4. The key parts of the theory of evolution
- • Charles Darwin’s observations and how they support the theory of evolution and the idea of natural selection.
- • The role of natural selection in adaptation.
- • Characteristics of micro evolutionary and macro evolutionary processes.
4.1. Top 5 misconceptions about evolution
4.1.1. It is just a theory
In everyday language theory’ might mean a hunch or a guess. For scientists theory refers to a well supported explanation.
Scientific theories and scientific laws are often confused.
Theories | Laws |
|
Why something happen | What will happen |
Explanation of Nature | Predictable outcome |
Based on evidence | Based on evidence |
Example: Atomic theory | Example: Newton law |
- *Evolution – The observation that organisms, including plants, bacteria and even molds change over time- depends on theory for explanation.
- *The most well know theory of evolution is the theory of natural selection.
4.1.2. Fittest survival
Is this accurate for Darwin’s theory of Natural Selection?
Fact 1 – Population tends to remain stable.
Fact 2 – Organisms reproduce more offspring than could be supported.
Interference 1 – Not all the offspring live long enough to reproduce.
Fact 3 – Resources are limited
Fact 4 – Individuals within population differ in individuality.
Fact 5 – Inherited characteristics are more.
Interference 2 – There will be differential survival and reproduction.
This is Natural Selection.
Interference 3 – Over time these differences will shift the makeup of the population.
This is decent with modification. Evolution will occur.
- *‘Fit’ organisms will live & thrive to pass their genetic material to the next generation.
- *Fitness depends on reproducing & ensuring the survival of population rather than strength, speed or length.
4.1.3. Humans descend from Apes
- *Evolution holds that all life on Earth share common Ancestry.
- *Decent with modification means that human are unique as species, and we share many characteristics with other species.
- *Primates share 90% DNA sequence identity with humans.
4.1.4. No one was there and It cannot be Proven
- *Scientists operate like detectives.
- *With a few pieces of evidence about an event the investigator searches for clues that would legitimize or refute a claim.
- *Where is the support evidence coming from?
Evidence of evolution
- -Biochemistry (DNA).
- -Bones and fossils.
- -Comparative anatomy and physiology.
- -Computer modeling.
- -Modern experiments.
- -Developmental biology.
Journals publish evidence
- *Before publishing, a journal will send a manuscript to other scientists who review and critique it.
- *Peer review process often rejects manuscripts because there is not enough evidence to support the claims of the author. Science publishes less than 7% of submissions.
- *This level of organized skepticism is unique to Science.
- *Scientists become famous for overturning ideas and expanding paradigms.
4.1.5. Darwin was wrong
- *Darwin lived in a different time. He constructed the theory of Natural Selection from observing the finches in the Galapagos Islands and many other species across the world.
- *Genes was an unfamiliar term to that world.
- *Cells were seen but not manipulated.
- *Darwin’s mechanism continues to unify all biology – a contribution comparable to those of Newton or Einstein.
- *Today we define evaluation as changes in allelic frequency over time.
- *If we map different forms of genes (alleles) of a population and after a few generations the frequency changes, evolution has occurred.
- *This description is the best to date that captures the over-changing living world.
- *There are still many questions to ask and answer.
- *How do genes play a role in producing the features of organisms?
- *Why do mutations accumulate with different rates?
- *How do we protect our crops if pests evolve?
- *Evolution does not explain what started life, only how it persists, adapts, and changes.
- *Life need only begin once for evolution to occur.
4.2. The origins of life
In the process of evolution a series of natural changes cause species to arise, familiarize yourself to the environment, and turn out to be extinct.
Evolution = Change
By the process of biological evolution all species originated. The term species refers to a group who can reproduce their fertile offspring. Scientist classify the species with two scientific name first is genus name and second is species name like humans referred as Homo sapiens. In populations, there are variations or differences between individual members because of the variety of genes (alleles). Examples are skin color in humans, coat color in foxes. When there is a change in genes inherited from parents to offspring in different proportions then evolution occurs. These variations in genes arose for either (1) recombination of alleles when they sexually reproduce or (2) mutations.
Mechanism of evolution occurs by different ways
- 1.Natural selection.
- 2.Biased mutation.
- 3.Genetic drift.
- 4.Gene flow.
Recombining genetic material can happen in three ways.
- 1.Independent assortment.
- 2.Crossing over during meiosis.
- 3.Combining egg and sperm when fertilization occurs.
Mutations are usually neutral or harmful. Sometimes they can be beneficial if the environment is under a state of change.
- 1.Point mutation – In this there is change in a single base pair in DNA.
- 2.Frame shift – a single base pair is added or deleted from DNA.
- 3.Chromosome mutations – mistakes that affect the whole chromosome.
- 4.Deletion mutation – chromosome segments break off and do not reattach itself à new cell lacks genes carried by the segment that broke off.
- 5.Duplication or insertion mutation – Chromosome segments attach to a homologous chromosome that has lost the complementary segment. Result one chromosome carries two copies of one gene.
- 6.Inversion mutations – A segment of chromosome breaks off and then reattaches itself to the original chromosome backwards.
- 7.Translocation mutations – A chromosome segment attaches itself to a nonhomologous chromosome.
These variations lead to adaptations. Adaptations are traits that aid a population’s chance of survival and reproduction (Hoyle, 1981).
A single individual does not change by the result of evolution, while it causes the change by inherited means of growth and development that are specified for a population. When the parent inherits these changes to the offspring then they become common in that population and as a result offspring inherit those genetic characteristics for probability of survival, capability to give birth which will work until the environment changes. Eventually, the genetic changes can modify a species overall way of life, like what it eats, how to grow, how it can live. As new genetic variations in early ancestor population’s preferential new abilities to become accustomed to environmental changes and so altered the human behavior causes the human evolution (John, 2007).
5. Conclusion
Science should forever support conclusions on what is seen and reproducible. So what is observed? We see variations in lizard and birds. If macroevolution occurred in between forms they never as fossils.
An alert viewer can typically see astonishing discontinuities in these claimed upward changes, as well as in the drawing above. From the time of Darwin, different excuses made by evolutionists that why the world and our fossil museums are not spilling over with intermediates. Evolution is a scientific theory in biological sciences, which explains the emergence of new varieties of living things in the past and present. Evolution accounts for the conspicuous patterns of similarities and differences among living things over time and across habitats through the action of biological processes such as mutation, natural selection, symbiosis and genetic drift. Evolution has been subjected to scientific testing for over a century and has been again and again confirmed from different fields.