Do you think morality is something humans discovered as they evolved, or something they created?

I was following this question posted today, about if killing killers is right. I frequently think about human evolution, and how the effect of a steady increase in brain size over 8 million years across many hominid species has resulted in modern Homo sapiens (Homo sapiens sapiens for those that prefer that distinction). Once modern humans arrived, with their larger brains and other optimal adaptations, improved tool-making, agriculture, and other technologies freed them to ponder. Eventually we discovered physics, electricity, chemistry, and so on.

We couldn’t have done this without our larger brains, that result in greater awareness and understanding of our surroundings, combined with an innate curiosity that drives our desire to understand our universe ever further.

My question is, did we create morality more as a means to govern ourselves effectively, or is morality a force of nature of which we became aware? Do our larger brains allow us to “discover” morality, analogous to how we’ve gradually discovered the sciences?

I don’t feel I’m phrasing this as well as I’d like to. Maybe my question is nuts. I don’t know. Be gentle. Hopefully a good discussion will help the concept coalesce. I also like to ponder the notion that if our ancestors had a cranial capacity of ~300–400cc, and we have ~1350cc (evolved over millions of years), in another million years where might human sensing and thinking be with, say, another 25% increase in brain size?