Category Archives: Religion

Our Common Ancestors, part 2

In my last post, I mentioned biologist S. Joshua Swamidass, who has taken the concept of genealogical descent in a theological direction. In his book The Genealogical Adam and Eve: The Surprising Science of Universal Ancestry he develops the idea that a man and woman who were miraculously created de novo in the Middle East 6,000 or more years ago and whose descendants interbred with people living outside the garden (who evolved over millions of years) would almost certainly not be detectable by any current scientific methods and could, by the beginning of the first century AD, be the genealogical ancestors of everybody on Earth without invoking any extraordinary coincidences or miracles beyond their initial creation.

Importantly, Swamidass does not argue that the scientific evidence supports this hypothesis, merely that it does not rule it out. That is, since it would be incredibly unlikely that one specific couple at that temporal distance would be detectable either genetically or archaeologically, the lack of evidence for their existence is meaningless. However, that lack of evidence also means that belief in their existence has to come from some other source, such as trust in the Bible; it is not a reasonable inference from the scientific data alone.

For believers, Swamidass shows that a traditional reading of Genesis 2-3 can be maintained without having to explain away the massive amount of scientific evidence that Homo sapiens shares common ancestry with apes and has never dropped to a population of less than about 10,000 individuals. The scientific account of human origins describes the people outside the garden, many of whom are every bit as much our ancestors as Adam and Eve. The Biblical account would be understood as describing two specific individuals of special theological importance. Because these people are universal genealogical ancestors, most theological understandings of original sin remain intact. (Understandings that depend upon genetics rather than genealogy are, in my view, suspect regardless, since the Biblical authors had no concept of genetics, but make extensive use of genealogies.)

This is a idea that offers people with different beliefs about human origins some common ground on which they can interact (hopefully) without hostility. And, interestingly, it also illustrates a practical application of Stephen J. Gould’s well-known concept of non-overlapping magisteria.


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Our Common Ancestors, part I

“To the extent that ancestry is considered in genealogical rather than genetic terms, our findings suggest a remarkable proposition: no matter the languages we speak or the colour of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who laboured to build the Great Pyramid of Khufu.” – Rohde, Olson, and Chang, “Modeling the recent common ancestry of all living humans” quoted in Swamidass 2019.

The quote above was a comment on a study the authors performed on universal genealogical (not genetic) ancestors. Understanding this begins with the realization that each of us has vastly more genealogical ancestors than genetic ones. Genealogical ancestry refers to every single person whom you can claim as a biological ancestor. Generally, that mean two parents, four grandparents, and so forth, doubling with each generation you go back. In just a few generations, the number of ancestors you have becomes enormous. However, most of those people have not contributed any DNA to you. This is because the DNA molecule, although made up of millions of base pairs, is not divisible just anywhere. During reproduction, it divides into discrete chunks, which are passed on as units. (The number of chunks involved is somewhat larger than the number of chromosomes you have, but not immensely so.) This means that just a few generations back, it’s impossible for most of your genealogical ancestors to have contributed any DNA to you. This is even more pronounced if you limit your search to certain portions of your DNA. Mitochondrial DNA, for example, only passes from mother to child, meaning that only one person in each generation is your mitochondrial ancestor.

Genealogical ancestors, as I mentioned above, double in each generation. So after 40 generations, or about 1,000 years if you consider a generation to be 25 years, you would have over one trillion ancestors. This is, obviously, far more people than have ever lived, so equally obviously, a large majority of your ancestors that far back will be people you are related to along more than one line. I have the same number of ancestors you do, so no matter how far different we seem to be, it’s very likely that within just a few hundred years, we start having ancestors in common.

In 1999, Joseph Chang published the results of a computer simulation in which he calculated that everybody alive on planet Earth was related through an ancestor who lived roughly 700 years ago. Chang used a very simple model, which didn’t take into account that some populations are more isolated than others. A more careful study in 2004 by Rohde, Olson, and Chang refined the date of the most recent universal genetic ancestor (MRUGA) to about 2,000 years ago, and this finding seems to be holding on pretty well. Even more interesting is the identical ancestors point (IAP). It should be apparent to anybody thinking about it that the further back in time you go, the more ancestors we have in common. The IAP is the point in time where everybody alive on the planet either has no descendants in the present day, or is an ancestor of everybody alive. That point comes roughly twice as far back as the MRUGA, or about 4,000 years.

This finding drives the last nail into any biological argument in favor of racism. Every single one of us is related to every other one of us so recently that any idea of race is simply absurd. It’s long been observed that human biological variation does not cluster into identifiable races, and genealogical ancestry reveals why that’s the case; no human population has been isolated anywhere near long enough for separate races to have evolved.

This finding also led computational biologist S. Joshua Swamidass to an even more interesting finding, with theological implications. But that’s a subject for another post.


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Safety Team

As I mentioned two posts ago, I started going to church again after not going for several years. This is not a fundamental change; I hadn’t stopped believing, I’d just gotten lazy. Also, the church I had been attending when I first came to Reno was just too big, and I realize now that it’s not good for me to attend a church where it’s too easy for me to hide and not get involved with, or even really get to know, the people. So about seven months ago, after looking at various church web sites, I decided to try visiting Outlook Christian Church, which looked good online and is close to my house.

You know how sometimes when you walk into a place you can immediately get kind of a feel for it? That happened here. At no point did I ever feel like I was a guest in that church; right from the beginning I felt like part of the family. So I went back. And kept going back, and got to know people. So now, seven months later, I’ve been recruited to be part of the security team (sometimes called the safety team, which might sound a little less off-putting for some people). When  I first found out they had a security team I was happy that the leaders were thinking about that, but also heartbroken that we live in a world where a church would even need security. Why I got asked to be a part of it is still a bit of mystery to me, since I don’t really have any security background. But Joe Lewis, the team leader, says they recruit for personality and train for competence. Okay.

I started last Sunday. It’s a little odd being in church during the service without participating in the singing or paying attention to the sermon. But I learned a lot, and I got a chance to pray with a couple of people I probably wouldn’t otherwise have interacted with. This is not a ministry that I ever really imagined myself doing, but I think it is where God wants me to be right now.

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Glory to God in the highest, and on earth peace to men on whom His favor rests

“Do not be afraid. I bring you good news of great joy that will be for all the people. Today in the town of David a Savior has been born to you; he is Christ the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.” – Luke 2:10-12 (NIV)

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ZOMG!!! Catholic University promotes Catholicism!!

And some morons apparently think that it’s a violation of their human rights if the meeting rooms at a private religious college all contain Catholic symbols.

If you’re deeply offended by Christian symbols, then perhaps a school named “Catholic University” might not be the best place for you. I’m just saying.

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