Scientists Study the Starling Invasion Unleashed on America by a Shakespeare Fan

On a warm spring day, the lawn outside the American Museum of Natural History in Manhattan gleams with European starlings. Their iridescent feathers reflect shades of green and indigo—colors that fade to dowdy brown in both sexes after the breeding season. Over the past year, high school students from different parts of the city came to this patch of grass for inspiration. "There are two trees at the corner I always tell them to look at," Julia Zichello, senior manager at the Sackler Educational Lab at the AMNH, recalls to Mental Floss. "There are holes in the trees where the starlings live, so I was always telling them to keep an eye out."

Zichello is one of several scientists leading the museum's Science Research Mentoring Program, or SRMP. After completing a year of after-school science classes at the AMNH, New York City high school students can apply to join ongoing research projects being conducted at the institution. In a recent session, Zichello collaborated with four upperclassmen from local schools to continue her work on the genetic diversity of starlings.

Before researching birds, Zichello earned her Ph.D. in primate genetics and evolution. The two subjects are more alike than they seem: Like humans, starlings in North America can be traced back to a small parent population that exploded in a relatively short amount of time. From a starting population of just 100 birds in New York City, starlings have grown into a 200-million strong flock found across North America.

Dr. Julia Zichello
Dr. Julia Zichello
©AMNH

The story of New York City's starlings began in March 1890. Central Park was just a few decades old, and the city was looking for ways to beautify it. Pharmaceutical manufacturer Eugene Schieffelin came up with the idea of filling the park with every bird mentioned in the works of William Shakespeare. This was long before naturalists coined the phrase "invasive species" to describe the plants and animals introduced to foreign ecosystems (usually by humans) where their presence often had disastrous consequences. Non-native species were viewed as a natural resource that could boost the aesthetic and cultural value of whatever new place they called home. There was even an entire organization called the American Acclimatization Society that was dedicated to shipping European flora and fauna to the New World. Schieffelin was an active member.

He chose the starling as the first bird to release in the city. It's easy to miss its literary appearance: The Bard referenced it exactly once in all his writings. In the first act of Henry IV: Part One, the King forbids his knight Hotspur from mentioning the name of Hotspur's imprisoned brother Mortimer to him. The knight schemes his way around this, saying, "I'll have a starling shall be taught to speak nothing but 'Mortimer,' and give it him to keep his anger still in motion."

Nearly three centuries after those words were first published, Schieffelin lugged 60 imported starlings to Central Park and freed them from their cages. The following year, he let loose a second of batch of 40 birds to support the fledgling population.

It wasn't immediately clear if the species would adapt to its new environment. Not every bird transplanted from Europe did: The skylark, the song thrush, and the bullfinch had all been subjects of American integration efforts that failed to take off. The Acclimatization Society had even attempted to foster a starling population in the States 15 years prior to Schieffelin's project with no luck.

Then, shortly after the second flock was released, the first sign of hope appeared. A nesting pair was spotted, not in the park the birds were meant to occupy, but across the street in the eaves of the American Museum of Natural History.

Schieffelin never got around to introducing more of Shakespeare's birds to Central Park, but the sole species in his experiment thrived. His legacy has since spread beyond Manhattan and into every corner of the continent.

The 200 million descendants of those first 100 starlings are what Zichello and her students made the focus of their research. Over the 2016-2017 school year, the group met for two hours twice a week at the same museum where that first nest was discovered. A quick stroll around the building reveals that many of Schieffelin's birds didn't travel far. But those that ventured off the island eventually spawned populations as far north as Alaska and as far south as Mexico. By sampling genetic data from starlings collected around the United States, the researchers hoped to identify how birds from various regions differed from their parent population in New York, if they differed at all.

Four student researchers at the American Museum of Natural History
Valerie Tam, KaiXin Chen, Angela Lobel and Jade Thompson (pictured left to right)
(©AMNH/R. Mickens)

There are two main reasons that North American starlings are appealing study subjects. The first has to do with the founder effect. This occurs when a small group of individual specimens breaks off from the greater population, resulting in a loss of genetic diversity. Because the group of imported American starlings ballooned to such great numbers in a short amount of time, it would make sense for the genetic variation to remain low. That's what Zichello's team set out to investigate. "In my mind, it feels like a little accidental evolutionary experiment," she says.

The second reason is their impact as an invasive species. Like many animals thrown into environments where they don't belong, starlings have become a nuisance. They compete with native birds for resources, tear through farmers' crops, and spread disease through droppings. What's most concerning is the threat they pose to aircraft. In 1960, a plane flying from Boston sucked a thick flock of starlings called a murmuration into three of its four engines. The resulting crash killed 62 people and remains the deadliest bird-related plane accident to date.

Today airports cull starlings on the premises to avoid similar tragedies. Most of the birds are disposed of, but some specimens are sent to institutions like AMNH. Whenever a delivery of dead birds arrived, it was the students' responsibility to prep them for DNA analysis. "Some of them were injured, and some of their skulls were damaged," Valerie Tam, a senior at NEST+m High School in Manhattan, tells Mental Floss. "Some were shot, so we had to sew their insides back in."

