Tag Archives: Fruit

Here are the world’s most favorite fruits — judging by production figures, at least

We’ve all heard time and time again how eating fruits and vegetables is healthy for us, and it definitely is. Hopefully, everybody here is getting their five-a-day. But that also raises an interesting question: which fruits do people prefer?

It’s practically impossible to track exactly how much of each type of fruit people consume worldwide, so we’ll use global production figures as a proxy. Presumably, farmers would be loathe to grow produce that nobody buys, so production figures should be a reliable indicator of consumption, as well.

Now, we all have our own preferences, and nowhere is that more true than when food is concerned. Don’t feel the need to change yours because of this list. But I always find it fascinating to see how individual choices compound on a global level. There are billions of people living on Earth today, and our food combined diets have, throughout history, shaped the world around us.

So let’s see what fruits we’re all munching on — statistically speaking.

Tomatoes

The least fruit-tasting fruit out there is, actually, the one that sees the highest production levels worldwide.

Image credits Hans Braxmeier.

Tomatoes are a bit of an outlier on this list. Taxonomically speaking, they are fruits (berries, to be specific). But from a practical point of view, they’re employed as vegetables for salads, sauces, or cooked dishes.

The tomato originates from the American continents and was introduced to the rest of the world following the Columbian exchange, the single largest transfer of people, plants, and animals in history. Our earliest records suggest tomatoes were being cultivated by locals in the areas where they’re endemic (in the Andes, Peru, Chile, Ecuador, and the western stretches of Bolivia) since around 700 AD. Today, they’re virtually indispensable in multiple culinary traditions, including Mediterranean cooking.

Spanish and Portuguese explorers brought tomatoes back to Europe — and from there, the world — but what really made them a hit was that, at first, rich people died trying to eat them.

When it was first introduced to Europe tomatoes were, quite understandably, very expensive. Due to that, only well-off people could really afford to buy them — and they were probably also quite interested in doing so, both as a status symbol and due to sheer curiosity. Another thing rich people of the time used to show off their wealth and status were metal plates and cutlery, generally made out of pewter. And it was these plates that would make the tomato one of the most feared fruits in 1700’s Europe — when it was widely known as the ‘poison apple’.

You see, tomato juice is quite acidic. Pewter is an alloy that’s in large part comprised of lead, and this will leach out when exposed to a strong-enough acid. Eat enough lead and you get lead poisoning and die. People at the time didn’t understand this process, but they could observe that nobles would eat tomatoes and die sometime later. So people started to avoid eating them, which dramatically lowered their price.

This, turns out, was a huge boon for the tomato, because poor, hungry people aren’t picky. They also don’t own pewter plates, so they wouldn’t get any lead poisoning from eating them.

Another issue that plagued the tomato during its early days is that the plant and roots themselves are quite toxic, even if the fruits are not. Until people learned to avoid these parts, this toxicity further helped lower the price of tomatoes, making them a staple of the common people.

Tomatoes today are virtually everywhere, and very popular for their versatility. They’re a great source of umami flavor, and one of the few plants out there that contain it, which would further explain their popularity.

In 2019, the world produced 181 million tonnes of tomatoes, with China being the main producer.

Bananas

The first undeniable fruit on the list also harbors a few secrets.

Image via Pixabay.

For starters, all the bananas you’ve ever eaten are, most likely, completely identical genetically. In essence, you’ve been eating the same banana over and over again. That’s because banana plants meant for commercial use are spread through saplings — they’re all clones.

They didn’t start out this way. The next time you bite into one, look for the very small seeds throughout the fruit’s pulpy core. Banana plants are spread through saplings because these seeds are very, very rarely viable. We’ve made them so. Wild bananas have large seeds in the middle of the fruit, to such an extent that eating one isn’t a pleasurable experience — it makes them borderline inedible, actually.

While the seeds of domesticated bananas are used for breeding programs, they have a low chance of germinating (growing into a plant). Furthermore, spreading the plants through samples of rhizome (a specialized type of root structure) allows farmers to reliably grow banana trees that have similar productivity, ensuring that their crops remain economically viable. This is made easier by the fact that bananas are parthenocarpic — they don’t need to be pollinated to bear fruit.

Naturally, there’s also downsides to this approach: for one, the root samples can carry diseases or pest from one plant to the new ones. Secondly, since all the plants in a crop are clones, a single pest or disease can wipe them all out. In theory, one could wipe out whole cultivars. It may sound like a pretty abstract issue, but it has actively lowered the quality of our bananas over time. Today, the Cavendish is the most common cultivar of banana. But up until the 1950’s, what you were most likely to find in a store were the Gros Michel variety. Taste-wise, these were reportedly much more enjoyable than the Cavendish. Artificial banana flavoring today tastes more like bananas than bananas themselves because they were based on the Gros Michel cultivar.

Sadly, the Panama disease virtually wiped out the Gros Michel — which, just like the Cavendish, were all clones of one another. The Cavendish cultivar was bred specifically to be more resistant to certain pests and diseases. That being said, in the wild or on small independent farms, bananas have much, much greater genetic diversity. Hopefully, this will act as an insurance policy, so we never have to give up bananas.

