Aliens, psychology by diet

When we expand into outer space, we may contact other sapient species, and it can be guaranteed that they will think differently than us. But we may be able to predict their behavior by their diet. Something that Larry Niven touched on with the carnivorous Kzinti and the herbivorous Puppeteers.

Carnivores: The first thing you should remember is that predators are opportunists, they always take the route that is least expensive. If they get to colonizing other planets I would expect them to have the capability to adapt considering their need for complex ecosystems that would be a hassle to terraform from scratch. Due to their opportunistic natures I doubt that they might go to the trouble of eating other sapient species like us humans, though if there is a massive technological difference they might enslave or domesticate the less advanced species. Relations with humanity would probably be neutral or even allies, we might colonize and terraform dead worlds while they adapt to living ones.

Herbivores: To an herbivore, any other animal is a potential enemy, a predator or a competitor. I expect that their planets would be ecological disasters devoid of any other animal species except in the most extreme regions they never got around to colonizing. Since their supporting ecosystems would be comparatively simple they would probably terraform their colonies, because of that I expect that they would use a lot of weapons of mass destruction in inter-species wars. In addition the fact that extreme paranoia would have been a survival trait in their early history (more than humans anyway) would make diplomacy with them very difficult.

Omnivores: Would probably be closest to humans psychologically, as we are omnivores ourselves. Kind of a wild card, they might terraform, they might adapt, they might exterminate, they might enslave. They might even join forces with us and form the galactic federation. Fortunately trends on earth make it seem like most sapient species will be omnivorous.

Plants: I don't see any reason for plants to become sapient, but maybe a machine civilization would be similar. In short, they wouldn't care about consumers unless we got in their way.

Uplift, Why Do it?

One idea that many transhumanists support is the idea of biological uplift, the possible modification of non-human animals so that they become at least as intelligent as humans. The concept was popularized, and named, by David Brin with his Uplift series of novels, where humanity has not only uplifted Dolphins and Chimpanzees but also discovered that almost every sapient species in the galaxy was uplifted by another species. Brin technically wasn't the first one to come up with the concept, H.G. Wells wrote about beasts vivisected to become men in The Island of Doctor Moreau back in the Victorian era (guess how it ended), in addition the hard sci-fi webcomics Freefall and Schlock Mercenary both involve characters that are genetically engineered animals and the Orion's Arm universe includes both provolves (they couldn't use Uplift for legal reasons) and splices. Now there are a number of transhumanists (such as Abolitionists) that think it is our moral duty to improve the quality of all sentient life, which includes most animals not just humans and maybe extraterrestrials.

But what they are not taking into account is whether animals would want to be uplifted, or even if humanity would have a practical reason to uplift others. Aside from attempting to colonize environments that humans couldn't survive in like in Freefall, I don't see much reason why anyone other than the military/police (and maybe Furry fans) would have a use for a talking animal. Maybe someone will think that society could benefit from having different points of view from multiple species or people will start wanting pets that can hold a conversation with them. But if you do think that non-humans should be uplifted to our level, you should consider whether a species would want to be uplifted. In some cases, such as great apes, it might be possible to simply ask a non-uplifted individual (using sign language or a computer) if they would like their kids to be able to talk like humans or be as smart as one. But for most other species it would be very difficult for them to understand the concept of intelligence and language, uplift would effectively create a completely different species so you might as well just uplift at least a few individuals and ask them what they think. So, if you think uplift sounds like a good idea, think it over a little more.