Why have humans evolved to have less body hair than apes?
-> The only hairs that humans have completely lost are the vibrissae, or sensory whiskers. The rest of our bodies are actually covered with very short, very fine hair called vellus. The difference between humans and apes lies in the relative proportions and distribution of vellus hair compared with our longer, darker hair (known as terminal hair). There have been many different attempts to explain the relative hairlessness of humans, but so far none have achieved general consensus. It has been suggested that our hair was lost during a semi-aquatic period of our prehistory, that it was lost to allow improved cooling from sweating on the hot African savannah and even that we didn’t lose our hair until Neanderthal man started wearing clothes about 200 million years ago. This is all speculative however as hair doesn’t fossilise well so we don’t even know for sure if hairlessness is unique to humans.

Why can’t seagulls fart?
-> I can find no published study or even an oblique reference to the myth that suggests they might not! Seagulls, and birds in general, have a single opening called the cloaca, which serves for removing both the waste products of the kidneys and the intestines. This has a muscular sphincter to hold it closed, much like the anus. The bird’s digestive tract, though shorter than ours, still contains bacteria and these bacteria will produce gas. When the gas pressure exceeds the elastic strength of the cloaca sphincter, the result must inevitably be a fart. Possibly the reason seagulls might have acquired a reputation for never farting is that when a seagull poops in mid-air the person below suffers the immediate consequences. But with a mid-air fart, who’s to know?

What exactly is 20:20 vision?
-> If you have ‘perfect’ visual acuity, you have 20/20 vision, as measured by the standard eye chart devised by a Dutch ophthalmologist called Dr Hermann Snellen in 1862. The charts, which are still in use, have a single large letter at the top and lines of progressively smaller letters below. The first figure refers to how far away (in feet) the person whose vision is being measured is sitting or standing from the chart. The second figure refers to how far away a person with good vision would have to be and still be able to read the same line of letters as the person being tested. If you had 20/30 vision, a person with perfect vision could read at 30 feet the same letters that you can just make out at 20 feet. These distances are now generally expressed in metres, so that ‘perfect’ 20:20 sight would now be written as 6:6.

Could a human genetic mutation produce a superhero power?
->No, genetic mutations just cause a gene that codes for one amino acid chain to code for another slightly different chain.

Do opposites really attract?
-> No, people are likely to choose partners who are similar when it comes to three of the big five personality traits – agreeableness, conscientiousness and openness, extraversion and neuroticism.

Do lions purr?
-> All members of the cat family purr, although the Pantherinae subfamily – which includes the lion – can only purr while exhaling.

Are some people born lucky?
-> Luck is random, or it isn’t really luck. What changes from one person to another is our perception of luck and good fortune. Professor Richard Wiseman, Focus contributor and author of The Luck Factor has concluded that some people are better than others in acting upon chance opportunities and adopting a relaxed attitude that is open to new experiences. The very fact that these people think of themselves as lucky, tends to mean that they interpret their life in an optimistic way that exaggerates the effect of good luck and downplays any bad luck.

How many cigarettes would I have to smoke to become addicted?
-> Nicotine addiction is assessed using the Fagerstrom Test. This is a short questionnaire that principally assesses how many cigarettes you smoke a day, and how soon after waking you smoke your first cigarette. It takes more than a single cigarette to become hooked, but addiction in young smokers is typically established within a year of first experimenting with tobacco. LV

Why do clouds float?
-> The updraughts of warm, moist air that form clouds as they cool also serve to keep them in the sky. The total amount of water in a typical cloud weighs as much as 200 bull elephants, but it doesn’t crash down to the ground because the water is broken up into tiny droplets and ice crystals. Even the largest dropletsonly have a radius of 0.1mm. A droplet of this size falling freely would experience so much air resistance that its maximum speed would be a mere 30cm/s, but in a cloud the downward speed is balanced by the upward speed of the rising air. Only when many such droplets coalesce can they become big enough to fall as rain The air speed necessary to keep clouds ‘floating’ depends on the type of cloud. Flat, spread-out stratiform clouds are formed and supported by weak air currents rising at only a few centimeters per second. Cumulus (or convective) clouds, which are the ones responsible for heavy rain and storms, contain bigger droplets and need updraughts of a few metres per second to support them.