Another unusual aspect of the banana is how surprisingly radioactive it is. Large batches have been known, for example, to trigger sensors meant to identify smuggled nuclear material. This comes down to their high content of potassium (which is a good thing). One isotope of this element, potassium-40, is naturally radioactive. But worry not — unless you plan to eat a few million bananas in one sitting, you’re not getting radiation poisoning. And, honestly, if you reach that point, radiation won’t be your main issue.

Today, bananas are among the most cultivated plants out there, being the 4th biggest crop worldwide. In 2019, around 117 million metric tons of this yellow fruit were produced across the world, with India being the single largest grower.

Watermelons

Although their name implies the existence of earth-, fire-, and air- melons, so far we’ve only encountered watermelons.

Image credits Pete Linforth.

But boy oh boy are we happy we did. Watermelons are one of the most popular fruits on Earth, both in regards to quantity eaten, where it’s enjoyed, and how long it’s been enjoyed. Originally an African species, watermelons are part of the Cucurbitaceae family and closely related to the cucumber, squash, zucchini, and gourds. Biologically speaking it is, again, despite its looks, a berry.

Our earliest evidence of watermelon farming comes from around 4000 to 5000 years ago in ancient Egypt. Seeds of various cultivars have even been found buried with the Pharaos, which showcases just how popular and appreciated these fruits were even back then.

It quickly spread to any and all areas with a favorable climate. By the 7th century watermelons reached India, and by the 10th century, China. Between the 10th and 12th centuries it was also introduced to Europe, mainly by Muslim peoples from Northern Africa, and it became quite common here by the 17th century. From here, it made its way to the new world, and even Native Americans are documented to have grown watermelons in the Mississippi and Florida areas in the 17th century. Pacific island natives were also quite excited to adopt the crop as European explorers first encountered them.

Why would explorers have watermelons on them? Well, with a water content that can reach up to 92% by weight, they make excellent canteens, especially on long voyages where wooden barrels holding drinking water would routinely rot or become salty.

One especially interesting variety of watermelon is the seedless kind. While it’s tempting to assume that someone messed around with some watermelon DNA to produce them, that isn’t exactly the case. Seedless watermelons are actually produced by crossing a variety with 22 chromosomes with one that has 44 chromosomes. This results in an infertile, seedless hybrid, much like a mule.

But if you get the variety with seeds, you can practice your hand at breaking a world record. More specifically, the seed-spitting world record. You’re trying to beat Jason Schayot who, according to the Guinness Book of World Records, spit watermelon seeds a distance of 75 feet 2 inches (22.9108 meters) on August 12, 1995, at a seed-spitting festival in Georgetown, Texas. The seeds are actually edible, however, and quite nutritious, if you’d rather not spit.

In 2019, around 100.41 million metric tons of watermelon were grown worldwide, with China leading production.

Apples

The humble apple is iconic in European and Asian cultures and is one of the oldest domesticated fruits on the planet.

Image credits S. Hermann & F. Richter.

Since it’s been grown for so long and carried around by various groups of people, exactly where it originates is still a matter of some debate — but for now, the consensus is that the apple was born somewhere in central Asia. According to our best estimates, people found and first domesticated the apple around the Tian Shan mountain range between 4,000 and 10,000 years ago.

In those days, they most likely resembled crab apples in both appearance and taste. These are considerably smaller and less sweet than the apples you’re used to today, and can be quite sour and hard to bite into.

Apple trees today are mainly grown through grafting. Basically, this involves cutting the mid-upper parts of a growing tree, and attaching (grafting) an apple tree cutting on top. It’s quite like making a Frankenstein tree, and it’s not that hard to pull off if you know how to do it.

One interesting tidbit regarding the apple is that it often pops up in mythos as the ‘golden’ apple, usually for a hero to take back from some monster or another. Probably the earliest example of this (at least in Europe) is Greek mythology. But — and this is an important but — in Middle English, which was spoken as late as the 17th century, the word ‘apple’ was used to refer to any fruit (apart from berries), so ‘golden apples’ aren’t necessarily apples. That being said, other languages didn’t have this peculiarity, so the golden apples of Greek or Romanian mythos were, indeed, apples.

Everybody here knows what apples are. Sweet, crunchy, juicy. They keep doctors away. We won’t dwell too much on them. However, there is one last tidbit I’d like to discuss here. You might have heard that apple seeds are toxic — they are. Apple seeds contain amygdalin, which is broken down into hydrogen cyanide during digestion. Hydrogen cyanide is a decidedly deadly compound. But there’s no need to panic if you’ve bitten into a seed or six — an adult would need to ingest between 150 and a few thousand apple seeds (depending on how crushed or chewed they are) to have any issues. And, if you don’t chew them at all, they just pass harmlessly through you.

In 2019, global production of apples reached around 87.2 million metric tons, with China being the leading producer.

And now, in last place on this list, we have a bit of a tie!

Oranges and Grapes

Oranges — the common name for ‘sweet oranges’ — aren’t actually a naturally occurring fruit. They were developed by people, as a cross between the pomelo and the mandarin orange. Our earliest written evidence of the orange comes from around 300 BC, from Chinese literature.

Image via Pixabay.

Interestingly, despite its artificial origin, the sweet orange is the most cultivated fruit tree in the world, and accounts for most of the citrus production worldwide.

