Hardin: Genealogy, Genetics, and the Power of Words

On p. 203 of GAE Swamidass writes, “I suppose I could have just made the scientific case and walked away…Somehow, I was seduced by the grander questions.” So he should have been, and so should we all. I look forward to future engagement of professional biblical and systematic theologians with GAE’s core ideas. The brief reflections in the Online Appendices of GAE and the reviews here by McCall and Collins are a start. A first book-length follow-up has just been released by @jongarvey . Space precludes analysis of Swamidass’s imaginative thought experiments about aliens, Narnians, and the like, not to mention the perplexing mystery of the fate of “biological humans”, how one might affirm their solidarity in universal sinfulness with those genealogically descended from A&E, and to what extent early Homo sapiens populations lacked organized aggression (e.g., p. 170). Swamidass’s intriguing threefold notion of the spread of human sinfulness (p. 185), which adds the notion of existential indebtedness through genealogical descent, is especially thought-provoking. I view this entire section as “public brainstorming” that should be encouraged.

As Swamidass says (p. 223),”The grandness of the question unsettles simple answers.” Amen!

1 Like

@dga471, you were mentioned here:

However, if one’s hermeneutical and theological commitments seem to require a recent, de novo created A&E who are UGAs, then one’s demand for positive evidence may become less important and one’s tolerance for low probability events that have not been disproven increases.[xxi] Physics graduate student Daniel Ang, a moderator on the Peaceful Science forum, encapsulates this essential difference in GAE’s approach well, and I refer interested readers to his discussion.

Though, I would point out the error in the quote that @dga471 uses (from another author, not @dga471 ):

Swamidass brushes aside Tasmania’s isolation as unreasonable and impossible to demonstrate.

That is not true. I explained that concluding Tasmania was isolated is reasonable, not unreasonable, but that concluding that it was not isolated is reasonable too, because the evidence is not definitive.


@dga471 and @jongarvey there is a surprisingly strong claim made in footnotes by Hardin:

For scientists, lack of positive evidence is usually a reason not to favor a hypothesis on the grounds of parsimony[xx]. However, if one’s hermeneutical and theological commitments seem to require a recent, de novo created A&E who are UGAs, then one’s demand for positive evidence may become less important and one’s tolerance for low probability events that have not been disproven increases.[xxi] Physics graduate student Daniel Ang, a moderator on the Peaceful Science forum, encapsulates this essential difference in GAE’s approach well, and I refer interested readers to his discussion.

[xxi] This is why, contrary to how secular scientists might approach this topic, Swamidass says (p. 76), “to demonstrate genealogical isolation, one has to prove that absolutely zero successful immigration has taken place over thousands of years.” I do not know of a way to achieve the “absolutely zero” criterion for any historical science, the problem of detectability notwithstanding. This is a standard that virtually all scientific hypotheses cannot meet.

I find it really interesting that I made neutral statement of fact:

to demonstrate genealogical isolation, one has to prove that absolutely zero successful immigration has taken place over thousands of years.

Hardin reads this as evidence I am breaking the rules of secular science. It is true that historical science can’t achieve the “absolutely zero” criterion, but this hardy a fair indictment of my methodology to note that this is what is required to demonstrate genealogical isolation. This is why the genealogical isolation of Tasmania is essentially outside the view of evidence.

How is explaining this brute fact a deviation from secular science?

Contrary to Hardin, I do believe I am approaching this topic as a secular scientist.


I think the validity of Hardin’s statement partially depends on the details of the Tasmania situation. For example, if we’re talking about the ability of Tasmanians to journey to the moon within the last 3,000 years, then I think we can all agree that the scientific probability of that is near zero. I would probably also say ditto for the ability of Tasmanians to journey from Tasmania to Antarctica. But Tasmania to the Australian mainland? I’m not sure. How small does the probability have to be before it’s virtually zero?


Well, that is aligned with my point. Historical science can conclude absolutely zero people traveled from Tasmania to the moon between 10,000 to 2,000 years ago, barring miraclesof course.

We can’t do the same regarding immigrants to Tasmania, but that “absolute” what is required to established genealogical isolation. Noting the limits of the evidence here is a fundamental activity of secular science, so I’m not sure why it is being presented as evidence otherwise. I wonder if part of it is that Hardin is over-relying on one of your early responses to the Tasmania question while ignoring my caution about your response:


I’m not sure this is the case. Take the example of isolation of the Moon. It is equally true that to demonstrate genealogical isolation of the Moon, one has to show absolutely zero migrants. In this case, however, we do have confidence that there were absolutely zero migrants, for several reasons included that there are no populations on the moon.

