Could you really inject someone else's memories? Could your brain be kept alive after your head is removed from your body? And will kissing enough frogs really see you find your prince? One book answers all these questions. Nick Morrison reports.

AT birth, Lucia Zarate weighed just under two and a half pounds. Today, a premature baby at that weight would have a good chance of survival, but Lucia was not premature. Instead, she suffered a severe form of dwarfism, which not only meant she started off small, but she was unable to grow and put on weight.

By the time she was 17, her weight had barely doubled, to just over four and a half pounds. She was heaviest when she was 20, at 13lbs. At two feet two and a half inches tall, Lucia was believed to be the smallest human ever to have lived.

The basis of dwarfism, commonly called dysplasia, is genetic, but nutrition can also play a role. Living in poverty in Mexico in the latter half of the 19th century, Lucia's diet may have contributed to her condition.

Her experience is in spite of the increase in height in humans throughout history. In developed countries, adult males are around three inches taller than 200 years ago, largely the result of an abundance of food, immunisation preventing growth inhibiting diseases and less physical labour during childhood.

It is just one of hundreds of facts about the human body contained in a book which aims to answer many of the most frequently asked - and some of the not-so-frequently asked - questions we have about ourselves.

The Odd Body, by Dr Stephen Juan, explains some of the mysteries of our bodies, from our heads down to our toes, as well as some rather unlikely-sounding, but true, developments for the future.

One of these is the possibility of injecting memories from one person into another.

Laboratory experiments involving a type of flatworm, the simplest life-form to possess a brain and nervous system, have shown that memories can be transferred from one organism to another.

The flatworms were taught to avoid electric shocks by swimming towards a light. They were then chopped up and fed to other, untrained, flatworms, while a second group of flatworms received only normal food. When the scientists then tested the two types, it was with extraordinary results.

The normal-fed flatworms showed no evidence of any learning, but those fed on trained flatworms avoided the shocks. While there may be a huge leap between flatworms and humans, the experiment suggests it may one day be possible to acquire the complete works of Shakespeare through a hypodermic needle.

Another scientific advance has been in keeping a severed head alive. A technique called perfusion keeps the brain supplied with oxygen, blood, fluids and other elements, and allows it to think as well as carry out other functions.

Although there is no working model, American molecular biologist Chet Fleming has been granted a patent on the basis of his blueprint. In an article in the British Medical Journal, he said he had been contacted by half a dozen people wanting to know when the operation to sever their heads and use the perfusion device would be available.

But if that technology is still in the future, reshaping the skull has been practised for centuries.

The practice of shaping the skull in infancy, usually sandwiching it between two tightly bound pieces of wood, dates back to at least 2000BC on Mediterranean islands, and has occurred in Europe, Africa and North and South America.

The Incas of Peru believed long heads should be made longer, and short ones shorter, while head shaping was a mark of royalty in Tahiti and Hawaii. Among the ancient Greeks, head shaping of young girls has been reported, perhaps because it was considered pretty.

But The Odd Body is not just about the bizarre: it also explains many common types of behaviour.

Squinting to improve our vision, for example, may seem odd, but it has the effect of cutting out light rays which enter the eye at an angle, which focus either in front of or behind the centre of vision, and so are blurred. The eye therefore concentrates on rays which come at a near 90 degree angle, and are more focused.

Yawning is more problematic, in that there is little evidence about why we yawn and what function it serves, although it is important in adjusting the air pressure in the middle ear. But what can be said about it is that witnessing yawning can provoke yawning, one of the few human behaviours where this occurs.

Just as common but far more distinctive is blushing. Blushing happens when the small blood vessels which supply the skin widen, allowing more blood to flow through, but it is one of only a handful of body changes which is triggered directly by the mind.

Despite numerous theories, there has been no definitive explanation of why humans are the only animals who blush. Some have suggested it is because humans are the only primates with their face completely exposed, so while other primates may blush, it is only visible in humans, while others claim it is because blushing requires the ability to be embarrassed.

Charles Darwin was the first to note that blushing was exclusively human and universal and concluded that it was triggered by thinking of what others think of us. Sigmund Freud suggested it was a combination of repressed sexual excitement, exhibitionism and a fear of castration.

Tickling is another little understood reaction. If it was just the result of a certain touch, we could tickle ourselves, but we can't. Part of being tickled is a sense of anxiety, which mingles with the pleasure of the touch, but if the tickling is too rough it becomes dangerous and is no longer a laughing matter.

Some features do have an accepted explanation, however. Fingerprints work on the same principle as tyres, channelling water away to help us to grip, and disperse pressure to prevent blisters. Fingers and toes wrinkle after a bath because the top layer of skin absorbs water and expands, but the bottom layer cannot get any bigger, so the top layer pleats. The membranes on our skin cells let water out more easily than they let it in so we shrivel up instead of swelling like a sponge.

A simple explanation also accounts for why we sometimes fail to recognise our voice played back on a tape. When we speak, we hear not just the vibration in the air which others hear, but also the vibration through the fluids and solids in our heads. Sound transmits differently through liquids and solids than air, and so sounds different to us than to others

The book also dispels a few commonly accepted theories. One is that the unpleasant feeling we get from hearing chalk screech across a blackboard is due to the high frequency sound.

In fact, experiments found that when the high frequency was removed, the chills remained. But what scientists did discover was that the sound bore an uncanny resemblance to the warning sound emitted by some monkeys, leading to the conclusion that it may be a reflex response left over from evolution.

Another myth is that it is changes in pressure which cause feet to swell up in aeroplanes. Feet swell up on planes for the same reason they do on the ground - inactivity. Gravity forces blood and other fluids to the lowest point, and happens just as easily sitting in an office.

But one myth which turns out to be true is that kissing a frog can lead you to your prince.

A chemical which causes hallucinations, and is also an aphrodisiac, particularly in women, is found in concentrated form in the skin of some frogs and toads. Kissing or licking one of these amphibians can result in hallucinations, and a feeling of romantic desire. At least, so the scientists say.

The Odd Body by Dr Stephen Juan (Collins, £9.99).