The empire hit a low point with Elagabalus, who was arguably the worst Roman emperor of all—which is saying quite a lot. Then Rome teetered on the brink of total collapse due to a deadly combination of civil war, barbarian invasions, economic collapse, and natural disasters. x

Just when the Roman Empire seemed on the verge of collapse, a series of hard-headed, practical emperors managed to rescue it. Follow the astonishing story of how these men, led by the reformer Diocletian, drove back the barbarians and stabilized the faltering Empire. x

Stability never lasted long in the Roman Empire. At the dawn of the 4th century, Christianity emerged as a major world force—made manifest by Constantine’s dramatic and unexpected conversion. Find out how and why Christianity developed and spread, and the role it played in subsequent political events. x

Take a closer look at Constantine and explore his motivations for converting to Christianity. Learn about the Arian Controversy and the Council of Nicaea, which codified key aspects of Christian theology. Then see why Constantine founded a new capital city at Byzantium, and the state of the empire at the end of his life. x

Gladiators dominate today’s popular imagination when it comes to ancient Rome—and indeed, the Romans loved their spectacles and sports. As you will find out here, gladiator combat was only one of many popular entertainments in the empire. Find out who the gladiators were and what their lives were like. Then turn to another popular contest: the beast hunt. x

Although gladiators dominate Hollywood films, chariot racing was actually the most popular sport in the Roman Empire. Go inside the Circus Maximus and learn about the factions and teams of chariot racers. Then shift your attention to the world of the theater, where plays, mimes, and music entertained the masses. x

No survey of the Roman Empire would be complete without a detailed look at one of its most central institutions: the military. Take a look at the organization of Rome's fighting forces. See what kind of equipment soldiers were outfitted with, how they trained, and what joining the military meant for farm boys in the provinces. x

Administration is only half the battle in maintaining a tremendous empire. You also have to defend the borders, and from the 3rd to the 5th centuries, Rome experienced an increasing wave of invasions by outsiders. Here, Professor Aldrete introduces you to the Huns, the Visigoths, the Vandals, and other invaders who penetrated Rome's borders and plundered the empire. x

While the western half of the Roman Empire had clearly collapsed by the end of the 5th century, the eastern Romans in the Byzantine Empire flourished for another thousand years. Visit the world of Constantinople, meet fascinating figures such as Justinian and Theodora, and see what made the Byzantine Empire so successful. x

Generations of historians have struggled over—and disagreed about---the fundamental questions of when and why the Roman Empire fell. This lecture critically evaluates a wide range of possible answers to these complex and enduring questions. x

Traditionally, historians have viewed the years 200 to 600 as a time of collapse and stagnation, the end of Rome and the arrival of the “Dark Ages.” Recent historians have taken another look at this era and seen a time of invigorating change, a vibrant mingling of cultures, and an exciting transition between antiquity and the Middle Ages. x

In this final lecture, consider the legacy of the Roman Empire, which influences us in innumerable ways, from our language to our legal codes. Because history is ultimately about people, Professor Aldrete closes with a few final voices to keep everyday Romans alive, and a reflection on what they might tell us today. x

Convergent evolution occurs when natural selection causes different species to evolve in similar ways. Does this mean that evolution follows a predetermined path? Focus on the recent debate between scientists Stephen Jay Gould and Simon Conway Morris. Gould perceived contingencies and unpredictability, but Conway Morris saw repetition and consistency. How do these views relate to human evolution? x

Life is even more adaptable than Darwin could have known. In this lecture, investigate extremophiles—organisms that flourish in extreme conditions. These have made biologists rethink the limitations of life on Earth. From bacteria existing miles underground that divide once every 10,000 years to creatures thriving next to superheated undersea volcanoes, life is programmed to adapt and survive. x

While Darwin knew of inefficient anatomical features of humans and other animals, he didn’t consider these a distinct category of evidence for natural selection. Explore ad hoc body designs—from our imperfect eyes and sexual anatomy, to the bizarre faces of flounders and the false thumbs of pandas. Each adaptation shows evolution devising a solution that is “good enough,” even if it is not ideal. x

Why was Darwin afraid that ants might undermine his theory of natural selection? Delve into the sterile worker paradox: the puzzle of why ants and other “eusocial” species evolved to have large numbers of non-reproducing offspring. Since the ability to reproduce is central to natural selection, this feature, which is common among insects and also present in other animals, demands explanation. x

Darwin saw that natural selection not only leads to species that evolve to their mutual advantage, but to enemies that wage an evolutionary arms race that ends up benefiting both sides. Study coevolutionary cases—from the yucca plant and its symbiotic partner, the yucca moth, to the fastest animal on Earth, the cheetah, and its prey the springbok antelope, which has evolved to be almost as fast. x

On the Origin of Species failed to account for a major part of the Tree of Life, namely bacteria and other microorganisms. These represent the original forms of life, and they have played a central role in the evolution of every species since. Study the symbiotic role of microbes in the functioning of plants and animals, and consider the view that all organisms are, in part, microbial. x

