science
Answers are hidden until you reveal them.
What is the difference between an ocean and a sea?
Our guess
A sea is smaller and partially enclosed by land, while oceans are contiguous.
A sea is smaller and partially enclosed by land, while oceans are contiguous.
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The answer
Seas are smaller than oceans and usually sit where land and ocean meet, partially enclosed by land; there is no single overarching rule.
Seas are smaller than oceans and usually sit where land and ocean meet, partially enclosed by land; there is no single overarching rule.
Verdict right
What is the longest continuous mountain range?
Our guess
Split between the Rockies and the Andes; settled on the Andes.
Split between the Rockies and the Andes; settled on the Andes.
Reveal the answer
The answer
The Andes, about 7,000 km.
The Andes, about 7,000 km.
Verdict right
What is Jupiter made of?
Our guess
Mostly gas, possibly with mercury vapors and sulfur, and maybe a small rocky core.
Mostly gas, possibly with mercury vapors and sulfur, and maybe a small rocky core.
Reveal the answer
The answer
Mostly hydrogen and helium, probably with a solid core of heavy elements. A swirling liquid metal ocean creates the strongest magnetic field in the solar system. It has 67 moons, 53 of them named.
Mostly hydrogen and helium, probably with a solid core of heavy elements. A swirling liquid metal ocean creates the strongest magnetic field in the solar system. It has 67 moons, 53 of them named.
Verdict partly
Why are dogs' noses wet?
Our guess
It helps them smell, by dissolving scents, and possibly cools them down.
It helps them smell, by dissolving scents, and possibly cools them down.
Reveal the answer
The answer
Moisture helps capture scent particles, and the wet nose also helps regulate body temperature.
Moisture helps capture scent particles, and the wet nose also helps regulate body temperature.
Verdict right
What is the difference between a llama and an alpaca?
Episode 6: Like a Chorizo (00:00)
Our guess
Closely related but different animals; alpacas live at higher altitude and are used for fur, llamas are pack animals.
Closely related but different animals; alpacas live at higher altitude and are used for fur, llamas are pack animals.
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The answer
Both are domesticated South American camelids. Llamas are bigger (up to about 400 lb) and bred as pack animals; alpacas are smaller (100-175 lb) and bred for fiber for about 6,000 years. Llamas have long banana-shaped ears, alpacas shorter spear-shaped ones. They can crossbreed, producing a huarizo.
Both are domesticated South American camelids. Llamas are bigger (up to about 400 lb) and bred as pack animals; alpacas are smaller (100-175 lb) and bred for fiber for about 6,000 years. Llamas have long banana-shaped ears, alpacas shorter spear-shaped ones. They can crossbreed, producing a huarizo.
Verdict right
What makes an animal domesticated?
Episode 6: Like a Chorizo (02:50)
Our guess
Being specifically bred for domestication, not just able to survive in the wild.
Being specifically bred for domestication, not just able to survive in the wild.
Reveal the answer
No answer was established.
Verdict unresolved
What is the history of daylight saving time, and what is it for?
Our guess
Started by Benjamin Franklin to help farmers; standardized time came from trains; Indiana adopted it in the mid-2000s.
Started by Benjamin Franklin to help farmers; standardized time came from trains; Indiana adopted it in the mid-2000s.
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The answer
Franklin only suggested Parisians save candles by waking earlier. George Hudson proposed modern DST in 1895; Germany and Austria-Hungary first used it nationally in 1916, with Port Arthur, Ontario trying it in 1908. The US adopted it under FDR in 1942 and standardized rules with the Uniform Time Act of 1966. A 2008 study found Indiana's adoption raised household electricity use by 1-4%.
Franklin only suggested Parisians save candles by waking earlier. George Hudson proposed modern DST in 1895; Germany and Austria-Hungary first used it nationally in 1916, with Port Arthur, Ontario trying it in 1908. The US adopted it under FDR in 1942 and standardized rules with the Uniform Time Act of 1966. A 2008 study found Indiana's adoption raised household electricity use by 1-4%.
