Finding the mitochondrial Na’ama

I was having a conversation recently about Biblical ancestry and the antediluvian generations, and it got me to thinking about how scientists sometimes like to use biblical references as attention-grabbing devices, without actually bothering to understand what they’re referring to — in this case, the so-called “mitochondrial Eve”. The expression was not used in the 1987 Nature paper that first purported to calculate the genealogical time back to the most recent common ancestor (MRCA) of all present-day humans in the female line, but it was a central to publicity around the paper at the time, including in academic journals such as Science.

The term has come to be fully adopted by the genetics community, even while they lament the misunderstandings that it engenders among laypeople — in particular, the assumption that “Eve” must in some sense have been the first woman, or must have been fundamentally different from all the other humans alive at the time. The implication is that the smart scientists were making a valiant effort to talk to simple people in terms they understand, taking the closest approximation (Eve) to the hard concept (MRCA), and the simple bible-y people need to make an effort on their part to understand what they’re really talking about.

In fact, calling this figure Eve is a blunder, and it reveals a fundamental misunderstanding of the biblical narrative. Eve is genuinely a common ancestor of all humans, according to Genesis, but she is not the most recent in any sense, and suggesting that she is just confusing. The MRCA in the Bible is someone else, namely the wife of Noah. Appropriately, she is not named, but if we want a name for her, the midrashic Genesis Rabbah calls her Na’ama. She has other appropriate characteristics as well, that would lead people toward a more correct understanding. To begin with, she lived many generations after the first humans. She lived amid a large human population, but a catastrophic event led to a genetic bottleneck that only she and her family survived. (That’s not quite the most likely scenario, but it points in the right direction.) And perhaps most important — though this reflects the core sexism of the biblical story — there was nothing special about her. She just happened to be in right place at the right time, namely, partnered with the fanatic boat enthusiast when the great flood happened.

The nature vs. nurture debate: High Christology edition

At least since the late nineteenth century the social interpretation of biology — and of genetics in particular — has devolved repeatedly upon the nature–nurture dispute: To what extent is a human’s individual characteristics determined by a predetermined essence or nature — qualities they are born with, commonly identified with inheritance; or by nurture, the particulars of the physical and social environment in which they develop after birth. From one of the most interesting books I’ve read recently, Bart Ehrman’s How Jesus Became God, I learned that an analogous debate roiled the early Christian Church.

One of the key disputes among early followers of Jesus concerned the nature and meaning of Jesus’s divinity. At the extremes you had the “low” christology belief that Jesus was a wise man and preacher, of the same nature as any other human; and the “high” christology claim that Jesus was identical with the creator God of the Hebrew Scriptures, and only appeared to be human. (Perhaps even more extreme were the gnostic claims that Jesus was an even higher being than that nasty Yahweh, who obviously fucked up his one major task*, for possibly nefarious purposes. In between were a range of beliefs that Jesus was entirely divine and entirely human. Ehrman points out that in the ancient Mediterranean world there were two “major ways” that it was believed possible for a human to be divine:

  • By adoption or exaltation. A human being… could be made divine by an act of God or a god…
  • By nature or incarnation. A divine being… could become human, either permanently or, more commonly, temporarily.

In other words, God by nurture or God by nature. Nurture is particularly emphasised in the Gospel of Mark, Nature in the Gospel of John. Reflecting the common prejudice in favour of “nature” as the more powerful, one typically thinks of incarnation as representing a more exalted view of Jesus. A Jesus who grew up as a human, and only in adulthood was adopted by God seems less genuinely godlike than one who is, so to speak, fruit of God’s loins — hence the virgin-birth story of Matthew and Luke.

One of the more fascinating novelties of Ehrman’s account is his elucidation of adoption customs in the Roman world, particularly as regards nobles and rulers. Of course, we know that Roman emperors commonly adopted heirs — most famously, Julius Caesar’s adopted son Octavian — but Ehrman explains how prevalent views of adoption were that today would be called progressive: Adoptive families are families by choice, so could be considered superior to the accidental biological families. An heir chosen by a great leader for the qualities he has demonstrated better incorporates and perpetuate’s the leader’s essence than his biological descendant.

Thus, a Christ nurtured by and ultimately adopted into the divine family by God after he had proved himself worthy is a more genuinely divine being than any merely so-to-speak genetically divine progeny, who might ultimately turn out to be a disappointment to his father.

