Sometimes I hear people say something like the example below. Is it correct to use the word since in this manner?

Mosquitoes are surviving on earth since millions of years.

  • You need to be careful who you listen to! As StoneyB says, your example sentence is poor English for several reasons, and would never be produced by a native speaker. Jan 17, 2014 at 6:09

2 Answers 2


No, this is not correct. Since is employed to designate a timespan running from a definite point in time up to the current 'Reference Time', whatever that may be:

Bob has lived here since 1992. ... The timespan runs from 1987 to the present.

In 1874 Wagner completed Der Ring des Nibelungen, which he had been working on since 1848. ... The timespan runs from 1848 to 1874.

If you want to define the timespan by its duration you should use for:

Bob has lived here for twenty-two years.

Wagner worked on the Ring for twenty-six years.

Mosquitoes have survived on Earth for millions of years.

This does not mean that the point must be defined with great precision. For instance, “Since the first millennium BCE” is acceptable.

  • What about "since millions of years ago"?
    – JiK
    Jan 16, 2014 at 18:07
  • 1
    @JiK That's fine, because "millions of years ago" identifies a "point" in time: RightNow minus millions of years. It's a very fuzzy point, but it's a point :) Jan 16, 2014 at 18:09
  • @StoneyB: Technically speaking I suppose you're right that "millions of years ago" identifies a "point" in time, so in principle it could be referenced by since. But precisely because it's such a "fuzzy" point in time, I'd have to say I don't like the usage much. Actually, if I'm honest, I don't think I'm keen on any variants of since [some length of time] ago. Jan 17, 2014 at 6:12
  • @FumbleFingers I don't much like it either, but it's hard to know where you can draw a line that excludes "since MM of years ago" and includes "since the species arose MM of years ago". Jan 17, 2014 at 12:32
  • Well, as it happens, all our examples are since [some point in past time], but in practice it might make more sense to say the basic usage is since [some prior event]. Specific dates (1848, December, last Tuesday, etc.) are more easily envisaged as "events" (capable of being identified on a calendar) than something like several years ago. If @JiK is indeed a "learner", he's a very advanced one who probably doesn't need my advice on this specific issue, but for the benefit of anyone else who might read this thread, I think it's worth noting that we [as natives]] don't like it. Jan 17, 2014 at 15:35

In your example sentence, for should be used in place of since.

Since is used when you are stating the start time(date/month/year/century etc.) of a duration in your sentence.


  1. He has been playing since five O'clock in the morning

  2. I have been working here since 1991.

  3. This festival has been going on since January.

For is used when you are using the duration only in your sentence:


  1. Mosquitoes have survived on earth for millions of years

  2. He has been playing for five hours straight.

  3. I have been working here for 10 years now.

  4. This festival has been going on for past 2 months

  • 1
    +1. But "is going" should be "has been going on". Jan 16, 2014 at 14:24

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