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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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November 10, 2010

Why Did Grok Live So Long?

By Mark Sisson
39 Comments

While I think the idea of adult Paleolithic hunter-gatherers regularly dying at age 30 can be laid to rest (sadly, I reckon that particular misconception has an impressive life expectancy), last week’s post on the Gurven-Kaplan paper brings up another question: if the human potential lifespan of 68-78 years, or roughly seven decades, is an evolved, inherent, even genetic trait, what is the evolutionary justification for its selection? Where is the advantage?

The classic Darwinian view is that selection of traits revolves almost entirely around fertility. Once an animal can no longer produce offspring, it has no “reason” to go on living. Since a genes’ survivability ultimately comes down to reproduction, whether an individual can have kids is the primary determinant of viability.

This makes sense when you look at the life cycles of various organisms. Lesser animals reproduce en masse, like spiders with hundreds of eggs in a single go or salmon with 2,500 eggs per kilo of bodyweight – quantity over quality. There’s very little, if any, mothering occurring with these types of animals. It’s just winning through numbers. They don’t have the capacity for socializing or organized communal child rearing; they just pump out as many kids/eggs as they can and hope for the best. Spiders typically die after spawning, and for Pacific salmon, spawning is usually the last thing they ever do. Their purpose in life – as laid out in their DNA – has been fulfilled. Their genes has been propagated, and there is, in the grand scheme of things, no “reason” for the reproducer to continue living. Further up the spectrum, reproduction becomes more of an ordeal and a sacrifice. It’s a general rule that mammalian pregnancy takes a lot out of the mothers; they must bear the fetus(es) for weeks or months, take in extra calories to sustain its growth and development, and eventually have their sexual anatomy ripped asunder by the act of giving birth. Larger or more complex mammals require more resources, more sacrifice, and more time committed. Canine pregnancies run about two months, chimpanzee pregnancies last around 220/230 days, and elephant pregnancies last about 22 months. Puppies nurse for ten weeks or so, while human infants (pre-formula) nurse for two or three years.

Humans represent the pinnacle of mammalian complexity. If they are regularly living past reproductive age and consuming resources that could otherwise go to younger, fitter, more virile members of the group, there must be a reason for it. The original assertion – that an organism’s fitness depends on its contribution to its genes’ survival – holds true, but the complexity of the human animal requires an expansion of the original idea. These old folks must be contributing to the success of the gene through non-reproductive means.

The obvious answer is the “grandmother hypothesis” – the idea that post-menopausal women can provide their children and grandchildren with a better chance to breed, and thus further contributing to the survivability of their own genes. Unable to reproduce themselves grandmothers care for little ones while the immediate parents are out gathering or hunting (or working a job in modern terms). Once that last batch of kids has reached young adulthood, at around age 15 when they can begin fending for themselves, the grandparents are no longer “needed.” The young adults are ready to start producing for the community and having their own kids, thus ushering in the new wave of grandparents (the young adults’ parents). The first set of grandparents, now beginning to hit age 70, can pass away without negatively affecting the genes’ survival. They’ve done their part and contributed to the survivability. There’s no longer a need for even more longevity. It all sounds pretty morbid, but that’s how this stuff is hypothesized to work. There’s also something called the “mother hypothesis,” which is similar to the grandmother hypothesis, except it explains human longevity by positing that if mothers have their last child by age 45 or so, they’re stuck raising the child until age 60 or 70. Both are valid and viable ideas, and I think both can coexist.

But what about grandfathers? A long-standing criticism of the mother and grandmother hypotheses is that no explanation is given for the longevity of the elderly male. What can Gramps contribute to society, and why does he live past the viability of his sperm?

Kaplan, Lancaster and Robson propose the “embodied capital” model of human longevity to encompass both sexes. Simply put, it suggests that male and female human longevity is necessary because of the slow, long development of human children. We aren’t like most mammals, who tend to spring forth from the womb with the ability to walk (or swim) and avoid embarrassing themselves; our infants are immobile fleshy bundles. Our children need guidance and instruction from our elders. They need support – the community needs material support, since the children consume resources without providing any. And both grandma and grandpa are involved in the teaching process. The emphasis here is on passing on knowledge and wisdom. They’re not just chasing little ones around.

