Millions of years ago, we evolved three basic drives: the sex drive, romantic love and attachment to a long-term partner. These circuits are deeply embedded in the human brain. They’re going to survive as long as our species survives.

Source: "Why We Love, Why We Cheat." TED2006. Feb. 2006. Conference Presentation. Additional Information: This quote by anthropologist Helen Fisher means that the human needs for sex, love, and marriage/long-term intimacy are instincts that developed when humans evolved millions of years ago, and that because they are so deeply ingrained in our DNA and essential to who we are, these drives will be with us as long as humankind exists. The quote is from Fisher's 2006 TED Talk about the biochemical foundations of love and marriage. Watch the full TED Talk here: Helen Fisher - Why We Love, Why We Cheat