On the other hand, we have grapes. These are wildly-occurring fruits (berries), unlike the sweet orange. Grapes are believed to have originated in the Middle East, and we estimate they’ve been cultivated for a very long time now: between 6,000 to 8,000 years.

Needless to say, you can’t make wine without grapes. But that’s true in more ways than one — yeast, probably the first domesticated microorganism, that’s been used since time immemorial to produce alcohol, lives on the skin of grapes. Perhaps unsurprisingly, then, our earliest evidence of wine-making hails from around 8,000 years ago in present-day Georgia (the one in Europe, not America). They didn’t waste any time getting brewing, did they?

You can’t talk about any of the ancient European civilizations, nor ancient Egypt, without mentioning grapes and wine. The Phoenicians, Greeks, Romans, and people of Cyprus grew grapes for consumption and wine-making. Ancient Egyptians also grew the purple variety. These are pigmented with anthocyans, a class of colored compounds that give red wines their incredible hues.

So, why are these fruits tied? Is it because they’re both tasty and a good base for drinks? No. Is it their bright colors? Their preference for warm climates? Not really. It’s just that, production-wise, they’re pretty much neck and neck.

In 2019, global production of oranges reached 78.7 million metric tons, while that of grapes was around 77.14 million metric tons. Brazil was the single largest producer of oranges that year, while China led the way on grapes.

Is the tomato a fruit or a vegetable? Why not both?

Credit: Pixabay.

Supermarkets place tomatoes in the vegetable aisles, but botanically speaking tomatoes are ripened flower ovaries and contain seeds, which technically makes them fruit.

This segues into the age-old question: are tomatoes fruit or vegetables? Here’s an answer you can try the next time this comes up with friends over drinks, which is sure to raise some eyebrows: they’re both!

What’s the difference between fruits and vegetables, anyway?

Fruits and vegetables have more things in common than differences. For instance, both are rich sources of vitamins, minerals, and fiber.

Botanically speaking, all fruits have seeds and grow from the flower of a plant. For the purpose of simplification, vegetables are all other plant parts, such as roots, leaves, and stems.

By this classification, it’s rather clear that seedy outgrowths such as apples, squash, and, of course, tomatoes are all fruits. It also makes cucumbers, green beans, and pumpkins all fruits.

Meanwhile, roots such as beets, potatoes, and turnips, leaves such as spinach, kale, and lettuce, and stems such as celery and broccoli are all vegetables.

However, people don’t eat or cook with a botanical atlas in hand. They might use a recipe book, though, where ingredients are mixed based on their culinary characteristics, such as texture, flavor, and taste.

So, if you ask a restaurant chef, rather than a botanist, what constitutes a fruit, he will come up with a totally different classification. He would tell you that fruits must have a soft texture and are generally sweet, while vegetables are blander, sometimes bitter, and have a tougher texture.

Fruits are considered deserts, whereas vegetables are suited for savory dishes like stews, salads, and stir-fries.

Tomato: both fruit and vegetables

So, scientifically speaking tomatoes are fruit, while in the kitchen most sensible people use them as vegetables.

Which weighs more, though? I guess if you want to be a wise guy, you can go ahead and insist that tomatoes are vegetables. In everyday language, however, people prefer to refer to things by their common usage.

The USDA, for instance, agrees that tomatoes are vegetables in its official listing. Legally speaking, the US Supreme Court also classed tomatoes as vegetables in 1893 when it ruled that imported tomatoes should be taxed under the Tariff Act of 1883, which does not apply to fruit.

“Botanically speaking, tomatoes are the fruit of a vine, just as are cucumbers, squashes, beans, and peas,” Justice Horace Grey wrote in the court’s opinion at the end of the 19th century.

“But in the common language of the people … all these are vegetables which are grown in kitchen gardens, and which, whether eaten cooked or raw, are, like potatoes, carrots, parsnips, turnips, beets, cauliflower, cabbage, celery, and lettuce, usually served at dinner in, with, or after the soup, fish, or meats which constitute the principal part of the repast, and not, like fruits generally, as dessert.”

Are you confused?

You came reading this article in hopes of settling this debate once for all. I’m sorry if you’re still confused. At least you’re not alone — the tomato is the official “vegetable” of New Jersey and the official “fruit” of Arkansas. Talk about a disagreement.

Bottom line: according to science tomatoes are fruits because they form a flower and contain seeds. Common culinary sense says that tomatoes are vegetables, though. For all intents and purposes, one can say the tomato is both a fruit and vegetable.

I think this line by Miles Kington from a century ago sums up this debate nicely:

“Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.”

Urban farming can feed surprisingly many people — at least in Sheffield

Using 10% of a city’s green spaces such as gardens and urban parks could provide the fruit and vegetables to feed 15% of the local population, according to a new study.

Gateway Greening Urban Farm, St. Louis, Missouri.
Image via Wikimedia.

Researchers at the Institute for Sustainable Food at the University of Sheffield analyzed the potential of urban horticulture in feeding Sheffield citizens by mapping its green and grey spaces.

Domestic gardens, allotments, and suitable public green spaces put together would correspond to 98 square meters per person in Sheffield for growing food. Commercial horticulture across the UK currently uses around 23 square meters per person, the paper adds.

