Rowan

Yeah, this is rather interesting. When Australia was first settled (and I suppose this happened in America, too), the houses were built with doorways just like back in England -- at a height that a six-footer couldn't get through without stooping a lot.

We get to watch a lot of shows done by British TV about homes in the country, and a lot of them have centuries of history behind them. Invariably, the ones built in the 15th, 16th and 17th centuries have low doorways. Look at how the ships of the day were designed -- they are almost impossible for anyone over 5'5" to get around inside.

I'd say the average height appears to have increased substantially since that period.

As to the less healthy, I think the longevity of the human also has increased substantially. This is quoted from a recent article about a Swedish researcher debunking modern urban myths:

Life expectancy

Average life expectancy in the world is currently 70 years. This is up from the average life expectancy of 60 years in the 1960s. But the current rate is much better news because it applies to the majority of the world's population. The 1960s figure was skewed because there was high life expectancy in wealthy nations and short life expectancy in poor nations.