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Beyond Ötzi: European Evolutionary History Together With Its Relevance To Diet. Purpose Iii

In previous posts, I reviewed some of the evidence suggesting that human evolution has accelerated chop-chop since the evolution of agriculture (and to some degree, before it).  Europeans (and other lineages amongst a long history of agriculture)  send known genetic adaptations to the Neolithic diet, together with at that topographic point are in all likelihood many adaptations that receive got non yet been identified.  In my terminal post service inwards this series, I'll fence that although we've adapted, the adaptation is in all likelihood non complete, together with we're left inwards a sort of genetic limbo betwixt the Paleolithic together with Neolithic state. 

Recent Genetic Adaptations are Often Crude

It may at outset seem strange, but many genes responsible for mutual genetic disorders demo evidence of positive selection.  In other words, the genes that displace these disorders were favored yesteryear evolution at some betoken because they presumably provided a survival advantage.  For example, the sickle jail cellphone anemia factor protects against malaria, but if y'all inherit 2 copies of it, y'all goal upwards amongst a serious together with life-threatening disorder (1).  The cystic fibrosis factor may receive got been selected to protect against i or to a greater extent than infectious diseases, but in i lawsuit again if y'all acquire 2 copies of it, character of life together with lifespan are greatly curtailed (2, 3).  Familial Mediterranean fever is a rattling mutual disorder inwards Mediterranean populations, involving painful inflammatory attacks of the digestive tract, together with sometimes a deadly status called amyloidosis.  It shows evidence of positive choice together with in all likelihood protected against intestinal illness due to the heightened inflammatory state it confers to the digestive tract (4, 5).  Celiac disease, a severe autoimmune reaction to gluten establish inwards some grains, may move a by-product of choice for protection against bacterial infection (6).  Phenylketonuria also shows evidence of positive choice (7), together with the listing goes on.  It's clear that a lot of our recent evolution was inwards reply to novel illness pressures, probable from increased population density, sendentism, together with contact amongst domestic animals.

Why are modern human populations riddled amongst these mutual deleterious mutations?  Presumably, these are "genetic shrapnel" that final result from rapid changes inwards the human environment, creating selective pressures that placed rigid novel demands on the genome.  The modern shape of malaria is only a few K years old, corresponding roughly to the evolution of agriculture inwards Africa together with the high population densities that resulted (8).  As shortly equally malaria evolved into its modern deadly form, at that topographic point was a massive selective pressure level to evolve resistance.  Resistance would move favored at almost whatsoever cost, fifty-fifty if it meant that a per centum of offspring would air current upwards amongst a serious disorder together with in all likelihood non reproduce.  So humans evolved this unsmooth stopgap measure, which basically deforms the hemoglobin molecule together with makes crimson blood cells to a greater extent than hard to infect yesteryear malaria parasites.  It also deforms crimson blood cells into a "sickle" shape if y'all acquire 2 copies, resulting inwards illness symptoms.

Even the less deleterious mutations similar lactase persistence (allows digestion of the milk saccharide lactose) are crude.  The mutation that causes lactase persistence basically breaks the genetic "switch" that turns off lactase production after infancy.  In genetics equally inwards life, it's much easier to pause something than to laid it, so these kinds of mutations are the low-hanging fruit.

Presumably, amongst time, natural choice would figure out a improve means of doing the same thing-- a to a greater extent than sophisticated genetic stair out that could fill upwards inwards for the unsmooth stopgap, which would together with so fade away.  This is the telephone commutation regulation I'm trying to illustrate amongst these examples: the crudeness of recent adaptations suggests that we're silent inwards the early on stage of genetic adaptation to the Neolithic environment.  Much of the low-hanging fruit has been picked, but I suspect there's a lot of fruit inwards a higher house that would also acquire picked if nosotros had some other 1000000 years to evolve (assuming our surroundings remained stable, which it won't).  In other words, I suspect most of us reading this are partially, but non completely, adapted to the Neolithic diet.

Evidence that Adaptation to the Neolithic Diet is Incomplete

Previously, I cited celiac illness equally an representative of incomplete adaptation.  Affecting exactly nether i percent of United States citizens, it's a serious autoimmune disorder that's provoked yesteryear gluten from wheat together with other gluten grains.  This is a major populace wellness burden coming from a unmarried nutrient type.  On farther reflection, I remember this isn't a practiced representative of incomplete adaptation, because the factor that confers gluten sensitivity was nether recent positive selection.  In other words, the people who outset domesticated wheat in all likelihood weren't genetically susceptible to celiac disease, but they later on acquired it through a twist of genetic irony (9).  Some geneticists suspect the factor confers illness resistance that outweighs its detrimental effects.  Live together with learn.  Thanks to Melissa McEwen for pointing this out to me.  I remember she heard near it from John Hawks.

