Explained (2018–2021)

1. S01E01The Racial Wealth GapMay 23, 2018 7.3Cory Booker and others discuss how slavery, housing discrimination and centuries of inequality have compounded to create a racial wealth gap
2. S01E02Designer DNAMay 23, 2018 7.8Scientific feat or terrifying social experiment? Specialists in the field discuss the high stakes and ethical controversies of gene editing.
3. S01E03MonogamyMay 23, 2018 7.3What do biology, human history and the promiscuity of bonobos reveal about monogamy? Experts and everyday couples weigh in on shifting cultu
4. S01E04K-PopMay 30, 2018 7.8Elaborate music videos, adoring fans, killer choreography. Learn about the global music phenomenon from South Korea that goes beyond "Gangna
5. S01E05CryptocurrencyJune 6, 2018 7.5Cryptocurrency has made people billionaires, but is digital cash the next revolution? Learn about this anonymous currency and how it's covet
6. S01E06Why Diets FailJune 13, 2018 7.4Atkins. Paleo. Keto. Do any work in the long term? Experts look at marketing, food environments and genes to explain why diets are often uns
7. S01E07The Stock MarketJune 20, 2018 6.8Does the stock market accurately reflect the status of the economy? Finance specialists discuss market history, valuations and CEO incentive
8. S01E08eSportsJune 27, 2018 6.8Is fake violence a sport? Fans, shoutcasters, and eSports icons break down today's video games and the explosive popularity of competitive g
9. S01E09Extraterrestrial LifeJuly 4, 2018 7.0Despite decades of searching, we have yet to discover extraterrestrial life. Scientists discuss the reasons, including: Are aliens just too
10. S01E10!July 11, 2018 6.0Do we overuse exclamation points!? Linguists and copy editors look at how the punctuation has adapted across history, literature and interne
11. S01E11CricketJuly 18, 2018 7.0Cricket experts look at how the confusing sport became so popular and discuss its evolution in becoming more accessible entertaining and pro
12. S01E12WeedJuly 25, 2018 7.5Marijuana experts discuss the rise of potent "sexually frustrated" cannabis plants, the quests for consistency in weed strains and the histo
13. S01E13TattooAugust 1, 2018 7.2They've been used to command respect, punish criminals and mark achievements. Tattooists speak about the origins of tattoo traditions and ri
14. S01E14AstrologyAugust 8, 2018 7.0Do zodiac signs prescribe your fate? Or do horoscopes' accuracy lie in the placebo effect? Take a look at the science, history and lure of a
15. S01E15Can We Live Forever ?August 15, 2018 7.5Can we uncover the secrets to extending the human lifespan? Experts discuss how developments in science -- even the French lilac -- hold som
16. S01E16The Female OrgasmAugust 22, 2018 7.0The female orgasm is more elusive when a man is involved. Discover the reasons why and how women are embracing hands on solutions.
17. S01E17Political CorrectnessAugust 29, 2018 7.5Political correctness can sometimes feel like a tug-of-war between inclusivity and free speech. Experts discuss the concepts behind the frau
18. S01E18Why Women Are Paid LessSeptember 5, 2018 6.7Hillary Clinton and Anne-Marie Slaughter discuss the cultural norms at the center of the worldwide gender pay gap, including the "motherhood
19. S01E19Season's bestThe World's Water CrisisSeptember 12, 2018 8.5The global water crisis is at an inflection point. How do we price our most valuable resource, while also ensuring access to it as a human r
20. S01E20MusicSeptember 19, 2018 7.2When does sound become music? Why are humans so uniquely able to master musicality? Researchers talk rhythm, octaves and the magic of song a

