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Evolution Introduction. To believe or not to believe BBT Video Discussion.

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Presentation on theme: "Evolution Introduction. To believe or not to believe BBT Video Discussion."— Presentation transcript:

1 Evolution Introduction

2 To believe or not to believe BBT Video Discussion

3 Evolution: Just a theory? A theory is a set of statements that explains a group of facts or phenomena. These statements have been tested repeatedly and are supported by evidence. A theory can be used to make predictions about natural phenomena E.g. the theory of gravity explains why objects fall to the ground

4 Evolution The process of cumulative change in the heritable characteristics of a population Evolution is the idea that all species are descendents of ancient species that were different from modern day species. Evolution is the biological history of life on Earth, from the earliest micro- organisms to the diversity of modern day organisms.

5 So that settles it then? F.R.I.E.N.D.S video Discussion

6 Changing Nature of Science Scientists make both the initial identification and the later revision. [Opponents try to focus on the errors alone without mentioning the correction made] Laws of physical sciences are typically deterministic while laws of biology usually have a probability factor associated e.g. Mendel’s laws of inheritance work only work with single gene pairs and not even with all such pairs. So we must say, “From what we know till now…” while stating scientific “fact”. That fact exists until somebody proves it otherwise.

7 Our Dear Old Planet James Hutton (Scottish) studied the rates of erosion and sedimentation and the thickness of bands of sedimentary rock. Uniformitarianism: Earth was formed entirely by slow moving processes like erosion and that these slow forces continue to shape the landscape. 1830, Charles Lyell (English) found further evidence to support this and he popularized this idea via his book Principles of Geology

8 Change in Life George Cuvier (French) compared Mammoth skeletons to Elephant ones He noticed that they were different enough to say that they were a separate species which had gone extinct. In early 1800s Jean-Baptiste Lamark (French) proposed that species evolve (change) over time He explained it as a process of Adaptation

9 Adaptation: Tendency towards Perfection? Adaptation is an inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment. He explained this by saying that: By using/not using certain body parts, an organism develops certain characteristics. e.g. Giraffes and their long necks These enhanced characteristics were then passed down to their offspring All organisms have a tendency towards perfection But…acquired characteristics don’t change DNA


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