Why Geneticists get touchy about Epigenetics

Disclaimer: I am not a geneticist. For those of you who are new here, this is basically a genetics fan blog. I am trying to learn about genetics, and you know what?

Genetics is complicated.

I fully admit that here’s a lot of stuff that I don’t know yet, nor fully understand.

Luckily for me, there are a few genetics basics that are easy enough to understand that even a middle school student can master them:

  1. “Evolution” is the theory that species change over time due to some individuals within them being better at getting food, reproducing, etc., than other individuals, and thereby passing on their superior traits to their children.
  2. “Genes,” (or “DNA,”) are the biological code for all life, and the physical mechanism by which traits are passed down from parent to child.
  3. “Mendel squares” work for modeling the inheritance of simple traits
  4. More complicated trait are modeled with more complicated math
  5. Lamarckism doesn’t work.

Lamarck was a naturalist who, in the days before genes were discovered, theorized that creatures could pass on “acquired” characteristics. For example, an animal with a relatively normal neck in an area with tall trees might stretch its neck in order to reach the tastiest leaves, and then pass on this longer-neck to its children, who would also stretch their necks and then pass on the trait to their children, until you get giraffes.

A fellow with similar ideas, Lysenko, was a Soviet Scientist who thought he could make strains of cold-tolerant wheat simply by exposing wheat kernels to the cold.

We have the luxury of thinking that Lysenko’s ideas sound silly. The Soviet peasants had to actually try to grow his wheat, and scientists who pointed out that this was nonsense got sent to the gulag.

The problem with Lamarckism is that it doesn’t work. You can’t make wheat grow in Antarctica by sticking it in your freezer for a few months and animals don’t have taller babies just because you stretch their necks.

So what does this have to do with epigenetics?

Pop science articles talk about epigenetics as if it were Lamarckism. Through the magic of epigenetic markers, acquired traits can supposedly be passed down to one’s children and grandchildren, infinitely.

Actual epigenetics, as scientists actually study it, is a real and interesting field. But the effects of epigenetic changes are not so large and permanent as to substantially change most of the way we model genetic inheritance.

Why?

Epigenetics is, in essence, part of how you learn. Suppose you play a disturbing noise every time a mouse smells cherries. Pretty soon, the mouse would learn to associate “fear” and “cherry smell,” and according to Wikipedia, this gets encoded at the epigenetic level. Great, the mouse has learned to be afraid of cherries.

If these epigenetic traits get passed on to the mouse’s children–I am not convinced this is possible but let’s assume it is–then those children can inherit their mother’s fear of cherries.

This is pretty neat, but people take it too far when they assume that as a result, the mouse’s fear will persist over many generations, and that you have essentially just bred a new, cherry-fearing strain of mice.

You, see, you learn new things all the time. So do mice. Your epigenetics therefore keep changing throughout your life. The older you are, the more your epigenetics have changed since you were born. This is why even identical twins differ in small ways from each other. Sooner or later, the young mice will figure out that there isn’t actually any reason to be afraid of cherries, and they’ll stop being afraid.

If people were actually the multi-generational heirs of their ancestors’ trauma, pretty much everyone in the world would be affected, because we all have at least one ancestor who endured some kind of horrors in their life. The entire continent of Europe should be a PTSD basket case due to WWI, WWII, and the Depression.

Thankfully, this is not what we see.

Epigenetics has some real and very interesting effects, but it’s not Lamarckism 2.0.

Adoption pt 4: Noble/Kin Fosterage and Ancient Rome

The nobility of ancient Rome came up with a creative solution to the difficulties of making sure everyone had a male heir (who made it to adulthood) without ending up with a bunch of excess heirs who would inconveniently divide up the inheritance: adoption–or to be clear, noble fosterage. A family with two males would send its extra to a noble family that had none, (perhaps in exchange for a wife for the other son.) This ensured that every family had an heir and cemented ties between the families.

The Roman emperors also made a habit of adopting their chosen successors–other adults. Julius Caesar, for example, adopted his great-nephew Augustus, who succeeded him as emperor. (Well, after that business with the triumvirate and the civil war and all.) Technically, you could be adopted in ancient Rome by someone younger than yourself, though this did not happen very often.

Wikipedia gives some technical details:

In Roman law, the power to give children in adoption was one of the recognised powers of the paterfamilias. The adopted boy would usually be the oldest, the one with proven health and abilities. Adoption was an expensive agreement for the childless family and quality had to be ensured. Adoption was agreed between families by the mother giving the boy they wanted to adopt (for the most part) equal status, often political allies and/or with blood connections. A plebeian adopted by a patrician would become a patrician, and vice versa; however, at least in Republican times, this required the consent of the Senate (famously in the case of Publius Clodius Pulcher[1]).

A sum of money was exchanged between the parties and the boy assumed the adoptive father’s name and a cognomen that indicated his original family (see Roman naming convention). Adoption was neither secretive nor considered to be shameful; the adopted boy was not even expected to cut ties to his original family. Like a marriage contract, adoption was a way to reinforce interfamily ties and political alliances. The adopted child was often in a privileged situation, enjoying both original and adoptive family connections. Almost every politically famous Roman family used it.