So merely stating “one has to show absolutely zero migrants” doesn’t suddenly bump us outside of secular science. That is just a brute fact of how genealogical isolation works.


Well, I think the question here is if specialists on Tasmania and the Bass Strait agree with your assessment that based on the current evidence, crossing the Strait is nowhere near as unlikely as going to the moon or Antarctica. And second is the question of how much that evidence can change. Is it a settled question (like the age of the earth) or just something that a few people have barely investigated? I personally think it’s plausible that Tasmanians crossing have not been completely ruled out, but I’m not an expert on this.

And by the way, I don’t think Johnson asking one professor a single question is enough to settle this question. One would need to dialogue with several experts on this to really ascertain the probability and the strength of the evidence.

But we don’t know with absolute certainty that there have never been any populations on the moon either, right? We haven’t dug up every single corner of the moon and made sure there are no remains of a hidden civilization there. We can’t completely rule out Silurian hypothesis (which posits the existence of an ancient, extinct advanced civilization on Earth) either. We can only work with the evidence we have to determine probabilities.


EDIT: I reread your section on Tasmania (p. 73). I think your statement there is fair. You say that “future work might settle this question.” And you posit a model for crossings to occasionally happen, by island hopping. So the next thing is to have experts on Tasmania assess the plausibility of that model. Is it unlikely, very unlikely, or impossible?

By the way, my confidence that no Tasmanians went to the moon 2,000 years ago is not based on the lack of population on the moon, but the technological level of development needed to go there. We have absolutely no evidence that there were modern advanced industrial civilizations in Tasmania 2000 years ago. And it seems a priori very unlikely that such evidence could just turn up in a corner of the island some time - such a civilization should have left over some stuff. So the probability of that happening must be very low.


It seems that Hardin concedes this himself, when he says:

I do not know of a way to achieve the “absolutely zero” criterion for any historical science, the problem of detectability notwithstanding.

I think his argument, rather, is “because science can’t tell us, it violates secular science to hinge on what the answer would be.” But that doesn’t make much sense. It isn’t capriciousness or unfairness that has me asking for this, it is just the definition of genealogical descent that leads us there.

Yes, but there is more too. Most experts are assessing this based on current indigenous technology in the area. But that is a red herring. Just as effective, and perhaps more likely, would be someone from outside the area with technology not currently represented in Tasmania who made the crossing. For example, perhaps explorers from the South East Asian islands.

This possibility is ruled out based on the claim that once a civilization has a technology they never loose it. However, we know for a fact that this heuristic was violated by Tasmanians. They certainly had fishing in the past, but lost that technology.

All this goes to say that this is the key direction to go:

However this will not be easy with people poisoning the well and with several assumptions polluting thought here. Another great example is that there is literally no publications, other than my article, that even considers genealogical isolation of Tasmania. All of them that I have found consider genetic and geographical isolation. Scientists don’t really study genealogical isolation, but that is what we are after here. So there is a great deal of misunderstanding to untangle around this before that conversation can even begin.


I think your hypotheses (outsider crossing and the technology being subsequently lost) sounds plausible on their face. You’re trying to provide an actual, believable model. But again, I’m not an expert.

I agree.

There’s another level to the question here. In light of the fact that most Tasmanian experts who aren’t already interested in the GAE probably wouldn’t spend too much time on assessing your specific model, what is the epistemic responsibility of non-experts while we’re in this uncertain situation with regards to the evidence? I think we should remember what C J Collins quoted in his review:

I once heard Peter Harrison say that if certain theological views are well-founded, and fundamentally important to a well-grounded system of belief, it can be rationally responsible to maintain those views, even if, for the time being, the science seems to call them into question. I believe he was right, at least for these basic beliefs about the origin of humankind and of sin. These are too well-connected to the kind of experiences that are universally accessible and all-but-universally recognized. Sometimes, if we wait, new light will come in the scientific thinking. And sometimes, as well, someone with enough imagination will propose a workable scenario that helps us past the apparent hump. It looks like Dr Swamidass has indeed provided an imaginative and serviceable tool for our toolkits, to promote “peaceful science.”

