The take-home message is: Multicellular reproduction can be a rewired unicellular program.
Please see the pre-print: bit.ly/4rr2mHU
Plenty more detail in the paper, plus some nice extra results.
End.
So to recap:
➡️ Early developmental programs evolve from the ecological dynamics of the unicellular ancestor.
➡️ Depending on resource distribution, our model yields different multicellular life cycles, including some that reproduce via unicellular propagules.
Why this matters: it suggests a general route to early development.
New multicellular traits can appear by co-opting existing regulation, repurposing when/where effector genes act.
In our model, the coupling of cell state (behaviour) and adhesion is what gets co-opted to generate propagules.
Re-playing the evolutionary steps from the unicellular ancestors to a multicellular group that reproduces through propagules: the adhesion mechanism of the ancestor becomes co-opted (incorporated) in the multicellular life-cycle.
Answer: co-option is pervasive.
The mechanism that makes propagules in the multicellular state—low adhesion during the dividing state—is co-opted from the ancestral unicellular life cycle, and repurposed during the transition to multicellularity to make offspring.
We then wondered how propagules evolved.
Are they constructed from scratch? Do they co-opt pieces of the unicellular ancestor?
Because it’s a computational model, we have the full fossil record. We can literally rewind evolution and watch the steps, generation by generation.
Following a single cell within a cluster - as it transition from high adhesion and migratory to down-regulating adhesion and dividing - thus forming a propagule. The cell then divides and the two offspring adhere to each other and migrate as a small offspring cluster.
Mechanistically, propagule formation is driven by a regulatory switch: cells stick strongly while migrating, but once fed they reduce adhesion and switch into division. Dividing cells then peel off as propagules (follow the white border cell).
When food patches are near, only unicellular solutions evolve: by not sticking cells disperse better and reach resources faster.
At intermediate patchiness, multicellular groups produce propagules. The group migrates rapidly towards food, and propagules colonise new patches—best of both worlds.
When resources are more homogeneously distributed, the system evolves unicellular solutions, when resources are patchy and far apart, multicellular life cycles evolve, including propagules and for high resource heterogeneity group splitting.
Why do different life cycles evolve?
Well, cells survive if they eat. So resource distribution is the key parameter.
When food is far apart, adhesion enables collective migration (see: bit.ly/4s9YIUa). So selection favours groups that reproduce by splitting—each daughter already functional.
And it’s not just this outcome.
From the same ingredients, we get a whole zoo of possible solutions: unicellular life cycles, single-cell and multicellular propagules (in the video), and large groups that split by tearing themselves apart.
Over generations, cells evolve adhesion and form multicellular groups.
But then: how does a group reproduce? In many runs, groups release single-cell propagules that detach and grow into new groups.
Single-cell propagules are everywhere in multicellular life—and here they evolve spontaneously 😎
In the model, each cell carries a gene regulatory network: a small circuit controlling when to forage, divide, and stick to other cells.
Mutations during division rewire the network, so these behaviours evolve. Cells that do not eat die.
That’s it! Mutation + selection. Can development evolve?
With @alefern.bsky.social and @renskevroomans.bsky.social, we built a model to fully recapitulate the transition.
But we didn’t want to pre-suppose any particular life cycle — we wanted them to evolve from scratch.
So we started simple: cells move (red) towards food (brown), and divide (blue).
Multicellularity makes reproduction... weird.
Single cells reproduce by division 🦠➡️🦠🦠
But multicellular life often reproduces via developmental programs: gene regulation, cell differentiation, etc.
Where do the first multicellular programs come from, before dedicated developmental machinery exists?
Curious about the origin of development during the transition to multicellularity?
A very belated preprint alert: bit.ly/4rr2mHU
Reproduction emerges from ecological interactions at the onset of multicellularity.
A short 🧵 with lots of videos...
Why this matters: it suggests a general route to early development.
New multicellular traits can appear by co-opting existing regulation, repurposing when/where effector genes act.
In our model, the coupling of cell state (behaviour) and adhesion is what gets co-opted to generate propagules.
In case you missed it: our review titled "Spatial structure: shaping the ecology and evolution of microbial communities" is out! 🚨
Let me hit you with some highlights on why spatial structure matters. (and why you should care!)
Sharing is appreciated 🙏 🧵👇
doi.org/10.1093/fems...
That a tiny polymerase ribozyme exists is good news *especially* for metabolism-first models of OoL, because it makes it easier to picture genetic memory emerging gradually within a self-maintaining proto-metabolic system.
Most microbes don't live in shaking flasks; spatial structure shapes how microbes interact and evolve at every scale, as we discuss in our recent review @jeroenmeijer.bsky.social @simonvanvliet.bsky.social @bedutilh.bsky.social @bramvandijk.bsky.social and others
academic.oup.com/femsre/artic... 🧵👇
Have a look at the Insight on Research story on our Science paper www.science.org/doi/10.1126/... on the @mrclmb.bsky.social website: mrclmb.ac.uk/news-events/... including a great little animation from LMB VisLab.
Great summaries of our paper www.science.org/doi/10.1126/... in Science: www.science.org/doi/epdf/10.... and New Scientist: www.newscientist.com/article/2515... and in the Science museum blog: blog.sciencemuseum.org.uk/in-the-begin...
New paper from my group in @science.org : "A small polymerase ribozyme that can synthesise itself and its complementary strand" www.science.org/doi/10.1126/...
Outstanding work by @edogia.bsky.social
How did life arise from simple chemical building blocks?
New #LMBResearch led by @edogia.bsky.social in @philholliger.bsky.social group has identified a small self-replicating ribozyme that could be the answer.
Read more: mrclmb.ac.uk/news-events/...
How could a simple self-replicating system emerge at the origins of life? RNA polymerase ribozymes can replicate RNA, but existing ones are so large that their self-replication seems impossible. Could they be smaller?
Excited to share our latest work in @science.org on a new small polymerase.
1/n
Very nice review! Congrats to all the authors.
Wrapping up a productive week: very glad to have contributed to this review on how spatial structure shapes microbial ecology and evolution, led by @marcelbaecker.bsky.social, @bedutilh.bsky.social, @bramvandijk.bsky.social and many others. doi.org/10.1093/fems...
New year, new conferences! Consider submitting to the symposium on Fitness landscapes and Genotype-phenotype maps, linking computational and experimental approaches (organising with @n-martin.bsky.social; @dbajic.bsky.social invited spreaker) at SMBE (28/6-2/7)! Abstract deadline February 3rd!
Very cool paper by Jyotsna Kalathera et al. from @iamsamayp.bsky.social 's-lab on
Bottleneck size drives the evolution of
cooperative traits in an aggregative multicellular
myxobacterium
just out @plosbiology.org
Congratulations to all coauthors.
journals.plos.org/plosbiology/...
Interior of Sainsbury Laboratory building showing experimental laboratories on left with floor-to-ceiling glass facing into the main central avenue with people walking on stairs and sitting at study boxes. Lots of natural light and views to the Cambrdge University Botanic Garden. Overlay text "Join SLCU" and logos and closing date of 15 January 2026.
🌱 2x David Sainsbury Career Development Fellowships at @slcuplants.bsky.social
Unique opportunity for early-career researchers to launch their own independent research programme in quantitative plant development, with generous support & world-class facilities.
www.cam.ac.uk/jobs/david-s...
1/28 New preprint up, which I think is the best theoretical idea I've ever had. We asked a simple question: what are the costs of investment into non-reproductive somatic cells? Turns out these costs decrease with the *logarithm* of organism size!
www.biorxiv.org/content/10.6...
