“Or so say scientists in the Royal Society journal Biology Letters.”

Question

The sentence is from the transcript of a podcast:

What does a bookworm have in common with a black-tufted marmoset? They both like a little quiet. Or so say scientists in the Royal Society journal Biology Letters. [Marina Duarte et al., "Noisy Human Neighbours Affect Where Urban Monkeys Live"]

• How should I understand the sentence in bold?
• What's the grammar phenomenon called in English?
• What does "or so" mean here?

Answer 1

"So" in this form refers to the previous statement. You could rewrite this paragraph as follows:

What does a bookworm have in common with a black-tufted marmoset? They both like a little quiet, say scientists in the Royal Society journal Biology Letters. [Marina Duarte et al., "Noisy Human Neighbours Affect Where Urban Monkeys Live"]

The implication is that the previous sentence could be taken as an opinion, which in most formal writing has little weight unless backed up. By saying "Or so say" immediately following the statement, the writer or speaker is inferring that while the speaker or their audience may not agree with this statement, or have enough knowledge to form their own opinion, the smart, educated, experienced people identified after those three words do agree with it. As such, it is a persuasive device to get you to think that both bookworms and black-tufted marmosets like quiet, because scientists said so in the Royal Society journal, Biology Letters.

Answer 2

It's not "or so" but "so say" that you need to explain. Think of it as: Scientists in the Royal Society journal Biology Letters say so.

Answer 3

As explained by others, the Or so say scientists part is a stylised alternative way of saying something like At least, that's what scientists say.

The overall effect of the passage is one of creative humorous juxtaposition, pointing out that neither bookworms (scientists or others immersed in texts) nor marmosets (shy monkeys from Brazil) like to be disturbed.