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An introduction to evolutionary theory, summarizing some of the key lines of evidence in support of the theory.

Evolution

How stupid of me not to have thought of that.
– Thomas Huxley, after reading Darwin’s Origin ( On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life ).

Introduction

What is Evolution? Surely everyone has heard the word, and perhaps a lot of other words to describe it, but do you really know what that word means, in the context of biology? Here are a few common notions about evolution. How many do you agree with?

  1. Evolution has never been observed directly.
  2. Evolution is only a theory, and has not been shown to be a fact.
  3. Evolution means that life originated, and living things change, randomly.
  4. Evolution is progress; organisms get “better” and more complicated whenever evolution occurs.
  5. Evolution means that individual organisms change.
  6. In order for evolution to occur, the offspring of some organisms will have to be radically different from the parental organisms.

If you said that all of these statements are false, then you have a good understanding of evolution. They are indeed all untrue. However, this is a list of some fairly common misconceptions about evolution, and many people in the world (and particularly in the USA) share one or more of these misconceptions. It is likely that you think that some or all of these statements are true. One of the hardest parts of learning is to undo a well-established misconception, so if you do think that one (or more) of those statements is true, this chapter might be a bit harder for you. But it will be worth the effort, since, as you will learn below, evolution is the guiding framework for modern biological science. Once you have a good understanding of evolution, and the mechanisms that drive it, you will be well-poised to learn and understand the biology that comes in the rest of this course.

Evolution – what is it?

The biological world is extremely diverse. In fact, that is one of the most powerful realizations that come from the study of biology, or even just from being an observant person in the world. Living things range from the microscopic bacteria to the immense blue whale. They have a diversity of life styles and metabolic capacities, from photosynthetic creatures who can make their own food from carbon dioxide gas, to predatory creatures, all the way to parasitic creatures who have some of the most complicated life styles of all. Within any one of these groups, there is also astounding diversity. Open any field guide, whether for birds, mammals, flowering plants, or mushrooms, and you will be confronted with an abundance of colors, sizes, shapes and behaviors. Even within a single species, say Homo sapiens, there is diversity. Look around your classroom and you will see people with a wide variety of skin colors, hair colors, eye colors, heights and weights. This diversity is a fact, and for many millennia, human beings have been trying to come up with explanations for that well-observed fact.

Questions & Answers

WHAT IS QUADRATIC EQUATION?
Charles Reply
WHAT IS SYSTEM OF LINEAR INEWUALITIES?
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WHAT IS SYSTEM OF LINEAR INEWUALITIES?
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The 47th problem of Euclid
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show that the set of all natural number form semi group under the composition of addition
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_3_2_1
felecia
⅗ ⅔½
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The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
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1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
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×/×+9+6/1
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Q2 x+(x+2)+(x+4)=60 3x+6=60 3x+6-6=60-6 3x=54 3x/3=54/3 x=18 :. The numbers are 18,20 and 22
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Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
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Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
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4
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x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
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Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
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(61/11,41/11,−4/11)
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6 years, a bond that paid 5.5% earned $594 interest.
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A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
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Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
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Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
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. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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Source:  OpenStax, Principles of biology. OpenStax CNX. Aug 09, 2016 Download for free at http://legacy.cnx.org/content/col11569/1.25
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