If you're curious about what makes us curious, crank up that new browser, and dive into The Why Files guide to yearnin' and learnin', version 2.0. When your computer memory gets stuffed, you can buy a bigger hard disk. But when your own memory wet-ware gets sluggish, your options are severely limited. That's odd because other organs are constantly being replenished. Shed skin cells are continually replaced by newly divided ones.
Blood cells live for a few weeks, then die off and are recycled.
If you scarf down a bucket of Sara Lee cheesecake, chances are your fat cells will divide and multiply. But scientists have long held that neurons have steadfastly refused to divide in mature mammals. Beyond the tactless idea of eloping in a hot pink economy car, there's considerable evidence that adult mammalian brains cannot grow replacement neurons. Many common brain diseases, for example, including stroke and Alzheimer's, do their damage by killing off brain cells that are never replaced. Undaunted by this gloomy news, we aging Why Filers managed to dredge up some encouraging discoveries in the neurology labs.