Why I'm becoming a vegetarian

[Viking]

I'm taking animal intelligence at face value. If dolphins could be shown to be as intelligent as people, then that would be a different argument with different conclusions. Until they can demonstrate that, we should restrict ourselves to assuming that they are stupid[...]

Of course we should not - that is completely illogical. I brought up technology and dolphins precisely because it would not be easy to measure intelligence of dolphins (they can't really develop any techonology). I may only assume that what you are trying to say is that you will only consider animals that actually are 'stupid' (which could well be 99.99%) for this debate.

To expand on the dolphins, different 'tribes' of dolphins may apply different, clever hunting strategies. Check it out:

Spoiler Alert, click show to read: 

Both will certainly continue to "improve", and one of the improvements of the latter should be the idea that it is wrong to kill for pleasure.

That it is wrong is your subjective opinion. Of course, the whole idea of 'civilisation' has a tendency of becoming a rhetorical device. If we define it as a society 'based upon' rational thinking, then you would have demonstrate why 'killing for pleasure' is wrong through argumentation. I do not see how you do this. What is the idea building on? What leads us to the conclusion that 'killing for pleasure' is wrong?

i heard u should steer clear from cucumbers.

Yeah, they have such an odd shape.