Darwin’s Theory Of Evolution And Its Components

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Darwin and Wallace’s Theory of Evolution

Charles Darwin’s Theory of Natural Selection is the process where creatures of a particular species evolve to be more well suited to live in a particular environment. The surviving animals have a higher chance to survive and reproduce, allowing them to pass on their genes for the future species.

The theory of evolution was first proposed by Jean-Baptiste Lamarck and was then further elaborated by Charles Darwin. Evolution can be caused by a plentitude of reasons but the factors of evolution are, environmental changes, food availability, predation, population density and human interaction. The process of evolution can take up to a million years depending on the different factors like reproduction rate and the pressure to evolve. Species affected by these factors have shown the effects of Evolution through their changes in behavior and physiology over time.

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Darwin’s Theory of natural selection consists of four main components:

  • Variation – Variation is having diversity within the species, this means things like body size, number of offspring, hair color and physiology. It is important to have variation within a certain species, this allows for the creature to better adapt when an environmental change happens.
  • Inheritance – Passing down genes or traits from a parent to its children, genes pass down are often due to mutations within the DNA.
  • High Population Growth – A higher population growth means that the species have more offspring, which means that the chances of better genes being passed down are higher and can easily be passed down onto their own offspring.
  • Differential Survival and Reproduction – Animals that have traits that benefit them in survival will pass on more for their offspring.

Evolution by natural selection can be categorized into: Biochemical Evidence, Comparative Anatomy, Comparative Embryology, Fossil Evidence and Biogeographical Evidence. These categories allow us to figure out the process behind evolution and the idea of natural selection.

Biochemical Evidence e.g amino acid sequencing, DNA hybridization and DNA sequencing.

Biochemistry is the process where chemistry is applied to the study of biological processes on a cellular and molecular level. Life is made up of variations of macromolecules from organism to organism such as DNA, proteins and structural chemicals. These chemicals can be used to analyze how similar an organism is to another and to find out if certain organisms shared common ancestors with another.

We can analyze the many proteins found inside their organisms body, these proteins are amino acids. These proteins display the similarities between the dietary intake and hemoglobin of these organisms. When we compare the essential amino acid sequencing with technology we can figure out the differences and the changes, therefore figuring out who shared common ancestors and the changes they went through.

Comparative anatomy e.g Homologous structures, analogous structures and vestigial structures.

Comparative anatomy is the study of similarities and differences in the anatomy of species.

Comparative Embryology

Embryology research can be used to demonstrate how species evolved and adapted to natural pressures. Comparative Embryology can be used to study the general overall features of the embryo before the specialized features are developed. Comparative Embryology supports the idea of common ancestry by explaining how organisms evolve differently from a common structure depending on the certain species they are from.

An example of similarities in embryo is vertebrae column, a structure that develops in all vertebrates in early stages of the development of the embryo. As such, organisms such as lizards and chickens have vertebral column. After some time of development displayed in the third row, the lizard begins to develop a hard casing outside whilst the chicken muscle block develop into claws.

Example is that during the embryo development we humans had temporary pharyngeal pouches (gill slits) leftover genetic information form our ancient fish ancestors, and this is not just evident within humans it also shared with: Fish, Reptile, Birds and more. These gills from fish ancestors have evolved into eare tissue in modern-day humans, further for evidence for the Theory of Evolution.

Fossil Evidence e.g relative dating and absolute dating, transitional forms

Paleontology is the scientific field for the study of fossils. Paleontology can be used to measure and track the similarities or differences of fossils. Studying the fossils for details allows for the figure out the common descendants between the organisms that have been fossilized. The fossils can be tracked from oldest to more recent, allowing us to study the changes that the organism went through throughout the time that had passed in between the dates of the fossils.

Homo sapiens (human) being ancestors of chimpanzees and gorillas, originated from Africa. Earliest human fossils found in North Africa, date back to roughly 315,000 years ago. During the time of dramatic climate change 300,000 years ago, Homo sapiens adopted many changes that allowed them to survive and respond to the challenges of survival more efficiently. These changes can be seen in the fossils of homo sapiens, the current structure of the human body today is very different to what it was 300,000 years ago. These changes include: a lighter build of the skeleton, bigger brains, smaller teeth and a less developed jaw. These changes in the fossils show that the skeleton the human has gradually gotten smaller over time.

Biogeographical Evidence

Biogeography is the study of the distribution of species and ecosystems in a geographic location and geological time. Isolation is the stem/foundation of Biogeographical evolution because organisms that are separated from each other evolve differently. Animals and plants evolving differently, creates a new species as they outlive the inferior relatives.

Biogeographical evidence of humans is shown by how humans originated from Africa and left Africa 200,000 years ago. Humans were separated when pangea slowly drifted apart, creating different environments for humans to adapt to. As humans slowly drifted away from each other, the environment to humans had to live in, had changed significantly. The drifting of the continents meant that the humans were isolated in their content and could not interact with the people of the other continents. This along with the different environment and availability of natural resources led micro evolution.

Charles Darwin was on a journey aboard ‘The Beagle’, where he encountered many unique plants and animals. He then thought up the theory that these animals and plants all had a common ancestor but had changed due to having to adapt to the new environment. The Galapagos Finches are a key example of adaptive radiation, the finches all originated from one island but were eventually spread out into the different islands of the galapagos. This led to the finches evolving differently to adapt better to the environment on the islands. The finches that didn’t have the better suited adaptation for their island all eventually died out because they were being outcompeted. This meant that only the Finches with better suited beaks could pass down their genes to their offspring.

Sources – Bibliography

  1. https://globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html
  2. https://www.khanacademy.org/science/biology/her/evolution-and-natural-selection/a/darwin-evolution-natural-selection
  3. https://www.mcgill.ca/biochemistry/about-us/information/biochemistry
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4418793/
  5. http://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens
  6. https://www.theatlantic.com/science/archive/2017/06/the-oldest-known-human-fossils-have-been-found-in-an-unusual-place/529452/
  7. https://australianmuseum.net.au/learn/science/human-evolution/when-and-where-did-our-species-originate/


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