So why do we, unlike lobsters, sene

So why do we, unlike lobsters, senesce as we get older? It’s tempting to say that we are like our cars: they get old. And even though we take them in for periodic tune-ups, they eventually fall apart, or senesce. We are like cars in a certain sense; that is, we and cars are complex systems that deteriorate with age (though we are infinitely more complicated). Unlike cars, we have built-in repair and maintenance systems. We are constantly replacing cellular compo- nents and checking and rebuilding the molecules that make up our cells. That would be like your car growing new tires or belts as the factory-installed parts aged. Unfortunately, these repair systems, too, deteriorate with age. The next chapter details the main processes that are damaged or lost with age.