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I QUESTIONS Introducing Developmental Biology

1. Developmental Anatomy

• 1.1 Conklin's Art and Science
  
• The Organization and Cell-Lineage of the Ascidian Egg - Edwin G. Conklin Journal of the Academy of Natural Sciences of Philadelphia 13: 1 -119
  

2. Developmental Genetics

• 2.1 Does the Genome or the Cytoplasm Direct Development?
  
• The Embryological Origins of the Gene Theory - Scott F. Gilbert
  The emergence of the gene theory from embryological research is a fascinating story and complements the history of genetics that begins with Mendel's experiments.
• Boveri's 1902 Paper - Theodor Boveri On Multipolar Mitosis as a Means of Analysis of the Cell Nucleus
  
• Baltzer on Boveri - Fritz Baltzer, 1967 Theodor Boveri: The Life of a Great Biologist 1862-1915
  
• 2.2 The Origins of Developmental Genetics
  
• Cellular Politics - Scott F. Gilbert Ernest Everett Just, Richard B. Goldschmidt, and the Attempt to Reconcile Embryology and Genetics
  
• Induction and the Origins of Developmental Genetics - Scott F. Gilbert
  The embryological framework of induction played a central role in the conceptual foundations of developmental genetics. This article concerns the transformation from embryonic induction to gene activation.
• Quicktime Movie of Salome Glueksohn-Waelsch
  
• Enzymatic Adaptation and the Entrance of Molecular Biology into Embryology - Scott F. Gilbert
  
• Quicktime Movie of Dr. François Jacob
  Nobel Laureate François Jacob (born 1920) has been extremely influential in constructing the major model describing differential gene transcription. In this fragment of an interview taped in 1996, Dr. Jacob mentions that although the data for this model came from experiments on unicellular bacteria, it was always intended as a model for the development of multicellular organisms.
• 2.3 Techniques of DNA Analysis
  
• Techniques of Molecular Biology
  
• Transgenic Cells and Gene Knock-outs
  
• Studying DNA Regulatory Elements
  
• Determining Methylation Status: Bisulfite Mapping
  
• 2.4 Techniques of RNA analysis
  
• Reverse-Transcriptase Tolymerase Chain Reaction (RT-PCR)
  
• Microarrays and Macroarrays
  
• In Situ Hybridizations
  
• 2.5 Bioinformatics
  
• An Introduction to Bioinformatics
  
• Developmental Biology, Bioinformatics and Systems Approaches
  
• 2.6 Cloning and Nuclear equivalence
  
• Evidence for Genomic Equivalence
  
• Why Clone Animals?
  
• 2.7 Silencing Large Blocks of Chromatin
  
• Chromatin Diminution CRMTIN DIMINTI
  CMI DI
  CD
  
• 2.8 So You Think You Know What a Gene Is?
  
• What Makes a DNA Sequence a Gene?
  

3. Cell-Cell Communication in Development

• 3.1 FGF Receptor Mutations
  
• Specific Functions of Fibroblast Growth Factor Receptors
  
• 3.2 The Uses of Apoptosis
  
• Apoptosis and the Removal of Unneeded Cells
  
• 3.3 Notch Mutations
  
• Mutations of Notch Proteins and Their Ligands
  

II SPECIFICATION Introducing Cell Commitment and Early Embryonic Development

4. Fertilization: Beginning a New Organism

• 4.1 Leeuwenhoek and Images of Homunculi
  
• Anton von Leeuwenhoek and his perception of spermatozoa - Adapted from an article by E. G. Ruestow, J. History of Biology 16: 185-224.
  Leeuwenhoek's ideas concerning sperm and their possible roles in fertilization underwent considerable development and were influenced by numerous intellectual and religious currents.
• Homunculus - Clara Pinto-Correia Historiographic Misunderstandings of Preformationist Terminology
  Calling something a "homunculus" is not a neutral act. C. Pinto-Correia analyzes the history of the "homunculus" and claims the homunculus is more a product of the 1930s than a model from the 1780s.
• 4.2 The Origins of Fertilization Research
  
• The Reemergence of Sex - John Farley, 1982 Chapter 6 of Gametes and Spores: Ideas About Sexual Reproduction 1750-1914
  
