There's this idea of shifting baselines. It was coined by a guy named Jeremy Jackson. It's the idea that every generation takes what it sees, and says, "Okay, well, that's the norm."

There are a lot of things that we could do to minimize what we're doing, but we're not getting back those frogs that I saw that no longer exist.

Letting things slide is always the easiest thing to do, in parenting no less than in banking, public education, and environmental protection. A lack of discipline is apparent these days in just about every aspect of American society. Why? This should be is a much larger question, one to ponder as we take out the garbage and tie our kids' shoes.

No matter what Donald Trump says, it's clear that global warming is rapidly changing conditions on our planet.

As best as can be determined, the world is now warmer than it has been at any point in the last two millennia, and, if current trends continue, by the end of the century it will likely be hotter than at any point in the last two million years.

Neanderthals were pretty smart, and if we actively killed them off, then probably we did so in the same way that humans kill each other.

Mitochondrial DNA, which is a sort of abridged version of DNA, is passed directly from mother to child, so it's something that can be looked at to trace matrilineal descent.