Did humans evolve from monkeys or from fish? In this enlightening talk, ichthyologist and TED Fellow Prosanta Chakrabarty dispels some hardwired myths about evolution, encouraging us to remember that we're a small part of a complex, four-billion-year process -- and not the end of the line. "We're not the goal of evolution," Chakrabarty says. "Think of us all as young leaves on this ancient and gigantic tree of life -- connected by invisible branches not just to each other, but to our extinct relatives and our evolutionary ancestors."

Tobacco causes more than seven million deaths every year -- and many of us are far more complicit in the problem than we realize. In a bold talk, oncologist Dr. Bronwyn King tells the story of how she uncovered the deep ties between the tobacco industry and the entire global finance sector, which invests our money in cigarette companies through big banks, insurers and pension funds. Learn how Dr. King has ignited a worldwide movement to create tobacco-free investments and how each of us can play a role in ending this epidemic.

"Building a 30-foot-high concrete structure from sea to shining sea is the most expensive and least effective way to do border security," says Congressman Will Hurd, a Republican from Texas whose district encompasses two times zones and shares an 820-mile border with Mexico. Speaking from Washington, DC in a video interview with former state attorney general Anne Milgram, Hurd discusses the US government's border policy and its controversial detention and child separation practices -- and lays out steps toward a better future at the border. (Recorded at the TED World Theater in New York on September 10, 2019)

Computational geneticist Yaniv Erlich helped build the world's largest family tree -- comprising 13 million people and going back more than 500 years. He shares fascinating patterns that emerged from the work -- about our love lives, our health, even decades-old criminal cases -- and shows how crowdsourced genealogy databases can shed light not only on the past but also on the future.

As a sex educator, Emily Nagoski is often asked: How do couples sustain a strong sexual connection over the long term? In this funny, insightful talk, she shares her answer -- drawing on (somewhat surprising) research to reveal why some couples stop having sex while others keep up a connection for a lifetime.

It's time for planetary-scale interventions to combat climate change -- and environmentalist Tim Flannery thinks seaweed can help. In a bold talk, he shares the epic carbon-capturing potential of seaweed, explaining how oceangoing seaweed farms created on a massive scale could trap all the carbon we emit into the atmosphere. Learn more about this potentially planet-saving solution -- and the work that's still needed to get there.

"Girls' education is the closest thing we have to a silver bullet to help solve some of the world's most difficult problems," says social entrepreneur Safeena Husain. In a visionary talk, she shares her plan to enroll a staggering 1.6 million girls in school over the next five years -- combining advanced analytics with door-to-door community engagement to create new educational pathways for girls in India. (This ambitious plan is part of the Audacious Project, TED's initiative to inspire and fund global change.)

We need a global weather service for water, says entrepreneur and TED Fellow Sonaar Luthra. In a talk about environmental accountability, Luthra shows how we could forecast water shortages and risks with a global data collection effort -- just like we monitor the movement of storms -- and better listen to what the earth is telling us.

"Doctor, is this really necessary?" Backed by startling statistics about overtreatment, neurosurgeon Christer Mjåset explains the power of this and other simple questions in the context of medical treatment and surgery -- and shares how patients can better work with doctors to get the care they need.

In a moving talk, journalist Johann Hari shares fresh insights on the causes of depression and anxiety from experts around the world -- as well as some exciting emerging solutions. "If you're depressed or anxious, you're not weak and you're not crazy -- you're a human being with unmet needs," Hari says.