Often it is a favor to a colleague that is serving as the (also unpaid) editor to get a line on their CV. Given that the fields are highly specialized, you tend

Often it is a favor to a colleague that is serving as the (also unpaid) editor to get a line on their CV. Given that the fields are highly specialized, you tend to work with the same small community of people (writing articles and getting project funding together, reviewing each other's articles, etc.), so it pays to be well-liked among your peers.