I read the previously submitted comments here in this thread before reviewing the link kindly submitted here. (I remember this report from the year it was first published.) The paper compares the country Finland to the region Karelia conquered from Finland by Russia and now part of Russia. Life expectancy in Finland[1] is much better than that in Russia,[2] so if the trade-off of growing up in a clean environment is that I don't die of something else but life into healthy old age with some annoying allergies (I do have allergies, so I am well aware of how annoying they can be), I'll take that trade-off. The last time we had an active thread about the hygiene hypothesis here on HN, there were all kinds of n=1 anecdotes from various participants here about refraining from using soap and other socially silly practices. There is a big attitude here on HN that modern life is bad for us somehow. That attitude is mistaken.

The article "The Biodemography of Human Ageing" by James Vaupel,[3] originally published in the journal Nature in 2010, is a good current reference on the subject of how much life expectancy has improved at ALL ages in the developed world. Vaupel is one of the leading scholars on the demography of aging and how to adjust for time trends in life expectancy. His striking finding is "Humans are living longer than ever before. In fact, newborn children in high-income countries can expect to live to more than 100 years. Starting in the mid-1800s, human longevity has increased dramatically and life expectancy is increasing by an average of six hours a day."[4] An article in a series on Slate, "Why Are You Not Dead Yet? Life expectancy doubled in past 150 years. Here’s why"[5] Provides some of the background. Yep, perhaps in the clean modern world, our immune systems aren't challenged as much as they used to be, but we also get sick less often and live to much older ages with good health. Life expectancy at age 40, at age 60, and at even higher ages is still rising throughout the developed countries of the world.[6] That's a trade-off I will happily accept. My mom (who also has allergies) is eighty-one years old and still living independently and enjoying her favorite activities, and she has sisters and brothers older than she is who are still in good health. Girls born since 2000 in the developed world are more likely than not to reach the age of 100, with boys likely to enjoy lifespans almost as long. If that's what I have to put up with after living in a clean environment in my youth, I can deal with that.

[1] https://www.google.com/search?q=Finland+life+expectancy

[2] https://www.google.com/search?q=Russia+life+expectancy

[3] http://www.demographic-challenge.com/files/downloads/2eb51e2...

[4] http://www.prb.org/Journalists/Webcasts/2010/humanlongevity....

[5] http://www.slate.com/articles/health_and_science/science_of_...

[6] http://www.nature.com/scientificamerican/journal/v307/n3/box...