While the crossing of Tasmania is not a first-order belief like original sin or the origin of humankind, it is related to them. The GAE model seems to past so many other evidence tests; it would be a waste to abandon it just because of one issue regarding one island on which not much extensive research has been done. And in this case, we don’t even have a direct contradiction to the model, just a semi-open question.


Exactly, as I explained:

Of course, here we are not talking about GAE per se but a GAE with a very recent Adam and Eve. For many reasons independent of this, as you know, we might want to understand AE more ancient any ways.


It seems to me that operating here is the myth that there is such a thing as a scientist who is not also a human being.

So, in this instance, the negative genealogical contact with Tasmania cannot be proven, in principle, scientifically. So strictly “the scientist” must say “I have no opinion about that, for there is insufficient evidence.”

In reality, real scientists will make some kind of probability judgement and (assuming they are interested in the subject) conclude either that the journey would be too difficult, or that the modern crossings by kayak, etc, make it possible. The grounds for even discussing those options goes beyond the scientific, which must remain entirely agnostic and admit its irrelevance to the issue.

The recourse to low probability as a deciding factor is entirely spurious whilst apparent impossibilities like the origin of life or the cosmological constants are regarded as matters of science.


OK, I’ve now read all 3 reviews and will comment separately.

But on Hardin’s Tasmanian remarks, in context, they are a small point which I don’t think will make anydispassionate reader question Josh’s scientific objectivity. However, they do stick out a little from the rest of his piece in hinting at non-scientific special pleading in the book, which I think is challengable.

Hardin’s assumption at this point is that the hypothesis “Tasmanians have not been totally genealogically isolated” normally requires positive evidence to be scientific. And so it does - but that’s not the GAE hypothesis, which is that “a common theological ancestor of the human race within the last few thousand years is possible,” for which GAE presents good evidence.

The Tasmanian problem is not a hypothesis, but a potential anomaly, and any general scientific theory crawls with anomalies that either await further evidence, or are judged beyond resolution and ignored. It may be Popperian to say that one contradiction destroys a theory, but even he wouldn’t say that one doubtful case puts one into the realm of holding the theory only by faith.

In a previous discussion I mentioned New World monkeys, whose origin requires near-impossible rafting. It would be overblown to talk about a “rafting hypothesis” as if there were any positive evidence for it: monkeys are simply grafted into the general pattern of evolution by allowing for it, in the absence of any better explanation.

One could, on the same evidence, say equally that nearly all creatures evolved, but that New World Monkeys followed some different path. But it’s reasonable to assume they didn’t, and either shrug off the difficulty or do more research on floating islands.


I wrote some comments on Hardin’s review over on the BioLogos Forum thread set up for discussion of the 3 book reviews:

Hardin’s review was excellent and gracious, which I really appreciated.

My favorite quote from Hardin was this one:

Many Christians who accept the evidence for humans as an evolved species, as well as non-Christians such as biologist Nathan Lents, have expressed the hope that GAE will provide greater space for acceptance of evolutionary biology among such “traditional” Christians. I pray that this will be so. There are some Christians who accept evidence for an ancient earth and other scientific data but feel compelled to reject evolutionary science because they thought an historical A&E were impossible. GAE is new option for such believers.

I like the validation of the struggle that Christians who accept evolutionary science face as we speak with our pastors and church friends. Not that he called out that particular struggle I have, per se, but I like that he acknowledges the difficulties, and why new options for discussion allowed by the GAE concept could be helpful.

With regard to Tasmania, I found the the main points that I recall from your book all to be reasonable and helpful:

  1. While is it is likely that Tasmania has remained isolated for thousands of years, it is not scientifically possible to prove complete and total genealogical isolation. Even if Tasmania had been fully isolated for the past 6,000 years, moving the date of Adam and Eve back to 15,000 years ago would decrease the likelihood of isolation.
  2. The Bible does not speak with such scientific precision. Even if a small number of people had remained genealogically isolated, they would be rare, undetectable exceptions. Thus, the genealogical hypothesis would satisfy the theological claim (which is not an absolutely precise scientific claim) that all people descend from Adam, and that sin and death spread to all people through Adam (Romans 5:12; 1 Corinthians 15:22).
  3. Christian theology can (and would) give full human dignity and worth to people outside the Garden