Top country to visit for Thus, education levels may serve as a signal of how productive one is. It should be noted, that as a lifelong educator, Spence has been disappointed by his model being interpreted to imply that education is merely a signal and does not serve productive purposes. It has been noted that signaling is not purely an economic phenomenon, as evidenced in biological natural selection. In order to attract mates, many animals will use resources, which by themselves serve little other purpose, to signal health and thus good genes (e.g., extravagant colorings and feather displays of male birds). BIBLIOGRAPHY. Top country to visit 2016.