Before the decade is over, David has sent Mike's discovery over to researches and scientists for testing.

I heard the following sentence on a documentary (names have been changed).

When and why would we use the above tenses?

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Comments  (Page 3) 
More simply, do you think "David sends" is the historic present?

The Historic Present:

The present tense used in the narration of events set in the past.

When telling stories about past events, people often switch into present tense, as in I was walking home from work one day. All of a sudden this man comes up to me and says....

It's part of dumbing down, a fad of current documentary narration. It's termed 'historical present' and hated by the educated classes but aimed at a wider audience to bring past events to life and sell to a wider dumber audience, in the quest for advertising revenue. It goes with speaking in a hushed reverential tone to make places appear more important and having the narrator in shot to create a personality pin-up, to sell future programmes. It's also helpful in an historical screenplay because we are following events unfolding before us not looking back on them.
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