Passage Summary: People usually feel better talking to strangers who look like they're the same age. Since most long friendships start by talking to a stranger, your old friends are probably your age.

Conclusion: Long-term friends are likely to be around the same age as one another.

Reasoning: People are generally more comfortable approaching strangers of a similar age, and most long-term friendships begin with such an approach.

Analysis: The argument suffers from a classic confusion between what makes an initial interaction likely and what characterizes the resulting group. Just because you are more likely to approach a peer doesn't mean that the subset of people who actually become long-term friends must be peers. It's a bit like saying you're more likely to buy a snack when you're hungry, so all the food in your pantry must have been bought while you were starving—it ignores the many other ways food (or friends) might be acquired.