The Berkeley Evolution Site
The Berkeley site has resources that can help students and teachers to understand and teach about evolution. The materials are organized into optional learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection states that over time creatures that are better able to adapt biologically to changing environments survive and those that do not become extinct. Science is concerned with this process of biological evolution.
What is Evolution?
The term "evolution" can be used to refer to a variety of nonscientific meanings. For instance it could refer to "progress" and "descent with modifications." It is an academic term that is used to describe the process of change of characteristics in a species or species. This change is based in biological terms on natural drift and selection.
Evolution is an important tenet in the field of biology today. It is an established theory that has withstood the tests of time and thousands of scientific studies. In contrast to other theories in science like the Copernican theory or the germ theory of disease, evolution is not a discussion of religious belief or God's existence.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a step-like way, over time. They called this the "Ladder of Nature" or the 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 claims that different species of organisms share an ancestry that can be determined through fossils and other evidence. mouse click the up coming post is the current view of evolution that is supported by many lines of research in science which includes molecular genetics.
While scientists do not know exactly how organisms evolved, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous characteristics are more likely than others to survive and reproduce. These individuals transmit their genes on to the next generation. As time passes this leads to an accumulation of changes to the gene pool that gradually result in new species and forms.
Some scientists also employ the term evolution to describe large-scale evolutionary changes such as the creation of an entirely new species from an ancestral species. Certain scientists, including population geneticists, define the term "evolution" in a more broad sense by referring to the net variation in the frequency of alleles over generations. Both definitions are valid and palatable, but certain scientists argue that allele frequency definitions do not include important aspects of evolution.
Origins of Life
The most important step in evolution is the development of life. This occurs when living systems begin to develop at a micro-level - within individual cells, for instance.
The origins of life are a topic in many disciplines such as biology, chemistry, and geology. The question of how living things started is of particular importance in science since it poses an important challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
The notion that life could emerge from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a popular belief before Louis Pasteur's tests proved that the development of living organisms was not achievable through a natural process.
Many scientists still think it is possible to move from nonliving substances to living ones. The conditions needed for the creation of life are difficult to replicate in a laboratory. This is why researchers investigating the beginnings of life are also interested in understanding the physical properties of the early Earth and other planets.
The growth of life is also dependent on a series of complex chemical reactions that are not predicted by the basic physical laws. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that carry out a function, and the replication of these complex molecules to create new DNA or sequences of RNA. These chemical reactions are often compared to the chicken-and-egg problem of how life came into existence: The appearance of DNA/RNA and protein-based cell machinery is crucial for the beginning of life, however, without the emergence of life, the chemical process that allows it is not working.
Abiogenesis research requires collaboration with researchers from different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The word evolution is usually used to describe the accumulated changes in the genetic characteristics of a population over time. These changes could be the result of 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 a group. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction, and gene flow.
While reshuffling and mutations of genes happen in all living organisms and the process by which beneficial mutations become more common is referred to as natural selection. As noted above, individuals with the beneficial trait have a higher reproductive rate than those who do not. Over the course of several generations, this variation in the numbers of offspring born could result in an inclination towards a shift in the number of beneficial characteristics in a particular population.
This is evident in the evolution of various beak shapes on finches from the Galapagos Islands. They have developed these beaks so that they can access food more easily in their new environment. These changes in form and shape can also help create new organisms.
The majority of the changes that take place are caused by one mutation, but occasionally several will happen simultaneously. The majority of these changes are neutral or even harmful to the organism, but a small percentage can have a positive impact on the survival of the organism and its reproduction, thereby increasing their frequency in the population over time. Natural selection is a process that can produce the accumulating changes over time that lead to the creation of a new species.
Some people confuse the notion of evolution with the notion that traits inherited can be changed through conscious choice or use and abuse, a concept known as soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that cause it. A more precise description is that evolution involves a two-step process, involving the independent and often antagonistic forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees and gorillas and bonobos. Our predecessors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities show that we share an intimate relationship with the chimpanzees. In fact we are the closest with chimpanzees in the Pan genus which includes bonobos and pygmy chimpanzees. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
Humans have evolved a variety of traits over time including bipedalism, the use of fire and advanced tools. It is only in the past 100,000 years or so that the majority of the characteristics that differentiate us from other species have emerged. These include a large brain that is complex human ability to build and use tools, as well as the diversity of our culture.
Evolution happens when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the mechanism that drives this change. Certain characteristics are more desirable than others. People with better adaptations are more likely to pass on their genes to the next generation. This is how all species evolve, and the foundation for the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which have an ancestor in common will tend to acquire similar traits as time passes. It is because these traits help them to survive and reproduce within their environment.
All organisms have a DNA molecule that is the source of information that helps guide their growth and development. The structure of DNA is made of base pairs that 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. The variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. Although there are some differences the fossils all support the idea that modern humans first appeared in Africa. The fossil and genetic evidence suggests that early humans left Africa and migrated to Asia and Europe.