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Join us as we explore the fascinating transition from early cells to multi-celled animals. This transition, as well as several other major evolutionary transitions, dramatically increased the complexity of lifeforms on our planet.

Before civilization began to impact the human life cycle approximately 10,000 years ago, human beings had high birth and death rates. Today the world is in the midst of a demographic transition - a transition to low birth and death rates - as the ability to control both disease and reproduction increases. Along the way, between these extremes, populations go through an intermediate period of continued high birth rates, combined with low death rates, resulting in a population explosion.

For years whale evolution was characterized by speculation and limited evidence. Evolution critics even focused on whales as a means to criticize evolutionary theory. Now whale evolution represents one of the best examples of "macroevolution." This "clicker case" uses this fascinating story of historical irony as a backdrop to the study of whale evolution. First, students study an array of whale fossils to learn how evolution is properly viewed as a branching, relationship-based process, not a linear, progressive, "chain-of-being." Using this view they learn how scientists seek to reconstruct past relationships and study transitional features, not search for "missing links." Students then learn that evidence for macroevolution relies on several lines of independent evidence from fossils, comparative anatomy, embryology, genetics, and paleoecology. With a focus on macroevolution, this case makes a critical contribution to evolution education. It could work well in a lower level undergraduate biology / evolution / paleontology course (non-majors or majors), or in an upper-level evolution course, perhaps early in the semester as a primer for related topics.

2 minute animation, (includes full body animation rendition of Australopithicus) A recent study of fossil shoulder bones from a human ancestor reveals that this ancient relative was still well adapted to living in trees, even after the evolution of bipedalism. Studying features like these helps scientists to better understand when modern humans moved away from a partly arboreal lifestyle and transitioned to living exclusively on the ground.

In a study published Thursday in the journal Science, they report that they've pinpointed the bit of finch DNA behind the swift transition: a gene called HMGA2. In finches, HMGA2 seems to be the primary factor in beak size - like a really good group project leader, it orchestrates the expression of a number of other genes, each of which tweaks the size of the bird's beak. The same gene also appears in dogs, horses, even humans, holding sway over body size and stature.

A researcher has gathered a piece of evidence that helps shed light on the evolutionary transition from soft-bodied animals with no well-defined heads to hard-bodied animals that sported heads. The clue comes from one of the oldest fossilized brains ever found-a more than 500 million-year-old specimen of the Cambrian arthropod Odaraia alata found in western Canada.

In the second film of the Great Transitions trilogy, paleontologist Julia Clarke takes us on a journey to uncover the evidence that birds descended from dinosaurs. The discovery of Archaeopteryx in a quarry in Germany in the early 1860s provided the first clue that birds descended from reptiles. But what kind of reptile? In the last 40 years, scientists have identified many shared features between birds and two-legged carnivorous dinosaurs called theropods. The film illustrates many of the practices of science, including asking important questions, formulating and testing hypotheses, analyzing and interpreting evidence, and revising explanations as new evidence becomes available.

This interrupted case study examines basic concepts of chemical bonding by telling the story of "Madison," a young girl eager to learn how her hair can transition from natural curls to straight, smooth tresses. The case can be used to teach or review the major categories of bonds (ionic, covalent and hydrogen), major macromolecules of life, and hydrolytic and dehydration reactions. It also explores how chemical relaxers and heat through blow drying and flat-ironing can change the nature of straight, wavy and curly hair through the disruption of protein shape. Students will thus learn what it means when a protein has become denatured and how various variables such as pH, heat and salts can lead to the unraveling of the three-dimensional shape of proteins. This case is suitable for an AP high school course, or for an introductory biology or chemistry course for majors or non-majors. This activity can also be used as a review of basic biology and chemistry for students in an upper-level biochemistry course.

This case study centers on symbiotic relationships between insects and bacteria using Drosophila melanogaster, the common fruit fly, and the recently discovered bacterial species Sodalis praecaptivus. Until recently, the only known Sodalis species of bacteria were symbiotically associated with several different species of insects. However, free-living non-symbiont Sodalis species are being tested in several different insect species to determine if they can transition into symbiotic relationships. A pre-class assignment (see Supplemental Materials) directs students to read an open access research journal article providing a comprehensive review of S. praecaptivus and describing an experimental weevil model that parallels that of the fruit fly. A PowerPoint presentation shown in class (see Supplemental Materials) provides further background before students work in small groups to complete the case study focusing on results from D. melanogaster and S. praecaptivus model experiments.  Although developed for a genetics course, this interrupted case is appropriate for an upper-level biology course. It can be completed within a 75-minute class meeting, or adapted for shorter time periods.

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Put together a video to help teachers making this shift during the Coronavirus Pandemic. Quality Matters Rubric - https://www.qualitymatters.org/sites/...