Verdict partly
What is the difference between a panther, a jaguar, a cougar and a mountain lion?
Our guess
Black cats vs. brown cats; the mountain lion is a puma, and the panther is a separate black cat.
Black cats vs. brown cats; the mountain lion is a puma, and the panther is a separate black cat.
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The answer
Cougar, puma, mountain lion and catamount are all the same animal. "Panther" is a loose term for leopards, jaguars or any black (melanistic) big cat. The four big cats in the genus Panthera are lions, tigers, leopards and jaguars; cheetahs are a separate genus. The lynx group includes four species, including the bobcat.
Cougar, puma, mountain lion and catamount are all the same animal. "Panther" is a loose term for leopards, jaguars or any black (melanistic) big cat. The four big cats in the genus Panthera are lions, tigers, leopards and jaguars; cheetahs are a separate genus. The lynx group includes four species, including the bobcat.
Verdict partly
What is the difference between a sweet potato and a yam?
Episode 17: I Yam What I Yam (00:30)
Our guess
Possibly the same thing with regional names, a marketing ploy, or closely related vegetables.
Possibly the same thing with regional names, a marketing ploy, or closely related vegetables.
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The answer
They are different plants. True yams (genus Dioscorea) are native to Africa, starchy, dry, white-fleshed and bark-skinned, while sweet potatoes are in the morning glory family. Most US "yams" are soft sweet potatoes; the mix-up goes back to the African word "nyami".
They are different plants. True yams (genus Dioscorea) are native to Africa, starchy, dry, white-fleshed and bark-skinned, while sweet potatoes are in the morning glory family. Most US "yams" are soft sweet potatoes; the mix-up goes back to the African word "nyami".
Verdict partly
Why do rabbits have little cotton-ball tails?
Episode 22: Too Cute To Kill (00:30)
Our guess
Not balance; more likely self-defense, such as confusing predators with the white flash or masking scent, or a vestigial leftover.
Not balance; more likely self-defense, such as confusing predators with the white flash or masking scent, or a vestigial leftover.
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The answer
A biologist's theory is that the white tail confuses predators during the chase: it disappears when the rabbit turns, forcing the predator to refocus. The research is not peer reviewed. Deer may also flick their tails to signal danger.
A biologist's theory is that the white tail confuses predators during the chase: it disappears when the rabbit turns, forcing the predator to refocus. The research is not peer reviewed. Deer may also flick their tails to signal danger.
Verdict right
Why are fire engines red?
Our guess
Red is the color of fire and stands out in traffic; early volunteer departments painted them whatever was cheap, such as old barn paint.
Red is the color of fire and stands out in traffic; early volunteer departments painted them whatever was cheap, such as old barn paint.
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The answer
There is no definitive answer. Popular theories are that red was the cheapest paint for poor volunteer departments, that it stood out among black vehicles, and that rival 1800s fire brigades chose it because it was an expensive, regal color. Lime green trucks are actually easier to see at night.
There is no definitive answer. Popular theories are that red was the cheapest paint for poor volunteer departments, that it stood out among black vehicles, and that rival 1800s fire brigades chose it because it was an expensive, regal color. Lime green trucks are actually easier to see at night.
Verdict partly
Why do we measure rain in inches instead of by volume?
Episode 28: The Angel Sniper (00:00)
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The answer
Not directly answered; the hosts only found that the standardized instrument is called a pluviometer (or ombrometer).
Not directly answered; the hosts only found that the standardized instrument is called a pluviometer (or ombrometer).
Verdict unresolved
Why do zebras have stripes?
Episode 43: Zeal or Dazzle (00:34)
Our guess
Heat regulation, or confusing predators when the herd runs together.
Heat regulation, or confusing predators when the herd runs together.
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The answer
Unsettled. A newer UCLA study suggests the black stripes help zebras stay cool in the midday heat, while the long-standing consensus is camouflage or confusing predators, with little direct evidence. A group of zebras is called a zeal or a dazzle.