As we discussed yesterday, a different system of fosterage existed in Scotland and Ireland:

In A Journey to the Western Isles of Scotland (1775), Samuel Johnson writes:

There still remains in the Islands, though it is passing fast away, the custom of fosterage. A Laird, a man of wealth and eminence, sends his child, either male or female, to a tacksman, or tenant, to be fostered. It is not always his own tenant, but some distant friend that obtains this honour; for an honour such a trust is very reasonably thought. …

Children continue with the fosterer perhaps six years, and cannot, where this is the practice, be considered as burdensome. The fosterer, if he gives four cows, receives likewise four, and has, while the child continues with him, grass for eight without rent, with half the calves, and all the milk, for which he pays only four cows when he dismisses his Dalt, for that is the name for a foster child.

Fosterage is, I believe, sometimes performed upon more liberal terms. Our friend, the young Laird of Col, was fostered by Macsweyn of Grissipol. Macsweyn then lived a tenant to Sir James Macdonald in the Isle of Sky; and therefore Col, whether he sent him cattle or not, could grant him no land. The Dalt, however, at his return, brought back a considerable number of Macalive cattle, and of the friendship so formed there have been good effects. When Macdonald raised his rents, Macsweyn was, like other tenants, discontented, and, resigning his farm, removed from Sky to Col, and was established at Grissipol.

The fostered Gael who comes immediately to mind is Cuchulainn. I was going to quote from the Tain Bo Cualnge, (pronounced “cooley;” Irish spelling is weird if you’re not used to it,) but the language in the translation is archaic so I’m gong to summarize.

Once upon a time, when Cuchulainn (who was semi-divine but being raised by his human mother,) was five years old, he decided he wanted to go play with some other boys he’d heard of who were under the care of his uncle. His mother told him he was too little to go, but he decided to go anyway.

When Cuchulainn arrived, he didn’t know that he was supposed to ask for permission (protection) before joining the other boys, so they all ran up and stated beating him up.

Five year old Chuchulainn responded in a way that must have scared the crap out of the bigge kids:

Thereupon contortions took hold of him. Thou wouldst have weened it was a hammering wherewith each hair was hammered into his head, with such an uprising it rose. Thou wouldst have weened it was a spark of fire that was on every single hair there. He closed one of his eyes so that it was no wider than the eye of a needle. He opened the other wide so that it was as big as the mouth of a mead-cup. He stretched his mouth from his jaw-bones to his ears; he opened his mouth wide to his jaw so that his gullet was seen. The champion’s light rose up from his crown.

Eventually the adults step in and stop Cuchulainn from beating up all the other kids, and inform him that he has to get their “protection” before entering the play field to prevent them from beating him up. Cuchulainn asks for protection and gets it, and the kids start playing with each other–at which point he starts beating them up again, because they don’t have protection from him. The adults intervene again and all of the kids ask for protection from this five year old.

The grown ups, of course, are impressed:

“A youngster did that deed,” Fergus continued, “at the dose of five years after his birth, when he overthrew the sons of champions and warriors at the very door of their liss and dûn. No need is there of wonder or surprise, if he should do great deeds, if he should come to the confines of the land, if he should cut off the four-pronged fork, if he should slay one man or two men or three men or four men, when there are seventeen full years of him now on the Cattle-lifting of Cualnge.”

“In sooth, then, we know that youth,” spoke out Conall Cernach (‘the Victorious’), “and it is all the better we should know him, for he is a fosterling of our own.”

150px-Harry_Potter_and_the_Sorcerer's_StoneThe English have their own version of this fostering tradition, called boarding school. Quidditch may be less violent than hurley, but I don’t know about rugby.

As I have noted before, leaving children with their kin, temporarily or for extended periods, is quite normal in many societies. There’s a definite logic to this–older grandparents can look after little ones while young, strong parents work in the fields or travel to distant villages in search of better jobs. When the parents become grandparents, then it becomes their turn to look after the children.

Mainstream US culture, by contrast, emphasizes the primacy of the nuclear family, with the relationship between two parents and their children given prime importance. The “ideal” is typically given as two parents, one of whom (usually the mom) stays home full-time with the child/ren. If both parents must work, then in place of relatives, we have daycare workers and babysitters, with whom the child is not supposed to form a long-term bond. (I suspect this contradicts the child’s natural instinct to bond with caretakers.)

Without a nuclear family, we tend to assume that children will grow up, in some manner, defective.

Our particular form of adoption is born out of this belief in the importance of the nuclear family + our belief in blank slate-ist theories of identity and personality, which thus allow for the incorporation of total strangers into our family structures.

We also tend to assume that any mother who gives up her children will be deeply saddened by the broken bond–but cross-cultural and historical analysis suggests this is not necessarily true. Infanticide and child abandonment were far more common, historically, than we like to admit. But giving one’s children to a sibling or cousin to raise, in a situation where you could visit them often and no one assumed that full parental rights were being terminated, probably did not entail the kind of emotions as giving a child to a total stranger.

Tomorrow: The Curious Case of the Trans-racial Indians