Reproductive Rights Short Quotes

Sexual reproduction is thus a costly investment that has to pay for itself in the short run. The details of theory and experiment on this topic are fascinating (see, e.g., Maynard Smith, 1978; Ridley, 1993), but for our purposes a few highlights from the currently front-running theory are most instructive: sex (in vertebrates like us, at least) pays for itself by making our offspring relatively inscrutable to the parasites we endow them with from birth. Parasites have short lifespans compared with their hosts, and typically reproduce many times during their host’s lifetime. Mammals, for instance, are hosts to trillions of parasites. (Yes, right now, no matter how healthy and clean you are, there are trillions of parasites of thousands of different species inhabiting your gut, your blood, your skin, your hair, your mouth, and every other part of your body. They have been rapidly evolving to survive against the onslaught of your defenses since the day you were born.) Before a female can mature to reproductive age, her parasites evolve to fit her better than any glove. (Meanwhile, her immune system evolves to combat them, a standoff—if she is healthy—in an ongoing arms race.) If she gave birth to a clone, her parasites would leap to it and find themselves at home from the outset. They would be already optimized to their new surroundings. If instead she uses sexual reproduction to endow her offspring with a mixed set of genes (half from her mate), many of these genes—or, more directly, their products, in the offspring’s internal defenses—will be alien or cryptic to the ship-jumping parasites. Instead of home sweet home, the parasites will find themselves in terra incognita. This gives the offspring a big head start in the arms race.