At what point does space begin?
-> Amazingly, more than 50 years after astronauts started exploring space, there’s still no internationally recognized legal definition of where they have ventured. NASA traditionally awards anyone who reaches an altitude of 80km ‘astronaut’s wings’. During the 1960s eight pilots from NASA’s X-15 experimental rocket plane were awarded this accolade, like the astronauts of the Mercury, Gemini and Apollo programmes, with pilot Joe Walker twice reaching a height of more than 100km in 1963. Most experts agree that missions to this altitude constitute genuine spaceflight, and it may yet become the legal standard, with lawyers in Australia in 2002 becoming the first to adopt 100km as the definition of where space begins.

Why do our noses run when we eat hot food?
-> A runny nose is normally caused by streaming eyes draining through the tear ducts into the nose. The watering eye’s response is mediated by the trigeminal nerve, which is the main facial nerve and has branches in the mouth, nose and eyes. The response probably evolved as a way of flushing the eyes and nose of irritants. With hot food, that irritant is the capsaicin oil; in cold weather, the drying effect of the wind is to blame.

How slow could I waterski before I’d sink? (I weigh 65kg)
-> A back-of-the-envelope calculation based on Newton’s Laws of Motion gives a figure of 20km/h. The lift force that keeps you up is a reaction to the force that you have to exert to move water out of the way as you travel through it. Its value depends on your speed, the area of ski in contact with the water, and the angle of attack of the skis with the water. From water-skiing photos and films it looks as though a typical angle of attack is around 15°, which gives a speed of 20km/h to just keep your weight up. Don’t take this figure too seriously though, as it doesn’t allow for frictional drag, bow wave effects or ski shape. It seems to fit with experience, however, and also with the claim that an elite K-4 kayaking team could tow a light waterskier at a record speed of just over 20km/h.

Why do humans laugh when tickled?
-> Most species respond to tickling or other light touches by withdrawing to avoid the attack on the vulnerable area. It appears that we learn to laugh at tickling as children only when we perceive the tickling as a mock attack that is actually an act of personal closeness. Interestingly, recent research by the cognitive neuroscientist Sarah-Jayne Blakemore has shown that we can’t tickle ourselves, no matter how hard we try.

Do fish drink?
-> Yes and no. While freshwater fish absorb more than enough water by osmosis through their gills, saltwater fish do drink because they lose water by osmosis.

Are Inuit loos made of ice?
-> Inuit toilets are just the same as yours or mine. The closest most Arctic people get to an igloo is watching Nanook of the North on DVD.

Can giraffes swim?
-> Yes, the BBC’s Big Cat Diary crew has filmed a giraffe swimming a short distance in Kenya’s Mara river.

Does playing music to plants help them grow?
-> No, there are a few plants that will react to sound vibration, for example Mimosa pudica, but musical appreciation is a different thing entirely.

Does peeing on a jellyfish sting really ease the pain?
-> No, urinating will probably cause even more ‘nematocysts’, tiny spring-loaded harpoons that inject venom under your skin, to fire!

Why do all planets and moons spin?
-> The reason is tied to the origins of the Solar System as a primordial Sun surrounded by initially randomly swirling clouds of dust and gas. Pulled towards the Sun by gravity, these clouds became denser, with internal collisions leading to a preferred direction of motion. Like water spiralling round a plughole, the collapsing clouds swirled in this direction at an ever-faster rate, eventually becoming dense enough to collapse under their own gravity and form spinning planets and moons. The one exception is Saturn’s moon Hyperion, which seems to have undergone a very violent impact, turning it into a potato-shaped rock that tumbles chaotically through space.

