Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
28 Oct

Just How Long Did Grok Live, Really?

It has become an article of faith among, well, basically everyone, that our ancestors lived short, brutal lives. What are they touting as the average lifespan these days – 35 years old or so? I’ve heard anything between 25 and 40 years. The common counter is that infant mortality rates were higher than they are today, thus skewing the average. It’s also often pointed out that a relatively benign accident or illness by today’s standards – a broken arm, a rolled ankle, or a minor infection – could have prematurely ended Grok’s life. And that these cases say nothing about Grok’s potential to live 70+ years. The “short and brutal” meme has wedged itself in the public psyche, and it’s going to take a lot to extract it from its seemingly intractable position.

I’m going to riff a bit on something I’ve been thinking about regarding ancient human bones. This isn’t an official stance or anything; I’m just thinking out loud. Let me know what you think in the comment board.

Now, bones are notoriously confusing, especially when we’re trying to figure out the age of the individual who died. We learn a lot from studying them, but only to a point. Just how do forensic anthropologists determine the age of death of a particular skeleton’s former owner?

For skeletons of infants, children, adolescents, and young adults, fossil analysis yields accurate age of death estimates. Human growth is fairly reliable for a while, and it’s easy enough to tell a kid apart from a really short adult, but things get tough once people stop growing and become adults. In fact, anthropologists have typically had trouble accurately determining the precise age of death for older adult remains. They’ll even tell you this. They can’t rely on the same methods and must turn to others.

One method is to measure bone mineral density, especially of the femur. It’s a general rule that bone density decreases with age. It’s a pretty accurate method for determining the age of death in modern people, but I’m skeptical of its utility when dealing with the bones of our ancestors. Even its proponents admit that while general age and sex-related trends can be observed for bone loss, there have been cases of “young adult” bone density patterns in skeletons of aged individuals. That is, bone density degradation is not linear, and it’s not set in stone. Instead, it depends on “numerous genetic, environmental, and cultural factors.” Old guys can have young guy bones, but it’s rare. Most modern old guys have old guy bones.

What kind of environmental factors can influence bone density – can give old guys young bones? Remember, environmental factors include anything that the organism interacts with, and as far as bone health, diet, activity level, and micronutrient intake are some of the big ones.

Vitamin D

Vitamin D status is a strong predictor of osteoporosis risk. Folks deficient in vitamin D tend to have lower bone mineral densities and are at a higher risk for breaks and fractures. If you slather on sunscreen, avoid the sun, avoid pastured animal organs and fatty fish, and do not supplement with vitamin D3, like most modern humans, you are most likely deficient and at risk for low bone density. Paleolithic humans, on the other hand, did not sit in offices all day shielded by windows that blocked UVB rays, nor did they wear sunscreen. They didn’t know about vitamin D, either, but they didn’t have to. They either spent most of their lives in sunny, tropical climates with plenty of UVB exposure, or, in the case of Europeans, had lighter skin selected for to ensure sufficient vitamin D synthesis from fewer UVB rays. They also ate plenty of animal foods, and they didn’t shy away from organ meat or fatty cuts. We don’t know exactly what our ancestors’ vitamin D statuses were, but we can surmise that, given their lifestyle, their exposure to the elements, and their diet, they probably had sufficient levels to avoid bone density deficiencies.


Although calcium gets all the press, magnesium is also vitally important for the building and maintenance of strong bones. In fact, serum magnesium levels are a strong predictor of bone mineral density. In “The Paleo Diet,” Dr. Loren Cordain estimates that the magnesium intake of Paleolithic humans ranged between 800 and 1,500 mg per day. Contrast that with the recommended daily intake of 400 mg and consider that very few people even reach that recommended amount – according to Cordain, 65% of the American population. If the average 55 year old American eats an inadequate amount of magnesium and sports a low serum level, while the average 55 year old Paleo (real Paleo, not one of you guys) ate plenty of magnesium and most likely had a high serum level, whose bones are going to be denser? Whose bones might an observer assume to be those of a younger man?

