The reason the Cambrian stands out is that it's the first period that saw widespread hard body parts that actually had a decent chance of fossilizing. And we even have some good reasons for the morphological variation seen.

https://xkcd.com/258/

How does this explain the reproductive system?

By small changes over a long time.

'Mutation' isn't like in the X-men, producing a full-blown new species. If it did, then yes, evolution (of multicellular sexually-reproducing organisms, at least) would be impossible, because you'd need a male and female that happened to be compatible. But that's not the model evolution actually proposes.

For a much clearer picture of how species really do come about, look up 'ring species'. For example, the Larus gulls are several subspecies where variants live in a ring around the Arctic. The Herring Gull in the U.K. can interbreed with the American Herring Gull, and the American can interbreed with the Vega Gull in Russia. And so on, until you come to the Lesser Black-Backed Gull in the Netherlands. It basically canâ(TM)t breed with the Herring Gull. Hybrids are extremely rare and don't seem to be fertile, like mules. So, is it a separate species? You could breed it with its relative to the East, and so on. But what if, say, the Vega Gull went extinct? Would you have separate species then?

Now, imagine such variations happening across time instead of (or as well as) space, and youâ(TM)ve got an idea how species actually do form, instead of the â(TM)saltationistâ(TM) strawman that many try to imply.

...and proving there's no need to do so, most people get busy on the proof." - John Kenneth Galbraith

David Sloan Wilson's "Evolution For Everyone". He's a group-selectionist in some ways, but don't hold that against him. He really does cover the basics in a way interested but non-technical readers can follow. He makes clear what evolution is, and - equally important these days - what evolution isn't.

True, but the main objections to raising the speed limits after the gas crunch eased were safety-based, and people still call for a return to 55MPH based on safety.

MPAA gets to choose their business model. They don't get to ban entire Internet protocols, arbitrarily shut down websites without due process, kick end-users off the Internet, or any other non-business-model-related "rights" they've been lobbying for.

It's a legit point. Claiming that "piracy isn't the problem the MPAA shrieks it is" is not the same thing as claiming that "piracy isn't theft".

You can't determine the appropriate response to a problem without correctly grasping how much of a problem it is. We as a country made a decision that the problem of highway accidents wasn't severe enough to justify a 55MPH speed limit, and raised it to 70MPH, for example. As a more appropriate example, we also decided that the threat of piracy by VCR was not severe enough to ban the production and sale of VCRs - as the MPAA tried to propose.

So, to reiterate: people can think piracy is theft while also thinking the MPAA is vastly exaggerating the severity of the problem.

Still has some minor rough spots (xfburn doesn't seem to let me drag-n-drop files from thunnar) but gets the job done. And I have to upgrade my parents' machine soon; I can't imagine trying to teach them Unity. So, Xubuntu for them, too.

Zombies and P=NP.