I'm seeing the usual comments about life expectancy and IQ here, so I had better respond to both issues.
First of all, and I encourage readers to follow the links for more details, today we have longer life expectancies at birth, at age 40, at age 60, and at even higher ages than ever before.[1] Whatever it is that we are eating these days, so far our diets aren't undermining the steady long-term trend of increasing life expectancy at ALL ages all over the developed world. An article in a series on Slate, "Why Are You Not Dead Yet? Life expectancy doubled in past 150 years. Here’s why"[2] tells the story of the steady improvements in prevention and treatment that have reduced all-cause mortality and morbidity for Americans and for most people in the developed countries. I have been stunned to realize I now have several aunts and uncles who are past the age of 90 and still living independently and in reasonably good health. A couple years ago I was shopping for a birthday present for my own mother, now more than 80 years old, and I found multiple birthday cards for 80th and 90th birthday cards for sale at the bookstore where I was shopping. Lots of people are living a long time now.
But don't just take my anecdotes as evidence. Check what professional demographers write about the issue in peer-reviewed journal articles and say about the issue in press interviews. 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. 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. 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]
There are also comments here about human brain size and human cognitive ability. First of all, it is entirely clear that human cognitive ability as gauged by "g-loaded" IQ tests has been rising for the last century.[5] That's over a time span that doesn't include any noteworthy increase in brain size and is surely a result of environmental factors. The general trend of hominin evolution over millions of years is a general increase in brain size and a general rise in signs of intelligent behavior like skillfully made tools and visual art, but there is not a completely linear relationship between brain size found in fossils (which are a very limited sample of early hominin specimens) and signs of cultural advancement.[6] Cultural innovation can now be transmitted culturally all over the world, so that a small number of innovators can change the material resources and improve the lifestyles of most of humankind. You may not need to be smart enough to invent anything, because you are already smart enough to use most new inventions, wherever they come from.
[1] http://www.nature.com/scientificamerican/journal/v307/n3/box...
[2] http://www.slate.com/articles/health_and_science/science_of_...
[3] http://www.demographic-challenge.com/files/downloads/2eb51e2...
[4] http://www.prb.org/Journalists/Webcasts/2010/humanlongevity....
[5] http://www.psychometrics.cam.ac.uk/about-us/directory/beyond...
http://www.ted.com/talks/james_flynn_why_our_iq_levels_are_h...
[6] http://phenomena.nationalgeographic.com/2013/03/13/from-nean...
