That humans are uniquely intelligent is a long-held sentiment. Instead, in thinking themselves a superior species, people are uniquely stupid.
Every cell and every organism must be aware and responsive to its environment. Hence, every living entity, from viruses and proteins on up, have a consciousness and a mind (mentation). All life forms possess intelligence.
The operational definition of intelligence is appropriate behavior: activity which strives to sustain living. The amenity in which many people live shows that humans are capable of a high level of intelligence. Yet such material comfort belies stupidity.
Industrial technologies and abstract cultural works are commonly pointed to as evidence that mankind has shown itself to have superior intellect. African termites build better buildings. Eusocial insects are much better organized. And industrial technology has proven to be a self-inflicted curse.
In less than 3 centuries since industrialization, men manufactured a major mass extinction event via horrendous levels of pollution. They poisoned their air and drinking water. Men wantonly killed billions of animals and ecosystems. And, upon realizing their mistake, they did nothing to alter the engine of self-extinction: capitalism, which is the dumbest way of running an economy. That many would disagree with that last statement exemplifies the cerebral problem with people – faith in ignorance.
The core problem with capitalism is that it is inherently wasteful. Producers make as much as they can based upon imagined demand. There is no order to the capitalist system, which relies solely upon an ersatz price mechanism which neither efficiently allocates resources nor engenders environmental nor societal well-being.
Any goodness that capitalism delivers is incidental to its mechanics. Humanity would have fared much better if economies were rationally planned, and if economics was enacted equitably, as contrasted with the gross social inequalities which capitalism invariably produces.
Every conscious thought is divorced from actuality: an abstraction that invariably involves categorizations, which are a ubiquitous mental convenience. Categories don’t exist.
The ease with which the human mind plays with concepts, coupled to gullibility, is the source of stupidity. Counterfactual thinking is essential to problem solving. Goals are only possible because situations which do not exist can be imagined.
All life forms exhibit goal orientation. Living is an exercise in desire fulfillment: the basest desire being continuing to live, which is supported by foraging for energy – a probabilistic endeavor, never random.
Humans are certainly not the smartest creatures. Whereas people invariably solve complex, multi-stage problems via trial and error, corvids do so in a single go after thinking the situation through. Rats are better at navigating mazes. Dolphins don’t war on each other to settle disputes.
People foolishly indulge their abstractions. By definition, beliefs involve concepts which assume information about unexperienced events, and are thereby imaginative.
Human cultures are built on belief systems, most notably religions. The idea the capitalism is a decent way to run an economy is a religion, as is scientific matterism (that matter is the be-all and end-all of existence). All religions are codified stupidity.
In sum, humans think they are smarter than they are, as evidenced by their sociality and environmental impact. Why is that?
The beginning of an answer from an evolutionary biology perspective is the manipularity–intelligence theory correlates innate shrewdness with manipularity: the ease by which an organism can manipulate its environment. Basically, organisms which have lesser ability to change their environment must have more “on the ball” to survive.
Microbes individually have little ability to alter their world. As such, they must rely upon their wiles: discernment at the molecular level, including being able to assess the utility of information resident in DNA. Microbes use sophisticated quorum sensing to assess the power they may have as a crowd. Pluricellularity has a power to craft fate which individual cells may only dream of.
Sessile plants survive by their wits. The head start of autotrophy – not needing to find food – belies the difficulties of managing the myriad of risk-based potentialities in a largely uncontrolled environment. A universe of decisions must constantly be made related to resource allocations and the probabilities of chance encounters, especially interspecifically (e.g., herbivory by savage animals). The unsurpassed intelligence of plants is amply illustrated by how they conduct their sociality with bacteria, fungi, other plants, and animals.
Humans have an unrivaled ability to control their environment. Hence, trial and error comes easy. Such ease of manipularity has led to lazy minds which default to sloppy heuristics rather than the rigor required to figure things out.
People habitually believe what their minds tell them, despite having suffered innumerable instances of their minds deceiving them. That is not intelligence, though the mind will insist otherwise.
The relative stupidity of humanity is demonstrated by their invariable environmental destruction. Throughout their existence, men sorely degraded their habitats as a basic modus operandi. Other species don’t do this.
Rare indeed have been the instances where humans have been able to sustain their populations without resort to technological advances, which only accelerate the sapping of natural resources. That humans have been unable to devise a socioeconomic system to sustain themselves without essentially enslaving sizable percentages of their societies further evidences the relative mental weaknesses of this species.
Because other species cannot easily manipulate their environments, they respect their situation in Nature, and hew close to actuality in their assessments. Men, on the other hand, have foolishly long held dear to the idea of “conquering” Nature, and of esteemed ideals which have no basis in fact.
The physical sciences can only have proximate answers. For the world is not as it appears. Nature is a ruse.
Living is ultimately a spiritual adventure. Every incarnation of a transcendental soul is an episode of an unending story. As with any life form, to be human is to be caged within a mind-body construct with a species-specific set of limitations and challenges – along with those which each individual has.
The apex of intelligence is to perceive the world for what it is. This level of consciousness is called realization. To achieve this state (for most people) is a most difficult challenge.
Categories are only fictional conveniences. The idea of “people” is a fiction. As every individual is unique, so too every life adventure. As thoughts are of categorical concepts, every thought is a fiction.
A primary obstacle to realization is recognizing that cognitive thought is the antithesis of intelligence – that the artifices which the mind proffers are insincere deceptions – that concept manipulation is not a hallmark of intelligence. The epitome of intelligence is to eschew thought for disciplined spontaneity.