TTC VIDEO - Major Transitions in Evolution

Evolution is the most remarkable force in the history of Earth, the organizing principle throughout the biological sciences, and the most important mechanism scientists use to understand the varieties of life on our planet.

How and when did life on Earth get to be the way it is today?

Imagine a world without bees, butterflies, and flowering plants. That was Earth 125 million years ago.

Turn back the clock 400 million years, and there were no trees.

At 450 million years in the past, even the earliest insects had not yet developed.

And looking back 500 million years—a half-billion years before the present—the land was devoid of life, which at that time flourished in a profusion of strange forms in the oceans.

These and other major turning points are the amazing story of evolution. To learn about these major transitions, each of which brought forth new possibilities for life, is to embark on an unforgettable look into the past. It’s also a captivating opportunity to get a deeper understanding of how evolution works, to draw intricate connections between living things, and to think about life—not just yours but the lives of everything around you—in new ways.

Major Transitions in Evolution tells this science-detective story in 24 lavishly illustrated lectures that focus on the giant leaps that gave rise to nature’s boundless diversity. In a course of breathtaking scope, you study the conditions that led to the first complex cells, flying insects, flowering plants, mammals, modern humans, and many other breakthroughs. And in the process of studying the past, you gain a powerful understanding of the present world.

Given the broad scope of the subject, this course is taught by two professors: Anthony Martin, a paleontologist and geologist at Emory University, and John Hawks, a paleoanthropologist at the University of Wisconsin–Madison. Each is an outstanding teacher in his field, adept at making the subject interesting and accessible no matter what your background in science. And in the final lecture, the two appear together for an absorbing conversation on common themes in the epic saga of life on Earth.

Giant Leaps that Brought Us to Today

Among the major transitions you cover are these:

* From simple to complex cells: Life’s first major evolutionary transition was the leap from basic prokaryotic to more complex eukaryotic cells, which contain a nucleus and other specialized structures. This was the crucial step that eventually led to plants and animals.
* Skeletons: Skeletons are a ubiquitous feature of the animal world, but where did they come from? About 500 million years ago, the evolution of predators triggered an evolutionary response: mineralized skeletons as a defense.
* From fish to four legs: The iconic image of evolution is a fish emerging onto land. This transition might not have happened without shade provided by the newly developing forests, whose protective canopy gave the first “fishapods” protection from the sun.
* The first eggs: The development of enclosed eggs in early reptiles about 320 million years ago freed animals from watery environments and led to the later evolution of mammals and dinosaurs, as well as flying and swimming reptiles.
* Dinosaurs become birds: Dinosaurs didn’t go completely extinct; they survive today as birds, whose distinctive wings, feathers, and other features are visible in transitional fossils such as Archaeopteryx, from about 150 million years ago.
* Modern humans: The evolution of tree-dwelling primates to upright-walking apes later led to the evolution of modern humans—a species that invented agriculture, poetry, computers, and the techniques to trace its own lineage and that of all life.

You also explore many other transitions that occurred between these milestones, and you take an intriguing look ahead to speculate about the future direction of evolution.

The Latest Details on the Oldest Events

New technologies, such as DNA analysis, together with the latest fossil discoveries, make this a fast-changing subject that has grown far more detailed and complete than the presentation you may have learned in school. Among the scientific and popular misconceptions that have been overturned are these:

* Neandertals: Recently sequenced DNA from Neandertals suggests that they were not an isolated throwback but contributed some genes to the modern human lineage. Genetic and other clues show that behaviorally Neandertals were very human-like.
* Ardipithecus: The 2009 discovery of a relatively complete fossil skeleton of Ardipithecus, an ape that lived about 4.4 million years ago, demonstrates that apes and humans are related in more complex ways than previously thought.
* Mammals: Early mammals did not simply “lay low” under the shadows of dinosaurs; they exploited promising niches, evolving traits that led to their adaptive explosion after the extinction of the dinosaurs 65 million years ago.

