Ok, it went like this.
Yesterday we were at one of four Saturday seminars. This one was about
attachement theory, which is a theory developed by an English physician and psychoanalyst (and "competent etologist", to quote his son) to explain how relationships with caregivers early in life affect our development and personality.
John Bowlby's son, a very nice man (now in his seventies) who was for all of his life a medical photographer (and whose son's racing team won the Indy 500 this year, he was proud to tell us), came and gave us a very clear and very touching lecture about it, complete with BABY ANIMALS footage. He particularly won me over because he stressed repeatedly that attachment theory was a way of explaining facts, and that if new facts came to light that contradicted it, it should be changed, because this is how science works. He also stressed that AT is not a therapy: it is just a way of explaining what goes on in the first two years of life.
(One of the most touching and chilling moments came when he showed a card given by the mother of a two-year old on the baby entering hospital for ten days. The card detailed the visiting hours for parents, which were
on every first Sunday of the month from 3:00 pm to 4:30 pm.)
Anyway, Richard Bowlby (the son) has put together a very nice documentary explaining the theory, in which he interviews among others a psychoneurologist who says:
'People often things that "genetical" means "everything that happens after birth". But at birth, your genes have still a lot of work to do as far as the brain is concerned.'
Photo of an infant brain, followed by one of an adult brain.
'The cortex has yet to develop, and most of the neurons are not even myelinized yet. Various part of the brain, including the areas that make language possible, only come "on line" much later in life.'
Scan of a normal child brain and of a severely deprived child brain (I think one of the Romanian orphanages children). Circles around the temporal lobes, which are red in the normal scan, and dark in the deprived child's scan.
'This is a particularly chilling image. The temporal lobes are literally black holes. The structures are simply not developed'.
Oh and of course the movie often mentions how poor parenting skills are transmitted from generation to generation, and it spends quite a long time over one particular family, whose shoplifting eleven-year old child is the product of two parents who have been deprived of love and affection themselves.
The documentary starts with cheerful baby elephants but ends with lots of damaged lives and the heartbreaking glint of unshed tears in Evan's eleven-year old eyes.
Anyway. At this point, lights up.
My tutor goes: "I find it so incredible to see how social factors can
change your brain."
I just listen, silently, because after the telepathic bushmen of the Kalahari I'm resigned to anything.
At this point my colleague Julia, which I like very much but is a bit of a hippie (in both the good and the bad senses!), says: "But then, if this social situations can change the brain at a genetic level, they can be passed down from generation to generation?"
I wait for somebody to explain. Preferably the tutor. There is instead a murmor of approval. Anna boggles. Anna tries to point out that no, it is not genetic. Is ignored. People are agreeing with the terrible prospect of the brain changing at a genetic level.
Anna loses it, goes into arrogant prick mode because that's what happen when she loses it, and says, "EXCUSE me, can I say something as a biology student? This is... the genes are... well, ok, there was this guy called Lamark, and he thought that evolution happened more or less like this, that a giraffe stretches her neck, and the neck becomes longer, so the giraffe's children inherited a longer neck, and then stretched it even more, and that is how they got a long neck and IT DOESN REALLY HAPPEN THAT WAY because then it was discovered how genes work, and genes are... are a project, and it can... and genes can be expressed in several different ways but you still inherit them from your parents, and..."
And I rambled on in this fashion for a bit. As you can see, Anna no good as biology teacher, especially in arrogant prick mode.
(BTW - I sent an apology note to my classmates this morning. I hope they get it, my guess is a lot of them are not too good with email).
Somebody, among the class that looks at me in stunned silence, gently says: "Yes, but we are talking about social factors here." As in, we are not talking of gross modifications as the giraffe's long necks, we are talking about much more refined modification, and That scientist just told us that genetics doesn't stop after birth did he?
Anna puts her face in her hands, trying to keep quiet, trying not to get up and walk out because how can a tutor who has not even grasp the basic facts of biology have anything to teach her about how the mind works? But instead starts to understand why Dawkins felt the need to bang on, and on, and on, and on, about evolution in "The God Delusion". "Why is he going on so much about it?" she though. "Everybody knows that."
Well, not everybody, apparently.
So yes: there was, before the Mendel's work was rediscovered, a great debate about how evolution worked. Lamark thought that
acquired characteristics could be inherited, and Darwin didn't. Darwin thought that evolution acted by promoting the survival of individuals who were
born with a different trait, while Lamark thought that use created the function, and non use would cause it to be lost (as is sightless moles, for example.) Darwin was right, but for a long tragic stretch of time
in Stalinist Russia the central dogma of biology was that Lamark was right in this.
What confused my colleagues is that the brain does actually change is a way similar to Lamark's model of evolution: neural pathways that are in constant use remain, while dendritical connections that are seldom or never used disappear. And yes, the development of the brain happens largely after birth, and is indeed dictated by genes, but the particular structures that will or will not develop only come about from the interplay of genes and environment. This means that if your brain develops particular structures that will later in life make you, for example, more prone to violence or more prone to depression (there is good experimental evidence to suggest that early attachment patterns are predictors of such outcomes), your genes will still codify for a brain that, exposed to a different environment, can give rise to a sunny, pacific, laid-back disposition.
The style of parenting you will display is heavily influenced by the parenting style you were exposed to as a child, because parenting is in part instinctive and in part learned. This is why animals in zoos often have troubles raising their offspring: they haven't seen other animals like them raise their young. And this is also why zookeepers will try all they can before hand-raising animals: because a hand-raised animal has very poor chances of becoming a good mum.
But none of this is genetic. The way you respond to your child is not written in your genes - or if it is, it is only a predisposition to certain patterns of behaviour. Genes can only dictate your physicality: they can code for an easier production of certain hormones, for example. OK, I am not a biologist here, so you can correct me, but if you system is easily flooded with oxytocin then you are more likely to bond easily with your child. But no matter how many times you've been hit or gurgled at when you were one year old, the genes you will transmit to your children will still code for high or low oxytocin (of course, the other parent's genes will either moderate or increase this). Your experiences, no matter how hard-encoded in your body, will not change this.
One of the enchanting things about this lesson was that it is now possibile to see how the mother and child system is a feedback system for the production of feel-good hormones, dopamine, oxytocin, and so on. And apparently dopamine is trophic - the happier, more gurgly, more laughing the mother-child system, the more those neurones will grow and branch and form new connections.
(Sorry - for the whole lesson Richard Bowlby was careful to say "primary caregiver", not "mother". The primary caregiver can be anybody, a nanny, a nursery attendant, a father, anybody. It is just the person that mostly comes when the baby cries, the one that laughs and plays with it.)