In the historical period, when technologically advanced humans encountered less advanced ones, there was cultural and genetic interchange, but in the end, the technologically advanced peoples . If any place on Earth could have been used as an illustration of the climate change hypothesis for the megafauna extinctions, ice age Europe would have been it. Ice sheets extended so far southward that Neanderthals lived in relatively few refugia, but I highly doubt that it caused their extinction. Neanderthals lived for at least 300,000 years and survived radical climate changes just fine. Human-agency skeptics have invoked unusually violent climate changes that coincidentally appeared when behaviorally advanced humans arrived around the world, but that seems to be grasping at straws. Again, there is nothing climatically unique about the past 60,000 years, , so invoking climate-change effects for humans and animals that weathered the ice age’s vagaries just fine seems to be a huge conjecture that may be politically motivated. Human-agency skeptics have crafted different kinds of climate explanations for each major extinction, such as drying in Australia, getting colder and dryer in Europe, or getting when most of the extinctions happened. At , climate was a proximate cause, not the ultimate one. The ultimate one was people virtually every time.
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One consequence of Locke’s treatment of attention as a mode ofthinking is that, once we have a theory of thinking before us, we needno further theory to account for how attention, contemplation, study,etc. are possible. (Just as, to use the classic example of‘modes’, we need no substantive independent theory, oncewe have a theory of walking, to explain how limping, pacing or amblingare possible.) We need to say something in giving an analysisof the nature of modes, but—once the thing-to-be-modified hasbeen accounted for—the thing that we say can be something brief,along the lines indicated by Locke. We do not need to give a theorythat postulates any substances or processes specific to theexplanation of attention.
Bottom-up limitation of predaceous arthropods in a detritus-based ..
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The critical feature of earliest life had to be a way to reproduce itself, and is common to all cellular life today. The DNA that exists today was almost certainly not a feature of the first life. The most accepted hypothesis is that . The mechanism today is that DNA makes RNA, and RNA makes proteins. DNA, RNA, proteins, sugars, and fats are the most important molecules in life forms, and very early on, protein “learned” the most important trick of all, which was an energy innovation: facilitate biological reactions. If we think about at the molecular level, it is the energy that crashes molecules into each other, and if they are crashed into each other fast enough and hard enough, the reaction becomes more likely. But that is an incredibly inefficient way to do it. It is like putting a key in a room with a lock in a door and shaking up the room in the hope that the key will insert itself into the lock during one of its collisions with the room’s walls. Proteins make the process far easier, and those proteins are called enzymes.