Language is often seen as something unique to humans, as we use and combine words, gestures, and expressions in complex ways to communicate. A key part of human conversation is its structure: we begin our interactions with greetings (openings), maintain them by speaking one after the other and showing that we are engaged (maintenance), and wrap them up with farewells (closings). This structure helps us navigate social interactions smoothly, making sure we understand each other and stay engaged. Studies have been showing that some primates, like chimpanzees and certain monkey species, also use different signals-such as sounds, gestures, and facial expressions-during their social interactions. In fact, they sometimes can combine these signals. However, we still do not fully understand how they organize these signals into clear phases like humans do, with openings, maintenance, and closings in conversations. This suggests that while human language is unique, it has some similarities with how our closest relatives, like chimpanzees, communicate.

This brings up an important question: Are these patterns of communication something humans inherited from a common ancestor, or have different primate species developed them independently because of similar social needs? Since language does not leave behind fossils, one of the best ways to answer this question is to study how other primates communicate today. To explore this, the EVOMICS project will observe different primates to help us separate the effects of evolutionary history, social needs, and living environments on how primates communicate: young children (6-24 months old), who are still learning language; chimpanzees, our closest living relatives; sooty mangabeys, a type of monkey that lives on the ground; and common marmosets, small monkeys known for raising their babies together similar to humans. By comparing these species, the project will address two major questions: 1. How do primates use and combine sounds, gestures, and touches to communicate, and is this similar to how we communicate? 2. How do primates organize their interactions, and do they structure them in a way similar to our conversations, with openings, maintenance, and closings? The goal of this project is to understand whether complex communication is more influenced by social needs-if so, we expect to find more similarities between humans and common marmosets-or by evolutionary history-where we would expect to find more similarities between humans and chimpanzees. Ultimately, this project will help us better understand where human language comes from and how it may have evolved over time.