Cross-species transplantation has been attempted in medicine for more than 300 years

See different pig-to-human xenotransplantation possibilities

Xenotransplantation can include the insertion of any organ, tissue, cells or fluids from any nonhuman animal into a human. This US Food and Drug Administration graphic about pig-to-human applications shows different possibilities, including the exploration of using pig pancreatic cells for treating diabetes.

Pig-to-human transplants have raised concerns about pig living conditions

Pigs are the current first choice for xenotransplantation procedures, yet such work gives some researchers and animal welfare advocates pause. Concerns include that pigs would have a poor quality of life since the animals must live in a strictly-controlled, hyper-clean environment to avoid risky pathogens.

Xenotransplants are an experimental last resort for the terminally ill

David Bennett Sr., the world’s first genetically modified pig heart transplant recipient, explained his reasoning to his University of Maryland Medical Center care team in 2022 regarding why he accepted a pig organ: He was dying and ineligible for a human heart transplant so this was a last-ditch effort, he said. He died two months after receiving the heart.

When was the first blood transfusion?

In the 1600s, an English doctor transferred the blood from one dog to another via quills. The procedure ended when one of the dogs died. This article details the early days of blood transfusions, which turned toward humans shortly after the 1666 dog experiment and involved putting the blood of a sheep into a human recipient (who reportedly survived the encounter).

Global xenotransplantation market may already be valued at more than $13B

With more than 100,000 people on the waiting list for organs at any given time in the United States, there's a known demand for organ transplants. Some estimates put the value of the global xenotransplantation market above $13B in recent years—and project the market to continue growing.

The first successful organ transplant was performed in 1954

The successful kidney transplant procedure, at what's now-called Brigham and and Women's Hospital, ushered in a new medical era and gave hope to patients with organ failure. The recipient, 23-year-old Richard Herrick, lived eight more years after receiving the donated organ from his living twin brother, Ronald.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

How fecal transplants work

1,700 years ago, Chinese alchemist Ge Hong was renowned for his soup that could cure diarrhea-stricken patients. It had a surprising secret ingredient: feces. While it might seem unwise to consume feces, exciting new research suggests that taking...

Six of history's most unethical human experiments, from deliberate flu exposure to withholding syphilis treatment

Some of the progress made in mental health treatment, vaccines, blood transfusions, and more came about before the advent of consent and ethics committees, resulting in serious physical and psychological harm that participants in studies were not even anticipating.

Biotech is trying to boost drug production efficiency—using chicken eggs

A company called Neion Bio is genetically engineering birds in a bid to produce medical compounds, a herculean task that scientists have struggled with for decades. The US FDA has approved only one chicken-derived drug in the past—an expensive treatment for a rare liver disorder. (Some users may encounter a paywall.)

Peptide research dates back to the late 1800s

Peptide science dates back to the late 1800s with some early peptide synthesis work, but peptides took off in the medical sphere after surgeon Frederick Banting and his colleague's isolation of insulin from dog pancreases in 1921.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Alpha-gal allergy is a problem for red meat lovers, and that same sugar is an issue for xenotransplants, too

In recent years, researchers have discovered ticks can induce spontaneous meat allergies in people they bite, a particularly problematic condition for previous meat lovers. This 18-minute podcast from RadioLab breaks down the cause.

The animals that paved the way for space travel

The history of animals in space exploration is often overlooked. Before humans first made their way to space in 1961, fruit flies, primates, and canines preceded us. Watch this video for a further appreciation of the contributions and sacrifices made by animals for scientific progress.

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

Cane toads are an example of an intentional species introduction turned invasive

In 1935, Australian scientists imported several hundred cane toads to hunt and eat beetles that were damaging sugar cane fields. However, the toads could not reach the bugs at the top of the plant or the grubs in the soil. Instead, they negatively affected native species populations as their numbers grew to over 2 billion.

The peer support movement may date back to 18th century France

At the Bicêtre Hospital, an asylum near Paris, Jean-Baptiste Pussin (who had previously been a patient but later led the hospital administration) tried to hire as many staff as possible from among recovered patients. Chief physician Philippe Pinel found these individuals to be kinder than other staff and "averse from active cruelty" which was common at the time. This approach allowed the facility to move away from shackling patients and other violent methods.

The history of ectogenesis and artificial wombs

While the science of artificial wombs is new, the idea goes back to a 1923 Heretics Society of the University of Cambridge lecture where an English biologist was one of the first people to propose an egg could be fertilized outside the womb. This...

Australia legalized 3-parent IVF in 2022

It was the second country, after the UK, to legalize the procedure, which is still prohibited in the US. There are more than 300 rare mitochondrial diseases that can be passed from a mother to her offspring.

What are zoonotic diseases?

Interspecies interactions are a breeding ground for disease transmission. This basic background information on zoonotic disease from the Centers for Disease Control and Prevention (CDC) chronicles the different ways humans can get sick, identifies what groups are particularly vulnerable, and offers links to other resources.

Prosthetics and orthotics have been 3D printed to improve the lives of animals

Shells for hermit crabs, wheelchairs for guinea pigs and dogs, and horseshoes for improved running performance have been created using 3D printers. Other artificial body parts made using this technology include a jaw for a loggerhead turtle, a beak for a toucan, and a tail for an American alligator.

Charles Darwin studied goose bumps by scaring zoo animals in London with a stuffed snake

Read the famous naturalist’s work from the late 1800s, detailing how he sought to draw comparisons between how animals and humans respond to fear. As part of that work, he exposed monkeys and a peccary to a stuffed snake and noted the animals’ hair-raising fear response.

Early 20th-century ID cards protected trans people in Germany using hormone therapy

A small number of passes were granted by the German police—with clinician support—between 1909 and 1933 that nominally allowed them to dress in ways that matched their gender identity, use experimental hormone therapies, and even receive early sex reassignment surgeries. At the time, individuals could be charged with "public nuisance" without the pass.

The US military, concerned about potential deployments worldwide, has long funded experimental hantavirus vaccines and therapies.

Collaborations between the military, biotech, and academic researchers led to an experimental antibody treatment for the Andes hantavirus strain—the one that more readily passes between humans. As of spring 2026, it had only been tested in animals. The US Army has also tested a potential hantavirus vaccine in people. It published early findings in 2023 that seemed promising, eliciting some immune system response. (Some users may encounter a paywall.)

Humans are more genetically similar to cats than to dogs

While humans are not closely related to either cats or dogs from an evolutionary standpoint, scientists find that human and cat chromosomes are organized more similarly to each other than human and dog chromosomes, making cats a better model for studying human diseases.

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

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

Evidence of cancer has been found in a 1.7-million-year-old fossil

Cancer has existed as long as humans have, with some of the earliest evidence found among fossilized bone tumors, human mummies in ancient Egypt, and ancient manuscripts. The oldest example was uncovered in a toe—millions of years old—from an ancestor of modern-day humans.

Limb regeneration research may lead to treatments for arthritis

For scientists pursuing the cure for arthritis, the holy grail of discoveries lies in how to regrow healthy cartilage inside human joints. While this feat has so far resisted our best scientific attempts, there are plenty of other human tissues—such as the liver and fingertips—that will successfully regenerate.

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

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

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

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

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.

Animal phobias are likely the most common type of phobias, followed by an extreme fear of heights.

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.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

American short story writer Flannery O'Connor raised 40 peacocks, which became potent symbols for her fiction's elegant violence

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

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

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

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.