Life and death since the Paleolithic, Part 1

There are a lot of differences between the life of a Paleolithic hunter-gatherer and the life of a modern, reasonably well-off human. We evolved and adapted in conditions that were simpler, rougher, and more physically demanding. Nowadays, we are more comfortable but that comfort has taken a toll in the form of chronic debilitating disease, which nobody wants. Looking back at our history – and especially our prehistory – can show how we’ve strayed from the way of life we were built for, but the past is a big place, people lived in many different natural environments, and we only have scattered clues about what actually went on. 

Anatomically modern humans emerged around 200,000 to 300,000 years ago in Africa, and we stayed there for most of our prehistory. Around 40 - 60,000 years ago, we started using complex language and moving around over long distances, exploring new continents. Recorded history covers less than 10% of the time since the first homo sapiens migrated to Europe. Most people didn’t live in cities until a couple of years ago. For an overview of the timelines, check out this excellent set of graphics: https://waitbutwhy.com/2013/08/putting-time-in-perspective.html

For the history of urbanization, see this page: https://ourworldindata.org/urbanization

So, what does this have to do with health? Each stage of cultural evolution placed different demands on us, and our health varied. In the old days, the most important thing for the continuation of the species was to reproduce. 10,000 years ago there were only about 4 million people in the whole world. That’s just a bit bigger than the population of Los Angeles, Berlin, Cape Town, or Taipei… and there are dozens of bigger cities. The world’s total population is now 7.5 billion. Here’s a graph: https://ourworldindata.org/uploads/2018/11/Annual-World-Population-since-10-thousand-BCE-for-OWID-800x498.png

To accomplish the massive expansion of our species, we made several big technological upgrades. Fire for cooking and the development of language were big ones. Farming, the development of cities and empires, the discovery of vaccines and antibiotics, everything helped us survive and live longer… in general. There were some ups and downs. People were always getting into fights and conflicts and war, which knocked out a lot of us. Before 1900, life expectancy varied quite a bit depending on where and when you lived and your resources (see https://en.wikipedia.org/wiki/Life_expectancy). Life expectancy is estimated to have been around 33 or 34 in the Paleolithic, once you survived infancy and childhood, and may have been higher. Hunter-gatherers living a more or less Paleolithic lifestyle who have been studied recently often live well into their 50s, but rarely much beyond that. In the Neolithic, with the development of farming, life expectancy dropped to 30-ish, and until 1900 it stayed mostly between 30 and 40, with occasional drops and, for some, pockets of good health that had people living as long as they do today.

In that time, before 1900-ish, the big killers were infant and early childhood mortality, death in childbirth, accidents and violence, and – especially after the development of agriculture and urbanization – infectious diseases. Currently, the biggest killers (according to https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death) are heart disease, stroke, COPD, lower respiratory diseases, Alzheimer’s and dementia, lung cancer, diabetes, road injuries, diarrhea, and tuberculosis… those last two being most prominent in poorer parts of the world. There’s not a lot of overlap between those two lists. The difference between them is that far more of the modern causes of death are preceded by a long life, and often a decade or more of ill health and disability. If you have any kind of cardiopulmonary disease, diabetes, cancer, or dementia, you’re likely to have a long period of feeling pretty crappy and maybe not being able to do much before it finally kills you.

Life expectancy still varies a lot depending on where you live, from a low of under 50 for some sub-Saharan African countries to a high of about 85 in Japan (estimates vary a lot. See https://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy) on average. Global average life expectancy at birth is now 70 years for males, 75 years for females. People who live to over 100 are not very rare. Are our modern causes of death the inevitable result of old age? I used to think so – my impression of old age was that nursing home care was almost inevitable for people over age 70- or 80-something, but you don’t have to look far to find examples of people in their 80s and 90s who are living independently and are still able to do most things they need to do (over 100, not so much). In the places observed in the Blue Zones project, it is common for centenarians to still be out there hoeing their vegetable plots.

You also don’t have to look far to see much younger people who are already struggling with diabetes, poor cardiovascular health, cancer, etc., so these problems are not simply related to our increased lifespan. In fact, they seem to be bringing life expectancy down. In the United States, life expectancy at birth has started to decline in 2014. The United States has pioneered a lot of recent lifestyle changes, for better or worse. We were fairly early to urbanize in the 19^th - 20^th centuries, assembly line car manufacturing was invented here, we developed modern advertising, television, junk food, and the internet. We are also behind the curve on health care access. That leaves many people to deal with the consequences of bad diets, bad sleep, and lack of activity more or less on their own.

Getting healthier is important here because if you’re not healthy, the US government is happy to let you die on the streets. Other countries have put more resources into promoting healthy lifestyles because they have mostly public health care systems, rather than the mostly for-profit US system. When it comes to health, we’re a special case, and not in a good way. I live in a very healthy area with a good medical system, but I still see a lot of cases of ill-health among my neighbors, just as much in younger adults as among the elderly.

I’m only a tiny portion of the way through the material I hoped to cover in this post, so in the interests of getting it posted today I’ll leave the rest for next time… and maybe the day after that, too.