* A classic joke with a gnostic perspective: A man goes to the tailor to order a new coat. The tailor fusses around taking measurements, asking exacting questions about the fabric, the cut, and so on. Having finished he names a price and tells the customer the jacket will be finished in three weeks. “Three weeks! The Lord created the whole world in just one week!”

The tailor shakes his head, picks up another recently completed coat, and beckons the man to come to the window. “One week you want? Look at the work here. The precision cuts. The minute stitching. The harmonious interplay of the parts. And now” gesturing out the window, “look at this world…”

Your shadow genetic profile

So, the “Golden Gate killer” has been caught, after forty years. Good news, to be sure, and it’s exciting to hear of the police using modern data systems creatively:

Investigators used DNA from crime scenes that had been stored all these years and plugged the genetic profile of the suspected assailant into an online genealogy database. One such service, GEDmatch, said in a statement on Friday that law enforcement officials had used its database to crack the case. Officers found distant relatives of Mr. DeAngelo’s and, despite his years of eluding the authorities, traced their DNA to his front door.

And yet… This is just another example of how all traditional notions of privacy are crumbling in the face of the twin assaults from information technology and networks. We see this in the way Facebook generates shadow profiles with information provided by your friends and acquaintances, even if you’ve never had a Facebook account. It doesn’t matter how cautious you are about protecting your own data: As long as you are connected to other people, quite a lot can be inferred about you from your network connections, or assembled from bits that you share with people to whom you are connected.

Nowhere is this more true than with genetic data. When DNA identification started being used by police, civil-liberties and privacy activists in many countries forced stringent restrictions on whose DNA could be collected, and under what circumstances it could be kept and catalogued. But now, effectively, everyone’s genome is public. It was noticed a few years back that it was possible to identify (or de-anonymize) participants in the Personal Genome Project, by drawing on patterns of information in their phenotypes. Here’s a more recent discussion of the issue. But those people had knowingly allowed their genotypes to be recorded and made publicly available. In the Golden Gate Killer case we see that random samples of genetic material can be attributed to individuals purely based on their biological links to other people who volunteered to be genotyped.

The next step will be, presumably, “shadow genetic profiles”: A company like GEDmatch — or the FBI — could generate imputed genetic profiles for anyone in the population, based solely on knowledge of their relationships to other people in their database, whether voluntarily (for the private company) or compulsorily (FBI).

Neanderthal science

I just listened to all of a two-hour discussion between journalist Ezra Klein and professional atheist Sam Harris, about Harris’s defense of the right-wing policy entrepreneur (as Matthew Yglesias has described him) Charles Murray, famous for his racist application of intelligence research to public policy, most famously in a notorious chapter of his book The Bell Curve. Klein pushes back effectively against Harris’s self-serving martyrdom — Harris, not unreasonably, identifies with the suffering of a wealthy and famous purveyor of quack science whose livelihood is ever-so-slightly harmed by public criticism* — but he doesn’t sufficiently engage, I think, with Harris’s contention that he is promoting the values of real science. Unfortunately, the “mainstream social science” that Harris and Murray are promoting exists only in secret messages from “reputable scientists in my inbox, who have totally taken my side in this, but who are too afraid to say so publicly”. Harris doesn’t allow for a second that there is any good-faith argument on the other side. Anyone who disagrees is merely trying to shut down scientific progress, or simply confusing scientific truth with do-gooding wishful thinking.

The truth of the matter is, Murray and other brave seekers of truth are doing the opposite of helping to clarify reality. They are wading into a swamp of confusion, and pulling out some especially stinky slime that they can hurl at disfavoured groups.

As much as Harris tries to promote Murray as a pure-hearted “content-of-our-character” anti-racist individualist, as long as “race” exists as a social factor affecting people’s self-image, the communities they belong to, and the way they are perceived by others, it remains a potent social force. When demographers argue that “race” isn’t “real”, they are saying that racial categories don’t separate natural clusters by genetic or physical traits. When Murray says, let’s stop talking about race, let’s talk about individual genetic endowments, he is saying that racial groupings have no causal effect on their own, but only label clusters whose difference arise from deep physical causes — wrong on both sides. Continue reading “Neanderthal science”

The biggest genetics-investment opportunity ever!

I was just looking at this paper from 2012, that purports to discover the heritability of economic and political preferences by slightly shady statistical analysis of GWAS data. And then it hit me: We could market

An investment plan tailored to YOUR genotype

Okay, we’ll have to work on the catchphrase. Feel free to send your seed money. (The genotype-based diet is running like gangbusters.) Excuse me while I go off for a moment to write the patent application.