Before enrolling in SRMP, most of the students' experiences with science were limited to their high school classrooms. At the museum they had the chance to see the subject's dirty side. "It's really different from what I learned from textbooks. Usually books only show you the theory and the conclusion, but this project made me experience going through the process," says Kai Chen, also a senior at NEST+m.

After analyzing data from specimens in the lab, an online database, and the research of previous SRMP students, the group's hypothesis was proven correct: Starlings in North America do lack the genetic diversity of their European cousins. With so little time to adapt to their new surroundings, the variation between two starlings living on opposite coasts could be less than that between the two birds that shared a nest at the Natural History Museum 130 years ago.

Students label samples in the lab.
Valerie Tam, Jade Thompson, KaiXin Chen and Angela Lobel (pictured left to right) label samples with Dr. Julia Zichello.
©AMNH/C. Chesek

Seeing how one species responds to bottlenecking and rapid expansion can provide important insight into species facing similar conditions. "There are other populations that are the same way, so I think this data can help [scientists],” Art and Design High School senior Jade Thompson says. But the students didn't need to think too broadly to understand why the animal was worth studying. "They do affect cities when they're searching for shelter," Academy of American Studies junior Angela Lobel says. “They can dig into buildings and damage them, so they're relevant to our actual homes as well.”

The four students presented their findings at the museum's student research colloquium—an annual event where participants across SRMP are invited to share their work from the year. Following their graduation from the program, the four young women will either be returning to high school or attending college for the first time.

Zichello, meanwhile, will continue where she left off with a new batch of students in the fall. Next season she hopes to expand her scope by analyzing older specimens in the museum's collections and obtaining bird DNA samples from England, the country the New York City starlings came from. Though the direction of the research may shift, she wants the subject to remain the same. "I really want [students] to experience the whole organism—something that's living around them, not just DNA from a species in a far-away place." she says. "I want to give them the picture that evolution is happening all around us, even in urban environments that they may not expect."

Being Surrounded By Greenery Can Be Good for Your Heart

iStock.com/Givaga
iStock.com/Givaga

Living in a place with a little greenery is good for your health in more ways than one. Recent research has found that people perceive their health status as significantly better if they live around trees, and for good reason—in addition to helping you chill out, exposure to lots of green vegetation may be good for your cardiovascular health, as Cardiovascular Business reports.

A new study in the Journal of the American Heart Association suggests that living in green areas is correlated with certain biomarkers for cardiovascular health. Scientists analyzed blood and urine samples from 408 people at a cardiology clinic, then compared the results to satellite-derived data on the levels of greenery around those patients’ homes (using 820-foot and half-mile radiuses).

Adjusting for age, sex, race, smoking status, “neighborhood deprivation” and other factors known to be linked heart disease rates, the researchers found that living in a green area was correlated with several markers of a healthy heart. Blood and urine samples from those participants who lived in green neighborhoods showed lower levels of sympathetic activation—the body’s automatic fight-or-flight response, which raises the heart rate and is involved in heart failure. Those participants also had reduced oxidative stress—an imbalance between free radicals and antioxidants in the body, which can cause tissue damage and is linked to chronic disease. And they had higher angiogenic capacity, which refers to the body’s ability to form new blood vessels.

All this suggests that being around trees is somehow linked to having a healthier heart, though these are just biomarkers, not rates of heart disease or major cardiac events. But while scientists have yet to prove directly that being around trees causes your heart to be healthier, it’s not the first study to suggest a link. In 2015, a study of American women found that rates of heart disease went up in certain areas after a beetle invasion killed off a significant number of trees. Other studies have suggested that being around trees can reduce stress, which in itself may affect your risk of heart disease. Luckily, whether it qualifies as heart medicine or not, spending more time hanging out under trees couldn’t hurt.

[h/t Cardiovascular Business]

14 Facts About Feet

iStock/pepifoto
iStock/pepifoto

The foot is one of the most overworked, under-appreciated parts of the human body. Think about it: In a single day, the average person takes 8000 to 10,000 steps. That works out to be four trips around the world over a lifetime, putting a lot of wear and tear on your intricate foot bones. The foot may be humble, but its design is essential to how we walk upright, and hoofing it on two feet is a defining feature of humanity. Here are some fun—and a few funky—facts about the human foot.

1. FOOT BONES MAKE UP ABOUT A QUARTER OF ALL THE BONES IN OUR BODIES.

There are 26 foot bones in each of your feet—one less than in each hand. When we’re born, those foot bones are mostly cartilage. They only completely harden around age 21.

