- Email: [email protected]
Smells fine to me
Last words past and present, plus questions, at www.last-word.com
THE LAST WORD Double trouble
bacteria. It has never actually been inside our bodies. Apart from the bile and one or two other remnants from our exocrine glands, it cannot be regarded as excreta, despite the common use of that word to describe it. Bryn Glover, Cracoe, North Yorkshire, UK
further: rather than having a distinct urinary system, insects rely on malpighian tubules in their digestive systems – outgrowths of the gut that perform the same filtration function as our kidneys. Shaun Hug La Mirada, California, US
Smells fine to me
as disposing of waste products in our bile. The other excreta our bodies produce include tears, earwax, and various secretions associated with our reproductive processes. If young Aisling suffers (or is about to suffer) from spots, then these too are caused by excretions which have gone awry. Our faeces, on the other hand, consist of undigested food and
■ The types of waste we excrete have two different origins. Faeces contains the leftover, indigestible portion of the food we eat, plus bile from the liver, which gives excrement its brown colour. Urine, on the other hand, is the result of blood filtration in the kidneys. Urine contains nitrogenous waste, primarily in the form of urea, which results from the metabolism of nucleic acids and proteins, separate from digestion. Furthermore, urine also contains water and solutes from the blood, and interstitial fluids – these are excreted to maintain water balance. Essentially, faeces are the result of a coarse, large-scale process of the digestive system alone, whereas urine production occurs at a much finer scale, eliminating wastes produced by all the body’s cells. Our two excretory systems are obvious because we have a separate opening for each: the anus and the urethra. In other organisms, the distinction between the systems isn’t as obvious. Animals such as birds, reptiles, and amphibians possess a cloaca, which serves as a common opening for both liquid and solid wastes. Insects blur the line even
Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format.
New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address.
Our daughter Aisling would like to know why we have evolved two bodily systems to excrete waste products. Why do we have to both poo and wee?
■ Strictly speaking, the question is misplaced. We do not “excrete” faeces because our bodies are long fleshy tubes which can be thought of as extremely elongated doughnuts. In a doughnut, one would not consider the hole to be “inside” the cake. Similarly, the tube from our mouth through our gut to our anus is technically “outside” our living body. The process of “excretion” is the passing of material from inside our bodies to the outside. Our kidneys excrete urine, our skin excretes sweat, our lungs excrete water and carbon dioxide, and the inside of our bowel tube excretes many things along its length to assist digestion, as well
“A human is an elongated doughnut: the tube from our mouth to our anus is outside our living body”
After buying a spray-on deodorant, I got home and realised it was intended for women. Nevertheless, not wanting to waste money I used it anyway. Nothing untoward happened and I received no strange looks from colleagues or friends. So what are the differences between deodorants meant for men and those that are meant for women? How might using the “correct” deodorant for your sex work better than using one meant for the opposite sex, and what are the pitfalls of applying a deodorant intended for the opposite sex?
■ The primary function of all deodorants is to inhibit growth of bacteria which feed on secretions from sweat glands. Deodorants are most often differentiated, if at all, by strength. But sex sells, so we have men’s and women’s. They have only three differences: advertising, packaging, and fragrance. Remove fragrance and there are only two differences: advertising and packaging. Formulations for both sexes contain such things as flowers, herbs, spices, fruits and woods, and are judged as suitable entirely by personal and cultural taste. For example, one upscale new fragrance contains citruses, herbs, ylang-ylang, jasmine and tiare flowers, musk, tropical woods and coconut – and it’s for men. And many women buy men’s fragrances, because there is none of the social embarrassment that the reverse carries. A fascinating discussion about fragrance sales and attitudes is online at www. tinyurl.com/bnublk Toshi Knell Nowra, New South Wales, Australia
THIS WEEK’S QUESTIONS BAD SOAP
I found this forgotten bar of soap after winter at my home in northern Sardinia. It had grown a coat of mould (pictured). What is the mould and how did it grow on soap, which is supposed to keep your hands clean? Patrizia Figoli Turchetti Bellaire, Texas, US
Do Polar Bears Get Lonely? A brand new collection serious enquiry, brilliant insight and the hilariously unexpected Available from booksellers and at www.newscientist.com/ polarbears
