When Does Human Life Begin?

This is an ancient and important question. People try to debate the ethics of abortion but how can they have an intelligent discussion when there is no agreement on precisely when human life begins. Sure, there are philosophical opinions and religious ideas but those are not facts.

I came across a fairly full discussion of this question at Development Biology Online. Read it if you want to be prepared for any sort of argument over abortion. Points that stand out for me include:

• At week 5 the first neurons begin to appear
• At 7.5 weeks the embryo displays its first reflexes in response to stimulus
• Around week 8 the embryo has a basic three-neuron circuit
• Not until around 20 weeks is the completion of the development of the thalamus, a region of the brain which enables the integration of the nervous system.

If you are concerned about causing pain, you might support an early abortion but not a later one. I'm not seeking to start an argument but it's something to think about.