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Wound licking
The last word– DEXTROUS DILEMMA
WOUND LICKING
Why are some people left-handed and others right handed? (Continued)
I know that some animals treat simple injuries by licking them. Are there any animals that, like humans, treat each other’s injuries, and do any animals have more sophisticated forms of “medical treatment”? (Continued)
● Your earlier correspondent (Last Word, 9 July) was not entirely correct when he stated that there must be advantages to having the genes for left-handedness. Surely it is only necessary that those genes, in any given environment, confer no relative disadvantage? Kevin Donaldson York, UK ● The previous correspondent is correct – in fact he doesn’t go far enough. Even if left-handedness is a disadvantage, there are all sorts of
“Mutations for left-handedness could arise faster than natural selection can eliminate them” reasons for genetic variations that favour the persistence of lefthandedness. The variations might protect against a disease or provide some other advantage unrelated to left-handedness, or may merely sit next to some other genetic variation that is highly advantageous. In addition, new mutations favouring left-handedness could be arising faster than natural selection can eliminate them from populations, since evolution is very weak in humans. It could also be related to the number of gene copies, rather than a specific variant, and so on... Alex Bentley Leeds, West Yorkshire, UK 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.
● A previous correspondent (Last Word, 5 April) wrote that “…saliva contains huge numbers of various bacteria. Fortunately these are largely beneficial or have no effect, and there is no evidence to suggest they are detrimental to wound healing.” On the contrary, there is compelling evidence that these bacteria (including Streptococcus and Pasteurella species) can colonise wounds and severely compromise healing. This is the reason for using Elizabethan collars on dogs and cats to protect both surgical and traumatic wounds, and I would strongly discourage pet owners from allowing their pets to lick their wounds. An alternative but more likely
explanation for the behaviour described in the question is that carnivorous animals enjoy licking a wound for the same reason they enjoy licking a bone: they like the taste. Mike Farrell European Specialist in Small Animal Surgery University of Glasgow, UK
SNAKES ALIVE On 22 September 2007 my wife and I were on the shingle beach at Dunwich in Suffolk, UK, when we spotted a snake wriggling along the water’s edge. It was about 50 centimetres long and light olive-brown. Behind its head was a bright yellow, deltashaped marking which pointed forwards. As we watched, it entered the water and swam strongly out to sea. Is this how a grass snake might behave – albeit one with atypical markings – or has climate change brought a sea snake north of its usual habitat? The weather was windy and it was neither warm nor sunny. Is it relevant that this
occurred about 2 kilometres north of the warm water outlets of the Sizewell B nuclear power station? (Continued)
● A previous answer (Last Word, 26 July) suggested this was probably a seafaring grass snake, although they are more commonly seen swimming in fresh water. However, there are other accounts of grass snakes at sea, including one captured many miles from land in the Bay of Biscay, cited in the Collins New Naturalist British Amphibians and Reptiles, published in 1951. This snake was “none the worse for its immersion in salt water”, as one might expect, thanks to the waterproof skin of reptiles. John Etherington Llanhowell, Pembrokeshire, UK
THIS WEEK’S QUESTIONS Turtle trauma My wife and I were driving near Oshkosh, Wisconsin, alongside a river when we spotted a soft-shelled turtle with a hump on its back (see photo). What would explain this anomaly? Larry Schaeffer Guelph, Ontario, Canada The birds In New Zealand one of our radio stations broadcasts native birdsong each morning. It is obvious that seabirds have a much harsher screeching sound than the more melodious bush and landbased birds. In fact, I can usually tell a bird’s habitat simply by the sound it makes. Why is there such a difference, and is it the same throughout the world? John Finlayson Maungaturoto, New Zealand
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.newscientist.com/lastword.ns (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.
