Vervet monkey (Chlorocebus pygerynthrus) is an African monkey who uses different alarm signals to warn of different types of predators, such as leopards, snakes or eagles. Many ethologists say these sounds are a proto-language.
In this video, Robert Seyfarth describes how these signals might be precursors to language.
This reminds me of a book I read last year about animal intelligence. It was called The Octopus and the Orangutan: More True Tales of Animal Intrigue, Intelligence, and Ingenuity. It was an interesting read and author Eugene Linden made a point that I’ve often thought, but that I’ve never expressed so eloquently:
“As we place ourselves in judgement of the cognitive abilities of other species, we would also do well to consider the biases we bring to our understanding of intelligence.”
And then a few pages later:
“We tend to be nicer to creatures we deem intelligent— perhaps this explains why we humans tend to be so stingy in acknowledging intelligence in other animals.”
Too true.