Local produce

Green spaces cover around 45% of the city, which is similar to other cities in the UK. Allotments represent 1.3% of this surface, with domestic gardens, which have immediate potential to start growing food, making up 38%.

Using data from Ordnance Survey and Google Earth, the team showed that a further 15% of the city’s green space (such as parks and roadside verges) could also be converted into community gardens relatively easily.

If all the green areas in Sheffield were to be turned over for food production, the team estimates it could provide fruits and vegetables for approximately 709,000 people per year (that number is, currently, 122% of the city’s population). But even if only 10% of available green space is used to grow food, it could provide for 87,375 people, or 15% of the city’s population. The team explains that this would greatly improve the UK’s food security, by increasing the share of locally-grown food in the economy.

The team also analyzed soil-free farming on flat roofs through means such as hydroponics (plants grown in a nutrient solution), and aquaponics (a system combining fish and plants). Such farms would allow year-round growing of food with minimal lighting requirements, and virtually no ecological impact — the greenhouses would be powered by renewable energy and heat captured from buildings, with rainwater harvesting for irrigation. The 32 hectares of flat roof cover in Sheffield would translate to only half a square meter per local, but the team says it could have a significant impact on local food security.

“At the moment, the UK is utterly dependent on complex international supply chains for the vast majority of our fruit and half of our veg — but our research suggests there is more than enough space to grow what we need on our doorsteps,” says Dr. Jill Edmondson, Environmental Scientist at the University of Sheffield and lead author of the study.

“Even farming a small percentage of available land could transform the health of urban populations, enhance a city’s environment and help build a more resilient food system.”

The paper “The hidden potential of urban horticulture” has been published in the journal Nature Food.

New genetic research effort aims to make watermelons tastier, more resilient

If you like watermelons, this team has big news for you.

Image credits Aline Ponce.

A new research effort aims to pave the way towards new and improved watermelons. The study took a comprehensive look at the genomes of all seven watermelon species to create a database that plant breeders can use to produce tastier, plumper, and more resistant watermelons.

The Better Melon

“As humans domesticated watermelon over the past 4,000 years, they selected fruit that were red, sweet and less bitter,” said Zhangjun Fei, a faculty member at Boyce Thompson Institute and co-leader of the international effort.

“Unfortunately, as people made watermelons sweeter and redder, the fruit lost some abilities to resist diseases and other types of stresses.”

Back in 2013, Fei co-led the creation of the first watermelon reference genome. This database was built from an East Asian cultivated variety ‘97103’. That variety, and likely the watermelon you’re imagining right now belongs to the Citrullus lanatus species, i.e. the sweet fruit with a juicy red interior.

However, Fei explains that there are six other wild species of watermelon that have pale, hard, bitter fruits, but possess other desirable qualities — such as a higher resilience against man-made climate change. Introducing the genes that generate such qualities into cultivated watermelon varieties can help make the fruits tastier, better able to grow in diverse climates, as well as more resistant to pests, diseases, and other factors. But, in order for us to get there, we first need to know which genes these are.

In order to find out, the team started with the reference genome Fei worked on in 2013, and created an improved version. The previous work relied on short-read sequencing technologies, Fei explains, while the newer one uses long-read sequencing technologies, allowing for “a much higher quality genome that will be a much better reference for the watermelon community.”

Next, the group sequenced the genomes of 414 watermelons across all seven species. By comparing these genomes both to the new reference genome and to each other, they were able to determine the evolutionary relationship of the different watermelon species.

“One major discovery from our analysis is that one wild species that is widely used in current breeding programs, C. amarus, is a sister species and not an ancestor as was widely believed,” Fei said.

Modern watermelon cultivars were domesticated by breeding out the fruits’ bitterness while increasing their sweetness, size, and reddening their flesh. Over the past few hundred years, the fruits kept becoming sweeter, but also improved in regards to flavor and crispiness of texture. The team identified several regions of the watermelon genome that could be leveraged to continue improving these qualities in cultivars.

“The sweet watermelon has a very narrow genetic base,” says Amnon Levi, a research geneticist and watermelon breeder at that U.S. Department of Agriculture, one of the study’s co-authors. “But there is wide genetic diversity among the wild species, which gives them great potential to contain genes that provide them tolerance to pests and environmental stresses.”

The team also published an accompanying paper analyzing 1,175 melons, including cantaloupe and honeydew varieties. The researchers found 208 genomic regions that were associated with fruit mass, quality, and morphological characteristics, which could be useful for melon breeding.

The paper “Resequencing of 414 cultivated and wild watermelon accessions identifies selection for fruit quality traits” has been published in the journal Nature Genetics.

link

The Kiwifruit duplicated its vitamin C genes twice — 20 and 50 million years ago

Kiwis employed a genetic trick, researchers say.

Fruits of different kiwi species.

Although kiwifruits are widely associated with New Zealand, they’re actually native to China, where more than half of the global kiwi supply is produced. A member of the gooseberry family, a kiwi contains about as much vitamin C as an orange, thanks in part to a genetic trick called polyploidy. Basically, the kiwifruit’s ancestors spontaneously duplicated their DNA — twice.