How to Fossilise Your Hamster
The latest collection from New Scientist featuring experiments for armchair scientists Available from booksellers and at www.newscientist.com/hamster
Last Words past and present, plus questions, at www.newscientist.com/lastword
WOUND LICKING
Why are some people left-handed and others right handed? (Continued)
I know that some animals treat simple injuries by licking them. Are there any animals that, like humans, treat each other’s injuries, and do any animals have more sophisticated forms of “medical treatment”? (Continued)
● Your earlier correspondent (Last Word, 9 July) was not entirely correct when he stated that there must be advantages to having the genes for left-handedness. Surely it is only necessary that those genes, in any given environment, confer no relative disadvantage? Kevin Donaldson York, UK ● The previous correspondent is correct – in fact he doesn’t go far enough. Even if left-handedness is a disadvantage, there are all sorts of
“Mutations for left-handedness could arise faster than natural selection can eliminate them” reasons for genetic variations that favour the persistence of lefthandedness. The variations might protect against a disease or provide some other advantage unrelated to left-handedness, or may merely sit next to some other genetic variation that is highly advantageous. In addition, new mutations favouring left-handedness could be arising faster than natural selection can eliminate them from populations, since evolution is very weak in humans. It could also be related to the number of gene copies, rather than a specific variant, and so on... Alex Bentley Leeds, West Yorkshire, UK 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.
● A previous correspondent (Last Word, 5 April) wrote that “…saliva contains huge numbers of various bacteria. Fortunately these are largely beneficial or have no effect, and there is no evidence to suggest they are detrimental to wound healing.” On the contrary, there is compelling evidence that these bacteria (including Streptococcus and Pasteurella species) can colonise wounds and severely compromise healing. This is the reason for using Elizabethan collars on dogs and cats to protect both surgical and traumatic wounds, and I would strongly discourage pet owners from allowing their pets to lick their wounds. An alternative but more likely
explanation for the behaviour described in the question is that carnivorous animals enjoy licking a wound for the same reason they enjoy licking a bone: they like the taste. Mike Farrell European Specialist in Small Animal Surgery University of Glasgow, UK
SNAKES ALIVE On 22 September 2007 my wife and I were on the shingle beach at Dunwich in Suffolk, UK, when we spotted a snake wriggling along the water’s edge. It was about 50 centimetres long and light olive-brown. Behind its head was a bright yellow, deltashaped marking which pointed forwards. As we watched, it entered the water and swam strongly out to sea. Is this how a grass snake might behave – albeit one with atypical markings – or has climate change brought a sea snake north of its usual habitat? The weather was windy and it was neither warm nor sunny. Is it relevant that this
occurred about 2 kilometres north of the warm water outlets of the Sizewell B nuclear power station? (Continued)
● A previous answer (Last Word, 26 July) suggested this was probably a seafaring grass snake, although they are more commonly seen swimming in fresh water. However, there are other accounts of grass snakes at sea, including one captured many miles from land in the Bay of Biscay, cited in the Collins New Naturalist British Amphibians and Reptiles, published in 1951. This snake was “none the worse for its immersion in salt water”, as one might expect, thanks to the waterproof skin of reptiles. John Etherington Llanhowell, Pembrokeshire, UK
THIS WEEK’S QUESTIONS Turtle trauma My wife and I were driving near Oshkosh, Wisconsin, alongside a river when we spotted a soft-shelled turtle with a hump on its back (see photo). What would explain this anomaly? Larry Schaeffer Guelph, Ontario, Canada The birds In New Zealand one of our radio stations broadcasts native birdsong each morning. It is obvious that seabirds have a much harsher screeching sound than the more melodious bush and landbased birds. In fact, I can usually tell a bird’s habitat simply by the sound it makes. Why is there such a difference, and is it the same throughout the world? John Finlayson Maungaturoto, New Zealand
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.newscientist.com/lastword.ns (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.
How to Fossilise Your Hamster
The latest collection from New Scientist featuring experiments for armchair scientists Available from booksellers and at www.newscientist.com/hamster
Last Words past and present, plus questions, at www.newscientist.com/lastword