I'm going to be a spoiler. Sorry.

"Average" life expectancy is very misleading. It was low only because infant mortality was still very high. If you survived childhood, you had a pretty good chance of joining the ranks of the elderly. Many of our founding fathers (and mothers) lived to be over 70, and that was 200 years ago. If you don't believe me, look at your own family history. People did not suddenly get old and drop dead at 47.

While people didn't wash their hair as often, I think once a month is a stretch. Homemade soap is quite suitable for washing the hair, and by 1903, the soap industry was going strong. I have never, ever, in all my research, EVER seen a reference to anyone using egg yolks and borax to wash their hair. Eggs were too valuable as food to be used for any other purpose.

These kinds of things are fun for comparison & whatnot, but not always entirely accurate. There was another one making the e-mail rounds about what life was like in Shakespeare's day. Most of it was complete BS.