How do we know the speed of light is the same for everyone?
-> This is the assertion behind the theory of special relativity – and it’s not obvious. The speed of a train may be 200km/h to a stationary observer, but 400km/h relative to a train coming the other way. Einstein’s claim that the speed of light is the same for everyone, regardless of how they’re moving, was confirmed by experiments at CER N in Geneva. Sub-atomic particles were accelerated to 99.975 per cent of the speed of light, but when the speed of light they emitted was measured, it turned out to be 300,000km/s – the same as when the particles are stationary, as Einstein predicted.

Read the full 101 Greatest Questions of All Time in the March issue of BBC Focus. Find out more at www.bbcfocusmagazine.com

101 greatest questions of all time: 1-20
101 greatest questions of all time: 21-40
101 greatest questions of all time: 41-60

Who do you think has the most dangerous job in the world? Could it be the window washer, who dangles dozens of stories above the concrete? Perhaps it's the circus lion tamer, who regularly sticks his head in the mouths of roaring animals?

Tell your wife that she looks pretty, even if she looks like a truck.
Ricky, age 10

How can a stranger tell if two people are married?
You might have to guess, based on whether they seem to be yelling at the same kids.
Derrick, age 8

What do you think your mom and dad have in common?
Both don’t want any more kids.
Lori, age 8

What do most people do on a date?
Dates are for having fun, and people should use them to get to know each other. Even boys have something to say if you listen long enough.
Lynnette, age 8 (isn’t she a treasure?)

On the first date, they just tell each other lies and that usually gets them interested enough to go for a second date.
Martin, age 10

What would you do on a first date that was turning sour?
I’d run home and play dead. The next day I would call all the newspapers and make sure they wrote about me in all the dead columns.
Craig, age 9

When is it okay to kiss someone?
When they’re rich.
Pam, age 7

The law says you have to be eighteen, so I wouldn’t want to mess with that.
Curt, age 7

The rule goes like this: If you kiss someone, then you should marry them and have kids with them. It’s the right thing to do.
Howard, age 8

What is the right age to get married?
Twenty-three is the best age because you know the person FOREVER by then.
Camille, age 10

No age is good to get married at. You got to be a fool to get married.
Freddie, age 6 (very wise for his age)

Is it better to be single or married?
I don’t know which is better, but I’ll tell you one thing. I’m never going to have sex with my wife. I don’t want to be all grossed out.
Theodore, age 8

It’s better for girls to be single but not for boys. Boys need someone to clean up after them.
Anita, age 9 (bless you child)

How do you decide whom to marry?
You got to find somebody who likes the same stuff. Like, if you like sports, she should like it that you like sports, and she should keep the chips and dip coming.
Alan, age 10

No person really decides before they grow up who they’re going to marry. God decides it all way before, and you get to find out later who you’re stuck with.
Kristen, age 10

The world's only pink Bottlenose dolphin which was discovered in an inland lake in Louisiana, USA, has become such an attraction that conservationists have warned tourists to leave it alone.

Charter boat captain Erik Rue, 42, photographed the animal, which is actually an albino, when he began studying it after the mammal first surfaced in Lake Calcasieu, an inland saltwater estuary, north of the Gulf of Mexico in southwestern USA.

Capt Rue originally saw the dolphin, which also has reddish eyes, swimming with a pod of four other dolphins, with one appearing to be its mother which never left its side.

He said: "I just happened to see a little pod of dolphins, and I noticed one that was a little lighter.

"It was absolutely stunningly pink.

"The mammal is entirely pink from tip to tail and has reddish eyes indicating it's albinism. The skin appears smooth, glossy pink and without flaws.

"Surprisingly, it does not appear to be drastically affected by the environment or sunlight as might be expected considering its condition.

"Albinism is a genetic trait and it unclear as to the type of albinism this animal inherited."

When LEGO employees get a business card like this, they even try to match the look of the minifig (gender, hair, glasses) to the person.

It’s a brilliant way for LEGO to use their brand and to create some happiness along the way.

