I agree that human beings haven't really had to bother evolving to be able to cope with lots of glucose (simple or complex) because as Nancy L.C and others pointed out, everyone worked so hard, they didn't really have to. Everyone except the really priviledged were probably hungry most of the time anyway, but so busy that they just learnt to ignore the hunger. The issue of wether punctuated equilibrium processes of 'accelerated' genetic change COULD have produced a more insulin capable version of homo sapiens than we are today, is sort of beside the point. It probably could have , and more than likely would have if back when agriculture first started we were all couch potatoes. But if you didn't work physically hard (particularly before the advent of the internal combustion engine), you and your growing family didn't eat)
Which begs the question of why we don't just enjoy the high complex carb food pyramid as the man says, and not take the lift and the last two bus stops to work. Well, and I think this is why low carb will always be a difficult sell for the majority, most people can do just that and have excellent quality of life with health 'problems' that are generally regarded as par for the course (occasional colds, moderate tooth decay, moderate bone density loss with age, moderate erectile dysfunction(boys ) with age, cancer or alzheimers/parkinsons disease/MS in your 70's or 80's if you are 'lucky' and in your sixties if you are 'unlucky' mild blood sugar problems but miles away from type two diabetes.... This is regarded as normal, and the pharmaceutical giants who medicate this slow insulin degenerative march to a perfectly acceptable and admirable grave want you to believe just that.
There's an ongoing thread about health improvements people have enjoyed from low carbing on this board somewhere. I glanced at it the other day and noticed somebody celebrating that they'd stopped needing expensive regular and lifelong medication for a common affliction since he had started low carbing 5 years ago. One tiny example of a tide of success stories that demonstrate so powerfully for me that selective pressure for high carb tolerance in the human species was not very high on the evolutionary agenda, even when agriculture made them so readily available.

Before the advent of agriculture, long term selective pressure had come up with an excellent mechanism for metabolic energy needs which suited a highly active lifestyle too, but also doesn't have the hunger/degenerative complications of insulin, wether you are highy active or not. It's called lipolysis. In my experience it's a much more user friendly system.
Fascinating thread!

The Eades point out that Egyptian mummies, probably the best source of ancient pathological data, exhibit exactly the same proportion of the four major metabolic disorders as contemporary people. And their diet was very close to that recommended by the AHA, mostly whole grains supplemented by lesser amounts of lean poultry and fish.

Perhaps a good example to look at for how long it takes to adapt to a radically different diet is the panda, which is essentially a bamboo-eating bear. How long did it take for the panda forebears to emerge as herbivores?

I read an article that documented how along with some of the oldest human remains that were ever discovered there were also scraped bones. If I remember correctly the Australopithecines were all primarily vegetarian, and the scraped bones started showing up at the same time as humans and our big brains started to evolve. Many scientists think it was meat eating that permitted our brains to develop, so I wonder if further development could stop or if we could actually regress if we started denying ourselves these nutrients over a long period of time. Any paleontologists around to tackle this one?

As a non-expert I was pondering on an early part of this thread concerning the amount of time it takes to adapt to a high-carb or cereal diet.
Clearly adaptation in humans can be very fast. An example (if the hypothesis is correct) would be the way in which North Europeans have a high tolerance for alcohol compared to Asiatics who tend to get drunk and ill pretty quickly. Supposedly this is an adaptation to using early brewing as a primary source of water sterilisation.
However, I think it is worth remembering just how late high levels of grain use may be for many of our ancestors.
Agriculture was a fairly late arrival in Britain. Maybe about 8 thousand years ago. This is a good link for a timeline - http://www.colbyweb.co.uk/cornwall/...es/tenthou.html

However, a lot of newish research indicates that, in Britain, almost none of this grain produce was used directly as food by humans. Instead it supported the primary activity of cattle raising. Indications are that grain use as a major diet component didn't come about until the late Iron Age, maybe a century before the Roman invasion! That's a VERY short period to make multiple morphological and metabolic adaptations in.

No wonder lc works for me, then. Among my mixed ancestry from the british isles (Scotch and Irish) is a strong dose of genetic material from American aborigines, which only started consuming high levels of carbs in the past 500 years or less, most of them much less than that.

I am a professional geneticists, so let me have a try.