In Darwin’s lifetime, comparisons between the brains of different species were restricted to examinations of anatomy alone. Today, researchers use genetic tools to gain deep insights into how behaviors and sensory abilities evolve. Study behavior in creatures from fire ants to crows to humans, asking how did human brains get so large—and why are big brains so useful anyway? x

Darwin devised his theory of sexual selection to explain many traits that can’t be understood through natural selection alone—from the peacock’s gaudy tail to the elaborate constructions of bowerbirds. Probe deeper to discover why sexual reproduction exists at all, what causes individuals to develop into males versus females, and why some males take on the role of raising the young. x

Darwin's writings seem to imply that evolution through natural selection should always favor longer lifespans. So why don't we live forever (or at least for several centuries)? Consider ways that evolutionary processes account for aging and death. Weigh factors such as accumulated mutations, programmed cell death, and genes whose multiple effects are antagonistically at odds with one another. x

Explore one of the ultimate applications of evolutionary principles: harnessing evolution to benefit human health. Study diseases such as malaria, AIDS, influenza, and cancer that evolve rapidly to outmaneuver the body's changing defenses. Also contrast our modern lifestyle with the physiology we inherited from our prehistoric ancestors, who evolved to compete in a far different world. x

Darwin contrasted natural selection with artificial selection—the time-tested techniques for selective breeding that promote desired traits in plants and animals. See how far we’ve come with 21st-century tools such as CRISPR, which allows precise edits to the DNA sequence of any species. Evaluate the promise and perils of this technology, which lets us take evolution into our own hands. x

What does the future hold? Will we evolve into new species? Or have we reached an optimum state that will see minimal evolutionary changes? Weigh the impact of our ever-more-sophisticated technology and consider what will happen to humans who leave Earth for another planet with new physiological challenges. As you learn in this course, evolution isn't just possible; it's inevitable. x

It's true that a lot of woodworkers, even seasoned ones, are challenged by making chairs. Because there are few pieces of furniture in a house that have to tolerate stress like a chair, it's essential that the joinery is the best it can possibly be. Here, examine the essentials of chair making, with a focus on offset mortise-and-tenon joints (as there are 24 such joints that go into the chair you'll learn how to make). Additional features you'll create include a handhold that makes it easy to move the chair around, and book-matched back slats made of walnut. Plus, you'll get more help from an expert upholsterer who shows you all sorts of accessible tips and tricks for making attractive, professional slip-seats for your chair. x

In this lesson, your project is a beautiful bedside table made of white oak that includes distinct features that will test your woodworking skills, including a full-extension drawer, leg and rail construction with mortise-and-tenon joinery throughout, two shelves that provide a unique opportunity to work with the expansion and contraction of solid wood, and a shelf bracket that's dadoed into the table legs. Mr. Vondriska takes you step by step through the process of making this table, instilling in you the confidence and knowledge to tackle a second table entirely on your own-because, of course, you'll need another table for the other side of your bed. x

Also known as drop-leaf tables, handkerchief tables may look complex. But with the tips you'll learn in this lesson, you'll be able to successfully complete one of these tables in your own workshop. One of the tasks you'll focus on is the joinery required to create the table's signature drop-leaf: a rule joint made with a match set of router bits specifically for drop-leaf tables. Other details you'll learn to make include the gate leg that swings not on a mechanical hinge, but a hinge you'll create using a dado head on a table saw; tapered legs that give the table a more delicate look; mortise-and-tenon joints at both 90- and 45-degree angles; and more. Never built a drop-leaf table before? Mr. Vondriska walks you through all the geometry and cool woodworking techniques you need. x

Join guest instructor David Munkittrick for a helpful, accessible look at how to design and build a classic style of leg-known for its s-curve and rounded foot-that goes all the way back to ancient Egypt and China. Like most complex woodworking projects, there are many ways you can go about shaping a cabriole leg, but Mr. Munkittrick simplifies the process so you can find the way that works best for you. Using a basic two-dimensional template, you'll built a Queen Anne-style cabriole leg that's 2-3/4 inches thick and 24 inches long. And the best part: Aside from a cabinet-maker's rasp, you won't have to spend lots of money on special tools to make this iconic leg. With just a little practice, you'll be surprised at how easy it is to make a cabriole leg of your own. x

Nervous about finishing a woodworking project you've spent so much time and work on? No need to worry. In this lesson on the essentials of finishing projects, Mr. Vondriska teaches you what he's learned about finishing from his own mistakes. The goal: to give you the confidence level you need to finish your projects the right way-the first time. What finish should you use? What are the best tools for applying them? How do you avoid honey-like layers of finish that never want to dry? What are the benefits of lacquer, varnish, and urethane? What's the difference between natural bristles and synthetic bristles on particular types of finishing products (whether man-made or water-based)? Whether you're finishing a chair, a side table, or a picture frame, learn how to give your projects the great finale they deserve. x