The total mass of the Virgo cluster is large enough that its gravity pulls nearby groups of galaxies (including the Local Group) toward it. (astronomynotes.com)
In Vancouver, I put myself on multiple wait lists that I never heard a peep from, and created a spreadsheet of nearby group centres and licensed in - home daycares. (canadianbusiness.com)
Modern hunter - gatherers likewise find partners among nearby groups (SN: 4/9/11, p. 13). (sciencenews.org)