WAYS OF THINKING ABOUT ANIMAL ORIGINS
Animal origins happened once. There is no replay — only living organisms, molecular traces and competing explanations. These are the ideas that guide how we look for evidence.
Enter the argument↓THE PREMISE
Reconstructing the first animals requires more than finding familiar genes. It requires knowing what has been lost, discovering what remains unseen and testing several cellular routes without assuming the answer in advance.
An ancestor is not observed directly. It is reconstructed from the organisms that survive around it. For example, if choanoflagellates — or filastereans — are treated as the only window onto the unicellular past, lineage-specific gene losses can be mistaken for ancestral absence.
Explore the incomplete tree ↗Animal biology has been studied across tissues, stages, species and centuries. Their closest unicellular relatives remain represented by comparatively few genomes, cultures and experimental systems. We are not comparing two equally known worlds.
Meet the organisms ↗Clonal colonies are one compelling route to animal multicellularity — but not the only plausible one. Aggregative multicellularity and cellularisation from multinucleate cells offer equally serious evolutionary hypotheses that can now be tested experimentally.
Explore experimental systems ↗
Many molecular and cellular technologies predate animals. The decisive transition may have been their integration: ancient modules brought under a shared regulatory system that coordinated cells in space and time and opened an entirely new ecological possibility.
Explore gene origins ↗Ancient modules.
New integration.
READING THE FIELD
Reviews do more than summarise facts. They reveal how the field has framed the problem — and how those frameworks change as new organisms and experiments appear.
This section will connect our perspectives with alternative models, emerging consensus and questions that remain genuinely open.
OUR PERSPECTIVE · OTHER PERSPECTIVES · EMERGING CONSENSUS · OPEN QUESTIONSIdeas are tools.
