When Two Parts of a Sentence Should Go Their Separate Ways

Academic writing requires a significant amount of explanation and careful word choice. The need to be perfectly clear can lead to lengthy sentences, however, especially when describing research methods or conclusions. In many other languages, sentences are quite long, but English (especially academic writing) is typically more concise. This article includes some examples of ways to cut overly wordy sentences into smaller pieces, making the text easier for a reader to comprehend.

Unfortunately, there is no good rule governing when a sentence should be split. An editorial in BioEssays briefly surveyed three major bioscience journals, finding a mean sentence length of 25 to 30 words for individual articles. Even Charles Dickens, a prolific writer with an extensive vocabulary, averaged fewer than 20 words per sentence, a good target to aim for. Of course, any article will require some sentences that are longer than 20 words. (There are some in this tip!) Twenty words per sentence is simply a desirable average. If any of your sentences greatly exceed this number, you may wish to revisit them to see whether a few shorter sentences could convey the same meaning.

Lists of basic information

Some lengthy sentences are simply conveying a number of facts that the author intended for the reader to learn. If these facts do not have a strong connection, however, there is little to be gained by making them all one sentence. Take the following example from paleontologist Kenneth Carpenter:

• On the tops of crinoids is a circle of plates called radials, which in some primitive crinoids is further divided into a lower inferradial and an upper superradial, and below the radials is a circlet of plates called basals. (39 words)
• Because this sentences simply relays information, it can be divided into three sentences without any adverse effect: On the tops of crinoids is a circle of plates called radials. In some primitive crinoids, these radials are divided into lower inferradials and upper superradials. Below the radials is a circlet of plates called basals. (Average, 13 words per sentence)

Sentences beginning with although, because, despite, etc.

Other sentences include two separate ideas with a specific relationship. Common examples include describing the cause of an observation, two opposing observations, or one event occurring even though another fact may seem to preclude it.

• Because only certain proteins are transported into the nucleus of the cell, and many such proteins contain nuclear localization signals (NLSs) that are recognized by importins, we searched the primary sequences of the two novel proteins for homology to canonical NLSs. (40 words)
• This sentence provides some information as a rationale for a homology search. Including a term such as therefore in the second sentence replaces the function of because at the beginning of the original statement. Thus, the background can be separated from the experimental design as follows: Only certain proteins are transported into the nucleus of the cell, and many such proteins contain nuclear localization signals (NLSs) that are recognized by importins. We therefore searched the primary sequences of the two novel proteins for homology to canonical NLSs. (Now 24 and 16 words)
• Although several previous studies have shown that there are seven components of the classical Heptad complex, our data show that an eighth protein should be considered an integral part in certain cell types and developmental stages. (36 words)
• As with because, constructions with although can be reworked to separate the unexpected observation from the prior or contrasting information. Two possibilities are shown in brackets: Several previous studies have shown that there are seven components of the classical Heptad complex. [In contrast,] our data[, however,] show that an eighth protein should be considered an integral part in certain cell types and developmental stages. (Now 15 and 21-22 words)

Timelines or disease progressions

Long sentences commonly appear when authors describe multi-step processes, especially with cause and effect relationships. Shorter sentences are still advisable. Proper use of transition words and/or clear sentence subjects can keep the process united as a single concept.

• The progression of liver disease to later stages occurs when hepatic stellate cells are activated by reactive oxygen species and cytokines such as TNF and produce profibrotic mediators, which cause the expression of receptors for factors such as PDGF. (39 words)
• The information about the initiation of disease progression can be split from the specific effect described: The progression of liver disease to later stages occurs when hepatic stellate cells are activated by reactive oxygen species and cytokines such as TNF. Activation leads to the production of profibrotic mediators, which cause the expression of receptors for factors such as PDGF. (Now 24 and 19 words)

Many an editor might describe lengthy sentences much like Justice Potter Stewart famously described obscenity: "I know it when I see it." Still, we hope that these examples will help you decide whether a sentence has become too long for readers to properly retain its message. If you have questions about a specific sentence, please contact us at [email protected]. Thank you!

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