Until we can objectively test the likelihood of humans that have never been taught a language, like "feral children" , to spontaneously develop a coding system on their own, can we really compare innate intelligence in these areas across species?
For all we know, the trigger for such developments may be watching others of your own kind doing something odd, that is interesting or beneficial enough to catch on for long enough to be passed on to offspring.
In the Blue Planet 2 series, there is a segment about an octopus and a grouper fish, entirely different species, communicating with each other via gestures and changing their skin colors, to work together in trapping prey.
Ants etc. use "abstract signs" of pheromones. Bees use 3-dimensional dances to communicate. Are we dumber than them because of our inability to do that?
Intelligence certainly isn't a linear 1D scale with discrete steps.
Nicaraguan Sign Language developed spontaneously among a group of deaf children.
How likely is a human to develop any of our abilities that we take for granted, in the wild?
Exposure to civilization is obviously not important, as all uncivilized people also speak. (Exposure to other people is important.)
Contact with language-using humans doesn't help in developing sign language either; deaf children exposed to speaking humans do not develop spoken language or sign language.
It is generally felt that what prompted the development of NSL was the fact that the children were put into a group. Children in a group want to communicate with each other. A hearing child in the same group would also have learned/participated in developing the language.
Thus there is indeed a class difference between humans and the rest of animals.
The rest of animals seem incapable of this ability, even when we try our best to teach them.
The first human language user managed without this. (Though, if used for communication, it takes two... so there couldn't have been a first. OTOH there's an argument that language is primarily for thought, not communication, so it only takes one person. Secondly, evolution doesn't usually build a complete perfect system, but iterates, gradually improving. A puzzle here is that abstraction seems to be all or nothing, you can't have part abstraction. One resolution is that the necessary neuro-machinary was built up for other purposes, and abstraction emerged when some crucial capstone happened to be put into place. Or... maybe you can have some kind of "partial" abstraction...?)
The bee-dance "represents" direction and distance, but only that.
AFAIK it's only very recently that we began to try and learn the languages of animals rather than teach them
In what contexts does abstract language confer a survival or reproductive advantage, beyond simple communication, which is a commonplace, e.g. predator warning, food location, mate-seeking.
One huge failure is thinking that animals should care to learn anything we teach them.
Does the fact that I have not adopted your position imply that I am unable to do so?
Why can't I be unwilling?
Regarding your speculation that it has to involve members of the same species, I don't see any evidence based reason to suspect that and plenty not to. It's looks a lot like special pleading. We've had great success teaching animals to do all sorts of complex tasks. You yourself cite an example of sophisticated inter-species communications and co-operation that argues pretty strongly against the expectation for any requirement for intra-special specificity to communications or learning in general. So given that there don't seem to be any other tasks, skills or communications facilities that require same-species specificity, I'd need to see an argument as to why this one skill is special and might not be communicable across species, when we've not come across such a barrier before.
Using pheromones to mark "food is here" vs. using an object to deface another object.
Or moving your body in space to communicate somewhat-abstract concepts like distance. 
Why would they need to "resort" to writing, yet?
"Famous Shoes was given a Bible, in lieu of the little white girl. He would have rather had the girl but he took the Bible and he pored over it for years, in his spare time. He had never seen tracks as strange as the tracks in his Bible. After much study he could see that the tracks were individual, as were the tracks of all animals. Even worms and snails made tracks that were unlike those of other creatures."
Famous Shoes strong desire to learn to follow the tracks in books surfaces a number of times in McMurtry's novels.
There is no Wikipedia link for Famous Shoes, my favorite character from the "Lonesome Dove" series.
Does anyone know if Szukalski has any credence among these researchers? He is definitely in the lunatic-fringe/crazy-guy sector - but maybe he was right that there is a common human language throughout all ancient art?
So crazy to see his claims being investigated now and confirmed by mainstream archeologists ..
"Zermatism, Szukalski's concept of world history, postulated that all human culture derived from post-deluge Easter Island and that in all human languages one can find traces of the original, ancient mother-tongue of mankind. In his view, humanity was locked in an eternal struggle with the Sons of Yeti ("Yetinsyny"), the offspring of Yeti and humans, who had enslaved humanity from time immemorial."
Apparently there's a Netflix documentary (Dec 2018) about him called, Struggle: The Life and Lost Art of Szukalski.
>Beginning in 1940, Szukalski devoted most of his time examining the mysteries of prehistoric ancient history of mankind, the formation and shaping of languages, faiths, customs, arts, and migration of peoples. He tried to unravel the origin of geographical names, gods, and symbols that have survived in various forms in various cultures. This work, called "Protong" (in Polish, "Macimową"), continued uninterruptedly for over 40 years. He wrote a manuscript of 42 volumes, totaling more than 25,000 pages, and including 14,000 illustrations. The volumes covered a variety of issues; his pen drawings of artifacts, which he considered "witnesses", were done to confirm his theories.
e.g. If everyone in the future uses always-connected AR glasses and personal AI assistants, would anyone bother to write much, "in the wild"?
Someone discovering a cool sightseeing/hiding spot may Instagram a few photos, saying "follow the arrows.", and we kind of already do that with geocaching etc. 
In the farther future, someone may only find the crudely-etched arrows, with no reason to assume that anything like the internet existed back now. :)
It's sad we cannot have a post on an interesting topic not spoiled by the gender war anymore. Moreover this remark is totally stupid: women are as much likely to formulate a biased opinion than men.
Test, everyone 8s biased by their own experiences, but those biases are very _useful_, especially when coupled with the biases of those who has a rather different background. They allow others to see ideas they wouldn't have thought of leading to true synergy.
That's the point being made: not that another group of researchers would have been better, but that a diverse group would be preferred to a not diverse one.
I'd totally buy that diversity was a problem because "all the people who looked at this were from a few schools studying the same degree, and came up in the same academic circles and so had the same idea.". But the fact that the people studying the issue had similar genitals seems irrelevant.
FTFY. Coming from a progressive socialist who doesn't like to stick his head in the sand
The point isn't that the researchers were biased, the point is that there was a monoculture of bias.