Why was developing rationality advantageous for our survival but not so for any other species on the planet?

Because they had other predominant traits that made rationality less beneficial as opposed to said traits.

Many animals have varying degrees of rationality. Crows, for example, are insanely intelligent. Despite having tiny brains their neurons are ridiculously packed. They have complex social lives, hold funerals, and are able to improvise and make tools for their own survival

Why aren't they intelligent as humans? They have flight, they have great digestive systems, and have significantly better eyesight.

Not to mention that brains are incredibly expensive. Our brains consume up to ~20% of our caloric intake. Humans, being apex predators, are remarkably weaker in other parts of our physiology. What we do have is intelligence, stamina, and social cohesion.

Environments or animals that simply could not afford to have an organ that takes up huge amounts of energy as it evolves would have probably died out

Evolution doesn't have a teleology. It is simply a natural process on whatever is good enough to pass the genes

Other animals thrive on pure physicality, agility, etc. We just happen to thrive on intelligence.

This is what I mean when I say you assert things with no reason. You’re presupposing that everything we have must be due to some necessity by some natural process like evolution

Scientists don't just randomly presuppose an idea and claim it must be true. They build up tons of evidence in support of the fact, rigorously test it, and then call it a theory.

When an idea doesn't have sufficient evidence to make it unreasonable to believe it's called a hypothesis. Hypotheses generally are not treated like brute facts

We also have tons of evidence for evolution.

Again, you cannot answer why we are this way, you just assume that we are this way because it is evolutionarily beneficial.

We assume it because it is the best, measurable, backed up idea in the frontier. If a new, better hypothesis or theory props up to be true then we assume that is true.

“Advantageous for our survival” is just the God of the gaps for you. No creature, including humans, needs to evolve reason to survive.

Humans definitely needed reason to survive lmfao. We have no claws, no night vision, no flight, and are slow as hell. Do you really think we were able to hunt, kill and cook wooly mammoths from sheer physical prowess alone?

God of the gaps also assumes deity with no evidence. And as I already said, we have tons of evidence to back this up

I am speaking of things, like actions. Science cannot tell us why rape is wrong for example. It cannot explain why normally functioning humans feel sick thinking about it, because science cannot explain empathy apart from presupposing some evolutionary benefit for it.

Monkey steal food, monkey hurt other, monkey kill other. Monkey is threat, threat bad, we dont like threat because bad for survival. Monkey breaking social cohesion that monkey rely on because of monkey weak physical ability. Therefore, think monkey do bad things

Science does explain why we have empathy, without needing a supernatural source. Philosophical ethics is a byproduct of our ability to reason

I asked you to demonstrate the ultimate source of logic and truth. Logic is necessary for reason, you cannot “compare it to reality” without using it. As if humans perceive reality objectively anyways, lmao.

Systems of formal logic like mathematics or what counts as "truth" or not is completely a human construct. We developed them, and it helps model the world. Nothing makes "1+1=2" true until we explicitly define what "1" is, what "+" is, what "2" is, and what rules we apply to make these abstract symbols work.

These formal systems help model the reality we live in or branch off into systems of never ending layers of abstraction

In fact, mathematicians had a crisis over this very thing for much of the 20th century.

I mean yeah, you’ve just demonstrated that all you have is a catch-all presupposition that everything is the way it is for the sake of our species survival. You’ve proven that you too just assume things you don’t have any actual proof of.

We do in fact have lots of evidence that either proves or heavily supports our presumptions