come to think of it... what happens to sperms that die?
anyway, i just found the meaning of life at
www.dictionary.com
–noun 1. the condition that distinguishes organisms from inorganic objects and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally.
2. the sum of the distinguishing phenomena of organisms, esp. metabolism, growth, reproduction, and adaptation to environment.
3. the animate existence or period of animate existence of an individual: to risk one's life; a short life and a merry one.
4. a corresponding state, existence, or principle of existence conceived of as belonging to the soul: eternal life.
5. the general or universal condition of human existence: Too bad, but life is like that.
6. any specified period of animate existence: a man in middle life.
7. the period of existence, activity, or effectiveness of something inanimate, as a machine, lease, or play: The life of the car may be ten years.
8. a living being: Several lives were lost.
9. living things collectively: the hope of discovering life on other planets; insect life.
10. a particular aspect of existence: He enjoys an active physical life.
11. the course of existence or sum of experiences and actions that constitute a person's existence: His business has been his entire life.
12. a biography: a newly published life of Willa Cather.
13. animation; liveliness; spirit: a speech full of life.
14. resilience; elasticity.
15. the force that makes or keeps something alive; the vivifying or quickening principle: The life of the treaty has been an increase of mutual understanding and respect.
16. a mode or manner of existence, as in the world of affairs or society: So far her business life has not overlapped her social life.
17. the period or extent of authority, popularity, approval, etc.: the life of the committee; the life of a bestseller.
18. a prison sentence covering the remaining portion of the offender's animate existence: The judge gave him life.
19. anything or anyone considered to be as precious as life: She was his life.
20. a person or thing that enlivens: the life of the party.
21. effervescence or sparkle, as of wines.
22. pungency or strong, sharp flavor, as of substances when fresh or in good condition.
23. nature or any of the forms of nature as the model or subject of a work of art: drawn from life.
24. Baseball. another opportunity given to a batter to bat because of a misplay by a fielder.
25. (in English pool) one of a limited number of shots allowed a player: Each pool player has three lives at the beginning of the game.
–adjective 26. for or lasting a lifetime; lifelong: a life membership in a club; life imprisonment.
27. of or pertaining to animate existence: the life force; life functions.
28. working from nature or using a living model: a life drawing; a life class.
—Idioms29. as large as life, actually; indeed: There he stood, as large as life. Also, as big as life.
30. come to life, a. to recover consciousness.
b. to become animated and vigorous: The evening passed, but somehow the party never came to life.
c. to appear lifelike: The characters of the novel came to life on the screen.
31. for dear life, with desperate effort, energy, or speed: We ran for dear life, with the dogs at our heels. Also, for one's life.
32. for the life of one, as hard as one tries; even with the utmost effort: He can't understand it for the life of him.
33. get a life, to improve the quality of one's social and professional life: often used in the imperative to express impatience with someone's behavior.
34. not on your life, Informal. absolutely not; under no circumstances; by no means: Will I stand for such a thing? Not on your life!
35. take one's life in one's hands, to risk death knowingly: We were warned that we were taking our lives in our hands by going through that swampy area.
36. to the life, in perfect imitation; exactly: The portrait characterized him to the life.
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[Origin: bef. 900; ME lif(e); OE līf; c. D lijf, G Leib body, ON līf life, body; akin to live1]
—Synonyms 13. vivacity, sprightliness, vigor, verve, activity, energy.
—Antonyms 13. inertia.
Life is also a section in the newspaper.
although more seriously, i think if you meant to say "what is the reason for our existance?" i believe its to have meaningful relationships with God and with people.