Isn’t it odd that, when something’s funny, you might show your teeth, change your breathing, become weak and achy in some places, and maybe even cry? In other words, why do we do this bizarre thing that is laughter? Since there’s no archaeological record of laughter, it’s impossible to say exactly how and why it evolved, but scientists have some theories. Sasha Winkler digs into the reflex. This TED-Ed lesson was directed by Hanna Rybak, narrated by Susan Zimmerman and the music is by Jarrett Farkas.

Catching cancer at its earliest stages saves lives. But in a body made up of trillions of cells, how do you spot a small group of rogue cancer cells? Biomedical researcher Hani Goodarzi discusses his lab's discovery of a new class of RNAs that, when paired with emerging AI tools, could help detect cancer earlier, more precisely and even through routine blood work — potentially transforming our understanding of the disease.

Since humanity’s earliest days, we’ve been plagued by countless disease-causing pathogens. Invisible and persistent, these microorganisms and the illnesses they incur have killed more humans than anything else in history. But which disease has been the deadliest? Dan Kwartler digs into how human progress and innovation throughout history exposed us to surprising new maladies. This TED-Ed lesson was directed by BASA, narrated by Addison Anderson and the music was created by Igor Figueroa, Estudio Mono.

Having your period is exhausting — and for many people across the world, menstruation is even more challenging because of stigmas and difficulty getting basic hygiene supplies, says social activist Ananya Grover. In this uplifting, actionable talk, she shares how "Pravahkriti," her campaign to spread period positivity, creatively engages with everyone to promote menstrual health, raise awareness and break taboos around periods. After the talk, Shoshana has a sweeping conversation with OB/GYN, activist and fellow TED Audio Collective host Dr. Jen Gunter on breaking down period myths and misconceptions.

Biologist Kathleen McAuliffe dives into emerging research that explores how certain gut bacteria can influence major parts of who you are, from your personality to life-changing neurological disorders. Learn more about how this ongoing clinical medical and pharmaceutical research might change how we treat disease — and discover the impact of your internal microbial makeup on your mood, weight and more.

Have we misunderstood pain? This week we’re revisiting a talk by researcher and physician Amy Baxter as she unravels the symphony of connections that send pain from your body to your brain, explaining practical neuroscience hacks to quickly block those signals. Her groundbreaking research offers alternatives for immediate pain relief -- without the need for addictive opioids. (Followed by a Q&A with TED current affairs curator Whitney Pennington Rodgers)

Have we lost the practical wisdom of what happens as people die? With lessons from a career witnessing thousands of people's final breaths, palliative care expert Kathryn Mannix urges us to demystify the experience of death, sharing how a better understanding of what actually happens can reduce fear in the final days, for you and your loved ones. After the talk, Shoshana shares how one patient changed her life forever and led her to found endwellproject.org, a platform dedicated to making end-of-life PART of life.

A Chinese saying goes, "There's no pleasure in eating without meat." And the data backs that up: every year, China consumes 26 percent of the world's meat and 45 percent of its seafood — numbers that could grow alongside rising incomes. Impact investor Tao Zhang shows why getting Chinese consumers to switch to plant-based alternatives is vital to tackling climate change and explores how it's also a massive business opportunity to bring tasty, affordable new proteins to market.

How does getting an abortion — or not — influence a woman's life? Demographer Diana Greene Foster puts forward the results of The Turnaway Study, her landmark work following nearly 1,000 women through abortion or childbirth, presenting definitive data on the long-term physical, mental and economic impacts of the right to choose on pregnant people and their families. "Access to abortion is about control over one's body, life and destiny," says Foster.

Legendary actor and mental health advocate Glenn Close is on a quest to change how we think about mental health, starting with her decision to speak out about her own family's struggles — a brave choice considering the stigma that pervades the topic. In a sweeping conversation with TEDWomen curator Pat Mitchell, Close shares the inspiration behind the advocacy group she founded to combat the crisis, underscoring the transformative power of community and the critical need for comprehensive mental health care systems.