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I’ve Got Your Missing Links Right Here (15 May 2016)

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Top picks

From me at the Atlantic:

Megan Garber’s epic piece on the history, technology, and sociology of high heels has a superb line in virtually every paragraph. It’s utterly fascinating.

This piece on a (perhaps quixotic) quest to get someone to run a marathon in under 2hrs is full of gold nuggets. By Yannis Pitsiladis

“Leave it to the youngest person in the lab to think of the Big Idea.” Great story about some critical Zika experiments. By Pam Belluck.

I’ve been reading Geoff Manaugh’s A Burglar’s Guide to the City and it’s incredible.

A repeatedly fascinating piece on post-mortem sperm donation by Jenny Morber.

Yes, the ongoing bleaching on the Great Barrier Reef is bad. But it isn’t dead or dying — yet. By Hannah Waters

The Computer Virus That Haunted Early AIDS Researchers. Kaveh Waddell on ransomware that was delivered by floppy disk.

A neuroscientist threatened to sue Jesse Singal when he asked about his side business selling brain tonics

John Oliver does p-hacking, bad science reporting, and oxytocin bullshit. It’s glorious

Computer gleans chemical insight from lab notebook failures



Concerns About Folate Causing Autism Are Premature

The 17-year cicadas are emerging

What Hillary Clinton Says About Aliens Is Totally Misguided

Did a teen discover a lost Mayan city? Not exactly.

This lab is trying to get more ethnic minorities into research studies

Sign language gloves? Not quite

How dust from the Sahara fuels poisonous bacteria blooms in the Caribbean

Siddartha Mukherjee caught some serious flak for a New Yorker piece on epigenetics. Michael Eisen has a good explanation: “Any sufficiently convoluted explanation for biological phenomena is indistinguishable from epigenetics.”

How disease and public health efforts shaped fashion trends

“She has a particular fondness for Iapetus, exomoons, words, and champagne”. Congrats to Nadia Drake for winning this award.

Oh look, 1,284 new Kepler planets

Parasite turns Alaska king crabs into zombies

Elephants winning the war against drones.

Untrue Grit: Daniel Engber versus Angela Duckworth’s self-help-ish psychology book?

BBC’s David Attenborough app will offer over 1,000 clips free

Will Jasha McQueen’s fight for her frozen embryos threaten abortion rights?

The worst-case scenario in using genetically modified mosquitoes to fight Zika is that it won’t work

Does online tool overstate the risk of heart attack and stroke — and the need for statins?

Two countries read the same evidence base on e-cigarettes and come to radically different policies

Mount St. Helens Is Recharging Its Magma Stores, Setting Off Earthquake Swarms



Medieval re-enactor takes out drone with spear

This ‘smart typewriter‘ is supposed to free you from your computer

How Dogs Make Friends for Their Humans

What are the most common kinds of coincidences people experience?

Social networks as the seven deadly sins

“Hostile architecture” aims to keep unwanted – homeless, skaters, teens, junkies – from using urban space

On Facebook’s unprecedented cultural power

How Rival Gardens of Eden in Iraq Survived ISIS, Dwindling Tourists, And Each Other

US Army fact-checks fan theory about how much back pay Captain America is due

A Blog by

Flies Could Falsely Place Someone at a Crime Scene

The Australian sheep blowfly doesn't just eat nectar. It has a taste for a particular human body fluid—and it’s not blood.
The Australian sheep blowfly doesn’t just eat nectar. It has a taste for a particular human body fluid—and it’s not blood.

This might be the grossest science experiment I’ve ever written about—which is really saying something on a blog called Gory Details—but it’s also one of the most fascinating. It has to do with the taste a certain type of fly has for human bodily fluids.

Blowflies, in case you’re not familiar with them, are the flies of death. As I learned when rats died in my ceiling, these big shiny flies have an amazing ability to appear seemingly out of nowhere within moments of blood being spilled or at the slightest whiff of decay.

So, a lot of blowflies are sometimes found buzzing around a gory crime scene. That got forensic expert Annalisa Durdle wondering: With all those flies doing what flies do—flying around and pooping on stuff—could they be contaminating crime scenes?

“Interestingly, fly poo can also look very similar to blood spatter,” says Durdle, who studied forensic science at La Trobe University in Melbourne, Australia.

“Anyhow,” she e-mailed in response to my indelicate questions about her research, “it turns out that you can get full human DNA profiles from a single piece of fly poo. (I tend to refer to poo rather than vomit because in my experience flies tend to eat their vomit and most of what you have left is poo—although they do eat that too!)”

Clearly, blowflies are gross.

But could they falsely incriminate someone? To find out, Durdle needed to know what blowflies would really eat at a crime scene.  

So she did the experiment. Her team offered Australian sheep blowflies a crime scene buffet, with body fluids collected from volunteers—blood, saliva, and semen—plus other snacks that flies might find in a victim’s home: pet food, canned tuna, and even honey.

“You draw more flies with honey,” my mother always told me. But in this case, she was wrong.

What you draw more flies with, it turns out, is semen.

“It’s the crack cocaine of the fly world,” Durdle says. “They gorge on it; it makes them drunk (they stumble around, partly paralyzed—I’ve even seen one fly give up hope of cleaning itself properly and sit down on its bum!). Then they gorge some more and then it kills them. But they die happy!”

Video: Meet Annalisa Durdle, the coolest fly-poop scientist ever.

The flies liked pet food too, but weren’t much into blood, and they were really uninterested in saliva. Maybe they go for semen’s higher protein content—it contains more than 200 different proteins, at much higher levels than in blood. (Update: or maybe not. Protein levels vary, and Annalisa Durdle notes that “flies are like people—they don’t necessarily eat what is good for them!” Flies are attracted to various aromas, including sulphur-based ones, so it may be that semen is simply more alluring than other food sources.)

Another thing semen has plenty of: DNA.

Durdle tested flies’ poop after various meals. “If the flies had fed on semen or a combination with semen in it, then you got a full human DNA profile almost every time. With blood, it was maybe a third of the time and with saliva, never.”

“It was also interesting to find the flies generally preferred dry blood or semen to wet blood or semen,” Durdle says. “This could be important, because it means flies could continue to cause problems at a scene long after the biological material had dried.”

How big a deal is this? Durdle says, “You really need to look at the probabilities… the chances that a fly might feed on some poor guy’s semen (after he’s had some innocent quiet time to himself), and then fly into a crime scene and poo, potentially incriminating him.”

There’s also the chance that a forensic investigator could sample fly poop thinking it’s blood spatter, she says, and find DNA that’s not from the victim.

A fly might occasionally be helpful to the cause of criminal justice. If a fly eats bodily fluids from a crime scene and then flies away into another room and poops there, it might save a sample of DNA from the perpetrator’s attempts to clean up.

Flies aren’t the only potential problem for interpreting DNA. As the technology used in forensic labs has become more sensitive, there’s greater risk of picking up tiny bits of DNA transferred to a crime scene, forensic scientist Cynthia Cale argued last year in Nature.

In fact, Cale showed that one person can transfer another person’s DNA to a knife handle after two minutes of holding hands. (Next she says she’ll try shorter times, to see if even a brief encounter could transfer DNA.)  

The fly-poop research is interesting, Cale says. Blowflies would probably be more likely to transfer DNA within a crime scene rather than bringing it in from outside, but even that could confuse the reconstruction of a crime.

“I think the biggest impact might be when a defense lawyer uses it to raise doubt in the mind of a jury,” Durdle says.