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Ancient cave dwellers also struck fruit flies: shots



Drosophila melanogaster The common fruit fly, is a mainstay of genetics and biology laboratories.

Courtesy of Marcus Stensmyr


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Courtesy of Marcus Stensmyr

Drosophila melanogaster The common fruit fly, is a mainstay of the laboratories for genetics and biology.

Courtesy of Marcus Stensmyr

The next time you pet a fruit fly in your kitchen, take in the fact that people seem to be struggling with this fly infection for about 10,000 years.

A study published on Thursday suggests Drosophila melanogaster For the first time it was crammed together with humans when the insects flew into the ornately painted caves of ancient humans living in southern Africa.

This is from a report published on Thursday in Current Biology ] This plague has shut down the $ 700 million fruit industry in South Florida “/>

Scientists say the flies have the seductive odor of stored marula Followed by fruits collected and stored by cave dwellers in Africa. This delicious yellow fruit was a staple food in this region – and was also the fruit that made wild flies dependent on nearby forests.

The modest fruit fly now lives with humans around the world is one of the most studied creatures in the world. For more than a century, biological and medical laboratories have relied on this fly – a scientist notes that at least nine Nobel Prize in Physiology or Medicine has been awarded for research on Drosophila . One of these awards was won by Thomas Hunt Morgan of Columbia University, whose fly research in the early 1900s robbed this species of darkness and turned it into a pillar of genetics.

"It's small, it's cheap to raise, it's interesting genetics," explains Thomas Kaufman, a biologist at Indiana University in Bloomington. "We think that flies are pretty charismatic, they are wonderful, they are beautiful little animals and we love them, seriously."

But in spite of all this love and study, the origin of this fly and how it first came together with people was a mystery.

"I've been asking myself for 20 years," says Marcus Stensmyr, a biologist at Lund University in Sweden, who uses these flies to study the olfactory system. "It really is a kind of lifelong ambition, if you want, where you come from."

Scientists have known for decades that the flies started like the humans in Africa – somewhere. 19659008] "You can find them in your kitchen, you can find them in my kitchen – you can find them in every kitchen," says Stensmyr. "But when you go into the woods, you just can not find them."

Recently, researchers collected flies from all over Africa and examined their genes. They found that the greatest genetic diversity was found in flies from Zambia and Zimbabwe, suggesting that this species originated in the south-central region of the continent.

But traveling to this region did not produce much. 19659008] "After a series of failed field trips to Africa," Stensmyr says, "we thought," OK, maybe they're related to certain fruits in their original home. "

Stensmyr and his colleagues investigated a long list of possible fruits and searched for all the features that D. Melanogaster is known to favor. The flies prefer citrus fruits – such as oranges.

The Marula Fruit seems to have a special power over D. Melanogaster who prefers it over all others.

Courtesy of Marcus Stensmyr


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The Marula Fruit seems to have a special power over D. Melanogaster who prefers it over all others.

Courtesy of Marcus Stensmyr

"We came to a candidate fruit – that was Marula fruit," says Stensmyr. The yellow fruit is about the size of a large plum, with a hard stone in the middle. "It has a sweet and nice taste."

The researchers traveled to the forests of Matobo National Park in Zimbabwe. They found fertile Marula trees and laid out traps. Bingo – they have caught D. Melanogaster .

"We found tons of flies," recalls Stensmyr.

Further investigations showed that wild d. Melanogaster Marula fruit strongly prefers oranges.

In addition, a fly used in laboratories plays a role. This strain was founded in 1916 from a fly population in Canton, Ohio.

"Actually, they have a preference for Marula," says Stensmyr. "You would go for the Marula as well."

The researchers isolated a specific chemical in this fruit – ethyl isovalerate – that seemed particularly important. Flies that were given a choice between Marula and Oranges spiked with this chemical could not be matched, suggesting that the two options are the same for flies.

All this gives a fascinating hint on how these insects can work began to make a home with humans. Near the researchers, the wild flies found caves where the San tribes used to live. These people left beautiful cave paintings – as well as the pits of Marula fruits that they had eaten. Out of a cave, excavators with 24 million marulasteins came up.

"They really loved Marula," says Stensmyr, who points out that the stones were found about 12,000 years ago or about 8,000 years ago. "During the time when these caves were inhabited, the San people must have brought enormous amounts of Marula into the caves."

This means that Marula was probably stored there and was available from wild animals in the forest long after the Marula had eaten. The strong smell of all this marula would have attracted the flies.

To test whether wild flies would actually invade a cave, the research team placed traps of fermenting marula along the opposite wall of Nswatugi Cave. Sure, over a few days, these traps have caught a number of D's. Melanogaster flies.

The study and the story that she tells us have completely inspired other scientists who study fruit flies.

"I especially like catching the flies in the painted caves," says Kaufman. "That was inspired, it's really a decent job."

"I thought it was fantastic," agrees Celeste Berg, a developmental geneticist at the University of Washington, Seattle, who has used flies in her research for 30 years. "I thought her data was really pretty striking."

Berg says she wonders how exactly the flies spread from these caves to the rest of the world.

"I find it exciting to learn the origins of fruit flies And even if you're not an ecologist or a population geneticist, I think it's only natural to be interested in the history of the organism you study," says Berg. "I had assumed that fruit flies like all sorts of fruits – especially bananas – I did not know they prefer citrus, and they are not even citrus fruits that they prefer, they prefer this particular Marula plant that I've never heard before of. "

Debbie Andrew, a developmental biologist at the Johns Hopkins School of Medicine, who has been working with fruit flies for four decades, says she loved the paper.

"You have a good story," says Andrew. "It's very hard to prove that something happened 10,000 years ago or more, I like the story."

Regarding the question of whether all the details are correct, she says, "I do not know, it seems plausible, based on the amount of Marula fruit stones they found in the cave."

Based on According to Andrew, this paper should really change the old adage, "Time flies like an arrow and fruit flies like a banana". [19659008] "Time flies like an arrow," she says, "and fruits fly like an orange, a marula fruit, or maybe an orange mixed with ethyl isovalerate."


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