2. HUMANS HAVE WORN SHOES FOR A VERY LONG TIME.

When did humans begin wearing shoes, anyway? About 40,000 years ago, according to research from Washington University in St. Louis that analyzed foot bones from Neanderthals and early humans. Older specimens had thicker, stronger toes, likely from gripping the ground as they walked barefoot. That’s around the same time that the archaeological record shows a burst of artistic and technological advancements among early humans, including the first stone tools, which may have aided in the production of shoes. The oldest preserved shoe, incidentally, is 5500 years old and was found in an Armenian cave, buried in sheep dung.

3. THE BIG TOE USED TO BE A KIND OF FOOT THUMB.

This grasping toe helped our predecessors climb trees and, when young, grip onto their mothers. Thanks to modern science, if you lose your thumb, you can now replace it with a toe: toe-to-thumb transplants are a surprisingly common procedure these days.

4. FOOT BONES HOLD BIG CLUES ABOUT THE EVOLUTION OF BIPEDALISM.

Scientists are studying Homo naledi, a specimen discovered in a South African cave in 2013 that many researchers believe is a new human relative. H. naledi had very human-like feet, but with somewhat curved toe bones that suggest it climbed trees. It could be that H. naledi was beginning to experiment with walking. 

5. THERE WAS A FOOT CHEESE EXHIBITION IN IRELAND.

Warm, sweaty feet make a perfect home for bacteria, which feed on our dead skin cells and produce gases and acids that emit those arresting foot odors. They're apparently also good at cultivating cheese. An exhibition in Dublin in 2013 displayed a variety of cheeses made with bacteria samples obtained from real people’s feet, armpits, and belly buttons. Delicious. (No one actually ate any of the cheeses.)

6. FEET ARE ONE OF THE MOST TICKLISH PARTS OF THE BODY.

There’s a good reason for that: Humans have nearly 8000 nerves in our feet and a large number of nerve endings near the skin. Having ticklish feet can be a good sign: Reduced sensitivity can be an indicator of peripheral neuropathy (numbness in the feet caused by nerve damage). 

7. FOOT NUMBNESS CAN CAUSE BIG PROBLEMS FOR DIABETICS.

Complications of diabetes include poor circulation and foot numbness that can lead to serious skin ulcers, which sometimes require amputation of toes or feet. In 2010 alone, 73,000 lower-limb amputations were performed on diabetics.

8. FOOT SIZES AND WIDTHS IN THE U.S. AND UK ARE INCREASING.

Feet are spreading to support extra weight as our populations pack on the pounds. According to a 2014 study by the College of Podiatry in the UK, the average foot has increased two sizes since the 1970s. As people have grown taller and heavier, feet respond by growing. It appears many people are still in denial about their expanding feet: Though retailers are starting to respond by making larger and roomier shoes, half of women and a third of men reported they buy poorly fitting shoes. Podiatrists say ill-fitting shoes are to blame for a significant portion of foot problems, especially among women.

9. MANY GLAMOROUS CELEBRITIES HAVE BIG FEET.

From the bound feet of female Chinese elites to Cinderella and Barbie, freakishly small feet are often celebrated as more feminine. But plenty of glamorous women both past and present have had larger than average feet, among them Jacqueline Kennedy, Oprah Winfrey, Uma Thurman, and Audrey Hepburn (size 10, 11, 11, and 10.5, respectively).

10. WOMEN HAVE FOUR TIMES AS MANY FOOT PROBLEMS AS MEN.

That painful fact is often attributed to wearing heels. Ironically, Western women started wearing heels to effect a more masculine look: European men adopted the look from Persian warriors in the 17th century, and women soon followed suit.

11. THE AVERAGE PERSON WALKS ABOUT 100,000 MILES IN A LIFETIME. 

That’s a lot of stress on our feet. It’s not surprising, then, that lower back pain, headaches, indigestion, and spine misalignment are often related to foot problems. Some runners blow way past this mark: They've logged at least 100,000 in running miles alone. One committed runner, Herb Fred, has run a whopping 247,142 miles.

12. FOOT SIZE HAS ZERO TO DO WITH PENIS SIZE.

In a study published in 2015, researchers synthesized data from 17 previous studies that included the penis measurements of more than 15,000 men from around the world. The results: There is little evidence that penis size is linked to height, body mass, or shoe size.

13. THERE'S A REASON GRANDPA'S TOENAILS LOOK LIKE THAT.

Ever heard someone describing their toenails as “horse hooves”? As we get older, our toenails tend to thicken, making them hard to trim. This happens because toenails grow more slowly as we age, causing the nail cells to accumulate. Stubbing toes, bad shoes, and dropping things on your feet can also cause thickening, as can fungal infections and peripheral arterial disease, which narrows arteries and reduces the blood flow to limbs.

14. THERE'S A GUINNESS WORLD RECORD FOR MOST FEET AND ARMPITS SNIFFED.

Odds are you don’t have any job-related tasks nearly as revolting as this one: In the 15 years that Madeline Albrecht worked for an Ohio lab that tests Dr. Scholl products, she sniffed more than 5600 feet and untold numbers of armpits. Albrecht currently holds the Guinness World Record for—yes, this is a category—the number of feet and armpits sniffed.

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