A posteriori, there may be 'evolutionary'-type reasons for say, our body's over-eagerness to eat sugary stuff [4]. That doesn't mean that you can attribute everything to evolution without sufficient evidence.

The truth is what it is: lack of exercise and poor diet both contribute to increased risk of diseases. You can appeal to 'our ancestors' lifestyle' as reliably as you can appeal to say, the benefits of 'biblical diet'. Both are identically fallacious.

(As an aside, there are several comments on different posts in HN that wrongly apply evolutionary principles to everything from coding practices to behavioral traits [5]!)

[1] http://www.scientificamerican.com/article/why-paleo-diet-hal...

[2] http://well.blogs.nytimes.com/2013/06/05/is-barefoot-style-r... [3]http://www.theguardian.com/books/2013/jan/09/history-society [4]http://www.nytimes.com/2012/06/06/opinion/evolutions-sweet-t... [5]https://news.ycombinator.com/item?id=7050286

As an aside, pre-seasoned processed food can give us a false sense of variety because even though most packaged foods have corn syrup or wheat or corn or one of those popular foods, by adding different spices or making different 'foods' out of it such as pizzas or other recipe transformations, it makes the same basic ingredients taste and seem different. But if you focus on eating whole foods with somewhat minimal processing or transformation into recipes, you can readily realize how much true variety you're obtaining.

Arguably, indeed. Before the invention of refrigeration, the average "state of freshness" probably was a lot less than what we now call fresh. Also, "quality sources" will have been rare in the not so uncommon years with harsh winters, failed harvests, etc.

As for barefoot running, the barefoot shoes are seen as a magic bullet, and of course that's not the case. They can be a guide to suggest that you fix your gait but if you don't want to do the work, you can harm yourself as much in Vibram Five Fingers as in Nikes or Adidas.

Paleo-izing everything is in fashion. That doesn't mean it's all wrong though.

[1] http://philosophyandpsychology.wordpress.com/2013/03/01/defe... [2] http://www.marksdailyapple.com/is-it-all-just-a-paleofantasy...

Well, sure, if you're claiming it's some sort of lemma in a proof. Stuff our ancestors used to do is likely to be neutral or good for you, due to the way evolution works. The key is likely. I'd agree with you that it's a fallacy to hold "ancestors used to do it" as some kind of oracle.

You can appeal to 'our ancestors' lifestyle' as reliably as you can appeal to say, the benefits of 'biblical diet'. Both are identically fallacious.

There should be a name for the meta-fallacy of treating what should be a hazy rule of thumb as a mathematical identity.

That's not true when it comes to age related diseases like cancer or heart disease. Through most of mankind's evolution these diseases did not affect our procreation rate at all.

Evolution optimizes for procreation not for longevity. It is very likely that an ample supply of burgers, fries and fat cheese (especially during winter) would have led to higher birth rates not lower ones.

It could well be that much of our ancestors' lifestyle is poison for anyone over 50.

Incorrect. Evolution optimises for propagation of genes. Procreation is one but not the element of that process.

Think about this way: if you are living by yourself in the forest and have octuplets, then you are very good at procreation; if you die immediately afterwards, then you are evolutionarily unfit despite your procreative abilities, because none of your young will survive to pass on their genes. For creatures like humans -- born with helpless young -- the person who has two children and lives long enough to ensure that they can pass on their own genes is more evolutionarily fit than the person who procreates like mad but lets all their children die.

In our evolutionary environment, post-procreative individuals played vital roles in ensuring the survival of the young: taking care of children while their parents were off hunting and gathering; preparing foodstuffs; passing on lore about which plants were dangerous to eat, etc. In this way, the presence of elders facilitated the propagation of genes -- right up to the point where the care and maintenance of said elders becomes such a drain on resources that it begins to diminish rather than enhance the survival and procreation prospects for the young. That's quite a long time, however, so generally speaking, genetic lines that produce long-lived healthy individuals who enhance the survival prospects of the young will be more successful than genetic lines which don't.

Older men can have children in principle, but older women can not. So those men would have to compete with younger men for the remaining fertile women. The birth rate of a woman would probably not change just because there are more old men available to her.

I don't think I was disagreeing with you, there. My point was that regardless of how much benefit an ancestor can give to their descendants, if you have declining fertility beyond some age the benefits of doing so attenuate with time.

The reason is simple: hunting and gathering is extraordinarily difficult when you've got a baby on your knee. If you reproduce at 20 and now you have to take care of a baby, then the people who are in peak hunting-and-gathering condition are suddenly unable to find food. Solution: leave the baby with the 40-year-old grandparents, and go off to hunt/gather.

Problem is, a lot of 40-year-olds are still in pretty good hunting-and-gathering condition, and won't be maximising the group's survival by sitting on their duffs doing baby-guarding duty. The solution: leave the baby with the 60-year-old great-grandparents, and go off to hunt/gather.

This isn't conjectural: this is how traditional societies actually work.

Now, the 60-year-olds definitely aren't in particularly great hunting/gathering condition, so taking care of children is a good way they can contribute to group survival. The children can grow up and become self-sufficient under their tutelage. There's little evolutionary need another generation beyond them, so you'd expect mortality to increase rapidly after 60. Which of course is exactly what we see.