We can’t survive on instinct alone. Our physical gifts aren’t sufficient. And we don’t pop out of the womb with knowledge and wisdom pre-installed. We come out with empty heads full of potential. We have to learn, or, more accurately, we have to be taught. And who teaches us? Experience is a stern, proven tutor, but exogenous instruction from experienced adults, parents, and grandparents – from society, really – is even more crucial. We need adults to live past reproductive age because human children are unproductive members of society for at least the first 12-15 years of their lives. They are either totally helpless babies (unable to walk, talk, and procure food), extremely annoying toddlers (now able to walk, babble, and get into trouble), or haughty mischief-making pre-teens. And all the while, they are students. They’re learning, watching, observing, and filling their big empty brains with the knowledge and experience that will help them be productive, resourceful adults. But they couldn’t do that if all the adults were dying off by age thirty.

While kids learn, work must be done. The animals must be hunted, the food must be gathered, the crops (if they’re horticulturalists) must be tended. The daily chores for a hunter-gatherer community require physical strength and know-how. Hunting requires endurance, precision, and fearlessness, which kids have little of. Gathering means carrying heavy loads, digging, climbing, and walking long distances. Kids undoubtedly accompany adults on outings (to learn, remember), but they cannot be expected to provide for the group. Adults aren’t just teachers, then. They’re also material producers. They hunt, fish, gather, build, carry, defend, and explore – all the nuts and bolts stuff that makes a society go.

Humans are animals, true, but a special kind of animal, one that has expanded the standard definition of evolutionary fitness. And no, I’m not trying to imbue our species with some sort of cosmic or spiritual significance; we create our own significance, our own meaning, by virtue of our massive brains. That’s the point. Our brains provide our consciousness, and, for all intents and purposes, set us apart from even our closest, brainiest cousins in the animal kingdom. Our tendency toward higher thought also allows us to exert mastery over nature. We plan. We study. We learn. We can develop the ability to spear a moving target – an ability that relies on our mastery of the physical and the mental realms. Hand eye coordination, spatial visualization. Memorization of the properties of thousands of wild plants – which are poisonous, nutritious, medicinal? Instinct and the subconscious save our rear ends in times of acute trouble, but our careful, measured intelligence and rationality puts us at the top of the food chain. We couldn’t take advantage of our brains without the security and dependability of having older humans around to teach us, train us, and support us. The kids may be the future, but adults set the path.

To summarize:

  1. In most hunter-gatherer/traditional groups, human lifespan extends past fertility. This indicates that elders contribute to the success of the group.
  2. Grandparents act as caregivers for children and grandchildren. Once the last set of grandchildren reaches maturity, older adult mortality rises, indicating that the grandparents’ “job has been done.”
  3. For the first fifteen years of their lives, children are information sponges. They’re learning how to be productive adults from productive adults, and they are physically immature and unable to keep up with heavy labor; until the children’s “formal” instruction ends and they become productive members themselves, the adults must provide material support for the group.
  4. Adults, especially older adults, act as knowledge reserves. The kids have to learn from someone, and elders are a powerful source of information. This role benefits the group by enabling the transformation of children into productive members of society.
  5. “Respect your elders” isn’t just a line thrown out by cantankerous grandfathers; it’s embedded in our hunter-gatherer past, and it might be the key to our species’ unparalleled success.

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35 Comments on "Why Did Grok Live So Long?"

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Uncephalized
Uncephalized
6 years 25 days ago
It all makes sense when you remember that the genes will code for any trait that will increase the propagation of those same genes. It makes sense that both old men and old women have valuable contributions to make to their own descendants’ survival, especially in traditional societies where their skilled knowledge is not obsoleted like it is in modern technological societies. Also, the fact that men live roughly as long as women could easily be explained by the fact that men remain fertile into old age; perhaps women live a long time to take care of grandchildren, while men… Read more »
Ruth
Ruth
6 years 25 days ago

One more major loss to CW. Grandparents now are just ‘old, messy people we don’t want to deal with’ and get locked away in nursing homes. It would be so great if we could bring back the multi generational household. Doesn’t even mean you have to share the SAME house but it sure would be nice if kids, parents and grandparents all lived very close together and shared more parts of DAILY life.

