This week’s new questions

Why do cats wash themselves a lot, while dogs don’t? And if 21st-century babies wean on a globalised diet that has only recently been available to them, what did babies wean on in prehistoric times?

21 June 2023

Bengal cat washing itself on bed; Shutterstock ID 1123136123; purchase_order: -; job: -; client: -; other: - — Shutterstock Copyright: Juhku/Shutterstock

Why do cats wash themselves, while dogs don’t?

Richard Grimmer,

Trowbridge, Wiltshire, UK

Portrait of mother and baby sitting at the table, and feeding her with food and fruit. close up. The concept of feeding and weaning baby from the breast. Hispanic family; Shutterstock ID 2260034413; purchase_order: -; job: -; client: -; other: - — Shutterstock Copyright: Davide Bonaldo/Shutterstock

If 21st-century babies are weaned on a globalised diet that has only recently been available, what was used to wean babies in prehistoric times?

Ian, Naraa and baby Vaughan Allardyce,

London, UK

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.

New Scientist Ltd retains…