As noted previously in this series, non-LDS scholars, who are likely unaware of the Book of Mormon-DNA issue, agree that some ancient American haplogroups have probably disappeared. All population geneticists understand that, worldwide, some haplogroups will disappear because of bottlenecks and genetic drift.

I preface my next remarks by recognizing that some faithful Latter-day Saints accept the dominant scientific theory for the evolutionary diversity of life on earth, while other faithful Latter-day Saints do not. And like Book of Mormon geography, the official LDS Church position on this issue is one of neutrality. I'm one who accepts the scientific principle, and for the purpose of this article I turn to the scientific data to better understand the nature of disappearing DNA.

Geneticists trace all modern human mtDNA to a common maternal ancestor (the "Mitochondrial Eve"); a single haplogroup that originated in Africa dating to about 200,000 years ago. Other women, carrying different and unknown mtDNA lineages, existed as well and would also have had sons and daughters, but their mtDNA eventually disappeared because of genetic drift and bottlenecks. When the first anatomically modern humans left Africa about 70,000 years ago they undoubtedly had several women in the initial group. Yet only one mtDNA lineage (L3) is the maternal ancestor of all the non-African people living today. That's only one single common female ancestor for all the people of Europe, Asia, Oceania and the Americas. Surely she was not the only woman to leave Africa, but the other mtDNA lineages disappeared because of genetic drift and bottlenecks.

Interestingly, LDS critics with training in genetics acknowledge that if a small group of Israelites came to the New World and intermixed with a larger Native American population, their DNA could have disappeared as well. But, they argue, for nearly two centuries the LDS Church has taught that the New World was uninhabited before Book of Mormon populations arrived — so no other DNA could have swamped out the Israelite presence.

Such an argument moves the goalposts from a scientific debate to a theological one. The belief that other Native Americans co-existed with the Lehites doesn't work for the critics, so they try to force Mormons into the precritical view that the Book of Mormon people were alone in the New World. Critics typically point to comments from the sermons of LDS leaders as well as the Book of Mormon introduction for support of their argument.

As new editions of the Book of Mormon have been published, some have added supplementary information to the actual text. In the 1879 edition, for example, Orson Pratt added non-doctrinal explanatory footnotes — including ones based on Elder Pratt's interpretation of Book of Mormon geography. In 1920 James Talmage added more introductory information while removing Elder Pratt's geographical footnotes.

In the 1981 edition Elder Bruce R. McConkie, who was appointed as part of the LDS Church scripture committee, added chapter headings as well as a new introduction that stated Lamanites are the "principal ancestors of American Indians." Like the chapter headings, footnotes and all other ancillary and explanatory texts added to the volume, the introduction doesn't carry the same weight as the actual scriptural text.

It's also important to note that in his 1966 "Mormon Doctrine" Elder McConkie acknowledged that modern Native Americans would have "had other blood than that of Israel in their veins." In 2006, The Church of Jesus Christ of Latter-day Saints clarified the Book of Mormon introduction to state Lamanites are "among the principal ancestors...." This change implies the issue has not been settled by revelation and there is no doctrinal position on the cultural composition of ancient America.

As to the comments of LDS leaders, it's ironic that critics — who do not believe in LDS prophets — claim Mormons must accept every word spoken by every LDS general authority as the inerrant word of God. Such a claim, of course, is absurd and already has been dealt with in past issues here and here.

We do not believe that every word of any LDS Church leader automatically constitutes the word of God, and we accept the fact, as noted by several church leaders themselves, that they also speak as men and voice their own opinions. As already noted in past issues, some LDS leaders have taught that "others" co-existed in the Americas.

The DNA issue is one of science. The belief that Lehites came to the New World is one of revelation. The question as to who lived in the Americas in addition to Book of Mormon peoples is not one of doctrine or revelation, but is one of personal opinion based on research and evidence, including textual evidence from the Book of Mormon.