Blood Collected From Mosquitoes Could One Day Be Used as Forensic Evidence


While blood collected from mosquitoes won’t be used to clone dinosaurs any time soon, it may one day be used as a tool to solve crime. A 2015 study published in the journal Genetics and Molecular Research [PDF] shows that human blood taken from the digestive tracts of mosquitoes in closed environments can provide accurate DNA profiles of the people nearby—perhaps including suspects.

To test their theory, researchers collected blood consumed by 26 female mosquitoes from two homes. From these samples they were able to assemble 11 DNA profiles that matched up with the saliva samples they had taken from the homes' residents. Mosquitoes have a tendency to feed quickly and remain at the site, so it's theoretically possible for specimens found at the scene of a crime to have bitten the perpetrator and stuck around for hours to follow. And because different species are active during different times of the day, a mosquito with a belly full of incriminating DNA that’s known to be active around the same time the crime occurred could add an extra layer of evidence to the case.

Another advantageous quality is that the mosquitoes only stop feeding when they're full, even if it means drinking from multiple hosts. Mosquitoes containing more than one DNA profile could possibly provide links between victims and criminals in future crime investigations. 

The support for mosquitoes' crime-solving potential was so strong that the scientists behind the study urged investigators to begin collecting the insects at indoor crime scenes. If unknown human blood was found inside one, they could run it through a DNA database of criminals. So next time you get annoyed by mosquitoes in your home, just think of them as tiny forensic detectives.

Human Body Temperatures Are Dropping, and Science Might Know Why

dcdp/iStock via Getty Images
dcdp/iStock via Getty Images

In 1868, German physician Carl Reinhold August Wunderlich started to popularize what’s become the most recognizable number in all of medicine: 98.6°F or 37°C, which is thought to be the normal average human body temperature. Though his methods later came under scrutiny—Wunderlich stuck an enormous thermometer under the armpits of patients for 20 minutes, a less-than-accurate technique—this baseline has helped physicians identify fevers as well as abnormally low body temperatures, along with corresponding illnesses or diseases.

More than 150 years later, 98.6° may no longer be the standard. Humans seem to be getting cooler. Researchers at Stanford University School of Medicine, in a paper published in the journal eLife, compared three large datasets from different time periods: American Civil War records, a national health survey from the 1970s, and a Stanford database from 2007-2017. By comparing recorded body temperatures, the researchers founds that men are now averaging a temperature .58°C less than what's long been considered normal, while women are .32°C lower. On average, each has decreased roughly .03°C every decade since the 1860s.

What drove us to chill out? Scientists have a few theories. A number of advances in human comfort have been ushered in since the 1800s, including better hygiene and readily available food, which may have slowed our metabolic rate (temperature is an indication of that rate). Chronic inflammation, which also raises body temperature, has decreased with the advent of vaccines, antibiotics, and better healthcare. The researchers propose that, on average, our bodies are healthier and slightly less warm.

After all, the average life expectancy in Wunderlich’s era was just 38 years.

[h/t The Independent]

You Should Never Put Batteries In Your ‘Junk’ Drawer. Here’s Why

naumoid/iStock via Getty Images
naumoid/iStock via Getty Images

The junk drawer is the MVP of making your home seem meticulously tidy, and it’s also proof that “organized chaos” is a valid method of organization. But you should still be careful about what you toss in there; loose batteries, for example, are a fire hazard.

If metal comes into contact with both the positive and negative posts of a battery, it could cause a short circuit that generates enough heat to start a fire. And chances are pretty good that your junk drawer is currently housing a few metallic materials: paper clips, hardware, coins, keys, tacks, spare chargers, steel wool, pens, and aluminum foil can all pose a threat.

As Reader’s Digest explains, 9-volt batteries are especially unsafe because their positive and negative posts are right next to each other. But even if you’re only storing AA or AAA batteries—or any other batteries where the posts are on opposite ends—it’s probably not worth the risk.

The easiest way to prevent a fire is simply to keep your batteries out of your junk drawer and away from metal objects altogether. If you’re short on space, however, there are a couple other safety measures you can take. The National Fire Protection Association recommends storing batteries in their original packaging, or covering the posts with masking, duct, or electrical tape when you’re not using them [PDF]. You also shouldn’t throw 9-volt batteries in a container with other batteries, since those count as metal objects, too.

Once you’ve fire-proofed your junk drawer, find out how to avoid six other common household fire hazards here.

[h/t Reader’s Digest]