Although there are other coastal deserts bounded by cool ocean currents (e.g., the Atacama, the Baja, etc.), the Namib is the only desert in the world where endemic flora and fauna have evolved in virtually vegetationless dunes. This is due partly to the Namib's lengthy period of stability, and also to the dunes' relative isolation. They are surrounded by arid plains, upon which rain never falls to the extent that grasses and shrubs can gain a foothold and colonize them.

As a consequence of the vegetationless nature of the dunes, larger predators also cannot inhabit them. However, many smaller, diverse species have adapted to the constantly changing desert environment, feeding on wind-blown detritus and capturing moisture from fog that rolls in from the sea.

The presence of these survivors suggests a great age for the Namib, since a vast period of time and geographic isolating mechanisms are needed before species with such high degrees of specialization and adaptive responses can develop. However, the present Namib desertification is estimated to be only three to four million years old.

Much knowledge about the geological history of the Namib has been gained through observing the canyon walls carved by the Tsondab and Kuiseb Rivers. Through these observations, it has been determined that an arid climate began to predominate in the region about 55 million years ago, leading to the formation of a sand sea that was up to 720 feet (220 meters) deep -- more extensive than that of the current desert. The remnant of this sea is now called the Tsondab Sandstone Formation. The Formation's bedding and sedimentary structure indicate that ancient dunes were formed in a manner similar to today's. This suggests that the southerly wind system has been in place since that time. About 14 to 18 million years ago, the climate changed from arid to semi-arid. Since the Benguela current came into existence, hyper-arid conditions have been characteristic of the Namib desert, and continue to progress to this day.

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