Episode 252. Topic: How we see. Theme: Eyes. How do eyes work? What are the steps required for light to turn into an image in our brains? 

Episode 251. Topic: The evolution of eyes. Theme: Eyes. Eyes seem so complex so how could evolution ever create them? Let us investigate how eyes evolved and how diverse they are among animals today. 

Episode 250. Topic: Fake teeth then and now. Theme: Teeth. When were dentures developed? Did George Washington really have wooden teeth? And why are celebrity teeth today so impossibly straight and white? 

Episode 249. Topic: The history of tooth decay. Theme: Teeth. Why do non-human animals so rarely get cavities? When and why did tooth decay become more common in humans? 

Episode 248. Topic: Cavities. Theme: Teeth. What are cavities and what causes them? How common are they and what increases risk for developing them? 

Episode 247. Topic: Baby teeth. Theme: Teeth. Why do humans have two sets of teeth? Do all mammals have two sets of teeth? How do different cultures deal with the loss of baby teeth? 

Episode 246. Topic: Evolution and wisdom teeth. Theme: Teeth. Why do human mouths rarely fit wisdom teeth? Why can other animals fit all their teeth? And why do some people not have wisdom teeth? 

Episode 245. Topic: Our Neanderthal ancestors. Theme: Ancestry. Learn about how Neanderthals interbred with modern humans  tens of thousands of years ago and how their DNA remains inside our genomes. 

Episode 244. Topic: How related are strangers? Theme: Ancestry. If you took two people at random, how far back would you expect to find their shared relative? And why do we befriend people slightly more related to ourselves? 

Episode 243. Topic: Y Adam and Mitochondrial Eve. Theme: Ancestry. All humans share at least one male and female ancestor. By analyzing mitochondrial and Y chromosome DNA, we can determine how far back these individuals lived. They were certainly not alive at the same time!