Currently, sure. Across all time, I'd go with blue-green algae.
I knew that someone were to point this out. Yes, of course across geological timeframes at the moment we're playing second fiddle at best. But over the course of, let's say, that past 10 million years or so, I'd say, we're a firm contender for first place.
Agreed, there is no hard threshold (biology seems to avoid those anyways) but subjectively there is some sum of fuzzy attributes in humans which allows for us to achieve the highest complexity of lifestyle(?) of all lifeforms on the planet.
A beaver might instinctively know how to build a dam because it's built into its DNA, but a human can read the writings of past dam builders, learn the abstract theory of dam building, come up with their own improvements, debate those changes with other people interested in dam building, communicate their design to dam builders, and publish their work to become a permanent part of dam building literature. For a beaver to change how it builds dams, it would require a change in their DNA to pass on to future generations.
I'm not denying that humans, in their current form, as a species are set apart from the rest of life on this planet.
Rather what I'm trying to get at is, that if you'd backtrace the evolution of humans, at no particular point in time you could make a clear desitinction of "this generation of pre homo sapiens species fundamentally differs in their linguistic capabilities from the next evolutionary step".
The linguistic capabilities of hominids and humans more likely than not developed gradually, just like every other feature that makes a distinct species. Eventually you'll be able to clearly tell them apart. But when applying a "derivative" operator on it, you'll find that evolutionary development is smooth and continuous.
And I think that also applies to linguistic capabilities. The proposition I'm making is, that the linguogenesis of homo sapiens can not be explained within the boundaries of that species. Rather I'd say that the roots of our language can be traced back far further than you'd presume by presence of certain vocal anatomical features alone.
Unless the hard threshold was created by an external force, such as humans killing off or interbreeding with every other ape species capable of high level language.
> The authors compared animal and human communication, eliminating the aspects of vocalization that are shared by both, and concluded that one operation alone distinguished human speech: recursion. In the course of working on the article, Fitch grew sympathetic to Chomsky’s ideas and became an articulate defender of the theory of universal grammar.
"(…) distinguished human speech(…)", if you think about it, that's a weird assertion/assumption to make. The idea, that there's a clear line between human and non-human communication, as if this was something binary.
We humans have this weird concept, that there's "something", that makes us fundamentally different from the rest of the animal life on this planet. Yes, we've got the largest impact on the biosphere, we can reason about it. But if you were to track back on the coginitive abilities of our evolutionary ancestors, I'd say it would be very difficult to put a hard threshold in the phylogenetic tree, where suddenly a whole subset of means of communication discretly vanishes.
Just my 2 cents…