Proper punctuation is critical for clarity, as made very clear in the very popular book, Eats, Shoots & Leaves by Lynne Truss. In English language editing of science manuscripts, punctuation is especially important for both clarity and conciseness. Proper punctuation can help you convey the take home message of your manuscript, while at the same time improper punctuation can lead to complete confusion. Use of the Oxford comma, also known as a serial comma, is generally considered optional, but science manuscripts are often characterized by long and complex sentences, and the Oxford comma is critical for clarity. The Oxford comma is placed right before the coordinating conjunction (and, or, or nor) in a list of items. Let’s look at the following sentence.
Duloxetine and citalopram may be prescribed for postpartum depression. We investigated the effects of these antidepressants, alcohol and barbiturates in an animal model of postpartum depression.
Now, a new mom who is fraught with anxiety and sleeplessness may be tempted to drink alcohol or take barbiturates, but these substances are certainly not known for their antidepressant effects. Without the Oxford Comma, it seems that the authors of this study are evaluating these substances for their antidepressant effects. The simple addition of the Oxford comma clarifies this sentence: Four different drugs are being investigated for their effects on postpartum depression: the antidepressants duloxetine and citalopram, alcohol, and barbiturates. The Oxford comma removes the ambiguity. The Oxford Comma allows you to be concise while keeping your meaning clear. On the other hand, knowing when not to use the Oxford comma is just as important as knowing when to use it. Consider the following example:
The effects of NMDA antagonists, MK-801 and DxM were evaluated in a model of chronic pain.
In this case, inserting a comma would be confusing because the NMDA antagonists being referred to are, in fact, MK-801 and DxM. In this case, only two drugs are being studied.