Even as the population of the world rose over the last few centuries, it plummeted as well. The advancements in telepathy in the 3400s have started a grand junction of being that has not stopped, and likely will not stop until there is only one person on this planet. It started with the establishment of the first permanent telepathic link in 3428, and by the year 3460, it was possible to entirely, irreversably merge two beings' minds into one. It took a few decades for this to catch on, but eventually lovers, close friends, and occasionally adventurous complete strangers were having their minds merged together. The merge meant an increase in intelligence, with the power of two minds in one, as well as the ultimate intimacy--and any merged being would have two entire bodies under their exclusive control, which has its own complement of advantages.

The merged mind acts exactly like an unmerged mind with respect to telepathic magic, which means that more individuals can be merged into an already-merged being. Over the course of a few centuries, merging became gradually more socially acceptable until, in the present day, there is no known adult who is not merged with at least one other, and most minds have over a hundred bodies. There are even beginning to be cases where new beings are born with two or three bodies.

It is unlikely that we will ever merge down to a single being over this entire world, but it should be noted that just over a century ago the common belief was that a merged group of more than five would never be the norm--and I write this as a mind of three hundred and eighty-four bodies now. Perhaps the tendency to underestimate is still there, perhaps we will be a single-inhabitant planet at some point--and perhaps, in the society of a few centuries from now, they (or he, she, shi, it, or whichever pronoun the single mind may choose) will look back at the present and laugh.