bio theories of evolution

• The earliest concepts of evolution did not start with Charles Darwin. It was in the 18th century that many naturalists began to state the idea that life might not have been fixed since creation.
• Paleontologists discovered many fossils that gave them a picture of the past. Their discoveries made them more interested in the evolution of organisms and their environment.
• John Ray


  Established the modern concept of a species, noting that members of one species do not interbreed with members of another species. He first used the term species as the basic unit of taxonomy. He also studied fossils and recognized them as remnants of organisms that were once alive.
• Carl Linnaeus


  Developed the modern taxonomic system that is still used today
• Georges Louis Leclerc, Comte de Buffon


  Wrote a 36-volume Histoire Naturelle (Natural History) series. He contributed to the debate on the age of Earth, suggesting that our planet had initially formed in a molten state and that its gradual cooling must have taken far longer than 70,000 years. He also considered the role of vestigial organs, creating a possibility of species descending from earlier organisms.
• Erasmus Darwin


  Charles Darwin's grandfather. He was aware that the modern organisms are different from the fossils scientists have collected. He believed that the offspring inherited features from their parents, and that the organisms today descended from a common ancestor.
• Georges Cuvier


  Proposed the theory of use and disuse, which stated that organisms develop their traits due to the frequent use of such. He also proposed that those traits may be passed on to their offspring.
• Jean-Baptiste Lamarck


  Proposed the theory of use and disuse, and the theory of inheritance of acquired characteristics.
• James Hutton


  Made a significant contribution regarding the understanding of the geological processes that shaped Earth. He recognized that Earth is extremely old (more than millions of years), and that there was no need for global catastrophes to shape the surface of Earth. He was the proponent of uniformitarianism, which states that the present geological features of Earth are the results of gradual processes such as erosion and sedimentation.
• Charles Lyell


  Considered the shaping of Earth's surface as a result of gradual long-term natural changes. He also collected many pieces of evidence to support the principle of uniformitarianism and wrote about them in his book Principles of Geology, which was also influential to the creation of Charles Darwin's theory.
• Charles Robert Darwin


  Came up with the idea that the best-adapted organisms are those that can survive to breed and pass on their traits to their offspring. One of his highlighted contributions was the development of his theory of evolution by natural selection as a coherent explanation for the form and distribution of species in different locations.
• Alfred Russel Wallace


  Although he made an independent study on the origin of organisms, he arrived at the same conclusion as Darwin's: that organisms with favorable traits are those that carry on to the next generation. Thus, Wallace had contributed to some of the postulates of Darwin's theory of evolution.
• Charles Robert Darwin contributed significant ideas on our current understanding of evolution. He was born in England on 12 February 1809. In 1831, Darwin went aboard the H.M.S. Beagle in its voyage around the world.
• Charles Darwin's travels


  1. Reading of scientific books

  2. Collection of plant and animal specimens

  3. Recording of observations, serving as hypotheses on how life changes over time
• Darwin's most famous travel involved a trip to the Galapagos Islands, composed of many small islands located 1,000 kilometers west of South America. The islands have differing climates despite the proximity of the islands with one another.

  
• Darwin noted that the characteristics of certain animals, such as the shape of tortoise shells or the beaks of birds, vary from one island to another. He also found out that the species present in one location were different from the species found in other locations, and what seemed like animals that look alike may actually belong to several different species (e.g., mockingbird).
• Darwin wrote and published a book entitled On the Origin of Species, in which he proposed the now famous theory of evolution by natural selection. He then presented pieces of evidence demonstrating this process, which according to him has been taking place for millions of years.
• Struggle for existence


  Members of each species compete to obtain food, living space, and other necessities of life. The stronger and faster are able to hunt for food and protect themselves from their enemies.
• Jean-Baptiste Lamarck


  Proposed that all species descended from other species. In 1809, Lamarck published his theory of how organisms changed over time. His main ideas included that through selective use or disuse of organs, organisms may acquire or lose certain traits during their lifetime. Additionally, those traits that have been acquired can be passed on to the next generation.
• Theory of use and disuse


  Organisms could alter the size, shape, or structure of particular body parts or organs by continuously using them in new ways. For example, the elongation of the giraffe's neck.

  
• Theory of disuse


  If an animal chooses not to use its body part, that body part or organ would eventually decrease in size for several generations until it finally disappears. An example is the vestigial limb structures found in snakes.
• Theory of inheritance of acquired characteristics


  Organisms inherited their traits from their parents, and they may also pass them on to the next generation of offspring. For example, the presence of long trunks in elephants.
• Lamarck's theories of use and disuse and of inheritance of acquired characteristics proved to be incorrect in several ways. Unlike Darwin, Lamarck was not aware of how traits were inherited. He did not know that inheritable characteristics of organisms are not affected by their behavior.
• Many other observations can be used as pieces of evidence for evolution. These include biogeography or the geographical distribution of organisms, fossil records, DNA and protein sequences, presence of homologous structures, and embryology.
• Biogeography


  The study of the distribution of plants and animals on Earth. The distribution of organisms in an environment can be used as an important tool for explaining evolution.
• Biogeography evidence


  • Finches with different shapes of beaks depending on their geographical locations in the Galapagos Islands
  • South American finch and three out of the 13 species of finches in the Galapagos Islands

  
• Fossil record


  Preserved remains or evidence of ancient organisms. Fossil records provide strong evidence of the history of life on Earth and how different groups of organisms have changed over time.
• Fossil records reveal that almost 99 percent of all species that have lived before became extinct.
• Homology


  Similarities in the bone structures of the limbs of different vertebrate animals, such as arms, legs, wings, and flippers. These homologous structures may have different functions but are constructed from the same basic features.
• Embryology


  Similarities in the early development of various organisms. Different organisms have similar structures during their early embryological development.
• DNA/Protein sequences


  The study of DNA and protein sequences is important for identifying the evolution of organisms on Earth. Similarities in DNA sequences among organisms indicate their close relation with one another.
• DNA/Protein sequence evidence


  • Chimpanzees have DNA that is identical to humans for about one-third of their genes
  • Dogs and wolves share many similarities in their DNA sequences
  • Dogs and mice, although distant in relation, may also share common ancestry