However, only a few LEGO employees get these - they’re expensive to make so only a few executives and people in PR roles get them.

What does your business card look like? Is it fun, surprising and memorable… or is it just like all the other ones out there.

If you need some business card inspiration, here are 51 very creative business cards.

Is the exterior of a soap bar always clean?
-> No. After use, soap has a film of water, soap and dirt left on its surface that dries out to leave the dirt stuck to the soap.

If you throw water in the air in the Russian winter, will it come back down as ice?
-> Yes. A cloud of water droplets at -30°C will fall to the ground as particles of ice.

What is ‘pins and needles’?
-> This is a form of paresthesia that is similar to, but milder than the feeling of a limb ‘going to sleep’. It can be caused by poor blood circulation but in healthy individuals it is more normally caused by compressing the nerves that run past the elbows or knees. This interrupts communication with the sensory nerve endings in the hands and feet and when the pressure is released the nerves suddenly begin firing wildly and randomly until a sensory threshold is re-established. It is normally very transient but certain medical disorders such as diabetes or hypothyroidism can cause chronic pins and needles.

Why do onions make you cry?
-> The action of cutting an onion releases a fine spray of droplets. Recent Japanese research has shown that these droplets contain an enzyme called lachrymatoryfactor synthase and sulphur-containing compounds, which react to produce a powerful irritant called Syn-propanethial- S-oxide. When a droplet strikes your eye, you respond by producing a copious flow of tears to try and wash the irritant away.

What happens to cells in our bodies when they die?
-> Cells on the surface of our bodies or in the lining of our gut are sloughed off and discarded. Those inside our bodies are scavenged by phagocytes – white blood cells that ingest other cells. The energy from the dead cells is partly recycled to make other white cells.

Do left-handed people think more laterally?
-> No, there are no studies to suggest the creative ability to see unusual or surprising solutions to problems varies between left- and right-handers

Can we correct colour blindness?
-> No, colour blindness is caused by an inherited defect in the genes that code for the colour-sensitive proteins in the eye.

Do any stars escape from their galaxies and roam through the Universe?
-> Yes, a star can end up hurled out of a galaxy after approaching a black hole on a trajectory that accelerates it above the galaxy’s escape velocity.

Does the size of your head affect your IQ?
-> No, a 1998 study concluded that there is a correlation between head size and brain size, but that IQ was not related to size, at least not in young, healthy adults.

Can the government track you if you have a GPS-enabled mobile phone?
-> Yes, if your phone has GPS, your location could be relayed to an operator, but you’d have to be on the phone to them.

How are birds’ feathers waterproofed?
-> Birds pick up oil on their beaks, by rubbing against the uropygial or preen gland near the tail, and then rub it over their feathers. This coating insulates the interlocking barbules in the feather. As water cannot penetrate through the oil coating, the feather is waterproof. LV

Why are lobsters cooked alive and do they feel pain?
-> Lobsters and other shellfish have harmful bacteria naturally present in their flesh. Once the lobster is dead, these bacteria can rapidly multiply and release toxins that may not be destroyed by cooking. You therefore minimise the chance of food poisoning by cooking the lobster alive. That’s great for us but what about the lobster? It has been argued that lobsters do not possess a true brain and so can’t feel pain. It is fair to say that they are not self-aware in the same way that we are, but they do react to tissue damage both physically and hormonally, so they are obviously capable of detecting pain on some level. In fact, the hormone that they release into the bloodstream, cortisol, is the same one that humans produce when hurt. But the most visible sign of distress is the twitching tail, which evolved as an escape reflex. Researchers at the University of Maine found that putting the lobster on ice for 15 minutes before dropping it into boiling water produced the shortest tail-twitching interval (20 seconds). Contrary to the popular urban myth though, placing the lobster in cold water that is then slowly brought to the boil does not anaesthetise the animal and appears to extend its suffering.

