Europeans' arrival to America brought disease to Indigenous populations

European diseases killed a massive share of the Native American population

After Western contact, epidemic diseases devastated Indigenous communities. By 1920, the Native American population of the US had fallen to roughly 270,000, compared with an estimated 1.2 to 18 million at the time of European arrival.

European colonization dramatically reshaped Native American life

As European settlers expanded across North America, Native Americans faced displacement, violence, and forced negotiations. Colonial powers used trade relationships, treaties, and military force to reshape Indigenous communities and claim their territories.

Measles reached global transmission during the 15th- and 16th-century Columbian exchange

Devastating diseases like smallpox, influenza, measles, and other viruses were largely introduced into the Western Hemisphere beginning with the 1492 arrival of Christopher Columbus and the ensuing age of exploration.

Recent research indicates leprosy was present in the Americas before European settlers

New research published in 2025 upended long-held notions that the disease was introduced to the Americas by European colonizers. Evidence of a lesser-known leprosy-causing bacterium was found in ancient human remains that date back 4,000 years.

The first Americans arrived between 14,000 and 40,000 years ago

Early peoples migrated to the Americas via the Bering Land Bridge or coastal routes, spreading across the continent as hunter-gatherers. Archaeological sites in present-day New Mexico containing stone tools and animal bones mark some of the earliest confirmed evidence of human life in North America.

The canal carried germs as well as goods

In 1832, North America’s first cholera epidemic spread inland by way of the Erie Canal, carried by immigrants arriving on ships. Fearful towns barred passengers from disembarking, yet cholera, smallpox, and other diseases still traveled the waterway.

In 2023, Native Americans had the lowest life expectancy at birth among all racial and ethnic groups

Native Americans and Alaska Natives face significant health disparities linked to chronic underinvestment in reservation health infrastructure, poverty, and multigenerational psychological harm—often called historical or inherited trauma.

The trans-Atlantic slave trade brought over 10 million enslaved people to the Americas

During the Atlantic slave trade (1526-1867), about 12.5 million Africans were forced onto ships; only 10.7 million survived to reach the Americas. Fewer than 400,000 arrived in what became the United States—the rest were taken to the Caribbean or Latin America.

The Trail of Tears killed thousands of Native Americans forced from their homelands

After the Indian Removal Act passed, the US Army marched the Cherokee and other nations hundreds of miles to the designated "Indian Territory" in present-day Oklahoma. Thousands died from starvation and disease along the way.

See a timeline of colonial settlement in North America

This interactive timeline uses archival maps, illustrations, and documents to trace early American history—from the failed 1590 Roanoke colony and Indigenous accounts of a devastating smallpox epidemic to the political tensions that culminated in the Revolutionary War.

Many early colonists came to America to escape religious persecution in Europe

Fleeing state-sponsored religious oppression in England and Europe, many early colonists sought freedom of conscience in the New World. Many—especially in New England—established their own religiously exclusive communities: They persecuted dissenters, expelled nonconformists, and enforced orthodoxy.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Native American tribes still are waiting for museums to return the remains of their ancestors

The remains of more than 100,000 Native Americans are held by prestigious US institutions, despite a 1990 law meant to return them to tribal nations. Here’s how their ancestors were stolen—and how tribes are working to get them back.

Even in recent history, adaptations to the environment drove human evolution

Through genetics, environmental pressures, and cultural influences, humans have evolved to tolerate lactose, develop varying skin pigmentation, and acquire genetic resistance to diseases like bubonic plague. The metabolic and digestive systems of Indigenous peoples have adapted to their diet, which is influenced by the availability of food and water.

The bubonic plague spread in three waves over 600 years

The Black Death refers to the first wave of the plague, which swept through Europe in the 14th century and killed 25 to 50 million people. Caused by the bacterium Yersinia pestis carried by fleas (often on rats), the human toll was roughly one-third of Europe's population at the time.

Invasive species may harm new ecosystems via the spread of disease

Besides damaging native species through direct interactions such as competition for resources and predation, invasive species may come from environments with greater biodiversity than the new environment. This makes them more likely to carry pathogens unfamiliar to native species, increasing the risk of biodiversity loss.

Neglected tropical diseases affect more people than the population of Europe

This group of conditions, which includes hookworm, sickens roughly one in seven people on the planet—a tally which dwarfs Europe's population of roughly 450 million. International cooperation and donations are helping to control some of these illnesses, which can be caused by parasites, viruses, and bacteria. They're all treatable or preventable, but primarily occur among poor, isolated communities that may not receive adequate care.

Diphtheria was once a leading childhood killer before antibiotics and vaccines

In 18th- and 19th-century outbreaks, some New England families lost as many as eight children to diphtheria, and fatality rates in hospitals often topped 60%. The invention of antitoxins, penicillin, and vaccines dramatically reduced deaths.

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.

40% of Americans have ancestors who immigrated via Ellis Island

For over 60 years, Ellis Island was the gateway to America, processing millions of immigrants seeking a new life. While many passed through with ease, others faced rigorous medical exams, legal scrutiny, and even deportation. Learn how this small island shaped generations of American families.

Early farming created population booms—and also major busts

Europe’s ancient embrace of farming took the continent on a demographic roller-coaster ride. Regional booms and busts in human numbers occurred between 8,000 and 4,000 years ago, a new study finds.

The American missionary and the uncontacted tribe

When a 26-year-old American missionary set out for a lush island in the Indian Ocean last year, it was with one objective in mind: to convert the uncontacted Sentinelese tribe, who had lived for centuries in isolation, free from modern technology, disease, and religion. John Chau's mission had ambitions for a great awakening, but what awaited instead was tragedy.

Squanto was a tragic character in the original Thanksgiving story

Tisquantum (also known as Squanto) played a crucial role in the survival of the Pilgrims. As an English speaker, Squanto assisted the Pilgrims in gathering food and communicating with other Native peoples. However, his story also involved being sold into slavery by an English sea captain and returning home to find his tribe decimated by disease during the Great Dying. Tisquantum met his end not long after that first Thanksgiving, with historians speculating he died either by disease or assassination.

Chimpanzees are dying from human colds

For some great apes, the threat of human-borne diseases outweighs poaching or habitat loss. This article details the danger of reverse zoonoses, which refers to diseases that spread from humans to animals.

Spanish colonists celebrated alongside the Seloy tribe in Florida in 1565

Long before the 1621 meal between the Pilgrims and the Wampanoag, Pedro Menéndez de Avilés and 800 Spanish settlers founded the city of St. Augustine in Spanish la Florida. They celebrated the founding with a Mass of Thanksgiving with the Indigenous Seloy tribe.

The Aztec capital fell after a brutal 75-day siege

The violent Spanish conquest ended with a 75-day siege of Tenochtitlan, where thousands died as Spanish forces and their Indigenous allies overwhelmed the city of 200,000. This animated explainer breaks down how those alliances enabled the empire’s collapse.

19th-century Americans discovered tipping in Europe

Tipping waiters was a custom in medieval Europe, where masters gave their serfs money for exceptional work. Wealthy Americans vacationing in Europe in the mid-1800s discovered the behavior and brought it back to the US.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

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

Cultural norms about how to handle the bodies of loved ones in communities in West Africa have hampered Ebola responses.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

11 people died from firework injuries in the US in 2024.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

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

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

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

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'