The Book of Mormon

by Joseph Smith Jr.

18 But, behold, the righteous, the saints of the Holy One of Israel, they who have believed in the Holy One of Israel, they who have endured the crosses of the world, and despised the shame of it, they shall inherit the kingdom of God, which was prepared for them from the foundation of the world, and their joy shall be full forever. 19 O the greatness of the mercy of our God, the Holy One of Israel! For he delivereth his saints from that awful monster the devil, and death, and hell, and that lake of fire and brimstone, which is endless torment. 20 O how great the holiness of our God! For he knoweth all things, and there is not anything save he knows it. 21 And he cometh into the world that he may save all men if they will hearken unto his voice; for behold, he suffereth the pains of all men, yea, the pains of every living creature, both men, women, and children, who belong to the family of Adam. 22 And he suffereth this that the resurrection might pass upon all men, that all might stand before him at the great and judgment day. 23 And he commandeth all men that they must repent, and be baptized in his name, having perfect faith in the Holy One of Israel, or they cannot be saved in the kingdom of God. 24 And if they will not repent and believe in his name, and be baptized in his name, and endure to the end, they must be damned; for the Lord God, the Holy One of Israel, has spoken it.

This leaves open the possibilty of other families besides Adam. e.g. the extinct neandrethal.