Hi, I am new to this forum so I hope I can contribute in a positive way. I have pondered and been asked this question many times by many people and found the following, I hope someone may find them useful.
The First Presidency: Joseph F. Smith, Anthon H. Lund, and Charles W. Penrose as quoted in Melvin A. Cook and M. Garfield Cook, Science and Mormonism, p. 156.)
"'Our father Adam -- that is our earthly father -- the progenitor of the human race of man, stands at the head being 'Michael the Archangel, the Ancient of Days,' and that he was not fashioned from earth life and adobe but begotten by his Father in Heaven.'"
Joseph Fielding Smith, Man: His Origin and Destiny, pp. 276-77
"Does it not appear to you that it is a foolish and ridiculous notion that when God created this earth he had to begin with a speck of protoplasm, and take millions of years, if not billions, to bring conditions to pass by which his sons and daughters might obtain bodies made in his image? Why not the shorter route and transplant them from another earth as we are taught in the scriptures."
Bruce R. McConkie, “Eve and the Fall,” in Woman (Salt Lake City: Deseret Book Co., 1979), pp. 60-61.
For those whose limited spiritual understanding precludes a recitation of all the facts, the revealed account, in figurative language, speaks of Eve being created from Adam's rib. (Moses 3:21-25.) A more express scripture, however, speaks of “Adam, who was the son of God, with whom God, himself, conversed.” (Moses 6:22.) In a formal doctrinal pronouncement, the First Presidency of the Church (Joseph F. Smith, John R. Winder, and Anthon H. Lund) said that “all who have inhabited the earth since Adam have taken bodies and become souls in like manner,” and that the first of our race began life as the human germ or embryo that becomes a man. (See Improvement Era, November 1909, p. 80.)
Christ is universally attested in the scriptures to be the Only Begotten. At this point, as we consider the “creation” of Adam, and lest there be any misunderstanding, we must remember that Adam was created in immortality, but that Christ came to earth as a mortal; thus our Lord is the Only Begotten in the flesh, meaning into this mortal sphere of existence. Adam came to earth to dwell in immortality until the fall changed his status to that of mortality.
Those who have ears to hear will understand these things. All of us, however, must know and believe that when Adam and Eve were placed in the Garden of Eden, there was no death. They were immortal. Unless some change occurred they would live forever, retaining all the bloom, beauty, and freshness of youth. Joseph Smith, Brigham Young, Orson Pratt, and our early brethren preached many sermons on this.
B.H. Roberts The Gospel and Man’s Relationship to Deity pg.268
The Prophet Joseph Smith is credited with having said that our planet was made up of the fragments of a planet which previously existed; some mighty convulsions disrupted that creation and made it desolate. Both its animal and vegetable life forms were destroyed. And when those convulsions ceased, and the rent earth was again consolidated, and it became desirable to replenish it, the work was begun by making a mist to rise, that it might descend in gentle rain upon the barren earth, that it might again be fruitful. Then came one of the sons of God to the earth--Adam. A garden was planted in Eden and the man placed in it, and there the Lord brought to him every beast of the field and every fowl of the air, and Adam gave names to them all. Afterwards was brought to Adam his wife, whom, since she was derived from man, he named woman; and she became his help-mate, his companion and the mother of his children. In this nothing is hinted at about man being made from the dust, and woman manufactured from a rib, a story which has been a cause of much perplexity to religious people, and a source of much impious merriment to reckless unbelievers. We are informed that the Lord God made every plant of the field before it was in the earth, and every herb before it grew on our planet. As vegetation was created or made to grow upon some older earth, and the seeds thereof or the plants themselves were brought to our earth and made to grow, so likewise man and his helpmate were brought from some other world to our own, to people it with their children. And though it is said that the "Lord God formed man of the dust of the ground"-it by no means follows that he was "formed" as one might form a brick, or form the dust of this earth. We are all "formed" of the dust of the ground, though instead of being moulded as a brick we are brought forth by the natural laws of procreation; so also was Adam and his wife in some older world. And as for the story of the rib, under it I believe the mystery of procreation is hidden.
Joseph Fielding Smith, Man: His Origin and Destiny, pp. 276-77
"Does it not appear to you that it is a foolish and ridiculous notion that when God created this earth he had to begin with a speck of protoplasm, and take millions of years, if not billions, to bring conditions to pass by which his sons and daughters might obtain bodies made in his image? Why not the shorter route and transplant them from another earth as we are taught in the scriptures."
Joseph Fielding Smith: Doctrines of Salvation vol 1 p.74,76
This we know, and that will suffice until all things are revealed, the inhabitants of these worlds created by Jesus Christ, are begotten sons and daughters unto God. Life did not originate here. Man did not first come into existence here. We are told by our Father in heaven that man is eternal; that he has always existed, and that all life on this earth came from elsewhere. We may not be able to comprehend all this now, but the time will come in the providence of the Lord, when all these things shall be made known and we shall have knowledge in the fulness....
....We were all created untold ages before we were placed on this earth.
Joseph Fielding Smith: Doctrines of Salvation vol 1 p.139-140
LIFE TRANSPLANTED FROM OTHER EARTHS. I tell you, life did not commence upon this earth spontaneously. Its origin was not here. Life existed long before our solar system was called into being. The fact is, there never was a time when man-made in the image of God, male and female—did not exist. The Lord revealed to Joseph Smith the truth that man was also in the beginning with God. . . .
The Lord has given us the information regarding his creations, and how he has made many earths, for there never was a beginning, never was a time when man did not exist somewhere in the universe, and when the time came for this earth to be peopled, the Lord, our God, transplanted upon it from some other earth, the life which is found here. Man he created in his own image. If it were our privilege to go out and visit some of the other creations, other worlds in space, we should discover that they are peopled with beings who look like us, for they, too, are the offspring of God, and of the same race from whence we came. Perhaps they would be more exalted, but, nevertheless, they would be in the image of God, and so are we. Adam was not a "cave man," but perhaps the most nearly perfect man in form and feature to our Father and Creator....
....It is true that all life does come from the same source, but that is not the scum of the sea, a jellyfish or a pollywog. God, our Father, is the creator of life, and he placed life on this earth in varied forms, and also on other worlds. He will continue his work on this earth and upon other planets, or worlds, which will take the place of this earth when it has been exalted and gone on to its celestial glory. He will continue to bring to pass his purposes by peopling worlds and bringing to pass the immortality and eternal life of his children.
Sorry for the long book, but if you find this helpful in your study, then enjoy.
