Human genetic diversity is too great for there to have ever been a human population size that consisted of much less than ca. 10,000 individuals. Pairwise Sequentially Markovian Coalescent (PSMC) analysis confirms a population bottleneck in humans that consisted of no fewer than probably ca. 10,000 individuals. (Li, Heng and Durbin, Richard ) "Inference of Human Population History from Individual Whole-Genome Sequences" Nature International Weekly Journal of Science 28 July 2001
http://www.nature.com/nature/journal/v47...10231.html
If there were the most severe population bottlenecking such as one breeding pair that is portrayed in the case of the Biblical Adam and Eve, then there would be a maximum of 4 alleles passed on by Adam and Eve to their children. Furthermore, the subsequent inbreeding would cause some loss of alleles due to genetic drifting. There would not have been genetic diversity in the small group of Adam, Eve and their children who would've had to commit incest among each other for the procreation of their inbred children. A lack of genetic diversity would have persisted for thousands of generations until genetic mutations could cause the genetic diversity of today's population. Based on the number of different alleles there are for the number of genes within the current population and the known rate of mutations per nucleotide sites in humans, geneticists can calculate the minimum number of people needed to create the current amount of genetic diversity. Numerous genetic studies suggest that there were several thousands of people more than two people during the most severe population bottleneck which ever occurred in human history.
DNA segments (Alu repeats ) insert themselves at various chromosomal locations. There are various forms of Alu sequences and several thousand families of Alu. One well-studied family of Alu is called Ya5, which has been inserted into human chromosomes at 57 mapped locations. If we were to have descended from a single pair of ancestors such as Adam and Eve, then we all would have each of the 57 elements inserted at the same location points of our chromosomes. "However, the human population consists of groups of people who share some insertion points but not others. The multiple shared categories make it clear that although a human population bottleneck occurred, it was definitely never as small as two. In fact, this line of evidence also indicates that there were at least several thousand people when the population was at its smallest". ( Venema, Dennis and Falk, Darrel ) " Does genetics Point to a Single Primal Couple?" 5 April 2001
http://biologos.org/blog/does-genetics-p...mal-couple
Coalescent theory analysis of single nucleotide polymorphism and linkage disequilibrium indicates the mean effective population size for hominid lineage is 100,000 individuals over the course of the last 30 million years. "The effective population size estimated from linkage disequilibrium is a minimum of ca, 10,000 followed by an expansion in the last 20,000 years." ( Tenesa, Albert, Navarro, Paul, Hayes, Ben J., Duffy, David L., Clarke, Geraldine, Goodard, Mike E. and Visscher, Peter M. ) " Recent Human Effective Population Size Estimated from Linkage Disequilibrium" Genome Research 17 April 2007
Ancestral Population Genomics: The Coalescent Hidden Markov Model Approach
Indeed, there is ample genetic evidence that the Biblical Adam and Eve never existed.
