Google’s John Mueller said in a webmaster hangout video that Google can show either the original published date or the last modified date of URL in their search results snippets. He said they are flexible about these dates and if the content substantially changed, they may use the last modified date as opposed to the first published date.

He said this at the 11:16 mark into the video:

Question:

Answer:

Of course, we know Google gets dates wrong often in search and it is something they continue to work on – in fact, as you can see above, Google has a “dates team” simply devoted to figuring out dates of content on the web.

Here is the video embed:

Hat tip to Deep Crawl for spotting this and @glenngabe for tweeting it.

Forum discussion at Twitter.