Why don’t spiders get stuck in their own webs?
-> A spider’s web is built like a bicycle wheel, with an outer rim and spokes running to the centre, and then a spiral from the centre back out to the rim. The spiral is the only bit that is coated with glue – the spokes and outer rim are made from dry silk. The spider mostly avoids the sticky sections as it moves and it has very minimal contact with the web, in any case. On top of this, spiders constantly groom their legs to keep them clear of silk and glue.

How high must you sing to shatter a wine glass?
-> The note that a wine glass makes when you hit it is its resonant frequency – the frequency at which the glass vibrates most efficiently. If you can match this tone you can smash the glass. The note will be around one octave above middle C, depending on the size of the glass. The real trick is singing loudly enough. Even with expensive,glasses, which vibrate with a clear tone that doesn’t damp down quickly, the amplitude required is at the limit for the human voice. An untrained singer can do it relatively easily with good amplification but achieving the same thing without a speaker has only been done once on TV, by singer and voice coach Jaime Vendera for the Discovery Channel’s Mythbusters show.

What would happen if there were no Moon?
-> The most immediate effect (other than the lack of moonlight, of course) would be on the Earth’s tides. With only the Sun’s gravitational influence, the difference between high and low tides would be reduced dramatically – as would tidal drag, which slows the Earth down at a rate adding about 0.002 seconds to the length of a day each century. Long term, the effects would be far more serious. The climate of the Earth is sensitively dependent on the 23.5° tilt of the Earth’s axis, and without the stabilising presence of our relatively huge Moon, the gravity of the other planets would produce big changes in this angle – as it does with Mars, whose tilt changes by 60° over a few million years.

Why do drugs have a shelf-life?
-> Cynics argue that shelflives are just invented by pharmaceutical companies to make us buy fresh batches of perfectly good drugs. In reality, government regulators demand extensive testing to find out how long the compounds retain their potency. When they’re kept at room temperature, the molecules that make up the drugs degrade just like foodstuffs – and can, in some antibiotics at least, even turn toxic. RM

Why do your eyes water when your nose is hit?
-> The nose is soft and sensitive, and the nasal passage is connected to the eyes via the tear ducts. Normally this allows the lacrimal fluid (tears) to drain through the nose. But when the fluid build-up in the nose is sufficient, the flow can block the normal draining path, so that the tears that are produced have nowhere to go.

Why do humans cry?
-> We produce three different kinds of tears. Basal tears lubricate the eyeball and make it optically smoother. These are produced continuously at a rate of almost 300ml a day. Reflex tears are produced in response to physical or chemical stimulus and wash away irritants. The third kind is produced in response to high levels of emotion. This stimulates the cranial nerve in the brain, which sends neurotransmitters to the lachrymal glands. It also raises the blood pressure in the face, which tends to increase the flow of tears. Emotional tears contain high levels of manganese and the hormone prolactin (which normally stimulates the mammary glands to produce milk). Humans are the only animals that cry in this way and it has been suggested that emotional crying may have evolved as a way to remove excess levels of certain chemicals and only later became ritualised as a way of signaling emotional distress.

Can dock leaves really sooth nettle stings?
-> No, the myth of dock leaves soothing nettle stings arose because of parents’ desires to find something close by with which to placate their stung child.

Read the full 101 Greatest Questions of All Time in the March issue of BBC Focus. Find out more at www.bbcfocusmagazine.com

101 greatest questions of all time: 1-20
101 greatest questions of all time: 21-40

"Very, very convincing footprints have been found," at 19,000-foot elevations, he said. "Nobody goes up to 19,000 feet just to make a joke."

Japanese mountaineers took this photo in September 2008 of what they believe is a yeti footprint.

It was taken on Mount Dhaulagiri at an altitude of 14,600 feet in northern Nepal. The group's leader, Yoshiteru Takahashi, said he saw a yeti in 2003. "It was in silhouette, it was walking on two legs like a human and looked about 150 centimeters [5 feet] tall."

Legend of the creature inhabiting the Himalayas dates back to at least the 1800s.

Do you believe that yeti exists?