Natural selection will only cause evolution if there is enough genetic variation in a population. Before the discovery of Mendelian genetics, one common hypothesis was blending inheritance. But with blending inheritance, genetic variance would be rapidly lost, making evolution by natural selection implausible.
Amazon Kindle Fire (2012) The Kindle Fire has a multitouch-capable 7-inch IPS display, a dual-core processor, and at 14.6 ounces, a pretty lightweight frame. The resolution on that screen is 1024 x 600. The battery is rated to last for eight hours of continuous reading or 7.5 hours of video playback (with WiFi switched off).
Once you start expanding the memory on the 8.9-inch Fire HD and driving the price up, you then might start to weigh storage space vs. screen size in terms of pure hardware comparisons. The 32GB Kindle Fire HD costs $369.