Still, I'm drawn to the evidence that early on agriculturalists showed signs of nutritional stress.  From Health together with the Rise of Civilization, yesteryear the anthropologist doc Mark Nathan Cohen:
H5N1 minute mutual tendency is that farmers seem to receive got been less well-nourished than the hunter-gatherers that preceded them, rarely the reverse.  For example, rates of porotic hyperostosis (suggestive of anemia) are almost universally higher amid farmers inwards a part than inwards before hunter-gatherers inwards the same region. [he goes on to propose that this tin final result from increased parasite charge inwards add-on to an iron-poor diet- SG].

Other independent measures of nutrition are less widely reported but most frequently seem to propose a reject inwards the character of nutrition associated amongst the adoption together with intensification of agriculture.
In the same book, doc Cohen comments on the improve nutritional state of modern-day hunter-gatherers relative to non-industrial agriculturalists amongst piteous access to creature foods together with depression diet diversity:
...levels of meat intake reported for most hunter-gatherer groups are comparable to intake yesteryear relatively affluent modern Western populations.  They are substantially improve than average Third World intake together with dramatically improve than that of the contemporary 3rd the world poor, who may average only a few grams of creature foods per mortal per day.

H5N1 broad gain of reports near contemporary hunter-gatherers inwards various parts of the the world suggests that they, similar the San, eat eclectic diets of fresh vegetable foods that, along amongst their meat intake, tend to assure a practiced remainder of vitamins together with minerals.  These observations near dietary remainder are largely confirmed yesteryear reports together with observations on hunter-gatherer nutritional health.

Most casual descriptions of hunter-gatherer groups inwards tropical or temperate latitudes comment on their apparent vitality together with the absence of obvious malnutrition...  Reports of needlelike malnutrition or kwashiorkor are extremely rare [kwashiorkor = poly peptide deficiency- SG].  These descriptions acquaint a striking contrast to descriptions together with evaluations of many Third World populations together with to descriptions of historic dietary character for the lower classes inwards Europe.
It's a swell volume if y'all haven't read it.  Anyway, the primary betoken is that hunter-gatherers, living the deep ancestral lifestyle, are mostly improve nourished than agriculturalists amongst diets restricted mostly to grains together with amongst piteous access to creature foods, together with this was peculiarly truthful of early on adopters of agriculture.  However, the nutritional status of agriculturalists improved over time, presumably because of the introduction of complementary foods (domestic animals, legumes, vegetables, etc.), grooming methods (e.g., fermentation), together with genetic adaptations.

If nosotros expect for it, at that topographic point is plenty of evidence to move establish that a grain-heavy diet is non optimal, especially inwards the context of depression creature foods.  Children are peculiarly sensitive, piece adults are fairly resistant to the negative effects of extreme diets.  For example, the macrobiotic diet is based exactly about whole grains, legumes, vegetables, together with some fruit, together with typically contains no creature foods.  It's non a 3rd the world diet-- it's a diverse, whole food-based diet that's composed amongst swell care.  It doesn't receive got much earthworks to disclose evidence of deficiency diseases inwards macrobiotic children, including rickets (10), vitamin B12 deficiency (11), together with assorted mineral deficiencies.  Here's a quote from a survey of macrobiotic children conducted inwards the Netherlands (12):
Ubiquitous deficiencies of energy, protein, vitamin B-12, vitamin D, calcium, together with riboflavin were detected inwards macrobiotic infants, leading to retarded growth, fatty together with musculus wasting, together with slower psychomotor development. Breast milk from macrobiotic mothers contained less vitamin B-12, calcium, together with magnesium.
There are a number of nutritional problems amongst grains, peculiarly whole grains, that emerge when they brand upwards equally good large a proportion of the diet.  One of the telephone commutation problems is that although whole grains comprise a sufficient quantity of many minerals, the availability of these minerals is frequently depression because they're fountain yesteryear phytic acid.  Much of it exactly ends upwards inwards the toilet.  This is why mothers on a macrobiotic diet, eating large amounts of magnesium-rich brownish rice, goal upwards amongst magnesium-deficient milk.