Unsettled. A newer UCLA study suggests the black stripes help zebras stay cool in the midday heat, while the long-standing consensus is camouflage or confusing predators, with little direct evidence. A group of zebras is called a zeal or a dazzle.
Verdict partly
How do volcanoes work, and are there volcanoes on every continent?
Our guess
A channel from the mantle where pressure builds until an eruption; probably none in Antarctica; "dormant" is basically extinct.
A channel from the mantle where pressure builds until an eruption; probably none in Antarctica; "dormant" is basically extinct.
Reveal the answer
The answer
Volcanoes are active, dormant or extinct depending on recent activity. There are volcanoes on every continent, including 91 newly discovered ones beneath Antarctic ice. About 1,900 are considered active, and Mauna Loa is the largest. The word comes from the Roman god Vulcan.
Volcanoes are active, dormant or extinct depending on recent activity. There are volcanoes on every continent, including 91 newly discovered ones beneath Antarctic ice. About 1,900 are considered active, and Mauna Loa is the largest. The word comes from the Roman god Vulcan.
Verdict partly
Why is red universally stop and green universally go?
Our guess
Red came first, tied to danger, blood or nautical lights, and green was chosen as the contrasting color after cars arrived.
Red came first, tied to danger, blood or nautical lights, and green was chosen as the contrasting color after cars arrived.
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The answer
The scheme comes from railroads, which have used it since the 1830s: red for stop because it signaled danger, white for go and green for caution. After a 1914 accident when a red lens fell out and white showed, green became "go". Automatic signals followed in the late 1920s.
The scheme comes from railroads, which have used it since the 1830s: red for stop because it signaled danger, white for go and green for caution. After a 1914 accident when a red lens fell out and white showed, green became "go". Automatic signals followed in the late 1920s.
Verdict partly
Is a slug just a snail without a shell?
Our guess
They are closely related but distinct species, because snails grow their own shell and slugs never do.
They are closely related but distinct species, because snails grow their own shell and slugs never do.
Reveal the answer
The answer
Both are gastropods in the phylum Mollusca, and slugs often have a small internal or vestigial shell. They are closely related but separate species, and land snails and slugs are the only gastropods living on land. Snails live 2 to 3 years in the wild and up to 15 in captivity.
Both are gastropods in the phylum Mollusca, and slugs often have a small internal or vestigial shell. They are closely related but separate species, and land snails and slugs are the only gastropods living on land. Snails live 2 to 3 years in the wild and up to 15 in captivity.
Verdict right
Where do coyotes and hyenas come from if dogs come from wolves?
Episode 67: Dogma (00:31)
Our guess
They're not descended from wolves or dogs; coyotes, wolves and perhaps hyenas share a common ancestor.
They're not descended from wolves or dogs; coyotes, wolves and perhaps hyenas share a common ancestor.
Reveal the answer
The answer
The gray wolf and coyote are close relatives from a common ancestor and were not bred by humans. Hyenas are not canids at all; they are their own family and are more closely related to cats than to dogs.
The gray wolf and coyote are close relatives from a common ancestor and were not bred by humans. Hyenas are not canids at all; they are their own family and are more closely related to cats than to dogs.
Verdict right
Why do we yawn, and why does yawning make other people yawn?
Our guess
An oxygen grab by a tired body, with contagion as a social or empathy cue that alerts the group.
An oxygen grab by a tired body, with contagion as a social or empathy cue that alerts the group.
Reveal the answer
The answer
There is no consensus on why we yawn (theories include respiration, cooling the brain and stretching tissue). Contagious yawning affects about 60% of healthy humans and is seen in chimps, dogs and others. It is linked to empathy and does not appear in children until around age four.
There is no consensus on why we yawn (theories include respiration, cooling the brain and stretching tissue). Contagious yawning affects about 60% of healthy humans and is seen in chimps, dogs and others. It is linked to empathy and does not appear in children until around age four.
Verdict partly
Why is February the shortest month?
Episode 78: Ol' Silent "R" (00:32)
Our guess
A Roman or Julian calendar fix, a math adjustment, or superstition.