• 4.3 The Egg and Its Environment
  
• The Egg in the Real World
  
• 4.4 The Lillie-Loeb Dispute Over Sperm-Egg Binding
  
• Gametes and Spores - John Farley, 1982 Ideas About Sexual Reproduction 1750-1914
  Here, historian John Farley gives a lively account of the Woods Hole fertilization physiologists in the early 1900s.
• The Mechanism of Fertilization - F. R. Lillie, 1913 Science 38 (1913): 524-528.
  In this classic paper, Lillie predicts the nature of cell surface receptors and their activation by the binding of ligands on their extracellular domains.
• On the Nature of the Process of Fertilization - Jacques Loeb, 1899 and the Artificial Production of Normal Larvae (Plutei) from the Unfertilized Eggs of the Sea Urchin
  In this paper, Loeb emphasizes the roles of ions in initiating early development.
• The Invention of Artificial Parthenogenesis - Philip J. Pauly, 1987 Chapter 5 in Controlling Life: Jacques Loeb and the Engineering Ideal in Biology, Oxford University Press, NY. Pp. 93-117.
  Jacques Loeb's research on fertilization was part of a larger agenda that he had for making biology a more physical discipline. Philip Pauley documents the larger context for Loeb's research.
• 4.5 Blocks to Polyspermy
  
• On Multipolar Mitosis as a Means of Analysis of the Cell Nucleus - Theodor Boveri, 1902 Über mehrpolige Mitosen als Mittel zur Analzyse des Zellkerns. Verhandlungen der physicalisch-medizinischen Gesselschaft zu Würzburg. Neu Folge 35: 67-90.
  Translated by Salome Gluecksohn-Waelsch
• Theodor Boveri: The Life of a Great Biologist 1862-1915 - Fritz Baltzer, 1967
  Boveri's student, Fritz Baltzer, wrote about the context in which Boveri made his discoveries about polyspermy and chromosomal individuality.
• The Fertilization Reaction in Echinarachnius Parma - E. E. Just, 1919 Cortical Response of the Egg to Insemination
  Here, Just describes the two blocks to polyspermy.
• 4.6 Building the Egg's Extracellular Matrix
  
• Building the Egg's Extracellular Matrix
  

5. Early Development in Selected Invertebrates

• 5.1 Sea Urchin Cell Specification
  
• Transcription Factor Activation in the Sea Urchin Embryo
  
• 5.2 Alfred Sturtevant and the Genetics of Snail Coiling
  
• Sturtevant's Guess The genetic approach to embryology: The case of Limnaea
  
• 5.3 Modifications of Cell Fate in Spiralian Eggs
  
• Modification of Spiralian Specification
  
• The Role of the Mesentoblast in Gastropod Evolution
  
• 5.4 The Experimental Analysis of Tunicate Cell Specification
  
• The Search for the Yellow Crescent Myogenic Factor
  
• 5.5 P-granule Migration
  
• P-granule Localization in C. elegans and Asymmetry during First Cleavages
  

6. The Genetics of Axis Specification in Drosophila

• 6.1 Drosophila Fertilization
  
• Fertilization in Drosophila
  Fertilization of Drosophila can only occur in the region of the oocyte that will become the anterior of the embryo. Morover, the sperm tail appears to stay in this region.
• 6.2 The Early Development of Other Insects
  
• Short and Intermediate Germ Band Insects
  Drosophila forms all of its segments simultaneously from a germ band that extends across the entire egg. Short- and intermediate- germ band insects form their head first. Then, a proliferative zone in the posterior of the embryo keeps forming the cells that provide the posterior segments
• Polyembryony: The Parasitic Wasps
  In parasitic wasps, the cells divide holoblastically and do not form a syncytium. The cleavage stage embryo then splits to form dozens or even thousands of cell clusters, each cluster forming its own embryo.
• 6.3 Evidence for Gradients in Insect Development
  
