Why do hair and fingernails grow after death? Surely dead means dead. How can our bodies continue to produce more cells?Shannon Smith, BermudaThe following answers were selected and edited by New Scientist staff. You can add your replies in the comments section below.This is something that we noticed as fresh-faced first-year medical students when confronted with the cadavers we were going to dissect over the next two years. All had slightly long fingernails, and all of the men had neatly cropped stubble. We assumed that these had grown while the cadaver was being prepared. However, an anatomy demonstrator assured us that nails and hair do not grow after death and that this phenomenon was actually the result of the surrounding tissue drying out and shrinking away from the nail folds and hair shafts, giving the impression of growth.David Pothier, Bristol, UKThis is a myth possibly spawned by Enrich Maria Remarque's novel All Quiet on the Western Front in which Paul Bäumer, the 19-year-old narrator, considers the death of his friend Kemmerich from gangrene. He writes: "It strikes me that these nails will continue to grow like lean fantastic cellar-plants long after Kemmerich breathes no more. I see the picture before me. They twist themselves into corkscrews and grow and grow, and with them the hair on the decaying skull, just like grass in a good soil, just like grass..."Sorry to disappoint anybody, but hair and fingernails don't grow after death. Instead, our bodies dehydrate and our skin shrinks and tightens, pulling away from the hair and nails, creating the illusion of growth. Interestingly, funeral parlours put moisturiser on corpses to help reduce this effect.Richard Siddall, Harrow, Middlesex, UKIt is quite a common error to believe that fingernails and hair continue growing after death. Some time ago a person convicted of murder asked my library's information service for literature relating to the effect. He wanted to prove his innocence by relying on the post-mortem growth of hair and fingernails which would throw doubt on the timing of the killing. Unfortunately for the individual, no scientific verification for this growth exists.Baerbel Schaefer, Marburg University Library, Germany

I am a general practitioner with an interest in eyes. I would like to know why green eyes are so rare in the UK. And is there anywhere in the world where they are common?D. R. Piechowski, Kettering, Northamptonshire, UK

I am short-sighted. However, if I remove my glasses and peer through a tiny hole made between my fingers, or a pinhole in a piece of card, I can read signs from an even greater distance than with my glasses on. Why is that?Rodney McManaman, Whitehaven, Cumbria, UK

How many human faces will I, an average person, see in my lifetime? What proportion of all the people that have ever lived am I likely to have seen?Henry Lacey, Bath, Wiltshire, UK

Why do we sometimes get “pins and needles”, especially in our arms and legs, and what exactly occurs in our bodies to make this happen?tbc

If aliens wanted to create new human pet breeds using only selective breeding, what traits would they find easiest or hardest to alter and what kind of timescales would be involved? Would we be easier or more difficult to breed selectively than, say, dogs?Gerry Walsh, Maynooth, Kildare, Ireland

My new shower gel proclaims: “New! Stimulates skin flora”. Is there any benefit in this?Peter Eaton, Porto, Portugal

Is there somewhere in the body that can store fluid, apart from the bladder? Most nights I wake to empty my bladder after exactly 4 hours sleep, but on occasional nights where I haven’t been to the loo all day previously I have to get up three of four times instead of only once. It’s obvious that the urine has been building up during the day, but it wasn’t here in my bladder before I went to bed. So where was it?Virginia Love, Ormond, Victoria, Australia