Explore Evolution

Meyer, Stephen C., Minnich, Scott, Moneymaker, Jonathan, Nelson, Paul A. and Seelke, Ralph

This is an attractive four-color textbook-like softback book having the appearance of a high school or beginning college textbook. In the intro they assert that it is designed to be an inquiry approach. Its approach is to have sections Case For, Reply, Further Debate where it is understood that the Case For is the current standard classroom model of evolution.

Introduction

p8 Three definitions of "evolution" 1: Change over time. 2: Universal Common Descent and 3: The Creative Power of Natural Selection

p9 I liked the conservative statement about the role of natural selection "natural selectioin acting as an editor, weeding out out harmful variatioins in body design, while conserving (keeping) helpful variations."

p9 "Neo-Darwinian biologist Francisco Ayala, for example, affirms that the "creative duet" of mutation and natural selection can produce the "organization of living beings."

p9 Dawkins "the power of natural selection to put together good designs." from The Blind Watchmaker.

p10 Common Descent with capital letters is the monophyletic view of all life descending from LUCA, the Last Universal Common Ancestor. But common descent without the caps leaves the possibility of multiple ancestors and is dubbed polyphyletic.

p 15 Fossil Succession:Case For

p 18 Geologic periods - chart

p 19 Discussion of LUCA

p 15 Fossil Succession:Reply

p 22 Animal forms appear abruptly. Cambrian explosion.

p 26 Stasis - stability of biological forms

p 26-27 Abrupt appearance followed by stasis is the majority picture.

p 27 Whale-to-mammal sequence

p 30 Fossil Succession:Further Debate

p 31 Absence of "trace fossils" or tracks in precambrian is tough on the Neo-Darwinist. My impression is that even if the soft bodies didn't leave evidence in the fossil record, their tracks should have been visible as they are in the Cambrian era.

p 32 Discussion of the Vendian fossils and the Ediacaran fossils. Reference to Eldredge and Gould as originators of the "punctuated equilibrium" paradigm.

p 38 Anatomical Homology:Case For

p40 The body parts of many animals are remarkably similar, suggesting common descent or even "Common Descent".

p 43 Anatomical Homology:Reply

p 44 Apparently homologous features that are produced by different genes weakens the case that homology implies "Common Descent"

p 43 Anatomical Homology:Further Debate

p 51 Molecular Homology:Case For

p 52 Molecules, as well as anatomical structures, display homology. In particular there is homology in proteins. Comment that proteins are the "molecules that perform most of the important jobs in the cell."

p 52 All proteins are formed with the same basic alphabet of 20 amino acids.

p 52 Actually now 22 amino acids with the addition of selenocysteine and pyrrolysine.

p 53 DNA, discussion of the A T G C bases

p 54-55 The genetic code

p 54 "nearly all organisms use the same codon-to-amino-acid code"

p 56 National Academy of Sciences version of common descent

p 56 Argues that molecular homology follows anatomical homology

p 56 The family tree constructed from myoglobin and hemoglobin "agreed completely with observations derived from paleontology and anatomy about the common descent of the corresponding organisms."

p 56 The molecular clock - the number of differences from a presumed ancestor is a measure of time since divergence.

p 57 Molecular Homology:Reply

p 58 18 different genetic codes, differ in stop codons

p 65 Embryology: Case For

p 66 Haeckel's biogenetic law "ontogeny recapitulates phylogeny"

p 68 Embryology: Reply

p 68 Haeckel's embryo diagram a major fraud. Both his and Darwin's discussion of embryos neglected the earliest stages where the differences are clearly observable.

p72 Gould recognizes the Haeckel fraud, but still argues that the "consilience" of multiple lines of investigation points toward Common Descent.

p 73 Biogeography: Case For

p 74 Darwin thought that the geographic distribution of animals could best be explained by descent with modification from a common ancestor. He used the Galapagos animals and plants to make his case. There were variations of birds on the three islands, but they were similar to birds in western South America. Migration from South America was deduced because only those species that could swim, fly or float are found in the Galapagos.

p 75 Drosophila in Hawaii and marsupials in Australia cited as examples. Premise is evolution in an isolated environment.

p 76 Biogeography: Reply

p 76 Evidence supports change in response to environment (Evolution#1), but does not show that animals everywhere have a common ancestor (Evolution #2). The observed variations are relatively minor and not macroevolutionary.

p 79 Biogeography: Further Debate

p 79 The observed evidence of variation could support either mohophyletic or polyphyletic development.

p 81 The Creative Power of Natural Selection: Case For

p 84 Darwin proposed natural selection as the mechanism by which evolution takes place - modern neo-Darwinists agree. It requires the three steps (visualized as a three-legged stool): Variation, heritability, differential reproduction.

