Avatar last respondent in forum

Suggestion and question. I would like to replace the avatar of the author with the avatar of the last respondent. LeonidS  Question do you have a miracle sql query for that?
Alex, Could you add an option of choice in the admin settings of forum?
Personally, I find that the last displayed respondent gives a greater impression of movement. Especially when we discuss topics that have been discussed for a very long time.
Thank you.