Chalk it up to changing social norms or shifting generational attitudes around relationships. But the bigger issue at play, according to Justin Garcia, is that we just don’t crave intimacy in the same way we used to. “Our species is on the precipice of what I have come to think of as an intimacy crisis,” Garcia writes in his new book, The Intimate Animal: The Science of Sex, Fidelity, and Why We Die for Love. Garcia suggests in the book that intimacy—not sex—is the “the most powerful evolutionary motivator of modern relationships,” but that our hunger for it “has been stifled by and misdirected in today’s digital world.”