• The Maternal Effect Genes
  
• 6.4 Christiane Nüsslein-Volhard and the Molecular Approach to Development
  
• Christiane Nüsslein-Volhard and Drosophila Embryogenesis
  
• 6.5 Asymmetrical Spread of Morphogens
  
• Asymmetric Movement of Wingless Protein in the Epidermis of Drosophila
  
• 6.6 Getting a Head in the Fly
  
• Genes Involved in Drosophila Brain Development
  

7. Amphibians and Fish: Early Development and Axis Formation

• 7.1 Amphibian Development Movies
  
• Amphibian development movies
  
• 7.2 Migration of the Mesodermal Mantle
  
• Migration of the involuting mesoderm
  
• 7.3 Spemann, Mangold, and the Organizer
  
• A Selective History of Induction
  
• A Selective History of Induction II Spemann's induction experiments
  
• 7.4 The Molecular Biology of Organizer Formation
  
• The Molecular Biology of Organizer Formation
  
• 7.5 Early Attempts to Locate the Organizer Molecules
  
• A Selective History of Induction III Mechanism of Organizer Action
  
• 7.7 Regional Specification
  
• A Selective History of Early Induction Research IV
  
• 7.8 Competence and Bias
  
• Competence and Bias
  
• 7.9 GFP Zebrafish Movies and Photographs
  
• Zebrafish Genetic Screens
  

8. Birds and Mammals: Early Development and Axis Formation

• 8.1 Epiblast Cell Heterogeneity
  
• Cellular Heterogeneity in the Epiblast
  Although the early epiblast appears uniform, different cells have different molecules on their cell surfaces. This allows some of them to remain in the epiblast while others migrate into the embryo.
• 8.2 Mechanisms of Compaction and the Formation of the Inner Cell Mass
  
• The Cell Surface and the Mechanism of Compaction
  What determines whether a cell is to become a trophoblast cell or a member of the inner cell mass? It may just be a matter of chance.
• 8.3 Human Cleavage and Compaction
  
• Sex Differences in Cell Divisions
  There is a slight growth advantage to XY blastomeres that may have had profound effects for in vitro fertility operations.
• 8.4 Placental Functions
  
• The Structure of Placentas
  Placentas are nutritional, endocrine, and immunological organs. They provide hormones that enable the uterus to retain the pregnancy and also accelerate mammary gland development. Placentas also block the potential immune response of the mother against the developing fetus. Recent studies suggest that the placenta uses several mechanisms to block the mother's immune response.
• 8.5 Nonidentical Monozygotic Twins
  
• Non-identical Monozygotic Twins
  Although monozygotic twins have the same genome, random developmental factors or the uterine environment may give them dramatically different phenotypes.
• 8.6 Conjoined Twins
  
• Types of Conjoined Twins
  The classification of conjoined twins concerns the parts of the bodies that are joined together.
• A Social History of Conjoined Twins
  Conjoined twins have fascinated people throughout history, and society has viewed their unique connectedness in different ways.

III THE STEM CELL CONCEPT Introducing Organogenesis

9. The Emergence of the Ectoderm: Central Nervous System and Epidermis

• 9.1 Homologous Specification of the Neural Tissue
  
• Homologous Specification of Neural Tissue between Vertebrates and Arthropods
  
• 9.2 Specifying the Brain Boundaries
  
• Marking the Brain Boundaries
  The Pax transcription factors and the paracrine factor FGF8 are critical in establishing the boundaries of the forebrain, midbrain, and hindbrain.
• 9.3 Constructing the Pituitary Gland
  
• Pituitary Development
  
• 9.4 Cerebellar Mutations of the Mouse
  
• Development of the Cerebellum: Insights from Mutant Mice
  The mouse mutations affecting cerebellar function have given us remarkable insights into the ways in which the cerebellum is constructed.
• 9.5 Constructing the Cerebral Cortex
  
• Three Genes and their Effects
  Three genes have recently been shown to be necessary for the proper lamination of the mammalian brain. They appear to be important for cortical neural migration, and when mutated in humans can produce profound mental retardation.
• 9.6 Neuronal Growth and the Invention of Childhood
  
• The Birth of Childhood
  
• 9.7 Why Babies Don't See Well
  
• Why Babies Don’t See Well
  The retinal photoreceptors are not fully developed at birth. As one gets older, the density of photoreceptors increases, allowing far better discrimination and nearly 350 times the light-absorbing capacity.
• 9.8 Developmental Genetics of Hair Formation
  
• Developmental genetics of hair formation
  
• 9.9 Normal Variation in Human Hair Production
  
• Formation of Mammalian Hair
  The human hair has a complex life cycle. Moreover, some hairs grow short (such as those of our eyelashes) while other hairs (such as those of our scalp) grow long. The pattern of hair size and of baldness is determined by paracrine and endocrine factors. The human hair has a complex life cycle. Moreover, some hairs grow short (such as those of our eyelashes) while other hairs (such as those of our scalp) grow long. The pattern of hair size and of baldness is determined by paracrine and endocrine factors.
• 9.10 Mutations of Hair Production
  
• The Red-Headed League: How melanocytes make red pigment
  In addition to normal variation, there are also inherited mutations that interfere with normal hair development.

