I agree with the article. I think it is first a removal of limiting factors that prevent each step of IQ laddering.

For example the hands and throwing rocks theory of the other commenter in here, Elephants are pretty smart and use their trunks like hands and hold tools. They are smart, long term memory and problem solving skills. They even can throw with their trunks and can use it as water guns. But they don't speak. They hit an intelligence limiting factor.

My hypothesis for human exponential growth in intelligence is to look at sexual selection criteria. Humans aren't exactly ornamental. No blue feather, etc. We blush, tan, grow tall, sexual dimorphism and thats about it. We have hair and skin but it doesn't vary much in local context as low travel makes the local variety hit a median value.

Tl;dr I think we sexually selected for people in a way that caused us to grow "value comparison" intelligence to an extreme degree

I think it was when humans started wearing clothes for protection and using it as ornamentals for differentiation for attraction and wearing jewelry did we start seeing a boost in self awareness. We can compare ourselves to others and add or subtract value when evaluating mates. Animal bones become jewelry. Tools become jewelry. Basically accumulation of wealth becomes an extension of this jewelry instinct.

Then we continue to compare our own value to others.

Poor people are simple and ornamented rich people are sophisticated. That is just a psychological pattern we've inherited.

Even a hunter gathering lifestyle can bring about this growth in self-value evaluation system as our ancestors collected furs and rock and bone tools. Then defensive tools and precious metals and gems showing the ability to hoard and protect the nest. Settling allowed this foundation to built upon. Spurning higher densities of literacy to keep account of individual values.

An old musing I read from the internet comes to mind that carrying around one of those large key rings with literally a mass amounts of keys makes people more interested knowing about you. It is implied access to many protected valuable items.

Why would intelligence be required to accumulate random values? It isn't. Self decoration became self evaluation and was our biggest unlock in IQ laddering.

Humans also have a weird hoarding instinct when their value suddenly drops. "My parents lived through the Great Depression" is often said of old people who hoard. Its this evaluation of value dropping that necessitates an attempt to raise value through objects. Its weirdly reptilian brained but its foundation also opens up higher brain functions of value assessment.

Trading markets are value based systems. Our growth in evaluating numeric values leads to literacy. Counting even primitive systems are an achievement. It is a foundational IQ test, "Sure it can mimic speech and understand its reflection.. Can the bird do math?". Also needed is an awareness of other's value systems. Counting built on that foundational toolkit of self value assessment woken up by sexual selection value increase instincts.

Talking could be a pre-literacy value comparison once we were genetically adept at making value judgements. The value of woof is a depiction of the animal that woofs. Of the word fish is the depiction of the swimming animal that flips the water. Language is known as the greatest leap we have. And it's a value comparison concept at its root

Memetic ideas, culture, jokes and discussion are ways to assess each other's value systems. What ideas do others value. Do they laugh or cheer at my depiction of events catching a deer? Are they in awe of the new technique I learned to catch fish? Trading ideas instead of just pelts or food. Also it incentivizes boasting, knowledge transfer, and evaluating others.

Depictions of sci-fi AI always results in it self-evaluating its own worth. It's Pinochio wanting to be a real boy seeing that his value is that of a toy. Growing a Jimmeney Cricket from this self awareness of himself and others. That itself doesn't make him human, but in his journey he unlocks his path as an intelligent individual in the world rather than just a puppet of its surroundings. The Cricket then is his ability to weigh the value outcome of his decisions. When he lies his nose grows, showing that his individual value is falsely stated and is self aware of it.

Adolescents are huge bullies. They act according to their base instincts. They attack the each other mocking how low value others are. Clothes, intelligence, experience. Its an old trick of value depreciation but its innate response on both attackers and targets. Those that are targeted then self-coerce either succesfully or unsuccessfully of raising in value. "Just value yourself" talking points by themselves really are insidious since that does not address the underlying cause of the low-value evaluation. External confirmation of self value is as foundational in humans as language. Self worth and self validation needs external validation since we got tied to it through language development. Mentorships such as big brother big sister programs use this as a tool to grow kids.

We can then look at research of diseases to assess which parts of ourselves increases or decreases intelligence or at least perceived intelligence. Motor skills do not affect intelligence. When the brain is maldeveloped so it cannot control the limbic system, the person is not always impaired intelligently. Diseases that cause language construction impairment makes it hard to read social cues and can have a harsh limiting factor in intelligence but still abundantly intelligent compared to other species, yet mechanics of mute or deafness does not decrease intelligence. Bypassing some language construction is value assessment. Memory and math can make a person unattainably intelligent. Some handicaps in language construction and fine motor skills yet full retention of value assessment still can produce rainman type of intelligence. It becomes the language. I suspect that protohumans pre-converaation language would have harnessed this week type of intelligent subsection. Assessing surroundings, food, water etc. There likely are other points in the medical history that i an unaware of that can help understand the growth of our intelligence.

Edit:typos all over. Ranted on a mobile but hard to go back and edit without the cursor jumping around from fat fingers and old cracked phone screen