The Charter of the Genome

Genetics truly is the language of love

A key aspect of any decently lurid romantic novel is opposition. One lover is rich, the other poor. One is from the north, the other is from the south. One is demure, the other is brazen. The families don’t approve, secrecy is a must, and the threat of disclosure ever looms. The books shall have titles like “My Reluctant Pirate Lord”, “To Capture a Viscount”, or “Ancient gene flow from early modern humans into Eastern Neanderthals” (population genomic article titles tend to lack some of the allure of a proper romance novel, but make up for it with better equations).

The latter tale of forbidden loves was just published in the journal Nature, and it recounts about 100,000 years of romance. Figuring a generation every twenty years and that their tale covers Africa and Eurasia, this article covers a lot passion. And just like a romance novel- despite its basis in genetics and statistics- population genomics delves into the love borne of contradictions.

The elements of opposition in a population genetic story are, of course, genetic differences. Though dairy maid vs. marquise is more standard novel fare, genetics must focus on differences in our DNA. Fortunately there is plenty of genetic variation to assess, though much is undetectable without having your own Illumina MiSeq to sequence a genome or two. As discussed here, mitochondrial DNA is often used to trace relationships between groups of people. These mitochondrial mutations probably have little if any effect on our physiology. However by assaying these mutations in many different groups of people, we can trace how different populations flowed over time across the lands.

Applications for the position are currently being accepted (not really)

Small things can become big things. Aeneas, fleeing from the destruction of his home town of Troy, fell in love with Dido, the queen of Carthage. That was a small thing, people fall in love all the time. Even I fell in love with Dido when, in her despair at finding that Aeneas was abandoning her to go found Rome, “Sleep fled her eyes, as quiet fled her mind. /Despair, and rage, and love divide her heart”.

That shouldn’t happen to anyone.

The news of their love affair was spread across the sea by Fama, the Roman goddess of gossip, rumor and fame. The bible says we’re supposed to love our enemies (and Crosby, Stills, Nash and Young say we’re supposed to love the one we’re with). The Aeneas and Dido affair was a case of prescient loving one’s enemy, for news of their aborted tryst, carried across the waters by Fama, led ultimately to the Punic wars (according to legend, at least). Virgil described Fama as, “at the start a small and cowardly thing, it soon puffs itself up, and walking upon the ground, buries its head in the clouds”. If you’ve ever read a copy of People’s magazine or Hello!, you know exactly what he meant about something small and inconsequential taking on giant proportions.

Surveys are collections of lots of small bits of information. William the Conqueror’s Domesday Book was one. The human genome project is another.

It’s not only gossip that can grow from the small to the large. Surveys are collections of many small facts and items of information; individually these facts are often inconsequential, but the survey may be greater than the sum of its parts. One of the first great surveys of public information was the Domesday survey, ordered by William the Conqueror of his new holdings in England. To make sure taxes and levies were correctly allotted, he ordered a survey of all the sources of income of the lords and counties. This included big things as well as the lesser. A coppice is a stand of small trees that is cut back periodically; the wood was used for baskets and barrels, poles and pikes, and whatever other uses one had of pliable wood before the advent of plastic and sheet metal, and in Domesday Book these are called silvia minutia, or ‘tiny woods’. A single coppice is not worth very much, but a single hamburger isn’t worth very much either, and yet McDonalds is worth over 100 billion dollars. Size may not matter, but numbers may. William had a lot of coppices, or at least, a number he felt was well worth counting.

A genomic sequence is another survey, with three billion entries per person. Even a simple survey of just a person’s most variable bits of their genome (since we are all 99.9% identical at the level of our genetic sequence) often has a million entries. Each entry in these surveys is a single base, just an A, C, T or G. Pretty small, and not very important.