The Grammarphobia Blog

Theories of relativity

Q: Is a group of people a ”which” or a “who”? Here’s the sentence I have in mind:  “It has only been studied in chronic alcoholics, which [or who] have reduced rates of muscle protein synthesis.” Please help!

A: In modern English the relative pronoun “which” isn’t generally used in reference to people. This wasn’t always so, however. Depending on when you lived, the use of “which” has been relative.

Until the 19th century, according to citations in the Oxford English Dictionary, “which” was used in relative constructions to refer to a person or people already mentioned.

(A relative pronoun introduces a subordinate clause: “I finally found my keys, which I’m always losing,” or “He’s the man that got away.”)

Here are two 19th-century examples from the OED:

“Dugald Stewart, one of the greatest men which Scotland has produced”—1836, from James Grant’s Random Recollections of the House of Lords. (Today, “that” or “whom” would be used instead.) 

“The wounded, which were carried past, … never failed to salute the Emperor”—1841, from Archibald Alison’s History of Europe, From 1789 to 1815. (Today, “who” would be used.)

But here’s a much older and more familiar example. In the original 1549 edition of the Book of Common Prayer, the Lord’s Prayer begins, “Our father, whyche art in heauen ….”

In the 1928 edition of the Book of Common Prayer, however, “who” was substituted for “which” to reflect modern usage.

Contrary to popular opinion, the relative pronoun “that” can often be used in place of “who.”

As we wrote on the blog in 2007 and 2006, “that” can properly refer to either a person or a thing, despite a common misconception that it’s only for things.

We could stop here, but your question touches on another problem: “that” versus “which,” and the kinds of relative clauses they introduce. We’ve discussed this subject on the blog too, in 2010 and 2008.

In modern American usage, the preference is to use “which” and “that” to introduce different kinds of relative clauses—“which” for inessential information (set off within commas), and “that” for essential information.

This means that in general, American writers use “which” for clauses whose information could be plucked out and still leave behind a sensible sentence (they’re called nonrestrictive or nondefining clauses).

And “that” is generally used for clauses whose information is essential and can’t be dropped (these are restrictive or defining clauses).

Many British writers use “which” for both kinds of clauses.

In the example you mention, the clause is nonrestrictive and would call for “which” if it didn’t refer to people: “It has only been studied in computer simulations, which [not that] show reduced rates of muscle protein synthesis.”

But since it does refer to people, you’ll want to use “who” instead: “It has only been studied in chronic alcoholics, who [not which] have reduced rates of muscle protein synthesis.”

In a restrictive clause, you could use either “that” or “who,” as in this sentence: “It has only been studied in patients who [or that] have reduced rates of muscle protein synthesis.”

By the way, we’re not saying “which” can never used to refer to humans—just not, for the most part, as a relative pronoun.

As The American Heritage Dictionary of the English Language (5th ed.) says, “which” can be used an as ordinary pronoun in place of “any of the things, events, or people designated or implied.”

Examples would be “Which of you is going?” … “Even after viewing the lineup, he couldn’t say which was the perpetrator.” … “Which is the better candidate, John or Mary?”

“Which” can also be used as an adjective in reference to people: “Which guy did she end up marrying?”

Finally, in case you’d like to brush up on “who” versus “whom,” we recently ran a roundup on how to use the two pronouns.

Check out our books about the English language