“Polyploidy is an abrupt evolutionary event that produces thousands of extra copies of genes overnight,” says senior author Xiyin Wang, an agricultural plant scientist at the North China University of Science and Technology. “These extra copies may greatly elevate the robustness of the plant, providing opportunities for natural selection to prune and rewire its biological system over time.”

They found these traces by comparing the kiwi genome to other related and better-studied plants: coffee and grapes. Kiwis, coffee, and grapes share a common ancestor and thus share large swaths of genetic information.

When they compared these genomes, they found that the kiwi genome had four or five copies of a gene in places where the coffee and grape genomes had only one. This particular gene was responsible for creating and recycling vitamin C.

Vitamin C isn’t only good for humans — it also contributes to plant growth and resilience, so the kiwi produced it to gain an evolutionary advantage. Meanwhile, the coffee plant didn’t need to utilize this method as its main asset was the production of caffeine — which is a natural pesticide that can also kill neighboring plant competition. Grapes, on the other hand, developed a dark pigment to give them an edge during cold spells.

Moreover, researchers say this was likely the result of an auto-polyploidization event, meaning that the kiwi duplicated its own genes (in other words, this was not a result of inter-breeding). It’s not clear how common this strategy is among other plants and plant groups.

Aside from offering some intriguing insight into the evolutionary history of the kiwi, this could also allow researchers to artificially mimic the technique, copying certain genes to grow more nutritious or disease-resistant produce.

“Our research has decoded the structure and evolution of the kiwifruit genome,” says Wang. “Kiwifruit is one important fruit, rich in vitamin C. Understanding its genomic structure may help us manipulate its genes to produce more nutritious kiwifruit.”

Wang and his team are currently looking at analyzing the genome of other agricultural plants to see whether other genes could be copied to produce more successful fruits and vegetables.

Journal Reference: iScience, Wang et al.: “Two likely auto-tetraploidization events shaped kiwifruit genome and contributed to establishment of the Actinidiaceae family.” https://www.cell.com/iscience/fulltext/S2589-0042(18)30115-9

Danger sign.

Scared? Here’s how your brain decides whether you freeze, flee, or fight

New research sheds light on how our brains react when faced with danger.

Danger sign.

Image credits spcbrass / Flickr.

Hear that? If you listen really hard, you can actually make out the sound of nothing hunting you right now. Safely ensconced in our society, we tend to take this for granted. Make no mistake, however: it’s anything but.

That’s exactly why we (and basically every other animal) evolved from the ground up with self-preservation in mind. Despite our sheltered existence, the brain circuits that generate our responses to perceived threats are still very much alive to this day. In a bid to better understand how these networks operate, and why they work the way they do, researchers at the Champalimaud Centre for the Unknown (CCU) in Lisbon, Portugal, set about to terrify the pants off some very tiny flies.

Fly, fruit fly!

“Just like any other animal in nature, our reaction to a threat is invariably one of the following three: escape, fight or freeze in place with the hope of remaining unnoticed,” says Marta Moita, co-lead author of the study.

“These behaviours are fundamental, but we still don’t know what the rules of the game are,” adds the study’s first author Ricardo Zacarias. “In each situation, how does the brain decide which of the three strategies to implement and how does it ensure that the body carries it through?”

Fruit flies (Drosophila melanogaster) might not seem like the coolest or smartest organism out there — in all honesty, they’re not — but they do have a few saving graces: they’re easy and cheap to care for in large numbers and they’re low maintenance. They also procreate fast and with a fury, so there’s always plenty of them to experiment on.

Given their simpler natures (and wings), Moita admits, many people “believed that flies only escape”, but the research showed that’s not the case. They devised an experiment in which the flies didn’t have the option of flying away and then spooked them to see their reaction.

The flies were placed in covered dishes and were then shown an expanding dark circle, which ” is how a threat looks like to a fly,” Moita explains. With flying away out of the question, the flies froze, the team reports. In a perfect mirror of the same behavior in mammals, birds, and several other species, the flies remained completely motionless for minutes on end. There’s no doubt as to why the flies froze since they would maintain positions that were obviously awkward and uncomfortable for them, such as half crouches, or holding a leg or two “suspended in the air,” Moita explains.

Some flies, however, decided to make a dash for it.

“This was very exciting,” says Vasconcelos, “because it meant that similarly to humans, the flies were choosing between alternative strategies.”

The next step was to take a closer look at what triggered each response. For this goal, the team used machine vision software to produce highly-detailed accounts of each fly’s behavior. Analyzing this data revealed that the flies’ response was determined by their walking speed at the moment the threat appeared. If the fly was walking slowly, it would freeze. By contrast, if it was traveling at speed, it would attempt to run away instead.

“This result is very important: it is the first report showing how the behavioural state of the animal can influence its choice of defensive strategy,” Vasconcelos points out.

The team later identified a single pair of neurons that underpin these defensive behaviors. The pair — with one neuron on each side of the flies’ brain — decided whether the flies would freeze or not. When the team inactivated these neurons, the flies stopped attempting to freeze and just ran away from threats all the time.

When the team artificially forced the neurons to stay active all the time, even without a threat being present, the flies would freeze depending on their walking speed — the fly would freeze if it was walking slowly, but not if it was walking quickly.

