More than 80 varieties of fish, amphibian, and reptile mothers are able to lay eggs that have not been fertilized and yet produce offspring. In a process called "parthenogenesis," these eggs hatch little clones of the mother, which in turn lay clone eggs themselves. Could this remarkable mode of unisexual reproduction have evolved?

Human eyes are well-designed to see objects using light transmitted through air, but not through water, because light travels at a different speed through the two media. However, intertidal-dwelling marine mollusks called chitons can see equally well in both environments. How did they acquire this unusual ability?

The human hand is undeniably a work of wonder. Its layout and suite of design features enable mankind―the only possessors of this particular arrangement of bones, tendons, muscles, and nerves―to type faster than 60 words per minute or swing a heavy hammer while holding a delicate potato chip. What would it take to duplicate a human hand?

When boring into wood in search of food, a woodpecker exerts so much force with each strike that its beak should crumble, its skull should crack, and its brain should be reduced to mush. However, a suite of design features absorbs the shock and ensures that these tragedies do not happen. How are these features able to provide such effective protection?