This episode is with Iñaki Ruiz-Trillo, whose research sheds light on one of the most fundamental transitions in the history of life—the evolution of multicellularity. Iñaki is a group leader at the Institute of Evolutionary Biology in Barcelona, where he investigates how unicellular organisms gave rise to complex multicellular life. Our conversation explores the deep evolutionary forces that shaped this transition, the role of cooperation and cell differentiation, and what studying the ancestors of animals can teach us about life’s complexity. We also discuss broader questions about biological organization, individuality, and the very nature of what it means to be a multicellular being.

Guests info:

Website: https://multicellgenome.com/

X: https://x.com/multicellgenome

Episode links:

Website: https://www.reasonwithscience.com/

Youtube: https://www.youtube.com/@ReasonwithScience

Spotify: https://open.spotify.com/show/5qFLGsPWjL4GAGidmF2nKh

Apple podcast: https://podcasts.apple.com/us/podcast/reason-with-science/id1641776894

YouTube music: https://music.youtube.com/playlist?list=PLila1Jm-QEwKu4xXtNpYFAsSDmPR9mlZB&si=5ehXeZhZ-z181G5b

Timestamps:

00:00:00 - Introduction

00:00:20 - Evolution of multicellularity with Iñaki Ruiz-Trillo

00:02:54 - Why compare animals with unicellular relatives?

00:05:11 - What defines multicellularity?

00:09:07 - Studying unicellular ancestors of animals

00:14:19 - Convergent vs. homologous evolution

00:22:26 - Why did multicellularity evolve?

00:27:53 - What did the first animals look like?

00:30:55 - Bilateral symmetry and its impact

00:33:27 - Predation, competition, and cooperation in evolution

00:39:09 - Comparing different multicellular lineages

00:52:22 - Searching for new unicellular relatives

01:03:30 - Experimenting with multicellular growth

01:07:08 - Can we fully understand the origin of animals?

01:09:47 - Closing remarks