In almost every animal species on Earth, equal numbers of males and females are conceived. Why is that? Especially in populations like lions or elephant seals, where most males don’t get to mate? That’s survival of the laziest, not...

Since the start of the coronavirus COVID-19 pandemic, the term “herd immunity” has been all over the news. But what does it really mean? One thing most people don’t realize about vaccines is that they aren’t just to protect the person...

We’re living longer. Dying less. Human life expectancy has doubled in just a couple centuries. Machines and meals and medicines keeping us alive long past the age where we can make babies. Does this mean our species is no longer under...

Solving food shortages caused by droughts is a big challenge that may benefit from a tiny ally. Turns out that the microbes living in the soil around plants can give them a boost when water's scarce, which means more food for us, which...

The human population of the world will soon peak – and then decrease – thanks to a combination of two quickly changing economic and educational trends.

There are many names for them, but here at SciShow we lovingly refer to them as 'Gingers'. In this episode, Hank explains what gene is responsible for the creation of redheads.

Lara Brenner talks about her research on how stressed cougars are and how the public views them. Then Jessi from Animal Wonders joins the show with Seraphina the red fox!

If, for some wild reason, we decided that breeding humongous spiders was a good idea, could we actually pull it off?

Got milk? Fact is, most people don't -- and shouldn't -- because for them, ice cream and milkshakes are basically toxic. So why can some people drink milk and survive? Turns out they're mutants! SciShow explains.

Hank brings us some late-breaking news from the genus Homo - a team of scientists has sequenced the genome of the Denisova hominin, the latest member to be added to the human family tree.

For one hundred days in 1994, the African country of Rwanda suffered a horrific campaign of mass murder. Neighbor turned against neighbor as violence engulfed the region, resulting in the deaths of over one-tenth of the country's...

For thousands of years, native Takhi horses roamed the steppes of Central Asia. But by the late 1960s, their extinction seemed inevitable. To prevent this, scientists and zoos started a breeding program and soon began releasing new...

In 2021, workers at a Sardinian aquarium were stunned by the birth of a smooth-hound shark. What was shocking was that, for the last decade, the shark's mother had been living only with other females. So, how was this birth possible? And...

Thomas Jefferson, founding father of the United States and primary author of the Declaration of Independence, was part of America's fight for freedom and equality. But in his personal life, he held over 600 people in slavery. Are his...

Mosquitoes are responsible for more human deaths every year than any other animal, but very few of the 3,500 mosquito species actually transmit deadly diseases to humans. Scientists have been conducting experiments using engineered...

We've been talking a lot about kings, and queens, and wars, and religious upheaval for most of this series, but let's take a moment to zoom out, and look at the ways that individuals' lives were changing in the time span we've covered so...

What is the derivative of a^x? Why is e^x its own derivative? This video shows how to think about the rule for differentiating exponential functions.

In which Hank and John Green teach you a Crash Course on the modern revolution, and the upside of the progress that humanity has made in the last 500 years or so. And while there are two sides to every history, and many of these changes...

What is the derivative of a^x? Why is e^x its own derivative? This video shows how to think about the rule for differentiating exponential functions.

How can a "thumbs up" sign help us remember five processes that impact evolution? The story of the Five Fingers of Evolution gives us a clever way of understanding change in gene pools over time.

Paul Andersen explains how to use mathematics appropriately. He begins by emphasizing the important role that mathematics plays in the life sciences today and in that the future. He describes important mathematical equations in each of...

What will become of humanity after spend a few hundred years on Mars? What will happen after a few thousand? Evolution has, and still is, shaping humanity in rather drastic ways. How long will humans stop being human and become Martian?

Today, about one-tenth of the world's population are southpaws. Why are such a small proportion of people left-handed -- and why does the trait exist in the first place? Daniel M. Abrams investigates how the uneven ratio of lefties and...

Hank brings us some late-breaking news from the genus Homo - a team of scientists has sequenced the genome of the Denisova hominin, the latest member to be added to the human family tree.