A Roman or Julian calendar fix, a math adjustment, or superstition.
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The answer
The first Roman calendar had 10 months, beginning in March. King Numa added January and February, giving them 28 days, and made January 29 because even numbers were considered unlucky, leaving February short. The Julian reform in 46 BC and Gregorian reform in 1582 kept that structure.
The first Roman calendar had 10 months, beginning in March. King Numa added January and February, giving them 28 days, and made January 29 because even numbers were considered unlucky, leaving February short. The Julian reform in 46 BC and Gregorian reform in 1582 kept that structure.
Verdict partly
How does praying mantis reproduction work given that the female may eat the male?
Episode 80: Snack Sized (00:37)
Our guess
Large clutches of eggs, possibly skewed toward males, with cannibalism not happening every time.
Large clutches of eggs, possibly skewed toward males, with cannibalism not happening every time.
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The answer
Cannibalism occurs in about 25% of encounters and is mostly seen in captivity, driven largely by hunger. Cannibalistic females laid more eggs (about 88 vs. 37 in one study). An egg case hatches 100-200 mantises, of which only about a third reach maturity.
Cannibalism occurs in about 25% of encounters and is mostly seen in captivity, driven largely by hunger. Cannibalistic females laid more eggs (about 88 vs. 37 in one study). An egg case hatches 100-200 mantises, of which only about a third reach maturity.
Verdict right
If a poisonous snake bites you, should you suck out the venom?
Our guess
No, it doesn't help and wastes precious minutes; get to medical care, and a tourniquet is a better option.
No, it doesn't help and wastes precious minutes; get to medical care, and a tourniquet is a better option.
Reveal the answer
No answer was established.
Verdict unresolved
Is horseradish actually a radish, and why is it called horseradish?
Episode 84: Rad-ish (01:42)
Our guess
A root vegetable related to radishes from Asia or Europe, named for being a strong, coarse "horse" version of a radish, or from a mistranslation.
A root vegetable related to radishes from Asia or Europe, named for being a strong, coarse "horse" version of a radish, or from a mistranslation.
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The answer
Both are in the mustard family (Brassicaceae) but are different species. Horseradish is probably native to southeastern Europe or western Asia, and the English word dates to the 1590s, with "horse" meaning strong or coarse. One theory is a mix-up with the German "meerrettich" (sea radish).
Both are in the mustard family (Brassicaceae) but are different species. Horseradish is probably native to southeastern Europe or western Asia, and the English word dates to the 1590s, with "horse" meaning strong or coarse. One theory is a mix-up with the German "meerrettich" (sea radish).
Verdict partly
Why do flamingos stand on one leg?
Episode 89: Crop Milk (00:33)
Our guess
To save energy and ease circulation for their long legs and small heart, and to avoid both feet getting stuck.
To save energy and ease circulation for their long legs and small heart, and to avoid both feet getting stuck.
Reveal the answer
The answer
A locking joint lets them stand on one leg with no muscle effort, and tucking a leg also reduces heat loss through their legs and feet. A study found they stand on one leg more in colder water. They are pink from carotenoids in algae and brine shrimp.
A locking joint lets them stand on one leg with no muscle effort, and tucking a leg also reduces heat loss through their legs and feet. A study found they stand on one leg more in colder water. They are pink from carotenoids in algae and brine shrimp.
Verdict right
Where does "proof" in alcohol come from, and why is it double the ABV?
Episode 91: Specific Gravity (00:32)
Our guess
A code for bootleggers or a way to cut grain alcohol, linked to "proving" as in yeast proving in bread.
A code for bootleggers or a way to cut grain alcohol, linked to "proving" as in yeast proving in bread.
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The answer
Dates to 16th-century England, where spirits were taxed by a burn test (alcohol that ignited was "over proof"). In 1816 England defined 100 proof by specific gravity (about 57% ABV), and the US simplified it to exactly twice the ABV. "Proof" comes from the Latin "probare" (to test), and bread proofing shares that root.
