The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are arranged in various learning paths that can be used in a variety of ways for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how over time, animals that are more adaptable to changing environments do better than those that don't become extinct. Science is concerned with this process of biological evolution.
What is Evolution?
The word evolution has many nonscientific meanings. For instance "progress" or "descent with modification." Scientifically, it refers to a changing the characteristics of living organisms (or species) over time. In biological terms this change is caused by natural selection and genetic drift.
Evolution is one of the fundamental tenets of modern biology. It is an established theory that has withstood the test of time and a multitude of scientific studies. In contrast to other theories in science like the Copernican theory or the germ theory of disease, the evolution theory does not address questions of religion or the existence of God.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a step-like manner, as time passes. 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 share an ancestry that can be traced through fossils and other lines of evidence. This is the modern view of evolution that is supported by numerous lines of scientific research that include molecular genetics.
While scientists don't know the exact mechanism by which organisms evolved however they are sure that the evolution of life on earth is the 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. Over time, the gene pool gradually changes and evolves into new species.
Some scientists use the term"evolution" to refer to large-scale changes, such the evolution of one species from an ancestral one. Some scientists, like population geneticists, define the term "evolution" in a broader sense by using the term "net change" to refer to the variation in the frequency of alleles over generations. Both definitions are accurate and acceptable, but some scientists argue that allele-frequency definitions omit important features of evolution.
Origins of Life
The development of life is a key step in evolution. This happens when living systems begin to evolve at the micro level, within cells, for example.
The origins of life are an issue in a variety of disciplines that include biology, chemistry, and geology. The nature of life is an area of interest in science because it challenges 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 called spontaneous generation or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments showed that it was impossible for the creation of life to be a result of a purely natural process.
Many scientists still believe that it is possible to transition from nonliving substances to life. The conditions needed to create life are difficult to replicate in a laboratory. This is why scientists studying the beginnings of life are also interested in determining the physical properties of early Earth and other planets.
The development of life is dependent on a number of complex chemical reactions, that are not predicted by basic physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that perform a function as well as the replication of these complex molecules to generate new DNA or RNA sequences. These chemical reactions can be compared to a chicken-and egg problem which is the development and emergence of DNA/RNA, protein-based cell machinery, is necessary to begin the process of becoming a living organism. However without life, the chemistry that is required to create it appears to be working.
Abiogenesis research requires collaboration between scientists from various fields. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" is typically used today to describe the cumulative changes in the genetic traits of a population over time. These changes could be the result of the adaptation to environmental pressures as explained in Darwinism.
This process increases the number of genes that confer an advantage for survival in a species, resulting in an overall change in the appearance of a group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction, and gene flow.
While mutation and reshuffling of genes happen in all living organisms, the process by which beneficial mutations become more common is known as natural selection. This happens because, as noted above, those individuals with the beneficial trait tend to have a higher fertility rate than those who do not have it. This difference in the number of offspring born over a number of generations could result in a gradual change in the number of advantageous traits in a group.
A good example of this is the increase in the size of the beaks on different species of finches in the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new home. These changes in the form and shape of organisms could also aid in the creation of new species.
The majority of the changes that occur are the result of a single mutation, but sometimes, several changes occur at the same time. Most of these changes are neither harmful nor even harmful to the organism, however, a small proportion of them 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 process that could result in the accumulation of changes over time that lead to a new species.
Many people confuse the concept of evolution with the idea that traits inherited can be changed through conscious choice or use and abuse, a notion called soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. It is more accurate to say that the process of evolution is a two-step, independent process, which involves the forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a species of mammal species which includes gorillas and chimpanzees. The earliest human fossils show that our ancestors were bipeds, walkers with two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In fact, our closest relatives are chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor shared between modern humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a wide range of traits throughout time including bipedalism, the use of fire and advanced tools. It's only in the last 100,000 years that we have developed the majority of our key traits. These include a large brain that is complex and the capacity of humans to build and use tools, and cultural diversity.
The process of evolution occurs when genetic changes allow members of a population to better adapt to their environment. Natural selection is the mechanism that drives this change. Certain traits are preferred over others. The more adapted are more likely to pass their genes on to the next generation. talks about it is the process that evolves all species, and it is the foundation of the theory of evolution.
Scientists call it the "law of natural selection." The law states species that have a common ancestor are likely to acquire similar traits as time passes. This is because those traits allow them to survive and reproduce in their environment.
Every living thing has an molecule called DNA that holds the information necessary to direct their growth. The structure of DNA is made of base pairs which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases found in each string determines the phenotype or the characteristic appearance and behavior of an individual. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
무료 에볼루션 from the first human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite some differences in their appearance all support the idea of modern humans' origins in Africa. The fossil evidence and genetic evidence suggest that early humans came out of Africa into Asia and then Europe.