Humans identify and call each other by specific names. So far this advanced cognitive behavior has only been identified in a few other species, dolphins, elephants, and some parrots. Interestingly, it has never been documented in our closest relatives, non-human primates – that is, until now. A recent study finds that marmoset monkeys have unique calls, “phee-calls”, that they use to identify specific individual members of their group. The study also found that within a group of marmosets, all members use the same name to refer to the same individual, so they are learning the names from each other. Also interesting, different families of marmosets use different kinds of sounds in their names, as if each family has their own dialect.

In these behaviors we can see the roots of language and culture. It is not surprising that we see these roots in our close relatives. It is perhaps more surprising that we don’t see it more in the very closest relatives, like chimps and gorillas. What this implies is that these sorts of high-level behaviors, learning names for specific individuals in your group, is not merely a consequence of neurological develop. You need something else. There needs to be an evolutionary pressure.

That pressure is likely living in an environment and situation where families members are likely to be out of visual contact of each other. Part of this is the ability to communicate at long enough distance that will put individuals out of visual contact. For example, elephants can communicate over miles. Dolphins often swim in murky water with low visibility. Parrots and marmosets live in dense jungle. Of course, you need to have that evolutionary pressure and the neurological sophistication for the behavior – the potential and the need have to align.

There is also likely another element – the quirkiness of evolution. Not all species will find the same solution to the same problem. Many animals evolve innate calls that they use to communicate to their group – such as warnings that a predator is near, or a summons that they have found food. But very few have hit upon the strategy of adjusting those calls to represent specific individuals.

The researchers hope that this one puzzle piece will help them investigate the evolution of human language. I find this a fascinating topic, but it’s one that is difficult to research. We have information going back preserved in writings, which go back about 5,400 years. We have extant cultural knowledge as well – the languages that people around the world speak today. But that’s it, a window going back about 5 thousand years. We also have information from our closest relatives – the uses of language and the language potential is non-human primates. This can give us a somewhat complicated window into the evolution of human language, but this picks up with our last common ancestor about 8 million years ago (with a wide range of uncertainty).

In between these two time periods, when all the interesting stuff was happening, we have almost no information. We have cave painting going back tens of thousands of years, and these give us some insight into the intellectual world of our ancestors, but not directly into their language. We can study hominid anatomy, to see if their larynxes were optimized for human speech. Only Homo sapiens have a “modern” vocal tract. Neanderthals were close but had some specific differences which likely meant their vocal range was lower than modern humans. But this does not mean that our older ancestors could not communicate vocally. Some researchers argue that primates have had sufficient vocal anatomy for some speech going back 27 million years.

But again, this gives us scant information about the evolution of language itself. Most of what we know comes from examining the direct evidence of actual language, from the last few thousand years. We can still learn a lot from this, from studying what different languages have in common, how they are structured, and their internal logic. We can also investigate the neurological correlates of language, and there are ways to disentangle which components of language are evolved (wired in the brain) and which are cultural and learned.

Once concept I find interesting is that of embodied cognition. We use a lot of words to represent abstract ideas that are metaphors for physical relationships. A boss is “above” their employee, but not literally physically above them. Ideas can be “deep”, and arguments can be “strong” or “weak”. This makes some evolutionary sense. Things evolve generally from simpler but fully functional forms. They do not evolve directly to their modern complexity. The eye evolved from simpler forms, but ones that were fully functional for what they did.

Similarly it is likely language evolved from simpler vocal communication, but ones that functioned. What is especially interesting about language is that language also relates to cognition. The two may have evolved hand-in-hand. First we developed sounds for the concrete things in our world, then for features of those concrete things. At some point there was a cognitive breakthrough – the metaphor. This stone is rough and it hurts to rub it. Your behavior is also “rough” and “hurts”. What’s interesting to think about is which came first, the idea or the word. Or did they crystalize together? Likely there was some back and forth, with ideas pushing language forward, which in turn pushed ideas forward. Language and ideas slowly expanded together. This resulted in a cognitive explosion that separates us from all other animals on Earth.

The elements that lead to this explosion can be found in our ancestors. But only in humans did they all come together.