Zhen Liu et al. in Nature
Zhen Liu et al. in Nature

Scientists Genetically Engineer Autistic Monkeys

Zhen Liu et al. in Nature
Zhen Liu et al. in Nature

Scientists in China have genetically altered monkeys to have a human gene associated with autism spectrum disorders. As a result, the monkeys show a range of symptoms associated with autism. Their findings were published today in the journal Nature.

Mutations of methyl-CpG binding protein 2 (MECP2) are found in 90 percent of patients with Rett syndrome, a severe developmental disorder affecting mostly girls that is classified as an autism spectrum disorder. MECP2 duplication syndrome, in which a person has multiple copies of the gene, also shares core symptoms with autism spectrum disorders. It mostly affects boys. The researchers inserted the MECP2 gene into oocytes, or egg cells, of Macaca fascicularis (known variously as the crab-eating macaque or cynomolgus monkey). After fertilization, 53 embryos were then transferred into 18 surrogate monkeys. Half became pregnant, and eight offspring were born. 

For the first year the monkeys were developmentally normal, but then issues began to appear. By about 18 months, "the first cohort of transgenic monkeys showed very similar behaviors related to human autism patients, including repetitive behaviors, increased anxiety, and most importantly, defects in social interactions," study co-author Zilong Qiu said in a press-only teleconference on January 21. The monkeys paced in circles around their cages and made a lot of anxious sounds, including grunts and screams. 

The researchers then used an "accelerated reproduction method" to produce a second generation of transgenic monkeys, which also showed defects in social interactions.

This genetic inheritance makes these transgenic monkeys "a very unique model for studying human autism," Qiu said.

Scientists generally use mice to study autism, but there are problems with that approach. For one thing, mice lack an area of the brain known as the prefrontal cortex, which is where some psychiatric disorders appear to be centered, MIT Technology Review notes.

"Mouse models have many advantages, such as low cost, the ability to generate large sample sizes and to carry out extensive pilot work quickly," Melissa Bauman, a researcher at the University of California who specializes in animal models of autism, said in a press statement to Nature. "However, given that Autism Spectrum Disorder (ASD) is [a] uniquely human disorder characterized by deficits in complex behaviors, there are limitations in relying solely on mouse models."

Another researcher cautioned that autism is an incredibly complex disease without a single underlying biological cause. "Some cases of autism do derive from relatively simple genetic events. Mutations in MECP2 and the duplication of MECP2 are only one of these myriad causes," said University of Mississippi Medical Center researcher Eric Vallender in another press statement. Vallender, who studies the neurogenetics of nonhuman primates (NHP), also noted that "repetitive motor behaviors and anxiety-like behaviors can be caused by many things, and 'decreased social interaction' is always tricky to both observe and quantify and to interpret.

"That said," he added, "they have created an excellent model of MECP2 duplication syndrome. This is not trivial and can be a major step forward for understanding neurodevelopmental disorders."

The researchers are currently conducting brain imaging studies of the MECP2 monkeys to try to identify the deficiency in the brain circuits that is responsible for autism-like behavior. Once they identify this brain circuit, they'll attempt to treat the monkeys using various methods, including more genetic modification: "We will use therapeutics, such as gene-editing tools like CRISPR-Cas9 … to explore the potential gene therapy," Qiu said. 

Meanwhile, the creation of transgenic NHPs raises ethical questions, as University of Toronto bioethicist Kerry Bowman told Gizmodo: “Transgenic NHP will potentially exhibit traits that are the most human-like; in turn this puts them at greater risk of research exploitation.”

The Real Bay of Pigs: Big Major Cay in the Bahamas

When most people visit the Bahamas, they’re thinking about a vacation filled with sun, sand, and swimming—not swine. But you can get all four of those things if you visit Big Major Cay.

Big Major Cay, also now known as “Pig Island” for obvious reasons, is part of the Exuma Cays in the Bahamas. Exuma includes private islands owned by Johnny Depp, Tyler Perry, Faith Hill and Tim McGraw, and David Copperfield. Despite all of the local star power, the real attraction seems to be the family of feral pigs that has established Big Major Cay as their own. It’s hard to say how many are there—some reports say it’s a family of eight, while others say the numbers are up to 40. However big the band of roaming pigs is, none of them are shy: Their chief means of survival seems to be to swim right up to boats and beg for food, which the charmed tourists are happy to provide (although there are guidelines about the best way of feeding the pigs).

No one knows exactly how the pigs got there, but there are plenty of theories. Among them: 1) A nearby resort purposely released them more than a decade ago, hoping to attract tourists. 2) Sailors dropped them off on the island, intending to dine on pork once they were able to dock for a longer of period of time. For one reason or another, the sailors never returned. 3) They’re descendants of domesticated pigs from a nearby island. When residents complained about the original domesticated pigs, their owners solved the problem by dropping them off at Big Major Cay, which was uninhabited. 4) The pigs survived a shipwreck. The ship’s passengers did not.

