The earliest accurate anatomic depiction of the human heart is usually credited to the sixteenth-century Flemish anatomist Andreas Vesalius. But this four-and-a-half-inch-tall ceramic vessel from Las Bocas, Mexico, antedates Vesalius’s work by some 2,500 years. Its style is characteristic of the Olmecs, a pre-Mayan people. It is not a perfect rendition of the heart--it shows two chambers instead of four, and the vena cava, the large vein that carries blood from the body to the heart, is on the far left instead of the right. But its sophistication far surpasses the crude valentine-shaped daubings of other peoples from similar periods, says cardiologist and part-time art historian Gordon Bendersky of Allegheny University-Hahnemann School of Medicine in Philadelphia, who has studied the effigy. How did the Olmecs acquire their keen knowledge of cardiology? They had not even invented the wheel, says Bendersky. They had no metal tools, so why would they know anatomy? Then I realized that they must have been the first to sacrifice humans by the technique of removing their hearts alive. The Mayans were thought to have invented that grisly ritual, but it seems the Olmecs were first there too.