How long is a generation these days
So far in this essay, mammals have received scant attention, but the mammals’ development before the Cenozoic is important for understanding their rise to dominance. The , called , first , about 260 mya, and they had key mammalian characteristics. Their jaws and teeth were markedly different from those of other reptiles; their teeth were specialized for more thorough chewing, which extracts more energy from food, and that was likely a key aspect of success more than 100 million years later. Cynodonts also developed a secondary palate so that they could chew and breathe at the same time, which was more energy efficient. Cynodonts eventually ceased the reptilian practice of continually growing and shedding teeth, and their specialized and precisely fitted teeth rarely changed. Mammals replace their teeth a . Along with tooth changes, jawbones changed roles. Fewer and stronger bones anchored the jaw, which allowed for stronger jaw musculature and led to the mammalian (clench your teeth and you can feel your masseter muscle). Bones previously anchoring the jaw were no longer needed and . The jaw’s rearrangement led to the most auspicious proto-mammalian development: . Mammals had relatively large brains from the very beginning and it was probably initially . Mammals are the only animals with a , which eventually led to human intelligence. As dinosaurian dominance drove mammals to the margins, where they lived underground and emerged to feed at night, mammals needed improved senses to survive, and auditory and olfactory senses heightened, as did the mammalian sense of touch. Increased processing of stimuli required a larger brain, and . In humans, only livers use more energy than brains. Cynodonts also had , which suggest that they were warm-blooded. Soon after the Permian extinction, a cynodont appeared that may have ; it was another respiratory innovation that served it well in those low-oxygen times, functioning like pump gills in aquatic environments.
Beating the Averages - Paul Graham
As our society grows towards being a culture connected through the Internet, and as prices of these machines gradually decrease, more and more have been purchased by families for their homes and as a result, children are beginning to learn to use the computer at an earlier age.
When I arrived at my office, I turned on my lights and computer. When I was eating, I put the food that I brought to work in a refrigerator under my desk. During my work day, I interacted with many people in my air-conditioned, high-technology office environment. My cellular telephone was never far away. The view from my office window of the was pleasant. My computer interfaced with our distant data centers and the world at large via the Internet. When my workday was finished, I rode the bus home. In the winter, the furnace is programmed to stop functioning when my wife and I leave for work, and comes on soon before we arrive home, so we never experienced a cold house. In the evening, we might watch a movie on a DVD on our wide-screen plasma TV. When I am not fasting, I usually eat dinner, with the food in my refrigerator usually purchased at a that has an enormous produce section, with food grown locally and imported from as far away as New Zealand, China, and Israel. We have a high-tech kitchen, with a “smart” stove, refrigerator, and other appliances.