When does the rapidly growing and sub-dividing set of cells within my wife's body become life? This seems a rather philosophical question (and I am thinking of it in terms of philosophy - or spirituality - and not biology), but it is one that has been niggling me for the last couple of days. This is my difficulty. You would happily call a plant alive (after all, we've all overwatered them and seen them die), but surely all it is, is a set of chemical responses to certain environmental stimuli? A plant will grow towards light - but do any of us think there is choice in that? My wife tells me that a foetus in vitro will turn away from light shone on the mother's tummy - is that a choice or a biological response?
Ultimately, my question is: when does my child develop a consciousness? This is quite a nice short article - http://www.guardian.co.uk/science/2005/feb/10/thisweekssciencequestions - and it is the first time I've heard of the primitive streak. With our growing baby at around six weeks, this suggests its central nervous system is already in place. Not fully developed but in place. So has my child started to have primitive thoughts?
This person says no: http://www.scientificamerican.com/article.cfm?id=when-does-consciousness-arise. Apparently integration of our cognitive circuits, which enable us to think, dream and so on, happens between the 24th and 28th week. So does this mean my child is not 'in there' until the third trimester? Yet premature babies as young as 22 weeks have lived - so there is a life in there before this time. So I still don't have a satisfactory answer. And nor, I suspect, is there a likelihood of me getting one.
(Quick note: I don't actually agree with some of the author's assumptions, particularly the newborn not being self-aware and that sleep lacks any form of consciousness, but then he is a biologist and I am a psychologist. But I would say it is worth a read and some of the comments are very interesting if this kind of thing floats your boat!)
But why is any of this important? I want to know my child. And, for me, that begins with consciousness, as this is what it separates my little boy or girl from a collection of biological and chemical processes. This is an entirely subjective belief; it is not one based in evidence. But I want to know if child is responding to the world. When do I start speaking to a swelling tummy with confidence that there is someone, rather than something, in there? I want to know when the child, that I am already beginning to love, is home. And I want them to feel safe and dream dreams of colour, movement, tranquility.