Resistance Training

Strength training builds muscles, but it also builds bones. Like muscles, bones are reactive things that respond to stress. When you lift heavy things, heavy enough to “threaten” your body, you are sending the message that the affected lean tissue must adapt. Muscles adapt by adding fibers; bones adapt by ossifying. Today’s sedentary populations are plagued with osteoporosis, partly because of nutritional deficiencies, but also because they are sedentary. Their bones, by and large, aren’t getting the stimulus required to maintain density. They don’t have to hunt, kill, and carry their food, nor do they have to build their domiciles. Heck, it isn’t even necessary to leave the house. Our hunter-gatherer ancestors, on the other hand, worked for their livelihoods. They were active by necessity; they lifted heavy things because their lives depended on it. Whose bones do you think would receive the stimulus necessary for maintaining density – the sedentary sitters or the active hunters?

The idea of strength training strengthening and fortifying bone is well supported in the literature. It’s true that some results have been mixed, but most reviews of the literature argue that the studies showing little effect employ insufficient intensity or improper training methods.

If anthropologists have included fossil bone density as a factor in their determination of age of death, I think the matter of vitamin D, magnesium, and resistance “training” (obviously, they weren’t lifting barbells in the Paleolithic, but they were certainly lifting heavy things, arguably at a greater intensity than many modern lifters) throws the popular notion of hunter gatherer’s lives being short and brutal into question. Were they shorter than ours? Yeah, on average. I’m not tossing everything out entirely. I’m just questioning whether modern bone density data are accurate reference points for analyzing the age of death of Paleolithic remains. It might be more accurate to simply say, “We don’t exactly know,” instead of tossing out the “cavemen died at 30!” knee-jerk response.

What if the dense bones of what appear to have been a robust 30-year old hunter were actually bones of an incredibly capable 60-year old?

Next time, I’ll discuss a paper that takes an in-depth look at hunter-gatherer ages. The results might pleasantly surprise you.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. The diets most associated with longevity (in good shape) are the Mediterranean and Okinawa diets. That’s not to say one can’t live a long time on a Paleo diet either though. More important than the kind of diet (vegetarian, paleo, etc) is just eating healthy foods. Any diet that avoids processed foods, sugar, salt, refined carbs and excessive saturated fat will likely lead to a long healthy life (assuming they’re thin, see a doc regularly, and remain active); aside from that the rest probably only makes a difference at the margins.

    One other thing I did want to point out is that aside from eating healthy foods and exercising, probably the most important thing is eating the right amount of food. There has been a well-established inversely proportional relationship between caloric intake and lifespan. (assuming u get good nutrition) So whatever diet one chooses, eating fewer calories and staying on the thin side of normal (not JUST avoiding obesity) is a good idea. Here’s a pretty good cache of evidence and info on this point:

    P.S. I wouldn’t put a whole lot of stock into what the Bible or other ancient books say about people’s lifespans. They say lots of stuff that has been disproved. (like the Earth only being thousands of years old) They aren’t health guides.

    Kim wrote on November 5th, 2010
    • Kim,

      Don’t you think it’s interesting that the Bible says that mans years will be capped at 120 and that most of the oldest people in the world live to just shy of 120? (with 2 exeptions)

      I wasn’t saying that Grok lived a natural life to 120. Just that he had the potential.

      I am a Christian and I think the earth is about as old as secular scientists say it is. Where does the bible say that the earth is only thousands of years old?

      Steve wrote on November 5th, 2010
      • It also says it is flat and the rest of the universe rotates around it. there is not 1 thing in the bible that has any relation to fact, history or truth. Just being on this site should prove that. Man is over 2,000,000 years old, the earth is 4.5 billion years old, not 6,000.

        B wrote on December 27th, 2011
        • B- just curious, where does the Bible say the earth is flat?
          While I agree with you on most points concerning the Bible, there is a ton of health information contained in the Pentateuch that still holds true today. In fact, some good stuff echoed in the Primal Blueprint.