10. Neural Crest Cells and Axonal Specificity

• 10.1 Communication between Migrating Neural Crest Cells
  
• Communication between Migrating Cardiac Neural Crest Cells
  Recent research has shown that neural crest cells might cooperate with one another as they migrate. There may be subtle communication between these cells through their gap junctional complexes, and this communication may be important for heart development.
• 10.2 Kallmann Syndrome
  
• The Kallman Syndrome: Sex, Smell, and Specific Adhesion
  Some infertile men have no sense of smell. The relationship between sense of smell and male fertility was elusive until the gene for Kallmann syndrome was identified as producing a protein that was necessary for the proper migration of both olfactory axons and hormone-secreting nerve cells.
• 10.3 The Evolution of Developmental Neurobiology
  
• S. Ramón Y Cajal, R. G. Harrison, and the Beginnings of Neuroembryology - Viktor Hamburger, 1980
  
• Viktor Hamburger - Adapted from D. Purves and J. W. Lichtman 1985. Principles of Neural Development. Sinauer Associates, Sunderland, MA.
  
• Rita Levi-Montalcini - Adapted from Purves, D. and Lichtman, J. W. 1985. Principles of Neural Development. Sinauer Associates, Sunderland, MA.
  
• 10.4 The Pathways of Motor Neurons
  
• Multiple Guidance Cues in the Motor Neurons Innervating Skeletal Muscles
  The homeotic gene mab-5 controls the direction in which certain neurons migrate in the nematode. The expression of this gene can alter which way a neuron travels.
• 10.5 Genetic Control of Neuroblast Migration in C. elegans
  
• Hox Genes and Nematode Development
  The homeotic gene mab-5 controls the direction in which certain neurons migrate in the nematode. The expression of this gene can alter which way a neuron travels.
• 10.6 The Early Evidence for Chemotaxis
  
• Earlier Evidence for Chemotaxis
  Before molecular techniques, investigators using transplantation experiments and ingenuity found evidence that chemotactic molecules were being released by target tissues.

11. Paraxial and Intermediate Mesoderm

• 11.1 Calling the Competence of the Somite into Question
  
• Tbx6 and the Specification of Somitic Mesoderm
  When the tbx6 gene was knocked out from mice, the resulting embryos had three neural tubes in the posterior of their bodies. Without the tbx6 gene, the somitic tissue responded to the notochord and epidermal signals as if it were neural ectoderm.
• 11.2 Cranial Paraxial Mesoderm
  
• Cranial Paraxial Mesoderm
  Most of the head musculature does not come from somites. Rather, it comes from the cranial paraxial mesoderm. These cells originate adjacent to the sides of the brain, and they migrate to their respective destinations.
• 11.3 Muscle Formation
  
• Myotube Formation: How We Learned that Skeletal Muscle is Made by Cell Fusion
  Multinucleated myotubes could arise either as (1) a fusion event between several mononuclear myoblasts, or (2) as a string of mitoses within a single myoblast. The former is thought to be the mechanism for myotube formation in skeletal muscle; the latter is thought to be the way heart myotubes are formed. v
• 11.4 Paracrine Factors, Their Receptors, and Human Bone Growth
  
• Specific Functions of Fibroblast Growth Factor Receptors
  Mutations in the genes encoding paracrine factors and their receptors cause numerous skeletal anomalies in humans and mice. The FGF and Hedgehog pathways are especially important.

12. Lateral Plate Mesoderm and the Endoderm

• 12.1 Coelom Formation
  
• Coelom Formation
  
• 12.2 Induction of the Lung
  
• Lung Branching Morphogenesis
  The induction of the lung also involves the interplay between FGFs and Shh. However, it appears to be different from the induction of either the pancreas or the liver.

13. Development of the Tetrapod Limb

• 13.1 Induction of the AER
  
• Pathway For The Induction of the AER
  The induction of the AER is a complex event involving the interaction between the dorsal and ventral compartments of the ectoderm. The Notch pathway may be critical in this process. Misexpression of these genes can cause absence or duplication of limbs.