THE LAST WORD Double trouble
bacteria. It has never actually been inside our bodies. Apart from the bile and one or two other remnants from our exocrine glands, it cannot be regarded as excreta, despite the common use of that word to describe it. Bryn Glover, Cracoe, North Yorkshire, UK
further: rather than having a distinct urinary system, insects rely on malpighian tubules in their digestive systems – outgrowths of the gut that perform the same filtration function as our kidneys. Shaun Hug La Mirada, California, US
Smells fine to me
as disposing of waste products in our bile. The other excreta our bodies produce include tears, earwax, and various secretions associated with our reproductive processes. If young Aisling suffers (or is about to suffer) from spots, then these too are caused by excretions which have gone awry. Our faeces, on the other hand, consist of undigested food and
■ The types of waste we excrete have two different origins. Faeces contains the leftover, indigestible portion of the food we eat, plus bile from the liver, which gives excrement its brown colour. Urine, on the other hand, is the result of blood filtration in the kidneys. Urine contains nitrogenous waste, primarily in the form of urea, which results from the metabolism of nucleic acids and proteins, separate from digestion. Furthermore, urine also contains water and solutes from the blood, and interstitial fluids – these are excreted to maintain water balance. Essentially, faeces are the result of a coarse, large-scale process of the digestive system alone, whereas urine production occurs at a much finer scale, eliminating wastes produced by all the body’s cells. Our two excretory systems are obvious because we have a separate opening for each: the anus and the urethra. In other organisms, the distinction between the systems isn’t as obvious. Animals such as birds, reptiles, and amphibians possess a cloaca, which serves as a common opening for both liquid and solid wastes. Insects blur the line even
Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format.
New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address.
Our daughter Aisling would like to know why we have evolved two bodily systems to excrete waste products. Why do we have to both poo and wee?
■ Strictly speaking, the question is misplaced. We do not “excrete” faeces because our bodies are long fleshy tubes which can be thought of as extremely elongated doughnuts. In a doughnut, one would not consider the hole to be “inside” the cake. Similarly, the tube from our mouth through our gut to our anus is technically “outside” our living body. The process of “excretion” is the passing of material from inside our bodies to the outside. Our kidneys excrete urine, our skin excretes sweat, our lungs excrete water and carbon dioxide, and the inside of our bowel tube excretes many things along its length to assist digestion, as well
“A human is an elongated doughnut: the tube from our mouth to our anus is outside our living body”
After buying a spray-on deodorant, I got home and realised it was intended for women. Nevertheless, not wanting to waste money I used it anyway. Nothing untoward happened and I received no strange looks from colleagues or friends. So what are the differences between deodorants meant for men and those that are meant for women? How might using the “correct” deodorant for your sex work better than using one meant for the opposite sex, and what are the pitfalls of applying a deodorant intended for the opposite sex?
■ The primary function of all deodorants is to inhibit growth of bacteria which feed on secretions from sweat glands. Deodorants are most often differentiated, if at all, by strength. But sex sells, so we have men’s and women’s. They have only three differences: advertising, packaging, and fragrance. Remove fragrance and there are only two differences: advertising and packaging. Formulations for both sexes contain such things as flowers, herbs, spices, fruits and woods, and are judged as suitable entirely by personal and cultural taste. For example, one upscale new fragrance contains citruses, herbs, ylang-ylang, jasmine and tiare flowers, musk, tropical woods and coconut – and it’s for men. And many women buy men’s fragrances, because there is none of the social embarrassment that the reverse carries. A fascinating discussion about fragrance sales and attitudes is online at www. tinyurl.com/bnublk Toshi Knell Nowra, New South Wales, Australia
THIS WEEK’S QUESTIONS BAD SOAP
I found this forgotten bar of soap after winter at my home in northern Sardinia. It had grown a coat of mould (pictured). What is the mould and how did it grow on soap, which is supposed to keep your hands clean? Patrizia Figoli Turchetti Bellaire, Texas, US
Do Polar Bears Get Lonely? A brand new collection serious enquiry, brilliant insight and the hilariously unexpected Available from booksellers and at www.newscientist.com/ polarbears