Dates to 16th-century England, where spirits were taxed by a burn test (alcohol that ignited was "over proof"). In 1816 England defined 100 proof by specific gravity (about 57% ABV), and the US simplified it to exactly twice the ABV. "Proof" comes from the Latin "probare" (to test), and bread proofing shares that root.
Verdict partly
Where did all of Earth's water come from?
Episode 94: Impact Hypothesis (01:16)
Our guess
Volcanic outgassing as the planet cooled, building an atmosphere, plus water brought by comets and meteors.
Volcanic outgassing as the planet cooled, building an atmosphere, plus water brought by comets and meteors.
Reveal the answer
The answer
Not settled, but the leading idea is that much of it arrived from asteroids and comets (the deuterium-to-hydrogen ratio matches asteroids), possibly including the giant impact that formed the Moon. Outgassing from the early magma ocean contributed, and an atmosphere was needed to hold it.
Not settled, but the leading idea is that much of it arrived from asteroids and comets (the deuterium-to-hydrogen ratio matches asteroids), possibly including the giant impact that formed the Moon. Outgassing from the early magma ocean contributed, and an atmosphere was needed to hold it.
Verdict right
Is "heat lightning" a real thing?
Episode 98: Grill That Bird (00:32)
Our guess
It's just regular lightning, perhaps cloud-to-cloud lightning with no thunder or storm directly overhead.
It's just regular lightning, perhaps cloud-to-cloud lightning with no thunder or storm directly overhead.
Reveal the answer
The answer
No. "Heat lightning" is ordinary lightning from a distant thunderstorm that is too far away for the thunder to be heard, and cloud-to-cloud lightning is common.
No. "Heat lightning" is ordinary lightning from a distant thunderstorm that is too far away for the thunder to be heard, and cloud-to-cloud lightning is common.
Verdict right
Why isn't every animal an elephant, since they are big, smart and have no real predators?
Our guess
Resource limits and slow reproduction, ecosystem diversity, and humans hunting big animals.
Resource limits and slow reproduction, ecosystem diversity, and humans hunting big animals.
Reveal the answer
The answer
No single answer. Elephants gestate for about two years and have one calf at a time, and their calorie demands cap population growth. Different species use different survival strategies (many offspring vs. few), and ecosystems depend on diversity. Humans are now the main predator of elephants.
No single answer. Elephants gestate for about two years and have one calf at a time, and their calorie demands cap population growth. Different species use different survival strategies (many offspring vs. few), and ecosystems depend on diversity. Humans are now the main predator of elephants.
Verdict unresolved
Why aren't humans furry?
Episode 108: Sexual Drift (01:19)
Our guess
Temperature control: sweating works better on bare skin, clothing replaced fur, big brains generate heat, and sexual selection or parasite control may have played a role.
Temperature control: sweating works better on bare skin, clothing replaced fur, big brains generate heat, and sexual selection or parasite control may have played a role.
Reveal the answer
The answer
No universally accepted answer. Leading ideas: thermoregulation (humans have the most sweat glands of any primate, which works better without fur when chasing prey on the savanna), parasite control, an aquatic-ape theory, sexual selection, and a "naked love" hypothesis that hairlessness increased maternal care.
No universally accepted answer. Leading ideas: thermoregulation (humans have the most sweat glands of any primate, which works better without fur when chasing prey on the savanna), parasite control, an aquatic-ape theory, sexual selection, and a "naked love" hypothesis that hairlessness increased maternal care.
Verdict partly
How does color photography and color film work?
Episode 112: Messed Up, Man (01:08)
Our guess
Film with three layers sensitive to different primary colors (red, green, blue) producing a color negative; digital pixels respond to one of three wavelengths. Mid-to-late 1930s.
Film with three layers sensitive to different primary colors (red, green, blue) producing a color negative; digital pixels respond to one of three wavelengths. Mid-to-late 1930s.