PrimalStyle-Real.Yummy.Food
6 years 25 days ago

Awesome articles as always! I usually can’t read them all the way through but I scan over and get what I need.
TY

winthorp
winthorp
6 years 25 days ago

read Jared Diamond’s “Why is Sex Fun” to gain a more thorough understanding of the relationship between human lifespan / sexuality / evolution.

shannon
shannon
6 years 25 days ago
This explains a lot, a lot of what’s wrong with industrial capitalist life: kids aren’t with their parents or grandparents; they’re locked up in schools, away from the real world, learning very little. Grandparents typically don’t live near their grandchildren. When kids become adults at 18, they suddenly have to figure out how to work and take care of themselves, something they’ve been protected from for 18 years. I teach college students, and I can’t figure out what they spent the last 12 years doing. Most of our students can barely read and write, and they don’t have any “real… Read more »
debbie_downer
debbie_downer
6 years 25 days ago

Getting pretty geeky around here lately, death, feces, intestinal bugs..

Love the recipe ebook to balance things out.

How about a post with primal insight on the twinkie diet Mark?

Paul C
Paul C
6 years 25 days ago

No post needed, as it is simply a starvation diet.

If that cruise ship would have been stranded a bit longer, we’d be hearing about the Spam & canned crab diet.

Kelda
6 years 25 days ago

Mmm, and I think we are now devolving because we have blocks of population who are unemployed, demotivated, incapable of critical independent thought; their children are not in a rich environment to learn life skills, they just learn to be dependent, demotivated unemployed people and grandparents are nowhere in sight.

Society seems to be in a complete mess.

How will that impact on ‘natural selection’? Have we completely neutralised the very mechanism that brought us this far?

debbie_downer
debbie_downer
6 years 25 days ago

Being blog fed too much re-meta analysis of yet someone elses work will do that to people.

Pat
6 years 25 days ago

Thanks for the post Mark. This is something I’ve always wondered about and your explanation makes a lot of sense. I really enjoy the geeky, evolutionary explanations/musings. For anybody out there that hasn’t read The Naked Ape Trilogy by Desmond Morris, I highly recommend it. He was thinking this way back in the 60’s.

Dawn
6 years 25 days ago

I love how this concept gives real value to grandparents and older people. We live in a society that worships the young. I it is nice to know that the older person has an valuable role to play.

Julie Aguiar
Julie Aguiar
6 years 25 days ago
I truly believe that multi-generational living is something meaningful that we are missing out on these days. Don’t get me wrong, I was raised to be independent early on, and the LAST thing I would want is to live with my parents..*shudder* but, it wasn’t too long ago that families stayed together…the old ones cared for and taught the little ones, the middle ones cared for the elders, wisdom was passed on…I do think this was most beneficial to the species…and now look at the Long Term Care Nursing Home Debacle, newborns in daycare, kids don’t know their family’s history..nevermind… Read more »
Tamin
Tamin
6 years 25 days ago
Great article and comments. i liked what Dawn and Shannon said. I try to teach my kids to respect their elders and they know better than to ‘dis’ old people because they get an earful from me. We spend some time with the older members of our family and we use to spend alot of time with elderly people before we changed countries and I found them a good source of information and inspiration and I try to pass the stories on to my kids because we don’t always have our old people around. I do have to laugh though… Read more »
Tamin
Tamin
6 years 25 days ago

Sorry went off subject a bit with my last comment but just a thought I had. Would it be right in saying that maybe once grandchildren arrive grandparents now have a new ‘reason for living’. From what I’ve seen the older generation seem to have a sense of unselfish sacrifice sadly I don’t think its genetic.

Paul C
Paul C
6 years 25 days ago

My dad taught my kids to lick their plates clean, literally. I suppose that gave them a tiny extra boost of nutrition.

Tamin
Tamin
6 years 24 days ago

LOL!! thats funny! my mum let us lick our plates when we were kids (still do sometimes when we eat at their house!)and that was because she was NEVER allowed to when she was a kid. My husband still can’t get over it even after 15 years of hanging out with us.

Leanne
Leanne
6 years 25 days ago
I completely agree that children brought up with grandparents and extended family helping to care for them as opposed to daycare with multiple children and high turn over of staff have a much richer environment, more one on one learning, stronger values and a host of other benefits. Not to mention it leaves the parents financially better off as daycare is expensive, which I am sure would mean less working hours for the parents and less stress in general. That said, Mark mentioned that most animals that have huge numbers of off spring, like salmon and spiders and what have… Read more »
Bob
Bob
6 years 24 days ago

Beautifully written. A great reminder that our seniors are a valuable treasure, not disposable has-beens. Thank you.

marketing funnel
6 years 24 days ago

Very interesting post, lots of good information. Thanks

Milly
Milly
6 years 24 days ago

It’s really only in our society that kids are unproductive. 200 years ago- or now, in third-world countries- children are definitely productive. They do farm work, take care of the younger children, cook, clean, at a remarkably young age.

