the beaks on different species of finches found on the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new environment. These changes in the form and shape of organisms can also be a catalyst for the creation of new species.
Most of the changes that take place are the result of one mutation, however occasionally, multiple mutations occur simultaneously. Most of these changes can be harmful or neutral however, a few may have a positive effect on survival and reproduce with increasing frequency as time passes. This is the way of natural selection and it can eventually result in the cumulative changes that eventually result in the creation of a new species.
Some people mistakenly associate evolution with the concept of soft inheritance, which is the idea that traits inherited from parents can be changed by conscious choice or abuse. This is a misinterpretation of the nature of evolution, and of the actual biological processes that lead to it. A more precise description is that evolution is a two-step procedure which involves the separate and often conflicting forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species which includes chimpanzees and gorillas. The earliest human fossils show that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor and 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 the development of advanced tools. However, it is only in the last 100,000 years or so that most of the essential traits that distinguish us from other species have been developed. They include a huge brain that is complex, the ability of humans to build and use tools, as well as the diversity of our culture.
Evolution is when genetic changes allow members of a group to better adapt to their environment. This adaptation is driven by natural selection, a process that determines certain traits are favored over others. People with better adaptations are more likely to pass their genes to the next generation. This is how all species evolve and is the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species that share an ancestor will tend to acquire similar traits in the course of time. This is because those characteristics make it easier for them to live and reproduce in their environment.
Every living thing has a DNA molecule that provides the information necessary to guide their growth and development. The structure of DNA is made of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite differences in their appearance, all support the theory of modern humans' origins in Africa. The fossil and genetic evidence suggests that the first humans left Africa and migrated to Asia and Europe.