Reveal the answer
The answer
The three-color method was suggested by James Clerk Maxwell in 1855 and Thomas Sutton produced the first color photograph in 1861. Kodachrome (1935) was the first modern three-layer color film. Digital sensors have pixels responsive to red, green or blue.
The three-color method was suggested by James Clerk Maxwell in 1855 and Thomas Sutton produced the first color photograph in 1861. Kodachrome (1935) was the first modern three-layer color film. Digital sensors have pixels responsive to red, green or blue.
Verdict right
Do fish actually drink water?
Our guess
They take in water through their mouths and gills, with saltwater fish handling salt differently from freshwater fish.
They take in water through their mouths and gills, with saltwater fish handling salt differently from freshwater fish.
Reveal the answer
The answer
Saltwater fish do drink water, directing some of it into the digestive tract to keep hydrated, while freshwater fish absorb water through their skin and gills by osmosis and do not need to drink.
Saltwater fish do drink water, directing some of it into the digestive tract to keep hydrated, while freshwater fish absorb water through their skin and gills by osmosis and do not need to drink.
Verdict right
Why do we name hurricanes alphabetically, and when did that start?
Episode 115: Space Hangovers (00:31)
Our guess
Late 1950s-early 1960s, with alphabetical female names, with male names added later.
Late 1950s-early 1960s, with alphabetical female names, with male names added later.
Reveal the answer
The answer
In the early 1950s the National Hurricane Center used the phonetic alphabet (Able, Baker, Charlie), switched to alphabetical female names in 1953, and added male names in 1978-79. A storm is named once its winds reach 39 mph.
In the early 1950s the National Hurricane Center used the phonetic alphabet (Able, Baker, Charlie), switched to alphabetical female names in 1953, and added male names in 1978-79. A storm is named once its winds reach 39 mph.
Verdict right
Why does a drop in barometric pressure signal a hurricane?
Episode 115: Space Hangovers (04:24)
Our guess
A hurricane is a massive low-pressure system that sucks in warm air.
A hurricane is a massive low-pressure system that sucks in warm air.
Reveal the answer
The answer
The eye of a hurricane is extremely low pressure, because warm air rises there, creating a cyclone. The lowest recorded pressure was Typhoon Tip at 870 millibars in 1979.
The eye of a hurricane is extremely low pressure, because warm air rises there, creating a cyclone. The lowest recorded pressure was Typhoon Tip at 870 millibars in 1979.
Verdict right
Can it be too cold to snow?
Our guess
No, it needs moisture; very cold air holds less moisture, so snow is less likely, but it can't be too cold in principle.
No, it needs moisture; very cold air holds less moisture, so snow is less likely, but it can't be too cold in principle.
Reveal the answer
The answer
It can be too warm to snow but not too cold. Snow can fall at very low temperatures given a moisture source, but heavy snowfall tends to occur when the air near the ground is relatively warm (about -9 C or warmer) because warmer air holds more water vapor. Very cold air is just too dry.
It can be too warm to snow but not too cold. Snow can fall at very low temperatures given a moisture source, but heavy snowfall tends to occur when the air near the ground is relatively warm (about -9 C or warmer) because warmer air holds more water vapor. Very cold air is just too dry.
Verdict right
What is a nautical mile, and why is it different from a land mile?
Episode 129: Oblate Spheroid (02:38)
Our guess
A unit based on latitude and longitude, about 15-20% longer than a land mile, used for navigation.
A unit based on latitude and longitude, about 15-20% longer than a land mile, used for navigation.
Reveal the answer
The answer
A nautical mile is one minute of latitude (about 1.15 statute miles). France tied it to the 1791 definition of the meter (one ten-millionth of a quarter meridian), and navigation by latitude and longitude took hold around 1500. A knot is one nautical mile per hour, originally measured by counting knots on a rope with a "common log". The statute mile goes back to the Roman 1,000 paces.
A nautical mile is one minute of latitude (about 1.15 statute miles). France tied it to the 1791 definition of the meter (one ten-millionth of a quarter meridian), and navigation by latitude and longitude took hold around 1500. A knot is one nautical mile per hour, originally measured by counting knots on a rope with a "common log". The statute mile goes back to the Roman 1,000 paces.
