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Do Mosquitoes Love You? It Could Be Genetic

Image Credit: Fernández-Grandon et al., PLOS ONE

When it comes to choosing a meal, mosquitoes may see some people as a bland bowl of whole grain cereal, while a select number of unlucky folks stand out like a giant, cheese-oozing pizza. The difference is in how you smell: Certain body odors are just more attractive to a mosquito on the prowl. But research published in PLOS ONE in 2015 suggests that your likelihood of getting bitten by a mosquito could be yet another thing you can blame on your parents: Your attractiveness to mosquitoes might be genetic.

To determine whether mosquito attraction might have a genetic component, researchers from the London School of Hygiene and Tropical Medicine studied the appeal of 18 identical and 19 fraternal twins (as a control mechanism, all were post-menopausal women, which the researchers said would "eliminate the variation introduced by sex or phase of menstruation") to female Aedes aegypti mosquitos, the species that carries the viruses for yellow fever and Dengue. To do so, the participants stuck their arms in a lab device called a “Y-tube olfactometer,” which allows the mosquito to choose between two divergent paths leading to the tasty hand of a human test subject. 

Image Credit: Fernández-Grandon et al., PLOS ONE

Identical twins (who come from the same egg and are more genetically similar than non-identical twins) proved to be more similar in their rates of attractiveness to the mosquitos than fraternal twins, suggesting that there may be a genetic underpinning to the body odors that attract or repel biting insects. 

Granted, the results of this pilot study aren’t quite powerful enough to make a definitive case for a mosquito-bite inheritance. And your parents wouldn’t be solely responsible for your itching: Studies suggest that pregnancy, body mass, and even beer consumption may also make people more attractive to certain species of mosquitos.

Twins using the Y-tube olfactometer. Image Courtesy London School of Hygiene and Tropical Medicine

But the idea is, if we can pin down the genetic aspects of mosquito attraction, we may also be able to find new ways to prevent mosquito bites. Aside from the obvious annoyance of constant itching, mosquitos spread deadly diseases (by some estimates, the mosquito is the most deadly animal on Earth). If there really is a genetic component to our susceptibility to mosquito bites, we could better tailor mosquito repellents to individual differences. 

“In the future we may even be able to take a pill which will enhance the production of natural repellents by the body and ultimately replace skin lotions,” senior author James Logan suggested in a press release.

[h/t: Eurekalert]

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Gino Fornaciari, University Of Pisa
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Stones, Bones, and Wrecks
Scientists Accidentally Discover Ancient Hepatitis B in a 16th-Century Mummy
Gino Fornaciari, University Of Pisa
Gino Fornaciari, University Of Pisa

Since the 1980s, a child mummy buried in the Basilica of Saint Domenico Maggiore in Naples, Italy in the 16th century has been known as the earliest recorded case of smallpox in the world. The problem is, the 2-year-old didn’t have smallpox, according to new research spotted by IFLScience. But, as the scientists reexamining the remains discovered, it’s still a landmark study in disease evolution. It appears to be the earliest instance of hepatitis B that researchers have ever found in Italy, giving scientists insight into how the virus has evolved over the last several centuries.

The hepatitis B virus (HBV) attacks the liver and can result in cirrhosis and liver cancer, killing around 887,000 people per year. Though it can now be largely prevented by a vaccine, the World Health Organization estimates that 257 million people around the world live with HBV. It often affects children, spreading from mother to child during birth.

For the current study published in PLOS Pathogens, a team of researchers from McMaster University in Canada set about studying the child mummy with the hopes of continuing their past work nailing down how smallpox spread and evolved over human history. But when they used molecular analysis to study the mummy’s skin and bones, they didn’t find anything that indicated that the toddler had smallpox. Instead, they found the hepatitis B virus—which can cause a rash called Gianotti-Crosti Syndrome that the original researchers studying the mummy may have mistaken for the telltale rash associated with smallpox.

The ancient HBV strain found in the mummy's tissues had a genome closely related to that of the modern virus, which, The New York Times explains, could very well mean that the mummy was contaminated when it was first studied in the 1980s. But after analyzing the genetic material further and studying other examples of older HBV strains, they found that it’s plausible that the virus just hasn’t evolved extensively in the past 500 years. Though the contamination theory is still possible, it’s more likely that the mummy really does carry an ancient version of the virus. Considering that HBV has also been traced back to the 16th century in Asia, it’s likely that Europeans were suffering from it around the same time.

[h/t IFLScience]

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Illustration by Eric S. Carlson in collaboration with Ben A. Potter
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Stones, Bones, and Wrecks
11,500-Year-Old Skeleton Reveals an Unknown Group of Ancient Migrants to the Americas
Illustration by Eric S. Carlson in collaboration with Ben A. Potter
Illustration by Eric S. Carlson in collaboration with Ben A. Potter

In 2013, deep in the forest of central Alaska's remote Tanana River Valley, archaeologists unearthed the remains of a 6-week-old baby at a Late Pleistocene archaeological site. The tiny bones yielded big surprises for researchers, who announced this week that the child's genome—the oldest complete genetic profile of a New World human—reveals the existence of a human lineage that was previously unknown to scientists. Related to yet genetically distinct from modern Native Americans, the infant offers fresh insights into how the Americas were first peopled, National Geographic reports.

Published in the journal Nature on January 3, the study analyzed the DNA of the infant, whom the local Indigenous community named Xach'itee'aanenh T'eede Gaay ("sunrise girl-child" in the local Athabascan language). Then, researchers used genetic analysis and demographic modeling to identify connections between different groups of ancient Americans. This allowed them to figure out where this newly identified population—named Ancient Beringians—fit on the timeline.

University of Alaska Fairbanks professors Ben Potter and Josh Reuther excavate at the Upward Sun River site in central Alaska.
Members of the archaeology field team watch as University of Alaska Fairbanks professors Ben Potter and Josh Reuther excavate at the Upward Sun River site.
UAF photo courtesy of Ben Potter

The study suggests that a single founding group of Native Americans separated from East Asians some 35,000 years ago. This group, in turn, ended up dividing into two distinct sub-groups 15,000 years later, consisting of both the Ancient Beringians and what would eventually become the distant ancestors of all other Native Americans. The division could have occurred either before or after humans crossed over the Bering land bridge around 15,700 years ago.

After arriving in the New World, Ancient Beringians likely remained north, while the other population spread out across the continent. Eventually, the Ancient Beringians either melded with or were replaced by the Athabascan peoples of interior Alaska. 

The study provides "the first direct evidence of the initial founding Native American population, which sheds new light on how these early populations were migrating and settling throughout North America," said Ben Potter, the University of Alaska-Fairbanks archaeologist who discovered the remains, in a news release. Potter was a lead author of the study, along with Eske Willerslev and other researchers at the Center for GeoGenetics at the University of Copenhagen's Natural History Museum of Denmark.

[h/t National Geographic]

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