Why are some people left-handed?

Why are there as many males as females?

Pretty much every species breaks down with an equal sex-ratio, with roughly the same number of males as females. But on the surface, it appears that most species wouldn't need many males to keep the population growing, with their energy-efficient, abundant sex cell production. So why is it equal? Scientists argue an equal ratio is the most evolutionarily stable. Learn about this quirk of biology here.

Less than 1% of people globally have schizophrenia, a syndrome strongly linked to genetics

Schizophrenia's causes remain largely unknown, though scientists suggest it's caused by multiple factors. Its symptoms include disruption of thought processes rather than the exhibiting of multiple personalities. This brief video provides an overview of the condition.

Why some people have allergies

Why do some people have allergies while others don’t? One theory suggests allergies are a relic of our evolutionary past. Our immune system, once primed to fight parasites, now mistakes harmless substances for threats.

Why cartoons only have four fingers

Ever notice cartoon characters only have four fingers? There’s a surprising reason why and it goes back to the first Mickey Mouse cartoons. From saving money to cultural taboos, here’s why animators draw hands this way.

About two-thirds of humans lose their ability to produce lactase after weaning

Lactase is an enzyme that digests lactose—a sugar in milk and dairy products. While genetics strongly determines lactase persistence, factors like famine, disease exposure, and gut bacteria also influence symptoms and evolution.

Left versus right brain strokes vary significantly in long-term effects

Due to the high complexity of the brain, the aftereffects of a stroke can have widely different manifestations, ranging from minor temporary impairments to rapid death. Whether a stroke results in paralysis, speech impairments, loss of bodily function, or death will depend on whether it occurs in the left or right hemispheres or the brain stem.

James Garfield, the first left-handed US president

Though he was assassinated only four months into his tenure, President James Garfield was a highly respected figure, a professor known for his mastery of several languages, success as a general in the Civil War, and accomplishments in Congress. He was also left-handed, the first southpaw to sit in the Oval Office. Learn more about Garfield's ambidexterity here.

Language is evolution's great mystery

What we call language is something more specific than communication. Language is about sharing what’s in our minds: stories, opinions, questions, the past or future, imagined times or places, ideas. So what does language mean for humanity, and how did we come to have it? Watch this brief video to discover more.

What percent Neanderthal are you?

Many of us carry around 2% Neanderthal DNA in our genes. Museum human evolution expert Prof. Chris Stringer discusses why and what it means.

Tinnitus estimates vary, but may occur in 10%-15% of the population

This video discusses the mechanisms underlying tinnitus and explores the knowns and unknowns about the condition. Tinnitus most commonly occurs among those with hearing loss, suggesting that cochlear damage may be a factor.

The fortunate factors that make life on Earth possible

The Earth is teeming with life while all the other exoplanets and planets aren't. A very specific set of aligned factors forms the habitability of our planet, and without just one of these fortunate factors, we might not be here. This piece lists...

Were humans the only hominin to walk upright?

When you imagine the line human evolution has taken, you might picture the March of Progress, an image of several chimp-like ancestors marching toward the implied final form: the upright bipedal Homo sapiens. Turns out this image, popularized in the...

Why do some people always get lost?

Using GPS, anthropological data, and VR, scientists have learned that one's sense of direction is largely influenced by upbringing. A person's wayfinding ability can be measured by how accurately they point toward an out-of-sight location, a challenge further complicated by imagining they're somewhere else and pointing toward a third location. Anxiety, safety concerns, and dislike of wandering can negatively impact one's sense of direction, which can improve with practice.

A small fraction of creators make money on YouTube

YouTube has become one of the world's leading entertainment platforms almost entirely on the back of users who upload their own content. An estimated 3.7 million new videos get uploaded to YouTube each day, but only a small, very popular fraction are able to make money from their content.

The rarest blood type in the world

Rh-null, also known as “golden blood,” is a blood type so rare, fewer than 50 people are known to have it. It lacks all 61 Rh antigens, making it a universal donor for rare Rh cases, but a nightmare in emergencies, since only Rh-null can be given back.

Here’s why genetically identical sisters can have different colored eyes

The sequence of DNA that we inherit from our parents encodes directions for making our cells and giving us specific traits. Identical twins have the same DNA sequence, so how can one twin end up with a genetic disorder while the other twin does not? Robin Ball explains how the secret lies in X chromosome inactivation.

The colonial origins of Haiti/Dominican Republic divide

This 16-minute video explores the colonial origins of the modern-day split between Haiti and the Dominican Republic. Haiti previously was the French-Caribbean colony of Saint-Domingue, which was torn off the Spanish colony of Santo Domingo in 1697....

Roughly 1 in every 4,300 individuals in the US has mitochondrial disease

Roughly 1,000 to 4,000 kids are born with these conditions each year in the US though many of the diseases are fatal. Mitochondrial disorders often affect the organs that require the most energy, including the heart, brain, and muscles.

It's unlikely that we will ever live in a completely cashless world

Although countries like China are moving toward a cashless system, many other countries still rely on physical money for everyday transactions. This article dives into the future of currency and includes a map of the percentage of adults who do cashless transactions around the world.

About 95% of people are naturally immune to leprosy

Contracting it requires prolonged contact with someone with the disease, meaning you'd have to be living with them. You cannot get leprosy from hugging someone with leprosy or sitting next to them. It's not known to pass from mother to fetus. The risk of transmission from armadillos is also likely low, but people should avoid touching wild animals for general safety.

The reptilian conspiracy theory posits that humanoid lizards run the world

Conspiracy theorists believe shape-shifting reptiles have taken human form and gained authority to manipulate human populations. From US politicians to British royalty, could lizard people be holding positions of power?

Europeans, on average, have double the amount of vacation time Americans have

Europeans average nearly double the amount of time off as their American counterparts. Why is that? It's due to a long history of European labor’s push for time off, including both left- and right-wing political groups that argued vacation could benefit their causes.

Roughly half of the world's nations are (relatively young) electoral democracies

Classifying countries by governance type involves leaning into technical systems like the Regimes of the World classification. In this data dive, see a map of the world's oldest and youngest electoral democracies, as well as liberal democracies (which are measured by the protection of minorities and checks on executive power from the legislature).

What happens to golf balls after they're used?

With over 1 billion golf balls produced annually, an estimated 300 million to 1.5 billion are lost worldwide. On average, thousands of balls are left behind on each course, often ending up in ponds, forests, and beaches. While many golf courses recover and reuse some of these balls, studies suggest countless remain unretrieved.

Why do people join cults?

This quick TED video dives into some of the social psychology behind membership in radical cults, including famous ones where members took their own lives.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

US consumers collectively owe more than $1T to credit card companies—almost as much as they owe in auto loans.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Children are now three times more likely to say they want to be a YouTuber when they grow up than an astronaut, with some even attending 'YouTube camps' that teach kids how to create content for the platform.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

The Brothers Grimm were lawyers before they were storytellers, but became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.