Evolution for creatures such as us takes millions of years, and so any changes that happen in a mere 8,000 years are going to be minuscule unless there's some considerable, probably unnatural, driving force. (More on this in a bit.)

As for saying that evolution stopped 10,000 years ago, I did not say that. However, consider how "survival of the fittest" works -- the fittest survive and pass their genes on to their children. Those that are not fit don't survive, and don't pass on their genes. Civilization, right or wrong, changes that, as what constitutes "fit" is different now, and even those who aren't fit are still likely to survive and reproduce.

Looking just at intelligence, it seems that studies have shown that fertility and intelligence has a negative correlation -- in short, the more intelligent people are, the fewer children they tend to have. If this trend continues, it could lead to mankind having a lower average intelligence over time.

Now, it certainly is possible for society to change this, but anything that's forced on people is going to be met with massive resistance -- people do NOT like to have their rights to reproduce messed with. And some world leaders have attempted to control who gets to reproduce, to wipe out "undesirable" groups and such -- and history has labeled these people as monsters.

This is pretty far off topic, however. And I don't think there's any need to dismiss any of the original poster's wife's concerns as being due to evolution or instinct or anything along those lines -- the concerns are valid (even if possibly blown out of proportion) and simply indicate genuine concern. (Which might be at least partially resolved by wearing a helmet (arguments about their effectiveness aside, it might make her feel better) and lighting one's bike up like a Christmas tree at night, reminding her that one generally obeys the traffic laws, get her out on her own bike more often, etc.)