          Mike Phelps wrote on December 27th, 2011
        • Sup B?

          Actually it refers to the earth as a sphere. Isaiah 40:21-22—“the sphere (חוג—chuwg) of the earth”. Job 26:10 refers to the waters of the Earth as “compassed”. The only way one could think the Bible says it is flat is if one doesn’t get the phrase “four corners of the Earth”, a reference to the directions of a compass & a naval phrase often used independently of scriptures.

          As far as your suggestion that you know how old the Earth is, try this the following. Work out the number of evolutionary steps and generations to make a human, then the number of seconds in 4.5bil years, then calculate the average number of generations we should have observed every second so far. It is astronomical. You’ll need to be good at using powers of ten. You’ll soon see that even 4.5billion years for human life is a more preposterous proposition than the alternative view. You might have to add a few more zeros to the age of the Earth or, at least, the age of life life to make your bellicosely religious view work.

          I’m a former evolution believer and one of the things I love about Mark’s site and book is it does not set out to prove evolution (Mark just uses his perogative to take it as a given). He then merely uses the theory as a launching pad to develop his hypothesis. The areas of science that seriously validate the concepts herein are the likes of biochemistry and neuroscience. I’m sure this comment comes much to the ire of many, but there are plenty of people in the AH community that hold an evolutionary view yet disagree with the notion that the primal approach can be justified with evolution.

          But hey, judging by the gross generalizations in your comment you just sound angry. Maybe a respectful discussion is too late?

          Btw Mark, love what you do, keep it up.

          Tim wrote on January 19th, 2012
    • The tomato was imported to italy in 1550’s.
      The grains were also imported, it was a trade good.
      Olives also are not italian.

      The italians true, primal food was seafoods. The pizza is a made-up modern food. Most people think mediterranian means italian and so they load up on rancid olive oil, nightshades and grains…don’t fall for it.

      Inge wrote on January 19th, 2012
  2. Steve,
    I agree with you about the 120 years. In the early Bible days people did not have pollution or pesticides or trans fats or processed foods or mortgage payments for that matter. They could have easily lived to 120 if they didn’t get killed by each other. Today, most people living past 100 live in remote regions although there are a few in the U.S. but they are the exceptions.

    Edie Zaprir wrote on November 5th, 2010
    • In Bible days there was agriculture and grains. and people killed each other in massive numbers fighting over whose god was the right god. And the bibles mean nothing in terms of fact and truth.

      B wrote on December 27th, 2011
      • Religion came AFTER the grains. With grains came population, with population came dissease, with disease came the question who or what is doing this?
        With that we went looking for answers (witches, devils) and with it all the perfect “book to rule them all with fear” was born: the bible.

        Written, rewritten, translated, written, rewritten and retranslated…and read to someone who can’t write to tell someone who could write then rewritten and retranslated, edited, written again and reedited…
        you get todays bible.

        Inge wrote on January 19th, 2012
        • You are both guilty of misreading. Edie was referring to a period in time. To be taken more seriously cut the emotional bigotry. You sound like religious zealots.

          Tim wrote on January 19th, 2012
  3. Is Grok Cro-Magnon and proto-European?

    Jon wrote on November 9th, 2010
  4. Any statistics yet on longevity of people today, who have practiced the paleo way?

    john wrote on November 10th, 2010
  5. I like the helpful information you provide in your LED WRITING BOARDS articles. I will bookmark your blog and check again here frequently. I am quite certain I will learn lots of new stuff right here! Good luck for the next!

    Sydney Boughamer wrote on June 18th, 2011
  6. As someone said above, nothing!

    jocuri wrote on November 8th, 2011
  7. At the age of 75 my Dad had a bone density of “more than that of a 30 year old”, it was off the charts. Was in Military his whole life, stayed in shape and never touched milk. So when he dies and they dig him back up they will think he was a 30 year old.

    Denny wrote on October 30th, 2015

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