That's exactly my point. Hunter-gatherer diet didn't need to work very well against cancer, heart disease or Alzheimer's and hence we shouldn't expect it to promote what we consider longevity today.

But I think you're overestimating the value of grandparents for breast feeding toddlers. Population growth wasn't very rapid back then because most kids died at birth or very soon after. So there weren't actually that many kids around I think.

Yes, in principle, and that is definitely a good point. But with hindsight we can observe that the part of the "design space" that includes 90 year olds was never before explored, and hence evolution tells us nothing about whether or not hunter-gatherer diets are good for longevity.

I didn't mean "ignoring social factors" - I meant "in theoretical human-design-space". Women don't produce new ova, but why does that necessarily have to be the case? Most cells in the body divide regularly.

Well of course! Whether it's "good" or "bad" is kinda hazy and contextual as well. A gene that might encourage heart disease at age 50 might also make us better at spearing ferocious animals at age 19.

It is very likely that an ample supply of burgers, fries and fat cheese (especially during winter) would have led to higher birth rates not lower ones.

I know of someone from the pacific island of Yap, and his entire generation was stunted in their growth from his culture's encounter with American junk food.

It could well be that much of our ancestors' lifestyle is poison for anyone over 50.

So then it's fine for young hipsters to practice?

That seems very hard to believe. Americans are rather tall on average.

http://books.google.com/books?id=p3liL6fAjrcC&pg=PA83&lpg=PA...

I suspect you are protecting some cherished preconceived notions.

American diet is not exactly a cherished notion of mine either. Neither is it my diet of choice nor am I American.

This long term under nourishment is very common. The WFP (world food program) gives estimates of 227 million for Africa and 553 million people in Asia and Pacific.

What happened when local diets were disrupted? Were local foods bought in return for much lower quality food? Was malnutrition made worse? Or did we just start documenting it better?

- I don't know, Bog. My parents have always eaten meat raw, and they lived healthily to the old, ripe age of 26.

http://www.smbc-comics.com/?id=2713

For me, a big one is dancing. Nothing formal, just going to a club or hanging out at freinds' places and having a dance party. It's fun for me (which is the point) - I don't think of it as exercise normally, just some socializing. Doing that once or twice a week regularly had a noticeable impact on my overall level of happiness and my diet plan. If I don't get to do it, I miss it and feel overly energetic, like too much coffee. (You know the "i didn't get enough exercise feeling).

Another is playing with dogs and kids. I am responsible for neither, but have friends with one or both, so I get lots of access. It's a fun time, just being silly and bonding with people I think of as family. And as a benefit I get some exercise.

Finally, as spodek mentions above - working in some manual versions of daily tasks can help a heck of a lot. Example: I live in the midwest, so lately I've been shoveling a lot of snow the old fashioned way. Sure I could use a snowblower, but doing it with a shovel is better exercise. Besides, the days I need to do it I know the roads will be crappy and slow, the gym may not even be open, and generally getting exercise via normal channels may be hard, so spending 50% more time on snow removal pays off overall, since I'll have more time to do things anyway. Other times where the slow manual way of doing something to sneak in some exercise are abundant and should be considered with similar "TCO" style reasoning.

I think that we could probably all go for eating less meat and a lot more fruits and vegetables. The flesh of other animals tastes so good though!

Whenever I've been in shape I haven't stuck to any diet or strict regiment. It's pretty easy to loose weight (in principle, not in practice) if you do some moderate exercise (like take a run a few times a week, take the stairs, etc) and avoid restaurants and processed foods. I think when you start cooking for yourself, you'll end up eating a lot more raw "real" food and will find it hard to cook the really unhealthy stuff you might feel totally fine about ordering. It just kind of works itself out.

There are clearly diets that allow for more than survival. Just be careful saying we evolved to do X. It's easy to get your causal arrows mixed up.

Yeah, that doesn't work for me. If I'm not thinking about health, I'm happy loading up on the cheese and fried things to a probably unhealthy degree - especially when I'm making it myself.

I think the more likely answer is that humans are capable of surviving on all sorts of foods, not "there is one hunter gatherer diet and it contained very little meat."

The so-called "LOREN CORDAIN, PH.D., THE WORLD’S LEADING EXPERT ON PALEOLITHIC DIETS AND FOUNDER OF THE PALEO MOVEMENT" claims:

Decades of research by Dr. Loren Cordain and his scientific colleagues demonstrate that hunter-gatherers typically were free from the chronic illnesses and diseases that are epidemic in Western populations, including:

Obesity Cardiovascular disease (heart disease, stroke, high blood pressure, congestive heart failure, atherosclerosis) Type 2 diabetes Cancer Autoimmune diseases (multiple sclerosis, rheumatoid arthritis, Crohn’s disease, ulcerative colitis, etc.) Osteoporosis Acne Myopia (nearsightedness), macular degeneration, glaucoma Varicose veins, hemorrhoids, diverticulosis, gastric reflux Gout