If the content on your blog is timeless and you could increase the amount of traffic coming to your blog from search engines, would you remove the post and comment dates?
While I appreciate a good habit of questioning best practices, I have a very strong feeling on this one. Never ever ever remove dates from the articles and comments. There is no such thing as “timeless content”. Dates are always relevant. Content easily outlives the author, the source, and anything that was considered “timeless” at the moment of writing. Time is a very important dimension. It is a crucial bit of metadata. Don’t lose it.
And on top of that, don’t try to make that kind of decisions for your visitor. It might appear rude and offensive. Let the visitor decide for himself if he wants to click through to your article from the search engine or not. Be transparent. Always let the visitor know when the article was written, which times it refers to, and when it was commented. Publish the date nearby. Also use it in the URLs whenever possible.
Even structure your text to refer to specific time periods (“March 2010”, “July 4th, 1985”, “Stone Age”, etc). Don’t use vague constructs like “yesterday”, “last year”, “when I was a child”. You never know how your content will reach its audience. Some people will find your article in full and on your site. Some will see an excerpt in their RSS feeder. Some will get just a quote emailed to them by a friend. The context might change, and the “timeless”-ness can disappear.
If you are still not convinced, try a practical example. Find some “timeless content” from before (last year, last decade, last century) and see how well it stands the test of times. Now break it in pieces and look again. Still there? Still timeless? Share your findings (both positive and negative) in the comments.
And in the meantime, keep your articles dated.