Occasionally evolution can be fast - as with the moths in England where the white ones are being eaten when the trees became black, and when the factories got cleaner, the black ones were eaten and now they are all white again - in 100 years.

The difference in human evolution is that in recent years there is little selection -we don't have the mortality. And since 1900, as said before, the highly refined carbs came up, and its only about 50 years that we have such an inactive life style. And the other point that was also being made: evolutionarily, it is fine if we die of cardiovascular problems at age 50 or so - we have raised our kids, and that is all evolution cares about.

But there are instances currently where evolution is taking place - just not here. In Africa is a massive selection for anyone with AIDS resistance genes going on that will surely show up soon. People in Tibet were just shown to have genetic variants that let them survive better at high altitiude.

The issue is not how many years did it take for the moths to adapt; the question is how many generations. What takes moths a hundred years could take humans 100,000 years. But it's really an academic question because the evidence is in that we haven't adapted to a grain based diet. For 700,000 years, the genus homo thrived on a protein-based low carbohydrate diet. 10,000 years of so-called civilization is not enough to change our metabolism. There is no pocket of human habitation which has developed resistance to metabolic syndrome. We're not likely to develop multi-chambered stomachs like cows and sheep, unless we also start walking on all fours and grow horns and hooves.

Fascinating thread as Fatburner said...
Made my day (night actually)!

Mitch

As a professional human evolutionary scientist-let me say that 99% of the above is correct. Although genetic adaptation doesn't have to take 100,000's of years, there does have to be selection. We primarily culturally adapt instead of biologically adapt now.

The only issue I have with the above post and it might be just my misreading is that there is evolution occuring today with us-not just in third world areas.

Genetic drift can be rapid, but this is usually associated with some stochastic event - like if due to rapid climate change (a la "Day After Tomorrow") all there was to eat was rice and beans for a long time, a lot of people (like me) might well bloat-up and die before they could reproduce much. But of course there would be other selection pressures involved in such an event that might compensate, who knows.

But sometimes I wonder if the rising incidence of juvenile obesity and diabetes is just a slow sort of selection... these poor kids appear to all have the genetic tendency towards IR, and they are at risk of being weeded out of the gene pool fairly early nowadays. It will be awful if the trend continues.

You may say that grains make us fat, but you can't say that this is because our bodies have not adapted to grains.

Fat is an energy reserve which our bodies generate when food is available and consume when food is scarce.

Grains are seasonal food. When your body sees that you are depending on grains for food, it expects that you will be running out of food in a few months when the grain season is over. So it makes body fat for you to fix the problem.

The other thing that I think you have to consider when you speak of the rapid changed in a human's appearance in the last 100,000 years is that as better tools were developed, and societies became increasingly more organized, and food was easier to gather, just having more nutrients, or even enough nutrients on a more regular basis could have has an extreme impact on the way humanity apeared, in terms of making us taller, more thickly muscled, etc. just by giving our existing genetic programming more raw materials to work with.

Now, that change might have, in turn, effected who got to breed, who got to be in charge, etc. etc. which would, in turn, effect our genetics.

I guess what I'm saying is that I don't think it would be necessary to alter the genes themselves to see a significant change in the appearance of humans. So I don't necessarily think that we are way off on our ideas of not having adapted to eating a carbohydrate rich diet.

Also, while animals do adapt and change relatively quickly, that often is a response, in my understanding, to a radical change in their environment. Such as a bird who's food source changes entirely and within a few generations, those traits best adapted to eat from that source now dominate.

If humanity was suddenly faced with the prospect of eating nothing but carbohydrates, then I would espect that we would see much of the same thing happen to us. Within several generations those of us who were best adapated to eating all carbs would be, genetically, more successful than others who were not. Most likely, those ill-suited would sicken, die, and not reproduce.

Because agriculture has always included animals as well as plants, and high-carb foods have been incorporated into our diets rather slowly, until very recently, it's likely that we haven't adapted, for the simple reason that we haven't needed to. There has always been a mix of dietary nutrient sources available. This sort of falls in line with the idea stated above of a two-stage dietary change.

That's just out of my arse, but what do I know?

Yup-it is called Secular Trends. Short term plastic changes due to environment. Could be be positive (like getting taller, longer life spans...) or negative (increase in obestity, increase in diabetes...)

This is very interesting, thanks ya'll.

Humans are no longer evolving