We are not especially 'interested in' animals. Neither of us had ever been inordinately fond of dogs, cats, or horses in the way that many people are. We didn't 'love' animals.

We see things like reciprocity which are fairly central to our view of ethics. But if you're talking about a set of worked-out rules on what we are supposed to do then, yes, it is a human product.

At the descriptive level, certainly, you would expect different cultures to develop different sorts of ethics and obviously they have; that doesn't mean that you can't think of overarching ethical principles you would want people to follow in all kinds of places.

Sometimes we know the best thing to do, but fail to do it. New year's resolutions are often like that. We make resolutions because we know it would be better for us to lose weight, or get fit, or spend more time with our children. The problem is that a resolution is generally easier to break than it is to keep.

If we are prepared to take the life of another being merely in order to satisfy our taste for a particular type of food, then that being is no more than a means to our end.

Suppose I grant that pigs and dogs are self-aware to some degree, and do have thoughts about things in the future. That would provide some reason for thinking it intrinsically wrong to kill them - not absolutely wrong, but perhaps quite a serious wrong. Still, there are other animals - chickens maybe, or fish - who can feel pain but don't have any self-awareness or capacity for thinking about the future. For those animals, you haven't given me any reason why painless killing would be wrong, if other animals take their place and lead an equally good life.

When fish experience something that would cause other animals physical pain, they behave in ways suggestive of pain, and the change in behaviour may last several hours.