Verdict right
Why do mosquitoes exist, and should we kill them all?
Our guess
They're food for birds, bats and fish and part of the food chain; gene editing might reduce disease carriers.
They're food for birds, bats and fish and part of the food chain; gene editing might reduce disease carriers.
Reveal the answer
The answer
Mosquito larvae feed fish and adults feed birds, bats and frogs, and males pollinate plants. Of about 3,500 species, only about 400 transmit diseases. Researchers are using CRISPR to make mosquitoes incapable of carrying disease or infertile instead of eradicating them.
Mosquito larvae feed fish and adults feed birds, bats and frogs, and males pollinate plants. Of about 3,500 species, only about 400 transmit diseases. Researchers are using CRISPR to make mosquitoes incapable of carrying disease or infertile instead of eradicating them.
Verdict right
Why is a rice cooker cup a different size from a measuring cup?
Episode 151: No Pressure (02:35)
Our guess
The rice cooker's "cup" is really a scoop or a metric-based unit, translated as "cup", perhaps from Japan.
The rice cooker's "cup" is really a scoop or a metric-based unit, translated as "cup", perhaps from Japan.
Reveal the answer
The answer
A rice cooker cup is about 180 ml, while a US cup is about 240 ml. The rice cooker uses a traditional Japanese measure (similar in volume to a sake cup), so the two are not interchangeable.
A rice cooker cup is about 180 ml, while a US cup is about 240 ml. The rice cooker uses a traditional Japanese measure (similar in volume to a sake cup), so the two are not interchangeable.
Verdict right
How can there be seedless fruit, and how does it reproduce?
Our guess
Crossbreeding and genetic engineering produce seedless fruit, and clones keep the plants going.
Crossbreeding and genetic engineering produce seedless fruit, and clones keep the plants going.
Reveal the answer
The answer
Seedless grapes began as a natural mutation (known since ancient Rome) and fruit plants are propagated from cuttings or grafting, so they are genetic clones. Seedless watermelons are triploid (three sets of chromosomes) from crossing a diploid with a tetraploid, which makes them unable to reproduce.
Seedless grapes began as a natural mutation (known since ancient Rome) and fruit plants are propagated from cuttings or grafting, so they are genetic clones. Seedless watermelons are triploid (three sets of chromosomes) from crossing a diploid with a tetraploid, which makes them unable to reproduce.
Verdict right
What is the difference between a jungle and a forest?
Our guess
The kinds of trees or the amount of rain, with "jungle" a pejorative term Europeans applied to tropical forests.
The kinds of trees or the amount of rain, with "jungle" a pejorative term Europeans applied to tropical forests.
Reveal the answer
The answer
"Jungle" is not a scientific term: it comes from Hindi (from Sanskrit "jangala", dry or uncultivated land), recorded in English in 1776, and was a colloquial term for tropical forests with very dense tangled undergrowth. Scientists call them tropical forests or rainforests.
"Jungle" is not a scientific term: it comes from Hindi (from Sanskrit "jangala", dry or uncultivated land), recorded in English in 1776, and was a colloquial term for tropical forests with very dense tangled undergrowth. Scientists call them tropical forests or rainforests.
Verdict partly
Why do dogs wag their tails?
Our guess
Nonverbal communication, plus balance, temperature regulation, hygiene or swimming (rudder).
Nonverbal communication, plus balance, temperature regulation, hygiene or swimming (rudder).
Reveal the answer
The answer
Mainly communication of excitement and mood, and tails also help with balance, temperature regulation (blood vessels) and swimming. A 2013 Current Biology study found dogs wag more to the right when relaxed or happy and more to the left when stressed or anxious.
Mainly communication of excitement and mood, and tails also help with balance, temperature regulation (blood vessels) and swimming. A 2013 Current Biology study found dogs wag more to the right when relaxed or happy and more to the left when stressed or anxious.
Verdict right