[_snydly]

> So basically you thwack all the cells with something that pushes their lifecycles towards a similar schedule, and then later-on they tend to all still be on the same cycle?

Yeah, that much is pretty well understood. http://journals.plos.org/plosgenetics/article?id=10.1371/jou...

> Isn't that like saying two pendulums in the same house have a "collective memory" of an earthquake?

The important point isn't that there's memory (which seems pretty easy to explain), it's that it's collective. Using your analogy, it would be like finding that two pendulums in the same house have memory of an earthquake, but if there's only one pendulum then there's no memory.

This result might be regulated by quorum sensing (https://en.wikipedia.org/wiki/Quorum_sensing). Like the pendulums are talking to each other.

[devishard]

I think the point your parent comment is making is that "collective memory" implies more than just a common cause causing synchronization. If, as you say, "the pendulums are talking to each other" that would fit my definition of "collective memory", but if the pendulums stay synched just because they started at the same time, that doesn't seem like collective memory.