Maybe we're not even true humans anymore.
A definition for species (though often contested) is a group of organisms capable of interbreeding and producing fertile offspring. No problems there, since we're all capable of interbreeding.
But this merely means that we're all the same species, not necessarily that we're human. Perhaps we've acquired so many minute mutations, so many incremental changes, that we're too different.
If there was a time machine, would we be able to successfully mate with an ancestor from many millennia ago?
A definition for species (though often contested) is a group of organisms capable of interbreeding and producing fertile offspring. No problems there, since we're all capable of interbreeding.
But this merely means that we're all the same species, not necessarily that we're human. Perhaps we've acquired so many minute mutations, so many incremental changes, that we're too different.
If there was a time machine, would we be able to successfully mate with an ancestor from many millennia ago?