How does the isolation of Tasmania impact recent universal ancestry?
The Genealogical Adam and Eve tests a provocative hypothesis, using this hypothesis to probe the limits of scientific understanding. Consider everyone who lives across the globe from AD 1 onward. It is possible, or even likely, that everyone in this group is a genealogical descendent of a couple in the Middle East that lived just 6,000 years ago?
Our best estimates of universal ancestry tell us the answer is yes. If Adam and Eve were real people in a real past, then they are ancestors of all of us, even if they lived just 6,000 years ago.
Science progresses as we diligently work to falsify our hypotheses. We question all our findings, especially when they are surprising. The simulations on which the estimate is based assumes that it is possible for migrants to access all parts of the globe, at least in principle. In chapter 6, I try to falsify this assumption. I do this by considering, separately, isolated islands (Hawaii and Easter Island), the Americas, the Andaman Islands, Australia, and Tasmania.
In the case of Tasmania, I find that the assumption may not be valid from 6,000 years ago to AD 1, but we cannot say for sure. It is possible that Tasmania was entirely isolated during this time. Though there is evidence of isolation, we struggle to evidentially demonstrate that there was preciselyzero immigrants, rather than almostzero immigrants. For this reason, there is legitimate dispute about the genealogical isolation of Tasmania.
For two reasons, the theological conversation, however, can move ahead as the scientific debate continues.
Moving Adam and Eve slightly more ancient takes the Tasmanian objection off the table entirely.
If nearly universal ancestry is sufficient for theology, then Tasmanian isolation would not matter any way.
Even if there was precisely zero immigrants, Adam and Eve at 6,000 years would still be nearly universal ancestors of everyone by AD 1, ancestors of everyone except those of solely Tasmanian descent. Nearly universal ancestry, 99.99% of the world population at AD 1, may be all that theology requires.
The figure visualizes how I summarize my findings. My precise scientific argument is nuanced and complex. It is possible the case by which I arrived at this conclusion can be refined. The scientific reviewers of the book agreed that this conclusion is sensible. Of course, it is possible these dates will be refined with further work. Consistent with the conclusion that this is a disputed assumption, some scientists contend Tasmania was totally isolated from before 6,000 years ago to AD 1. After they read the book, I invite scientists to submit any errors they find for review. All substantive errors will be identified and corrected. I hope to correct the typos too.