p 86 The problem comes in visualizing how complex structures like the eye could be created by such a process. Some see it as an extrapolated microevolution process. Cites the finch beaks and the pepper moth as examples of evolution.

p 90 Natural Selection: Reply

p 90 Assertion that using artificial selection as a model for what evolution might do is invalid because intelligence is used in the selection. Also there appear to be fairly narrow limits of change even for artificial selection.

p 92 Finch beak evolution in response to stress tends to revert when stress is removed. Peppered moth story completely invalid because both species existed all the time of observation. There was just an adjustment of population.

p 94 Argument that limits are inevitable because significant change requires new information. For example, they would require new types of cells.

p 97 Natural Selection and Mutation: Case For

p 98 "even if the existing gene pool doesn't supply enough information to build a fundamentally new organism, new mutations in the genes can."

p 99 Mentions point mutations, duplication mutations, and inversion mutations.

p 99 Antibiotic resistance

p 100 An antibiotic may work by "throwing a monkeywrench in the machinery" of a bacteria by attaching to a specific protein. But if that protein mutates in such a way as to change the shape of that active site, the antibiotic may not stick to it. That variation of the bacteria will quickly reproduce to dominate the population.

p 101 Four-winged fruit fly demonstrates that a genetic manipulation can cause the replacement of the small "halteres" by a second full set of wings.

p 102 Natural Selection and Mutation: Reply

p 102 A mutation changing a binding site and thereby achieving resistance to an antibiotic does not make the case that it can provide the changes necessary for the forming of a new type of organism.

p 102 Usually the mutations which offer resistance to antibiotics are otherwise deleterious to the bacteria.

p 104 The rapid reproduction of bacteria make them a good laboratory for mutations, but no new bacteria have been produced, despite large numbers of generations.

p 104 The point mutations that produce a specific changes that confers antibiotic resistance certainly do not offer a strong case that mutations can create a new organism.

p 105 The four-winged fruit fly is a large change, but it had to be induced by skilled researchers inducing three mutations. In addition, it took careful control to maintain the survivability of the intermediate stages - typically intermediate products in a large change are not survivors in the wild. Finally, the four wings don't work!

p 106 "Major mutations can fundamentally alter an animal's anatomy and structure, but these mutations are always harmful or outright lethal. Either way, as University of Georgia geneticist John McDonald has pointed out, the kind of mutation that natural selection requires - namely, large-scale, beneficial mutation - does not occur."

p 108 Natural Selection and Mutation: Further Debate

p 108 A mutation to confer antibiotic resistance may be deleterious to the cell, but if there is a compensating mutation, it might achieve the resistance without being otherwise costly to the organism.

p 109 "Hox genes are 'master regulator' genes that turn other genes in the cell on and off during the developmental process."

p 109 "precisely because hox genes are so influential, no experimental mutations in hox genes (so far) have proven helpful to the organism."

p 109 "it requires a great many coordinated changes to transform one system into another without losing function in the 'in-between' steps."

p 110 "But some scientists contnd that while the genes in DNA carry assembly instructions for building proteins out of amino acids, they do not carry the assembly instructions for building organs out of proteins, or for building whole creatures out of organs and other body parts." This has references in the technical literature.

p 110 "beginning to think that genes do not (by themselves) carry the instructions for buiding a whole organism or animal."

p 111 "It also needs higher-level assembly instructions to arrange tissues and organs into body plans. Scientists are not entirely sure where these higher-level assembly instructions are stored. However, thes instructions are clearly necessary, and many scientists now doubt that they are stored in DNA alone."

p 115 Molecular Machines: Case For

p 115 Note that the "case for" is now the position of those who challenge the standard neo-Darwinist view, so the order has switched.

p 116 "If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down", wrote Darwin. "But I can find out no such case."

p 116 Description of complex molecular motors like the bacterial flagellum treated so prominently be Michael Behe.

p 117 "motor only functions after all 30 of the motor's protein parts are in place." Discusses Behe's idea of irreducible complexity. Nice diagram of ATP Synthase machine.

p 119 Molecular Machines: Reply

p 119 One response to irreducible complexity argument is to posit that something created for another purpose was coopted for use in the developing structure.

p 120 Ken Miller says parts of bacterial flagellum are also found in a protein pump, a simpler machine, and may have been coopted from simpler machines.

p 121 Molecular Machines: Further Debate

p 121 The co-option hypothesis can be criticized because the cooption process would disrupt the original motor, and offer no advantage in the intermediate steps.

p 121 For this particular case, genetic research suggests that the flagellum is older than the pump.

p 121 Only 10 proteins in the pump, 30 in the bacterial flagellum

p 121 Even with the parts, you need assembly instructions. Where do they come from?

p 126 Natural Selection and Survival of the Fittest

p 128 What Fossils Can't Tell You

p 142 The Nature of Dissent in Science

Audio/Video Reference

R Nave