“This result places these neurons directly at the gateway of the circuit of choice,” says Zacarias.

“This is exactly what we were looking for: how the brain decides between competing strategies,” Moita adds. “And moreover, these neurons are of the type that sends motor commands from the brain to the ‘spinal cord’ of the fly. This means that they may be involved not only in the choice, but also in the execution”.

The findings should help provide a starting point for identifying how the brains of other species handle defense, the team explains, as “defensive behaviors are common to all animals”.

The paper “Speed dependent descending control of freezing behavior in Drosophila melanogaster” has been published in the journal Nature.

Mangoes may improve your cardiovascular and gut health, new study shows

Delicious and nutritious: a mango a day is good for your body, a new study on women found.

Yum!

The study was carried out on 24 postmenstrual women, who consumed two cups (330 grams) of mango every day for two weeks, after which they resumed their normal diet, eliminating any mango consumption from their diet. Researchers found that systolic blood pressure was significantly lower two hours after mango intake, compared to the baseline value. Values for pulse pressure were also significantly lower.

“This is the first study to demonstrate positive vascular effects of mango intake in humans,” said lead researcher Robert Hackman, with the UC Davis Department of Nutrition. He presented the findings today at the American Society for Nutrition annual meeting, Nutrition 2018, in Boston. “Our results build on previous animal and cell studies that point to the potential benefits of mangos to promote health.”

So how does the mango work its magic? Well, mangoes contain polyphenols, including mangiferin, quercetin, gallotannins, and gallic acid. These substances have long been suspected of having a beneficial effect on the human body, but these effects haven’t been conclusively demonstrated. While the study didn’t establish a direct causality, Hackman and colleagues suspect that these polyphenols are responsible for the improvement. For this study, researchers chose a particular type of mango rich in polyphenols (honey mango, often called Ataulfo).

Researchers also measured levels of hydrogen and methane in participants’ breath, which are an indicator for microbial fermentation in the intestinal tract. Out of the 24 women, 6 produced methane. After consuming mango, 3 of them showed a significant reduction in produced methane, which is considered a healthy improvement.

Of course, this study comes with several drawbacks. For starters, its sample size was only 24 women, which is quite small. Also, two cups of mango a day is quite a bit, and it’s unrealistic for most people. Still, results are encouraging, and seem to suggest that mango can play a significant role in a healthy diet.

This is not the first study to suggest that mango consumption can boost the body’s health. Previous studies have found that it helps fight inflammatory bowel disease, obesity, and contains a wide variety of important nutrients.

Results definitely warrant longer-term studies with a broader sample size, which researchers will look to carry out in the future.

Journal Reference: Li X, Vanness MA, Holt RR, Horn WF, Keim NL, Keen CL, Hackman RM. Effects of two weeks of daily mango fruit intake on vascular function, blood pressure and gut fermentation in healthy adult women. The FASEB Journal, June 2018.

Credit: Flickr, Hafiz Issadeen.

What gives durian, the world’s smelliest fruit, its distinctive pungent scent

Durian: you gotta love it or hate it. The infamous and divisive Southeast Asian fruit smells a lot like onions and rotten eggs, but despite the unflattering description, durian (Durio zibethinus) certainly has its following. Now, researchers have finished the first complete map of the fruit’s genome which revealed the genes responsible for its distinctive odor.

Most Westerners stay away from durian, which they often see as repulsive. Due to its stinkiness, people are banned from carrying the so-called “king of fruits” in many hotels and public transit in Singapore, for instance. The fruit can grow as large as 30 centimeters (12 in) long, 15 centimeters (6 in) in diameter, and typically weighs one to three kilograms (2 to 7 lb).

The team of researchers from Singapore, Hong Kong, and Malaysia collected specimens from around 30 species of the fruit grown in Malaysia, Thailand, and Indonesia. This included the more popular varieties like Musang King, which is unusually bitter, or Monthong, which is the sweeter sort of durian. For each species, the researchers sequenced its genome, identifying around 45,000 genes in the process, twice as many than in the human genome.

Durian is seen as delicious in Southeast Asia. Credit: Pixabay.

Durian is seen as delicious in Southeast Asia. Credit: Pixabay.

The durian genomes were then compared to those belonging to ten other different fruit-bearing plant species such as cacao (Theobroma cacao). This comparison confirmed that durian shares the most genes with cacao and cotton, which was to be expected seeing how they all belong to the same Malvales family. 

According to the paper published in Nature, the distinctive sulfur-and-onion smell is produced by a group of genes called methionine gamma lyases (MGLs), which are associated with pathways that produce sulfur-containing compounds. According to the researchers, the durian plants evolutionary benefited from this strange aroma by attracting animals that dispersed its seeds.

“Our analysis revealed that volatile sulphur production is turbocharged in durians, which fits with many people’s opinions that durian smell has a ‘sulphury’ aspect,” said geneticist Patrick Tan, who co-led the study.

This was the first and most complete genome assembly of durian. Seeing how it’s such an important edible fruit, the findings should greatly improve durian agronomy and might even help scientists breed a durian variety which is far less stinky. Although, let’s be honest, where’s the fun in that? One fan expressed a much better idea on social media: breeding avocado with durian’s odor. “Durian fans will know what I am talking about,” he said.

