The cursive logo has remained a globally recognized constant, but the shape of Coca-Cola bottles has progressed dramatically since 1899. Bottles in this image are from 1899, 1900, 1915, 1916, 1957, and 1986.  The two bottles at left were probably more fun at parties than their descendants. From Mark Pendergast, author of For God, Country, and Coca-Cola:

"Coca-Cola was named for its two principal drug ingredients. Coca leaf from Peru contained cocaine. Kola nut from Ghana contained caffeine. Original Coca-Cola had a very small amount of cocaine in a six-ounce drink, about 4.3 milligrams. The company took out all but a minuscule amount of cocaine in 1903 and the final amount in 1928."