Integrating Evolution: An ENSI-Based Teaching Sequence
An Overall Course Outline,
Incorporating Evolution and the Nature of Science as
Themes Throughout the Course.
Nature of Science (about 2-3 weeks); focus on correcting MISconceptions: What science is NOT, vs what it IS, including its limits and basic uncertainty, and the important elements of inference, bias, evidence, social context, and processes of science. Recognize examples of pseudoscience and where there are political, economic, or religious distortions of good science. Seriously consider using the Science Surprises unit.
Intro to the Science of Biology: Cells,Survey of Life, and Classification (about 4 weeks); overview of the familiar groups of the living world; peek at groups of microorganisms (intro to use of scopes), intro to cells; introduce Lynn Margulis' hypothesis that the mitochondria, chloroplasts and other eukaryotic organelles originated as endosymbionts of prokaryotic cells - an idea widely tested and confirmed in many ways; intro to classification concepts and terminology, the how and why of biological systematics being different from the categorizations of non-biological assemblages; peek at past lives (patterns of fossils: extinctions and origins, include brief detour into deep time and why we’re so confident of it. Also work with scale, and branching of vertebrates as presented in Patterns in Time. Whenever possible, point out "problem organisms" that don't fit cleanly into distinct categories, and possess a mix of traits typical of 2 major groups, e.g. Peripatus, platypus, coelacanth, archaeopteryx), suggesting a history of transitions. Explore anatomical series showing change over time (e.g., the hominid Skulls lab and their chronology), showing gradual and mosaic changes over time. “Does this fit with traditional thinking?” More observations that don’t fit traditional explanations.
Intro to Evolution(about 4-5 weeks); “We get lots of problems when we study life! What might be a scientific (testable) process that could explain (answer) all of those observed problems? How about this thing called “evolution?” There are lots of popular MISconceptions about evolution: what it is NOT vs what it IS; exploring some of the many clear examples of micro and macro evolution, and an introduction to Darwin and Natural Selection (vs Lamarck and his evolution mechanism); be sure to bring out the cumulative aspect, and the mix of random with non-random elements; introduce phylogenetic trees and cladograms; do the "Becoming Whales" lesson, with its elements of prediction and "gap-filling" with transitional forms.
Intro to Molecular Biology, Origin of Life Hypotheses, and the Evolution of Key Life-Processes (about 6-8 weeks); ask "We've looked at the origin of species, but how did the origin of life happen?" Examine the distinction between the tenuous "origin of life" hypotheses, and the reality of biological evolution, with its abundance of totally supportive explanations about HOW it happens. Take a look at a few of the currently popular origin of life scenarios, and the likely emergence sequence of fermentation, photosynthesis, and respiration, and an intro to the biochemistry necessary to deal with those processes. In this context, explore some of the gross anatomy and physiology associated with those processes. New familiarity with proteins enables students to compare amino acid sequences in proteins from different groups to shed light on likely degrees of relationship. Do "Tutorial: Using Online Databases.." lesson.
DNA Structure and Function (about 4 weeks); include the current topics of biotech and genomics; provide lab experience in some DNA lab techniques; DNA in forensics; genomes, and comparisons of DNA sequences in different groups to shed light on likely degrees of relationship, build phylogenetic trees; include examples of tracing the evolution of viruses in fighting HIV and influenza.
Reproduction and Development (about 3 weeks); includes mitosis, meiosis, examples of evolution patterns in plant reproduction, different patterns in animal reproduction and comparative embryology (and their significance to survival); provide emphasis on less familiar but critical aspects of human reproduction, including potential ease of conception, unreliability of menstrual cycle timing, and potential pitfalls of the many contraceptive methods; explore the emerging field of "Evo-Devo."
Genetics (about 4-5 weeks); intro to Mendelian inheritance and chromosomal changes, with some examples and experiences in mechanisms of macroevolution. Look at chromosome comparison, gene duplications, pseudgogenes and speciation.
Behavior (about 2 weeks); focusing on genetically influenced behavior vs learned behavior, evidence for the evolution of behavior; explore primate studies on the critical importance of positive and supportive parenting, from both mother and father. Consider doing the Footsteps in Time lesson here.
Ecology: Populations, Societies, and Ecosystem Interrelationships (about 2 weeks); including how human populations, and continued population growth, especially in our industrialized societies, excessively impact the world ecosystems. Could easily include some elements of public health and modern medicine from the perspective of evolution (see Moalem's Survival of the Sickest. 2007). Refer to environmental pressures and their influence on natural selection. Take a look at a new and growing website on Environmental Science, with career information and teaching ideas. As we probe the climate influences on how populations evolve (paleoclimate and modern climate changes), looking for trends, this subject becomes increasingly important. Be sure to share with your students.
Organ Systems (Vertebrate Anatomy & Physiology) Elements of this topic are incorporated into other units as appropriate. The Blocks & Screws lesson works well here.
Throughout the course, numerous opportunities arise in which evolution uniquely provides reasonable explanations for otherwise puzzling phenomena or features. There are many examples of morphological and biochemical features variously referenced as "imperfections", "contrivances", "adaptive compromises", "preadaptations", "atavisms", "pseudogenes" and by other terms, depending on their nature and/or circumstances. Pointing these out where appropriate in the course will bring attention to their easy expectation in an evolutionary context.
Consider a visit to a zoo or aquarium to have students look for contrivances, rather than adaptations: structures typically associated with one function, but being used for another, e.g. the elongated wrist bone used for a thumb by pandas, or the elephant's trunk used for grasping, the elephant's ears for body temperature control, or a kangaroo's tail used for a fifth leg in slow walking, or a sea horse's tail used for grasping.