“The Durio genus comprises more than 30 known species, some of which do not produce edible fruit (for example, Durio singaporensis) and others that are outcompeted in nature and face extinction. Further studies will help to elucidate the ecological roles of these important and fascinating tropical plants,” the authors concluded in their paper.

Diversity in tomato fruit weight is explained in part by a mutation in the Cell Size Regulator gene that arose during domestication. Credit: Alexis Ramos and Esther van der Knaap.

Gene variant that makes plump, juicy tomatoes identified by scientists

A mutation in the Cell Size Regulator (CSR) gene responsible for making tomatoes nicely plump has been identified by American researchers. The findings might one day help farmers grow bigger tomatoes which so many people enjoy and demand.

Diversity in tomato fruit weight is explained in part by a mutation in the Cell Size Regulator gene that arose during domestication. Credit: Alexis Ramos and Esther van der Knaap.

Diversity in tomato fruit weight is explained in part by a mutation in the Cell Size Regulator gene that arose during domestication. Credit: Alexis Ramos and Esther van der Knaap.

Tomatoes, the wild kind, are originally from the Andean mountain regions of Ecuador and Northern Peru. Evidence suggests these were first cultivated by the Aztecs and Incas as early as 700 AD. By the time the conquistadors came to Central and South America, there was widespread cultivation of tomatoes, which they brought home to Europe. By the mid 16th century, it had been mentioned in a Nepalese cookbook. Ironically, though tomatoes were present in Mexico, the fruit only arrived in Canada and the United States regions after European immigrants brought it with them. Quite the detour.

Anyway, since the Aztec grew the first tomatoes, much has changed. It’s believed that your typical market-sourced tomato is 1,000 times heavier than the fruits of their ancestors. What’s more, early wild tomatoes tasted terrible and European colonists reportedly first grew them for decorative purposes. But by steadily selecting those tomato strains that were bigger, juicier, and tastier, farmers finally turned these wildlings into an essential ingredient in any modern kitchen. In fact, according to the U.S. Department of Agriculture, there are 25,000 tomato varieties.

Few tomato varieties, however, are as favored as the plump kind. Now, Esther van der Knaap and colleagues at the University of Georgia, Athens have identified the gene mutation that makes tomatoes bigger.

According to their investigation published in the journal PLOS Geneticsa mutation in the CSR gene makes the fruit heavier by increasing the size of individual cells in the pericarp, the fleshy part of the tomato. Previously, researchers located the CSR gene at the bottom of chromosome 11 as only a small genetic contributor to tomato weight but now it’s clear its influence is much more important.

“CSR is required to create the large tomatoes that are needed for the industry. This is because large tomatoes critically raise the profit margins for farmers. The knowledge of the gene will now open up avenues of research into how fruit size can be increased further without negatively impacting other important qualities such as disease resistance and flavor,” says Dr. van der Knaap.

[NOW SEE] Why supermarket tomatoes are less tastier than garden-grown

edible-fruit-map

Falling Fruit map shows where to find free food in and around your town

Why buy red cherries when you can forage them from nearby? Credit: Pexels.

Why buy red cherries when you can forage them from nearby? Credit: Pexels.

Money doesn’t grow on trees but food does. Even if you live in a mega metropolis like New York or London, you’ll still find many fruit trees in the parks or surroundings woods. Unfortunately, most of the time all these fruits are left to rot on the streets. This is a huge waste, especially when you consider half of all our food, which you probably paid for, gets thrown away. 

Seeking to address this issue, a group of dedicated young people started Falling Fruit, a non-profit that aims to build the most comprehensive map of free edibles throughout the world.

Falling Fruit imported datasets which range from small neighborhood foraging maps to vast professionally-compiled tree inventories. Foragers, foresters, and freegans are also welcome to register an account and contribute. Tagging and labeling a fruit orchard in some city park or woods is as easy as using Google Maps.

edible-fruit-map

There are many tagged fruit trees and plants in the San Francisco Bay area, for instance. Credit: Falling Fruit screenshot.

So far, Falling Fruit features 1,798 different types of edibles (most, but not all, plant species) distributed over 1,198,682 locations, most of which are in the United States.

“Falling Fruit is a celebration of the overlooked culinary bounty of our city streets. By quantifying this resource on an interactive map, we hope to facilitate intimate connections between people, food, and the natural organisms growing in our neighborhoods. Not just a free lunch! Foraging in the 21st century is an opportunity for urban exploration, to fight the scourge of stained sidewalks, and to reconnect with the botanical origins of food,” the volunteers write on their project’s website. 

You should be mindful, however, of some caveats when foraging fruit trees in cities, especially if these are heavily polluted. One of the most important contaminants alongside roadsides is particle matter — the microscopic bits of carbon that can damage our lungs when inhaled. It’s because of particle matter spewed by the exhaust of vehicles or even fossil fuel power plants that you get that ‘smoky’ appearance on buildings. A much bigger health concern, however, is the metals in the soil and air. Plants can take up metals through their roots, so there is a risk to intake mercury, arsenic, and lead. Most plants, however, don’t efficiently move metals from the roots up into the shoots so it’s unlikely to see roadside fruits contaminated with heavy metals. 

