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Across laboratories worldwide, researchers are currently focused on developing authentic human-animal hybrids.
It may sound like a concept straight out of science fiction, but merging human and animal DNA isn’t a distant dream—it’s a reality that has already occurred multiple times, bringing with it ethical dilemmas we never anticipated.
According to researchers, the human-animal hybrids they’ve created will serve a beneficial purpose. These groundbreaking creations will enable us to conduct medical trials on entities they view as less than human.
However, we are still undecided on where the boundary between human and animal lies. It remains an open debate: Are these beings mutated animals, or are they the dawn of something closer to humanity?
10. The Rabbit-Man Grown in a Petri Dish
The first successful human-animal hybrid was created in a laboratory dish in Shanghai back in 2003. A group of scientists merged human cells with rabbit eggs, producing embryos that were part rabbit and part human.
They were not the first to attempt this. Scientists in the United States had been in competition, trying to create their own animal-human hybrids. However, none of their efforts succeeded. The Shanghai team was the first to achieve it.
What set this experiment apart from others was that the vast majority of the DNA in the growing creatures inside the rabbit eggs was human. Only a small portion of the DNA came from rabbits, meaning the result would have been more human than animal.
The world never got the chance to witness what they created. The creature was only allowed to develop for a few days before it was destroyed and its stem cells harvested.
9. The Human-Chimpanzee Hybrid
According to two Chinese scientists, China nearly achieved the first human-animal hybrid several decades earlier. In 1967, they came very close to creating a human-chimpanzee hybrid—and if the experiment hadn't been halted prematurely, success was within reach.
Two researchers from Shenyang claim that they were involved in an experiment where they successfully impregnated a female chimpanzee with human sperm. Their aim was to create a new, more advanced chimpanzee with a larger brain and a wider mouth. Ultimately, they envisioned a creature capable of speech.
The hybrid, dubbed the 'humanzee', wasn’t intended for kind treatment. Their plan was to use the creature as a laborer, making it drive carts and herd sheep. They even envisioned sending it on space missions.
The project collapsed during the Cultural Revolution. Revolutionary zealots destroyed their lab and all of their work, and the chimpanzee died before she could bring the pregnancy to term. The researchers assert she was already three months pregnant when it happened.
In 1981, the researchers stated their intention to attempt the experiment again. However, nothing came of it, likely due to the growing concerns about human ethics.
8. Pigs With Half-Human Blood
At the Mayo Clinic in Minnesota, scientists injected human stem cells into pig fetuses, successfully creating the first pig with human blood flowing through its veins.
The goal of their experiment was to observe how human and pig cells would interact when fused. They found that some cells remained separate, with purely human and purely pig cells located in different parts of the animal's body, while others merged to create unique DNA that had never been seen before.
The result was a creature that appeared like an ordinary pig on the outside. But inside, it had a mix of human and pig cells throughout its body. Most notably, the animal had a type of blood that the world had never encountered, formed by the fusion of human and pig DNA.
7. Goats and Cows That Produce Human Milk
In 2009, scientists from Russia and Belarus genetically engineered goats to produce human breast milk.
Although they couldn’t make the milk entirely human, they successfully infused it with human cells, resulting in milk that contained 60 percent of the lysozyme and lactoferrin found in human milk. They weren’t alone in this endeavor. Soon after, a Chinese team developed a herd of 300 cows that also produced human milk.
The goal was to get human breast milk onto store shelves. The scientists envisioned a way to mass-produce human milk, certain that consumers would rush to buy it for their families. The Russian team even promoted the idea that their human milk could be used to make delicious cheese.
The Chinese team initially planned to have their product available by 2014, but a tepid response delayed their launch. Now, they’re working on convincing the public that human milk produced by a genetically modified cow is a product worth purchasing. Once they succeed, you may find it on store shelves near you.
6. Pigs and Sheep with Human Organs
One of the main objectives behind creating human-animal hybrids is to establish a farm of animals that can be harvested for human organs like hearts and lungs.
In the US, this is a prominent field of research, though it remains somewhat controversial worldwide. Hiromitsu Nakauchi, one of the top scientists working on this project, had to leave Japan due to the illegality of his work there. However, in the US, his research is supported, with the US Army awarding him a $1.4 million grant.