14. Sex Determination

• 14.1 Social Critique of Sex Determination Research
  
• A Gendered Critique of Sex Determination Hypotheses
  In numerous cultures, women have been seen as the "default state" of men. Historians and biologists have shown that until recently such biases characterized the scientific study of human sex determination.
• 14.2 Finding the Male-Determining Genes
  
• Method for Identifying the Region of the Y-chromosome Containing the Testis Determining Factor in Humans
  The mapping of the testis-determining factor to the SRY region took scientists more than 50 years to accomplish. Moreover, other testis-forming genes have been found on the autosomes
• 14.3 Dihydrotestosterone in Adult Men
  
• 5α-Dihydrotestosterone in Adults
  The drug finasteride, which inhibits the conversion of testosterone to dihydrotestosterone, is being used to treat prostate growth and male pattern baldness.
• 14.4 Insulin-like Hormone 3
  
• Insulin-like Hormone-3 and Secondary Male Sex Determination
  In addition to testosterone, the Leydig cells secrete another hormone, insulin-like hormone 3 (Insl3). This hormone is required for the descent of the gonads into the scrotum. Males lacking this hormone are infertile because the testes do not descend. In females, lack of this hormone deregulates the menstrual cycle.
• 14.5 Forms of Hermaphroditism
  
• Human Hermaphrodites
  
• Normal Hermaphroditism in Nematodes and Fish Hermaphroditism in the Nematode C. elegans
  

15. Postembryonic Development: Metamorphosis, Regeneration, and Aging

• 15.1 The Molecular Biology of Wing Formation
  
• Intercellular Interactions Establishing the Dorsal-ventral Wing Surfaces
  The juxtaposition of those cells expressing Apterous with those that do not initiates a cascade of gene expression that results in markedly different cell types. These events were predicted by theoretical biologists years before the molecules were discovered.
• 15.2 Homologous Specification
  
• Homologous Specification
  If a group of cells in one imaginal disc are mutated such that they give rise to a structure characteristic of another imaginal disc (for instance, cells from a leg disc giving rise to antennal structures), the regional specification of those structures will be in accordance with their position in the original disc.
• 15.3 Insect Metamorphosis
  
• Hormonal Control of Insect Metamorphosis
  This article describes the experiments of Wigglesworth and others who identified the hormones of metamorphosis and the glands producing them.
• Drosophila Metamorphosis
  This article describes the variations that Drosophila and other insects play on the general theme of metamorphosis.
• Remodeling The Insect Central Nervous System
  This article describes the remodeling of the insect nervous system during metamorphosis.
• Microarray Analysis Of Drosophila Metamorphosis
  This article describes a microarray analysis of Drosophila metamorphosis, wherein several thousand genes were simultaneously screened.
• 15.4 Precocenes and Synthetic JH
  
• Environmental Control Over Larval Form and Function: Precocenes and Plant Juvenile Hormones
  Given the voracity of insect larvae, it's amazing that any plant exists. However, many plants get revenge on their predators by making compounds that alter their metamorphoses and prevent the animals from developing or reproducing.
• 15.5 Regeneration in Annelid Worms
  
• Annelid Regeneration
  An easy laboratory exercise can discover the rules by which worms regenerate their segments. This website details some of those experiments.
• 15.6 The Polar Coordinate and Boundary Models
  
• The Polar Coordinate Model of The Polar Coordinate Model of Positional Information in the Developing and Regenerating Limb
  The phenomena of epimorphic regeneration can be seen formally as events that reestablish continuity among tissues that the amputation has severed. The polar coordinate model attempts to explain the numerous phenomena of limb regeneration.
• 15.7 Ethel Browne and the Organizer
  
• Ethel Browne Harvey (1885-1965) and the Organizer
  

16. The Saga of the Germ Line

• 16.1 Germline Sex Determination in C. elegans
  
• Translational Regulation of Germline Sex Determination in C. elegans
  The establishment of whether a germ cell is to become a sperm or an egg involves multiple levels of inhibition. Translational regulation is seen in several of these steps.
• 16.2 Mechanisms of Chromosome Diminution
  
• Chromatin Diminution
  
• 16.3 The Insect Germ Plasm
  
• The Discovery of Insect Germ Plasm
  The insect germinal cytoplasm was discovered as early as 1911, when Hegner found that removing the posterior pole cytoplasm of beetle eggs caused sterility in the resulting adults.
• 16.4 Human Meiosis
  
• Human Meiosis
  Nondisjunction, the failure of chromosomes to sort properly during meiosis, is not uncommon in humans. Its frequency increases with maternal age.
• 16.5 The Nebenkern
  
• Fuzzy Onions and the Nebenkern
  Sperm mitochondria are often highly modified to fit the streamlined cell. The mitochondria of flies fuse together to form a structure called the Nebenkern, and this fusion is controlled by the fuzzy onions gene.
• 16.6 Synthesizing Oocyte Ribosomes
  
