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Chapter 2a.docx

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Christine Dupont

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Chapter 2 (Pages 37 – 49 and 53 – 65) The Pattern of Evolution  The first scientist to give a definition of species, John Ray, states that “…[O]ne species never springs from the seed of another.”  The Theory of Special Creation had been the leading explanation in Europe for the origin of species until a certain point where scholars began to challenge that notion (i.e. when Darwin started to study biology seriously) and research in biology and geology grew rapidly to disprove the theory.  Darwin drew up evidence suggesting that the pattern of life’s history is different than is claimed by Special Creation. (Read Page 39 for elaboration) 1. Species are not immutable, but change through time 2. Species are derived not independently, but from common ancestors 3. The Earth and life are considerably more than 6 000 years old.  Darwin also introduced a process to explain this pattern called natural selection 2.1 Evidence of Change through Time Evidence from Living Species  The living evidence for descent with modification comes in two forms: o By monitoring natural populations, we can directly observe small scale change (i.e. microevolution) o If we examine the bodies of living organisms, we can find evidence of dramatic change (i.e. macroevolution)  Direct Observation of Change Through Time o Read examples of the change of the Soapberry bug over time on Page 40  Vestigial Organs o A vestigial structure is a useless or rudimentary vision of a body part that has an important function in other, closely allied species (e.g. the remnant hind limbs on the rubber boa). o Humans have muscles attached to the hair follicles that make hair stand up when cold, intimidated, or needed to seem bigger. These muscles are effective for animals that are very hairy like chimpanzees. Most of us are not that hairy (except some of you hormone excessive freaks), and thus the result of these muscles contracting is goose bumps. This implies that we descended from ancestors who were hairier than us. o Read page 42 for more examples o Vestigial traits also occur at a molecular level.  Humans have one on chromosome 6; a DNA sequence that looks like a gene for the enzyme CMAH  It is actually disabled by a 92-base-pair deletion and humans cannot manufacture CMAH  Chimpanzees however are able to  This explains that the human race must have descended from a common ancesto
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