Adam and Eve: When and Where?

[The following is a cross-post from Mormons and Evolution.]

Earlier I discussed some of the issues surrounding how Adam and Eve were created, and listed two tentative suggestions for reconciliation with science. Here I will discuss some of the issues involved in placing Adam and Eve in time and geography. Up front I want to point out that I am not a geneticist, archeologist, or anthropologist. My understanding of the issues involved come primarily from writings for non-expert audiences.

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The LDS Model:

The traditional LDS placement of Adam and Eve is straightforward. Using Biblical chronology and other supportive scriptures, Adam and Eve became mortal around 6,000 years ago. Scriptural statements place the future (and by implication the past) site of Adam-ondi-ahman in Missouri. A number of personal accounts state that Joseph Smith identifed Jackson county as the site of the Garden of Eden, and identified some stones as part of an altar that Adam built after leaving the garden. Some presume that Noah was responsible for transfering the human race to the Eastern Hemisphere.

The Scientific Models:

One of the components of evolutionary theory is the concept of common descent--that all living organisms descend from previously living organisms and that ultimately, all living organisms share common ancestors. For humans this means that our physical bodies share common ancestry with other primates. Long ago it was recognized that the closest living relative, with which we share a common ancestor, is the chimpanzee. This hypothesis is supported by both anatomical, archeological, and genetic evidence. Since chimpanzees are only known to have lived in Africa, the origination of humans was hypothesized to have taken place there.

Accumulating evidence has continued to support Africa as the place of human origins. The oldest hominid (including Homo sapiens) remains are found there. Genetic diversity in humans is greatest in Africa and less diverse outside of Africa, which suggests that populations throughout the rest of the world are descended from a subset of early African populations.

The relatedness of hominid species is still under debate. As I understand it, the current dominant model of human development and expansion is called "Out of Africa 2." In this model, modern humans developed in Africa after other hominids had migrated to Asia and Europe. Modern humans eventually moved out of Africa and replaced other hominids who became extinct. The other main model is called the "Multiregional" model. In this model, early hominids moved out of Africa to colonize Asia and Europe as described above, but modern humans arose gradually through genetic mixing of these populations. Other models contain a mixture of these two models. One recent paper, based on genetic evidence, argues for genetic mixing with several major migrations, including three from Africa.

Below is a rough, brief timeline of significant events in hominid evolution:

>1 million years ago: First hominids leave Africa
200,000 years ago: First anatomical Homo sapiens in Africa
~160,000 years ago: "Mitochondrial Eve"
~60,000 years ago: "Y-chromosome Adam"
40-50,000 years ago: Development of culture (more sophisticated tools, art, ceremonial burial of dead)
15-30,000 years ago: Colonization of North America
10,000 years ago: Development of Agriculture
3-4,000 years ago: Development of written language

Placing Adam and Eve in light of current scientific understanding and without additional revelation is highly problematic. The qualities associated with Adam and Eve in the scriptures include intelligence, writing, and agriculture. Further, the LDS model places Adam and Eve in North America around 6,000 years ago. This timing is reasonably consistent with agriculture and writing, but is inconsistent with genetic or geneological ancestry to all living humans. Placing Adam and Eve in a position of genetic or geneological ancestry is inconsistent with writing and agriculture, as well as with placement in North America. The concepts of "mitochondrial Eve" and "Y-chromosome Adam" are not helpful her because, in spite of their naming, they do not refer to the biblical persons. That this is true is evident from the different times that these two individuals lived.

With scientific debate still surrounding how early hominids relate to each other it seems premature to pose any scenario that accounts for Adam and Eve, much less their placement in North America. Such a proposal would also require revelatory clarification on the timing and geography of Adam and Eve, and whether the identification of stones derived from Adam's altar was a matter of speculation or literal truth. (Duane Jeffery recently pointed out the problem these stones pose for a worldwide flood scenario.) Until information is more forthcoming, on both sides, it seems best not to force a reconciliation. Speculation is all we can do right now.

Further Reading
There are a number of explanations of human development and migration available on the internet. I will list just a few here.
Origins of Modern Humans: Multiregional or Out of Africa, by Donald Johanson
Alan Templeton, Out of Africa again and again
Becoming Human
Out of Africa, EvoWiki
Human mtDNA Migrations

There are a number of books that likely give good general explanations of current scientific thought. Since science moves, sometimes quickly, it is important to seek out information that is as fresh as possible. It is also important to read from multiple sources in order to not mistake one person's opinion for generally accepted conclusions. This advice applies to all scientific fields.

Comment at Mormons and Evolution.