
Why do humans enjoy black-and-white photos or videos, but have less tolerance for images that have only two other colours?

If two chromosomes are better than one, why not three? Wouldn’t this give you a better chance of surviving environmental change?
Last Word is New Scientist’s long-running series in which readers give scientific answers to each other’s questions, ranging from the minutiae of everyday life to absurd astronomical hypotheticals. To answer a question or ask a new one, email lastword@newscientist.com
To answer this question – or ask a new one – email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
The use of AI tools (e.g. ChatGPT, Claude) to write either questions or answers is forbidden, and any submissions found to have been written using AI tools will be withdrawn.