• Synthesizing Ribosomes
  Ribosomes are almost a Ribosomes are almost a "differentiated product" of the oocyte, and the Xenopus oocyte contains 20,000 times as many ribosomes as somatic cells do. Gene repetition and gene amplification are both used to transcribe these enormous amounts of rRNA.
• 16.7 Hormones and Mammalian Egg Maturation
  
• Hormones and Mammalian Egg Maturation
  
• 16.8 The Reinitiation of Mammalian Meiosis
  
• The Reinitiation of Meiosis in Mammals
  The hormone-mediated disruption of communication between the oocyte and its surrounding follicle cells may be critical in the resumption of meiosis in female mammals.

IV SYSTEMS BIOLOGY Expanding Developmental Biology to Medicine,Ecology, and Evolution

17. Medical Aspects of Developmental Biology

• 17.1 Human Embryology and Genetics
  
• Human Embryology and Genetics
  
• 17.2 Thalidomide as a Teratogen
  
• Thalidomide as a Teratogen
  The drug Thalidomide caused thousands of babies to be born with malformed arms and legs, and it provided the first major evidence that drugs could induce congenital anomalies. The mechanism of its action is still hotly debated.
• 17.3 Our Stolen Future
  
• Our Stolen Future and The Contest for Truth
  
• 17.4 Therapeutic Cloning
  
• Therapeutic Cloning
  

18. Developmental Plasticity and Symbiosis

• 18.1 Inducible Caste Determination in Ant Colonies
  
• Inducible Defense in the Ant Colony
  In some species of ants, the loss of soldier ants creates conditions that induce more workers to become soldiers.
• 18.2 Volvox: When Heat Brings Out Sex
  
• Volvox: When Heat Brings Out Sex
  
• 18.3 Mechanisms of Diapause
  
• Diapause in Insects
  
• 18.4 Pressure as a Developmental Agent
  
• Pressure as a Developmental Agent
  
• 18.5 The Dictyostelium Life Cycle: Variations within Variations
  
• The Dictyostelium Life Cycle: Variations within Variations
  
• 18.6 Developmental Symbioses and Parasitism
  
• Developmental Symbiosis as Protection
  Embryos often do not have the time to form an immune system before they encounter pathogenic microbes. Developmental symbioses can protect the embryo against such predation.
• How Do Symbionts Get Together?
  How are developmental symbioses established? Mechanisms of external transfer (from the environment), horizontal transfer (from other members of the species), and vertical transfer (in the oocytes) have been documented.

19. Developmental Mechanisms of Evolutionary Change

• 19.1 Relating Evolution to Development in the Nineteenth Century
  
• Edmund Beecher Wilson and Frank R. Lillie and the relationship between evolution and development
  
• Ernst Haeckel and the Biogenetic Law (An informed opinion)
  In the early 1900s, a fusion of evolution and embryology was wrongly interpreted to support a linear (as opposed to a branched) model of evolution. The interpretation of Ernst Haeckel was that every organism evolved by the terminal addition of a new stage to the end of the last "highest" organism. Thus, he saw the entire animal kingdom as representing truncated steps of human development.
• Haeckel and the Vertebrate Archetype
  In the early 1900s, a fusion of evolution and embryology was wrongly interpreted to support a linear (as opposed to a branched) model of evolution. The interpretation of Ernst Haeckel was that every organism evolved by the terminal addition of a new stage to the end of the last "highest" organism. Thus, he saw the entire animal kingdom as representing truncated steps of human development.
• 19.2 Correlated Progression
  
• Developmental Correlation
  
• Evolution and Domestication: Selection on Developmental Genes?
  Domestication appears to be selection for neotenic conditions. In selecting for behavioral plasticity, changes in skull shape and pigment patterns are also produced. This phenomenon can also be seen in current attempts to domesticate wild wolves and foxes.
• 19.3 The Search for the Urbilaterian Ancestor
  
• The Search for the Urbilaterian Ancestor
  
• 19.4 How the Chordates Got a Head
  
• How the Chordates Got a Head
  
• 19.5 "Intelligent Design" and Evolutionary Developmental Biology
  
• Evolution and "Scientific Creationism"
  Scientific creationism is not science, but is a strong social phenomenon that unites three strands of popular American Protestant thought: natural theology, fundamentalism, and scientism. This essay examines the underpinnings of the Creationist critique of evolution.

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