Among the pagan practices vanquished by early Christians was infanticide. As Christianity fades in the West, so do our defenses against infanticide in all its grisly forms.
Since its beginning, the pro-life movement has argued that the logic that justified abortion-on-demand could, at some point, be also used to justify infanticide.
And for just as long, defenders of abortion rights have rolled their eyes, literally and figuratively, regarding our concerns about the slippery slope of killing innocents as "kooky" and "alarmist."
But then in 1997, Steven Pinker, one of the leading lights of what's known as "evolutionary psychology," published a piece in the New York Times that argued for the "naturalness" of infanticide.
While not denying that under modern conditions, "Killing a baby is an immoral act," it was a kind of triage for our not-so-distant relatives to separate those likely to survive from those unlikely to survive.