These are just some of the many pieces of the evolutionary puzzle that have been enriched by new research and that you explore in depth in Major Transitions in Evolution.

Wondrous Life

Few subjects are as visually rich as the history of life, and Major Transitions in Evolution includes a wealth of images, including photos of fossils and their settings, reconstructions of ancient life and ecosystems, geological timelines, maps of paleogeographic continent positions and current fossil locations, cladograms showing the shared characteristics of different organisms, and specially commissioned art by an expert paleo-artist skilled at visually recreating the past.

While it may not be possible to visit the past in person, you can still range across eons of time with this course: watching Earth and its evolving population of plants and animals adapt in startling ways to changes in the environment and challenges from each other; witnessing periodic, devastating mass extinctions—due to asteroids and other cataclysms—and seeing the survivors repopulate the globe with an explosion of new species; and charting the inexorable transformation of our planet from a hostile place we would scarcely recognize to the verdant world we now know. It’s a story with countless subplots, false leads, and reversals of fortune, but it has one overarching theme—that life is wondrous, resilient, and endlessly surprising.

About Your Professors

Dr. Anthony Martin is Professor of Practice in the Department of Environmental Studies at Emory University, where he has taught courses in geology, paleontology, environmental science, and evolutionary biology since 1990. He earned his B.S. in Geobiology from St. Joseph’s College (Indiana), M.S. in Geology from Miami University (Ohio), and Ph.D. in Geology from the University of Georgia. At Emory, he has been recognized with both university- and student-sponsored teaching awards, including the Emory Center for Teaching and Curriculum’s Award for Excellence in Teaching.

Dr. Martin’s research focuses on ichnology, the study of modern and fossil traces, such as tracks, trails, burrows, nests, and other signs of behavior. Among his notable achievements is his codiscovery of the only known burrowing dinosaur. Dr. Martin has authored more than 30 peer-reviewed publications, as well as three books, including Introduction to the Study of Dinosaurs.

Dr. John Hawks is Associate Professor of Anthropology at the University of Wisconsin–Madison, where he has taught courses ranging from biological anthropology to brain evolution since 2002. He earned his B.S. in Anthropology from Kansas State University and M.S. and Ph.D. in Anthropology from the University of Michigan.

Early in his career, Dr. Hawks focused on fossil and archaeological evidence for human evolution. But as the Human Genome Project was completed, he became one of the first paleoanthropologists to use both genetic and fossil information to test hypotheses about human prehistory. More recently, his work on Neandertals has broken new ground, and his prediction that humans and Neandertals likely interbred has been confirmed by the analysis of Neandertal DNA. He is the author of groundbreaking research papers, and he has a devoted following on his science blog, where readers can follow the latest news in paleoanthropology.

Course Lecture Titles
1. Macroevolution and Major Transitions
2. Paleontology and Geologic Time
3. Single - Celled Life - Prokaryotes to Eukaryotes
4. Metazoans - The Earliest Multicellular Animals
5. The Development of Skeletons
6. The Rise of Vertebrates
7. Colonization of the Land
8. Origins of Insects and of Powered Flight
9. Seed Plants and the First Forests
10. From Fish to 4 - Limbed Animals
11. The Egg Came First - Early Reptile Evolution
12. The Origins and Successes of the Dinosaurs
13. Marine and Flying Reptiles
14. Birds - The Dinosaurs among Us
15. The First Flowers and Pollinator Coevolution
16. Egg to Placenta - Early Mammal Evolution
17. From Land to Sea - The Evolution of Whales
18. Moving on Up - The First Primates
19. Apes - Swinging Down from the Trees
20. From 4 Legs to 2 - The Hominin Radiation
21. First Humans - Toolmakers and Hunter - Gatherers
22. From Homo to sapiens - Talking and Thinking
23. Our Accelerating Evolution
24. Reflections on Major Transitions
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