It is theorized that humans are the only species that embraces bitterness. A sensation that once indicated poison, or danger, bitter now is embraced as one the five tastes that create complexity and pleasure.

We have written before about bitterness in columns on vermouth and amari. Those are known as potable bitters, meaning that, with their level of bitterness and alcoholic proof, they can be enjoyed on their own — or, at least, be the star in a cocktail.

But, what about nonpotable bitters, the ones whose strength and intense flavor are more suited for dashing, instead of pouring? The best-known brand is Angostura, with its too tall paper label and yellow cap.

Most bitter brands were started as a “cure” for stomach ailments. Whether that was science or a snake-oil pitch, the concoctions of bitter barks, spices, dried citrus and other ingredients, in a high-alcohol infusion, soon found their way into other spirits and beverages.

The original “cock-tail,” as explained in a late 18th century newspaper, is a spirit with sugar, water and bitters. If this sounds familiar, it might be because that is the recipe for an Old-Fashioned.

Bitters make an appearance in another of our favorite cocktails, the Sazerac. In the 1830s, a New Orleans apothecary, Antoine Peychaud, happened to be compounding a liquid bitters potion on the same block as the Sazerac coffeehouse, where they sold more cognac than coffee. When they got together, the cognac helped the medicine go down, but its unique spice and bitter blend made the spirit taste great. Add a little sugar and lemon peel, and the official cocktail of New Orleans was created.

Bitters add complexity that elevate a cocktail. We think of bitters in cocktails almost like salt in cooking. You wouldn’t spend 45 minutes stirring the perfect risotto and not add salt. The same holds true with a classic cocktail, like the Manhattan. While it is a simple recipe of two parts rye whiskey and one part sweet vermouth, without the two dashes of Angostura bitters, the drink would be dull and flat.

Which bitters do you need for your home bar? While there has been a boom in the number of flavors in the market, including celery, cardamom and Oaxacan chocolate, we think there is a holy trinity of bitters.

Angostura, Peychaud’s and orange bitters, like Regan’s No. 6, can get you through a large repertoire of classic and modern cocktails. The tawny spice of Angostura will do the heavy lifting on Old-Fashioneds and Manhattans. You need Peychaud’s for Sazeracs, but, also, for sours, like the Pendennis Club. And, orange bitters are used in a wide array of cocktails, but are a must when we make martinis.

The Slaters are beverage industry veterans and the proprietors of the Expat and the Lark Winespace in Athens.

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