The AFFECT-EVO COST Action officially launched with its first in-person meeting in Lisbon from 1 to 3 April 2025, gathering researchers from across Europe and beyond to explore the evolution of affect and emotion in animals. The event focused on two of the Action’s four Working Groups:

• WG1: Advancing our fundamental understanding of affective states across species, and
• WG2: Societal impacts of understanding animals’ affective states.

The meeting opened with a welcome address from Tom Smulders, followed by Rui F. Oliveira outlining the aims of WG1 and the goals of the meeting.

The morning plenary session, chaired by Oliveira, addressed terminology and conceptual frameworks for a phylogenetic approach to affect. Highlights included:

• Carrie Figdor (Iowa, USA) on translating affect and emotion theories across species
• Liz Paul (Bristol, UK) on defining affective terms for nonhuman animals

The session concluded with a wrap-up discussion led by WG1 leaders Rui Oliveira and Thibaud Gruber.

The afternoon plenary, chaired by Gruber, focused on frameworks for studying affective states across species:

• Mike Mendl (Bristol, UK) explored emotion concepts and their translational potential
• Edmond Rolls (Warwick, UK) discussed relationships between emotion, motivation, and reasoning
• David Anderson (Caltech, USA) presented on neural dynamics and the encoding of emotion primitives

These sessions laid the foundation for WG1’s future work, addressing major conceptual and methodological challenges.

The second day was dedicated to interactive discussion and planning. WG1 participants broke into three rotating discussion groups, facilitated by M. Mendl, C. Figdor, and L. Paul, to identify priority research questions, terminology challenges, and future collaboration opportunities.

Meanwhile, WG2 convened for its first session, chaired by Rebecca Nordquist and Andy Jin, featuring talks by:

• Emily Haddy (Portsmouth, UK)
• Michael Kisley (Colorado, USA)
• Beth Clark (Newcastle, UK)
• Eva Bernet Kempers (Antwerp, Belgium) on the legal implications of understanding animals’ affective states

The day concluded with a plenary consensus session for WG1, where participants began drafting concrete plans for the next steps and future workshops. The final day brought WG1 and WG2 back together. Morning sessions in each group focused on summarizing the outcomes of earlier discussions into actions and identifying subgroups for next steps.