In 2017, they successfully created 186 embryos for a pig-human hybrid, and are now working on a sheep-human hybrid. Each hybrid is only allowed to develop for 28 days before it is destroyed.
Their most human-like creature so far was still largely an animal. It contained only 0.01 percent human DNA. Nakauchi acknowledged that this amount isn’t enough to create a creature with human organs, but he believes they are making significant progress, insisting that they are getting closer every day.
5. Mice with Human Livers
In 2010, researchers at the Salk Institute successfully created a mouse with a nearly fully human liver. They then injected the animal with various diseases.
The goal of the research was to conduct experiments on diseases such as malaria and hepatitis B and C, which only affect humans and chimpanzees. In the past, such studies were limited to chimpanzees. The researchers hoped to bypass ethical concerns by using mice instead.
It remains a point of debate which method is more humane. After creating the genetically modified mice, the researchers intentionally infected them with hepatitis B and C. They then attempted to treat the diseases they had introduced into the animals' bodies.
Scientists believe that this could pave the way for major medical breakthroughs. However, it remains to be seen whether people will embrace this approach more than testing on chimpanzees.
4. Mice with Human Anal Sphincters
In perhaps the oddest experiment involving human-animal hybrids, researchers in 2011 successfully grafted human anal sphincters onto mice.
The scientists engineered the anal sphincters, complete with human nerves and muscles. They were thrilled to find that the sphincters developed their own blood supply and integrated with the surrounding tissue when transplanted into the mice. The mice were even able to contract and relax them as naturally as human sphincters.
The goal was to conduct preliminary trials for a procedure intended for humans. Scientists are working to create personalized replacement anal sphincters for patients, made from their own skin and nerve cells. While it may sound unpleasant, this could potentially save lives.
3. Monkeys With Human Neural Cells
The researchers who implanted human brain cells into mice defended their approach by clarifying that they had avoided using monkeys. They acknowledged the ethical concerns, stating that enhancing an animal so closely related to humans was a line they weren’t ready to cross.
However, Yale University took a different stance.
In 2007, Yale researchers introduced human neural stem cells into five monkeys to observe the effects on Parkinson’s disease. The results were medically encouraging.
All of the monkeys, who were suffering from the disease, displayed significant improvements—they could walk, eat, and move more easily. Tremors were greatly reduced, and there were no adverse side effects such as tumors or toxicity.
From a philosophical standpoint, the experiment raised some unsettling questions. The human neural cells not only survived but also migrated within the monkeys’ brains, altering how their brains functioned.
In this study, a limited number of cells were used, so there wasn’t a significant change in the monkeys' behavior. However, this leads to a crucial question: how many human neural cells must be integrated into a monkey’s brain before it becomes something more than just an animal?
2. Mice With Half-Human Brains
While giving a pig a human lung is one thing, a 2014 experiment crossed a boundary that hadn’t been explored before. In this study, researchers introduced millions of human brain cells into mice.
The scientists replaced nearly all of the cells in the mice’s brains with human cells, leaving just the original mouse neurons. The human cells quickly dominated the mouse brains, and within a year, the glial cells were entirely replaced by human brain cells. Each mouse had approximately 12 million human cells functioning in their hybrid brains.
The researchers conducted disturbing experiments on the mice. In the primary test, they played a sound before delivering an electric shock. They then observed how the mice reacted when hearing that sound again. Though cruel, the experiment demonstrated that the memories of these altered mice were four times more potent than those of regular mice.
1. The Mouse With An Ear On Its Back
The most famous human-animal hybrid wasn’t exactly one. However, had the experiment been completed, it would have been.
In 1997, a team of scientists from Harvard and MIT successfully bioengineered a mouse with a human ear on its back. They created a scaffold in the shape of a human ear, made from biodegradable materials. Over time, the scaffold was absorbed into the mouse’s body, resulting in a real biological ear of cartilage and flesh that could, in theory, be surgically removed and grafted onto a human.
The project aimed to assist plastic surgeons struggling with ear reconstruction. The idea was to grow a human ear on a mouse, then transplant it onto a person, providing a human with an ear made from animal cartilage and flesh.
Unfortunately, the project ran out of funding before it could progress to human trials. The lead researcher believes that, with “roughly another million dollars in funding,” he could still bring the project to fruition.