The purposeful tourist trap theory is probably the least likely—VICE reports that the James Bond movie Thunderball was shot on a neighboring island in the 1960s, and the swimming swine were there then.

Though multiple articles reference how “adorable” the pigs are, don’t be fooled. One captain warns, “They’ll eat anything and everything—including fingers.”

Here they are in action in a video from National Geographic:

Christine Colby
job secrets
13 Secrets From the Ravenmaster at the Tower of London
Christine Colby
Christine Colby

Christopher Skaife is a Yeoman Warder at the Tower of London, an ancient fortress that has been used as a jail, royal residence, and more. There are 37 Yeoman Warders, popularly known as Beefeaters, but Skaife has what might be the coolest title of them all: He is the Ravenmaster. His job is to maintain the health and safety of the flock of ravens (also called an “unkindness” or a “conspiracy”) that live within the Tower walls. According to a foreboding legend with many variations, if there aren’t at least six ravens living within the Tower, both the Tower and the monarchy will fall. (No pressure, Chris!)

Skaife has worked at the Tower for 11 years, and has many stories to tell. Recently, Mental Floss visited him to learn more about his life in service of the ravens.


All Yeoman Warders must have at least 22 years of military service to qualify for the position and have earned a good-conduct medal. Skaife served for 24 years—he was a machine-gun specialist and is an expert in survival and interrogation resistance. He is also a qualified falconer.

Skaife started out as a regular Yeoman Warder who had no particular experience with birds. The Ravenmaster at the time "saw something in him," Skaife says, and introduced him to the ravens, who apparently liked him—and the rest is history. He did, however, have to complete a five-year apprenticeship with the previous Ravenmaster.


The Tower of London photographed at night
Christine Colby

As tradition going back 700 years, all Yeoman Warders and their families live within the Tower walls. Right now about 150 people, including a doctor and a chaplain, claim the Tower of London as their home address.


Skaife used to live next to the Bloody Tower, but had to move to a different apartment within the grounds because his first one was “too haunted.” He doesn’t really believe in ghosts, he says, but does put stock in “echoes of the past.” He once spoke to a little girl who was sitting near the raven cages, and when he turned around, she had disappeared. He also claims that things in his apartment inexplicably move around, particularly Christmas-related items.


The Ravenmaster at the Tower of London bending down to feed one of his ravens
Christine Colby

The birds are fed nuts, berries, fruit, mice, rats, chicken, and blood-soaked biscuits. (“And what they nick off the tourists,” Skaife says.) He has also seen a raven attack and kill a pigeon in three minutes.


Each evening, Skaife whistles a special tone to call the ravens to bed—they’re tucked into spacious, airy cages to protect them from predators such as foxes.


One of the ravens doesn’t join the others in their nighttime lodgings. Merlina, the star raven, is a bit friendlier to humans but doesn’t get on with the rest of the birds. She has her own private box inside the Queen’s House, which she reaches by climbing a tiny ladder.


Ravens normally pair off for life, but one of the birds at the Tower, Munin, has managed to get her first two mates killed. With both, she lured them high atop the White Tower, higher than they were capable of flying down from, since their wings are kept trimmed. Husband #1 fell to his death. The second one had better luck coasting down on his wings, but went too far and fell into the Thames, where he drowned. Munin is now partnered with a much younger male.


Only the Yeoman Warders, their families, and invited guests can go inside a secret pub on the Tower grounds. Naturally, the Yeoman Warder’s Club offers Beefeater Bitter beer and Beefeater gin. It’s lavishly decorated in police and military memorabilia, such as patches from U.S. police departments. There is also an area by the bar where a section of the wall has been dug into and encased in glass, showing items found in an archaeological excavation of the moat, such as soldiers’ discarded clay pipes, a cannonball, and some mouse skeletons.


The Byward Tower, which was built in the 13th century by King Henry III, is now used as the main entrance to the Tower for visitors. It has a secret glass brick set into the wall that most people don’t notice. When you peer inside, you’ll see it contains a human hand (presumably fake). It was put in there at some point as a bit of a joke to scare children, but ended up being walled in from the other side, so is now in there permanently.


Skaife considers himself primarily a storyteller, and loves sharing tales of what he calls “Victorian melodrama.” In addition to his work at the Tower, he also runs Grave Matters, a Facebook page and a blog, as a collaboration with medical historian and writer Dr. Lindsey Fitzharris. Together they post about the history of executions, torture, and punishment.


2013’s Muppets Most Wanted was the first major film to shoot inside the Tower walls. At the Yeoman Warder’s Club, you can still sit in the same booth the Muppets occupied while they were in the pub.


Ravens are very clever and known for stealing things from tourists, especially coins. They will strut around with the coin in their beak and then bury it, while trying to hide the site from the other birds.


Skaife, who’s covered in scars from raven bites, says, “They don’t like humans at all unless they’re dying or dead. Although they do love eyes.” He once had a Twitter follower, who is an organ donor, offer his eyes to the ravens after his death. Skaife declined.

This story first ran in 2015.


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