Scientific prose works bests -- that is, avoid confusion -- when the same word is used for the same concept every time.

Recently in Nature a letter writing compained that this can be carried to extremes"

Increase' and 'decrease' are serviceable English words, so why is it my mission to winnow them from the prose that I edit daily? As a technical editor in a university department, I do not demand poetry from my writers; scientific accuracy and logical flow are paramount. Nevertheless, I long for an occasional fresh alternative to 'increasing' and 'decreasing' quantities, measurements and all manner of other too-familiar turns of phrase.

Must mice always have 'a decreased tail length'? I admire the professionalism that refrains from a description of 'adorable, stumpy little mouse tails', but what is wrong with 'shorter tails'? It saves two words for writers tearing their hair out over journals' word counts, and is no less precise....

I challenge all scientific authors: search your documents and count how often you use these two simple words, not forgetting permutations such as 'increasing' and 'increased'. You may be surprised at how frequently they rear their heads.

If so, I urge you to seek a remedy. There are times when only an increase or a decrease will do. Make those times count, and use the full expanse of the English language to broaden your prose elsewhere. Sheer repetition is anaesthetizing, and the aim (one hopes) is to keep the reader awake as well as informed. Strive for accuracy, logic and truth; but in matters of style, simple variety is a welcome spice.

The important difference is that the appeal is to the adjective used. The writer is not suggesting that different words be used for `tail.'

This part is lifted from Wikipedia

Elegant variation is a phrase coined by Henry Watson Fowler to refer to the unnecessary use of synonyms to mean a single thing. In Modern English Usage (1926) he wrote:

"It is the second-rate writers, those intent rather on expressing themselves prettily than on conveying their meaning clearly, & still more those whose notions of style are based on a few misleading rules of thumb, that are chiefly open to the allurements of elegant variation. [...] The fatal influence [...] is the advice given to young writers never to use the same word twice in a sentence -- or within 20 lines or other limit."

When Fowler coined the term "elegant variation", in the 1920s, the word elegant had a pejorative connotation of precious over-refinement, which it has since lost. Bryan Garner, in The Oxford Dictionary of American Usage and Style, unambiguously renamed the term: inelegant variation.

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In The King's English (1908), Fowler gives as one of his examples this passage from The Times:

• "The Emperor received yesterday and to-day General Baron von Beck... It may therefore be assumed with some confidence that the terms of a feasible solution are maturing themselves in His Majesty's mind and may form the basis of further negotiations with Hungarian party leaders when the Monarch goes again to Budapest."

Fowler objected to this passage because The Emperor, His Majesty, and the Monarch all refer to the same person: "the effect", he pointed out in Modern English Usage, "is to set readers wondering what the significance of the change is, only to conclude that there is none."

Elegant variation is still common in modern journalism, where, for example, a "fire" often becomes a "blaze" or a "conflagration" with no clear justification, and it is considered an especial fault in legal,

• One of the commonly cited examples of the potential negative effect of elegant variation is the use of "elongated yellow fruit" as an elegant variation of "banana".
• Another bad example in a newspaper was "the red-headed non-driver" to avoid repeating the name "Mrs. Thatcher".
• Fowler also quoted: "At the sixth round, there were almost as many fellows shouting out 'Go it, Figs', as there were youths exclaiming 'Go it, Cuff'. -- Thackeray." Were older men supporting Figs and teenagers supporting Cuff? Or not?
• Fowler described an article in the Westminster Gazette which, in 20 lines describing a sale of pictures, used eleven apparent synonyms for 'sold for x amount of money'; some of those synonyms may have implied varying success at the sale, some not.
• JWW note: a more modern example is sport prose for winning or losing a game, espeically in baseball. blank, blow, lose, nail down the win, shut out, smoked, sweep, ...[donations welcome]
• In a BBC TV report in March 2005: "Kabul had just fallen ... he brought a satellite [communications unit] in ... (the road was impassable to wheeled traffic, so) he broke [the unit] down and carried it on donkeys ... with his load on 35 mules ...": with "mule" and "donkey" used as elegant-variation synonyms although they are different sorts of animals.
• Another elegant variation nuisance can happen with dates: e.g. replacing "1947 [...] 1963" by "1947 [...] sixteen years later", forcing the reader to ferret back through the text for the previous date, and then do arithmetic to find the date. This can also cause ambiguity: "1947 [...] sixteen years later [...] twenty years later" may mean "1947 [...] 1963 [...] 1983" or "1947 [...] 1963 [...] 1967".