Facebook is the largest social media network in the world. As of March 2019, the company claimed 2.38 billion users who had logged in at least once in the past month (1.56 billion had logged in daily). Öhman and his co-author David Watson, also of the Oxford Internet Institute, used Facebook data from the end of 2018, which put the number of monthly active users at 1.43 billion. This data included nationality and self-reported user ages.

The researchers then extrapolated the death rate of those users, based on United Nations mortality data. They found more than 500 million will be dead by 2060, and 1 billion will be gone by 2079. By 2100, 98 percent of today’s monthly active users will be dead.

Those numbers assume no new user growth after 2018, which is unrealistic; the company already claims that more have signed on. To pinpoint the other extreme, the researchers assumed a scenario in which Facebook grows by 13 percent each year until everyone in the world is on the site. More living users mean, eventually, more dead users. Under those assumptions, Facebook is littered with the virtual gravestones of 4.9 billion people by 2100. In that scenario, the dead won’t outnumber the living until the early part of the 22nd century, however.