Season 1 ranked & reviewed

1. S02E01CultsSeptember 26, 2019 7.3How do cults lure people in and exert control? Learn a cult’s telltale signs, and how loneliness and life online makes indoctrination easier
2. S02E02BillionairesOctober 3, 2019 7.8There are more billionaires than ever. But how does this vast accumulation of wealth affect the world? Mark Cuban and Bernie Sanders offer i
3. S02E03Animal IntelligenceOctober 10, 2019 7.6What goes on inside an animal's mind? Figuring out how they think and feel might just be the key to understanding our own place in the world
4. S02E04AthleisureOctober 17, 2019 7.2It began with bloomers. Then came spandex. Now we sport leggings and other activewear everywhere. How did comfy, casual clothing go mainstre
5. S02E05CodingOctober 24, 2019 7.2Computer code now controls how we live. But how did these programming languages evolve? And how can they be used to build a new and better w
6. S02E06PiratesOctober 31, 2019 7.3In pop culture, pirates are often depicted as booty-looting rogues, but their history is far more complicated. See how they became enemies o
7. S02E07Season's bestThe Next PandemicNovember 7, 2019 8.2If you're not worried about a looming global pandemic, you probably should be. Are we prepared for an outbreak? Bill Gates and other experts
8. S02E08The Future of MeatNovember 14, 2019 8.2The planet's current rate of meat consumption is unprecedented -- and becoming unsustainable. In the future, will meat alternatives be the a
9. S02E09BeautyNovember 21, 2019 7.0Beauty may be in the eye of the beholder, but what exactly makes things such as art and architecture aesthetically pleasing, and why do we l
10. S02E10DiamondsNovember 28, 2019 7.0A diamond is forever. But why is that? Dig into how these mined pieces of carbon became both a status symbol and a sparkly sign of everlasti

Season 2 ranked & reviewed

1. S03E01Season's bestSugarJuly 16, 2021 8.0Once crucial for survival, sugar now poses a health risk. Is there a way to satisfy our primeval craving for sweetness in a healthy, balance
2. S03E02RoyaltyJuly 23, 2021 7.3How do monarchies survive when they no longer wield power? By presenting a royal fairy tale that may not reflect the reality of the past — o
3. S03E03FlagsJuly 30, 2021 7.5A flag can unite, divide and terrorize. Explore how a piece of cloth transformed into a powerful symbol of both love and hate, freedom and o
4. S03E04DogsAugust 6, 2021 8.0Who's a good dog? They all are! From puppy-dog eyes to feats of heroism, see how canines evolved into humankind's best friends and sources o
5. S03E05The End of OilAugust 13, 2021 6.8Oil led to huge advancements - and vast inequities. As the planet warms, why is it so hard to turn away from fossil fuels, and can it be don
6. S03E06ChessAugust 20, 2021 7.0For centuries, chess has captured hearts and minds — and pawns — and it's more popular than ever. What makes this ever-changing board game s
7. S03E07Your SkinAugust 27, 2021 7.0Don’t panic, but our skin plays host to trillions of bacteria, fungi, mites and other microscopic guests. Go beyond skin-deep with our large
8. S03E08ApologiesSeptember 3, 2021 6.5Apologizing is tough, and in this era of public mea culpas, forgiveness isn't guaranteed. What makes for a good apology, and why does it hol
9. S03E09HurricanesSeptember 10, 2021 7.0As the planet warms, hurricanes could become even more dangerous and destructive.
10. S03E10Plastic SurgerySeptember 17, 2021 7.5The Instagram face. A shapely posterior. Cosmetic surgery can make the latest beauty trends a reality. Explore its origins and effects, insi
11. S03E11Dance CrazesSeptember 24, 2021 7.0From the waltz to voguing, dance crazes have connected people throughout history. But when a dance catches on, who gets the credit — and com
12. S03E12TimeOctober 1, 2021 7.5Time flies… sometimes. Its passage can seem to speed up and slow down. Why do we experience time the way we do, and how do we take back some
13. S03E13Country MusicOctober 8, 2021 7.0Dirt roads. Pickup trucks. Hip-hop? As the borders around country music shift, who decides what defines the popular genre, and who gets to b
14. S03E14Fairy TalesOctober 15, 2021 8.0Fairy tales have survived thousands of years for a reason. Explore their far-flung history and how the stories speak to fundamental human co

Season 3 ranked & reviewed