Tamin
Tamin
6 years 24 days ago
Oh yeah but in the ‘modern western world’ its almost classed as child abuse if you make your kids clean their rooms or actually do some manual labour for free! My kids have been taught how to do all those kinds of domestic chores but the older they get the more I have to ‘get on their case'(patiently) to do their part but they are actually very good at it once they get going!Its a shame when you see teenage kids who don’t know how to cook or do any basic cleaning these are the skills that will help them… Read more »
moebius
moebius
6 years 24 days ago
One quality, more than any other, defines human beings as an elite survivor – the ability to create, replicate, and disseminate sophisticated memes. Tracking game, building tools, traps, and shelter, preserving food, navigating terrains, forecasting weather, identifying edible plants or healing herbs, all examples off the top of my head. Simply being old in paleolithica implies that you are an expert survivor. Even without the ability to pass on genes, tribal elders still possess the most valuable memes through accumulated knowledge and endless practice. These memes vastly improve a tribe’s chance for survival, and in turn translating into an evolutionary… Read more »
Paul C
6 years 24 days ago

Technology has really screwed up this process of passing down information. Many grandkids have taught grandparents how to respond to a blog post using a smartphone.

Spence
Spence
6 years 24 days ago

Our steroetype of “grandparents” is furthered the same way CW has furthered our “health”. Paleo Grandparents were probably more robust than our middle aged people today,which isn’t saying much.

C2H5OH
C2H5OH
6 years 24 days ago

Guess there are a lot of “grass is greener” posts here. If my grandparents were full of wisdom, I would visit them more often 😉 But since their offspring so often seem to be grown-up kids with salary, I don’t want THAT kind od wisdom for myself. And I guess many, many more people don’t have respect for their parents and grandparents, because respect has to be earned ^^ And I see that everywhere

Michael
6 years 24 days ago

This is something I have spent a lot of time thinking about as I am an academic sociologist.

My guess is that it comes down to culture (which is what you more or less said). Humans don’t evolve as individuals, they evolve as social groups. Our physical gifts are kind of pathetic compared to the other animals. So we get by on our shared survival knowledge – our culture. As such, the oldsters carry a lifetime of knowledge around that helps us overcome with culture evolutionary problems that would stump us individually and physically.

kem
kem
6 years 24 days ago

Nice post, but “unparalleled success”? You can’t really go past ants for that.

Phyllis
Phyllis
6 years 24 days ago
I thik all this information is helpfull in understanding the primal pholosophy. I am disappointed however that you are contributing to the maintenance of the myth that learning is about filling an empty vessel (the brain). Learning is a social process in which ‘learners’ take, make and give meaning to the world around them. This is why each of us will TAKE only part of what we read in this blog, Make meaning with it as we process it along with passed knowledge — yes, even a child born an hour ago has previous knowledge, the brain is involved in… Read more »
localad
localad
6 years 24 days ago

Grok’s Grandparents were his Google!

Jeff
6 years 23 days ago

I read somewhere that the inuits put their old folks on a piece of ice to be floated off into the ocean.

Paul
Paul
6 years 23 days ago

Grandaddy Grok’s fertility into old age could have influenced the longevity of both his male and female progeny. He would have been passing on good old age genes to both genders.

Lockie
Lockie
6 years 20 days ago

So it’s geneticaly programmed in our DNA that if where old and our grandchildren and children dont need us anymore we will drop dead?

Lockie
Lockie
6 years 20 days ago

What if you have other reasons to live beside children/grand children?

Cpap Mask
6 years 16 days ago

You have a beautiful and interesting blog. your post is very nice,

Milla
5 years 21 days ago

“cantankerous grandfathers”
lol, Mark, where do you store all these awesome words? Must be those crosswords you do with your morning coffee!!!

Great post, I’m happy you put it in the time capsule! 🙂 I think humans just evolved to be a cut above other species, so much we are radically different from other animals; philosophy debates on “I think/am therefore I am/think” nonwithstanding, we are being of reason, not just driven by carnal instinct (though occasional hedonism is very Primal. *hand reaches into bag to retrieve slab of dark chocolate*)

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