The bottom line is that you should be pretty safe eating roadside fruit most of the time, though you should be mindful of root vegetables which may be contaminated with heavy metals. Always wash roadside fruit before consuming them. Peel them before eating to be extra safe.

Happy foraging, everyone!

Lion-tail Macaque eating a fruit.

Eating fruit may have given primates their big brains, paving the way for social structures

A New York University doctoral student has found evidence that would support an alternate explanation of why primates evolved such big brains — the secret isn’t social interaction, but a diet rich in fruit, she says.

Lion-tail Macaque eating a fruit.

Lion-tail Macaque eating a fruit.
Image credits Tambako The Jaguar / Flickr.

Primates don’t have big fangs, menacing claws, or imposing horns to fight off predators or take on pray. They rely on a more subtle, but much more powerful, ace up their sleeve. Namely, primates distinguish themselves from almost all other animals through their big brains. They keep primates safe, let them do all sorts of smart things like use tools or go to the Moon, and help them navigate the ever-busy social life with grace.

Why the long brain?

But it’s not clear why they have evolved these big brains in the first place. The prevailing theory today is the social brain hypothesis, according to which primates evolved a bigger brain because they don’t have claws or horns — they needed to bunch up and work together for safety, which required more processing power to understand all the subtleties of social interaction.

A new study comes to offer another, and somewhat unexpected, explanation to the big brain: fruit. Alex DeCasien, a doctoral student in biological anthropology at the New York University initially set out to see how the brains of monogamous primates stacked up to those of more promiscuous species. She and her team collected data on the social life and diets of over 140 species throughout all four primate groups — monkeys, apes, lorises, and lemurs — and crunched all the data to see which features were most likely to associate with bigger brains.

Her results show that it’s neither monogamy nor promiscuity that best predicts the size of a primate’s brain. Neither did other measures of social complexity, such as average group size. The best indicator of brain size, the team explains, is diet — specifically whether a specie’s diet is fruit or leaf-based.

Squirrel monkey eating fruit.

Rumor has it that eating fruit also correlates well with maniacal cackles and evil in small packages. Like this guy.
Image credits Tambako The Jaguar / Flickr.

But the paper has come under some fire from one of the original authors of the social brain theory. Robin Dunbar, an evolutionary psychologist at the University of Oxford in the United Kingdom, said that while more nutrients do allow for a bigger brain, they can’t become a selective evolutionary pressure by themselves — meaning that better food makes bigger brains possible but not necessary, so they aren’t needed.

He agrees that primates who primarily consume fruits can get a whole lot more energy from their diets than leaf eaters. The nutrients in leaves are locked behind thick cell walls that are hard to break down, so leaf-eating primates have to lie around for hours redirecting all their energy towards digestion. Fruits, on the other hand, are much more nutritious and easily digested, meaning they release more energy for less investment and a lot of that extra energy gets gobbled up by the brain.

“In order to have a bigger brain, you have to have a change in diet,” Dunbar said.

But comparing diet with social life is like “comparing apples and oranges,” he argued. His main gripe with DeCasien’s theory is that it doesn’t offer a reason for which all that energy goes towards a bigger brain and not bigger muscles, for example. The social theory does link those two together, he further explains. Living together helps keep the primates safe and gives easy access to mates, two very powerful selective pressures. But it also requires a bigger, more capable brain to navigate and keep track of increasingly complex social structures — so there’s also an evolutionary incentive to invest energy in bigger brains.

“[Diet and sociality] are not alternative explanations,” Dunbar concludes. “They are complementary explanations.”

DeCasien in turn argues that fruit-eaters need more cognitive oomph to get dinner than their counterparts. If you’re a prima.. If you’re a wild leaf-eating primate chances are there will be leaves all around you, so getting dinner should be as easy as stretching out a hand to get them. Fruit-eaters on the other hand have to remember where the best fruits can be found at different times of the year, so their brain needs to be able to handle a map and a calendar app at the same time. They also need good problem solving skills, or even the capacity to use tools, since fruits can be hard to reach or protected by wooden shells or spines.

Floss silk tree bark.

Go on. Take my fruit. I dare you.
Image credits Brisbane City Council / Flickr.

So it makes sense to assume that smarter primates (those with bigger brains) could get more fruit — creating an evolutionary pressure for bigger brains. This explanation could even go so far as to making social life irrelevant to brain size, even make it a by-product of fruit diets — with bigger brains, primates could now handle social interaction so they bunched up.

Still, DeCasien admits that the answer likely isn’t as clear cut. Diets may have initially promoted brain-growth, enabling social groups — and those groups in turn then drove further evolution.

“It’s definitely impossible to tease apart at some point,” she says.

Problem is, you can’t really pick apart evolutionary pressures and beneficial physiological changes in a study such as this — because again, correlation doesn’t imply causation. But seeing the huge impact cooked food has made for humanity, it’s obvious that diet has a role to play in evolution. Whether it’s the hand that points the way or one that simply shapes in the details will have to be answered by future research.

The paper “Primate brain size is predicted by diet but not sociality” has been published in the journal Nature Ecology & Evolution.