This explains why cultures that rely equally good heavily on whole grains (particularly unfermented) tin goal upwards amongst mineral deficiency symptoms despite a seemingly adequate provide of minerals inwards the diet.  One representative is rickets.  Normally associated amongst vitamin D deficiency, it tin also move caused yesteryear mineral deficiency, principally calcium, fifty-fifty when vitamin D status is good.  In Dublin inwards 1942, the incidence of rickets rose sharply, coinciding amongst a switch from refined wheat flour to whole wheat flour.  Investigators had this to say near it (13):
It hence appears likely, equally Jessop (1950) suggested, that the major alter inwards the
extraction charge per unit of measurement of the flour used equally a staple item of diet inwards Republic of Ireland was responsible for a marked simultaneous ascent inwards the incidence of rickets, independent of changes inwards vitamin D intake [or Sun exposure- SG]. This hypothesis is supported yesteryear the subsequent reject inwards the incidence of rickets inwards older children betwixt 1 together with 4 years equally the extraction charge per unit of measurement of flour was reduced. The observation that the incidence of rickets changed niggling inwards children nether 1 twelvemonth who consumed niggling or no breadstuff is consistent amongst this hypothesis...
The traditional Asian [they hateful Indian here- SG] diet contains much unleavened high-extraction cereal equally chapatty together with a variety of pulses. In Islamic Republic of Iran Amirhakimi (1973) together with Rheinhold (1971) establish rural rickets inwards children whose sunshine exposure appeared normal but whose diets contained large quantities of unleavened wholemeal breadstuff equally tanok. In rural Kashmir Wilson (1931) establish severe osteomalacia inwards acre workers who spent many hours a twenty-four hr catamenia outdoors but whose diets were exclusively vegetarian, consisting almost only of rice, lentils (dal) together with wholewheat flour (atta). Pettifor et al. (1978) establish severe adolescent rickets inwards rural Bantu children inwards Natal whose diet consisted almost exclusively of maize together with light-green vegetables; their sunshine exposure was high.
Investigators receive got shown that a diet high inwards unleavened whole grain breadstuff causes mineral loss from the torso over time, together with this cannot move corrected yesteryear supplementing vitamin D (14, 15).  These diets atomic number 82 to zinc deficiency equally well, together with correcting this deficiency alleviated growth stunting inwards Iranian children eating a diet rich inwards unleavened wheat breadstuff (16).

Heavily grain-dependent cultures also frequently demo signs of severe vitamin H5N1 together with poly peptide deficiencies (17).  Dr Edward Mellanby commented on the high susceptibility to infectious illness inwards the agricultural Kikuyu tribe compared amongst their neighbors the milk-drinking Masai, who also physically dominated the Kikuyu together with other surrounding agricultural groups.  Based on his studies of vitamin H5N1 together with infectious illness resistance, he attributed this inwards purpose to improve vitamin H5N1 status amid the Masai (Edward together with May Mellanby. Nutrition together with Disease. 1934):
The high incidence of bronchitis, pneumonia, tropical ulcers together with phthisis amid the Kikuyu tribe who alive on a diet mainly of cereals equally compared amongst the depression incidence of these diseases amid their neigh­bours the Masai who alive on meat, milk together with raw blood (Orr together with Gilks"), in all likelihood has a similar or related nutritional explanation. The differences inwards distribution of infective illness establish yesteryear these workers inwards the 2 tribes are most impressive. Thus inwards the cereal-eating tribe, bronchitis together with pneumonia accounted for 31 per cent. of all cases of sickness, tropical ulcers for 33 per cent. together with phthisis for six per cent. The corresponding figures for the meat, milk together with raw blood tribe were 4 per cent., iii per cent. together with l per cent.
This is a employment that's to a greater extent than related to a depression intake of creature foods together with light-green vegetables than to grains per se.  Animal foods are a to a greater extent than effective rootage of vitamin H5N1 than works life foods, peculiarly inwards the subset of the population that converts works life carotenes into vitamin H5N1 inefficiently. 

Another number is that grains are depression inwards potassium compared amongst tubers.  Potassium is an of import nutrient for os together with cardiovascular health, together with insufficient intake (i.e. the amount most Westerners eat) may promote osteoporosis together with hypertension (18, 19).  All else beingness equal, a diet based on tubers such equally potatoes, sugariness potatoes, or taro volition move higher inwards potassium than i based on grains.

The betoken of all this is to demo that nosotros aren't yet good plenty adapted to an agricultural diet that nosotros tin subsist primarily on a high-grain, rattling depression creature nutrient diet without facing wellness consequences, peculiarly if diet multifariousness is low.  If nosotros had some other 1000000 years of grain-heavy diets, nosotros would probable move able to subsist on them to a greater extent than effectively, similar rodents who are to a greater extent than able to access minerals from whole grains than humans (20).  That beingness said, this does non propose that grains, including whole grains, cannot move purpose of a salubrious diet inwards moderation.  To receive got that contestation out of double negative land, inwards my persuasion good prepared grains tin move purpose of a healthy, diverse, omnivorous diet for most people, peculiarly if they're "externally digested" yesteryear fermentation.  Some people volition do goodness from avoiding wheat however, peculiarly flour.

Conclusion

It's fourth dimension to roll upwards this lengthy series.  I promise a few people followed along to the end.  The evidence suggests that many human populations receive got been chop-chop evolving since the goal of the Paleolithic, together with that some of this evolving has made us improve suited to consuming agricultural foods such equally grains together with dairy.  We aren't exactly hunter-gatherers inwards a suit together with tie-- we're an amalgam of hunter-gatherer together with non-industrial agriculturalist adaptations, amongst a lot of population together with private variability.  The implication is that grains, dairy, together with maybe legumes are purpose of the European ancestral diet, stamped into our genome, together with this applies to many other human lineages equally well.  If these foods concur amongst you, inwards my persuasion they tin move purpose of a salubrious diet inwards moderation.  However, some people are healthier together with experience best when eating a stricter "Paleolithic" diet that excludes agricultural foods, together with at that topographic point is currently practiced evidence from controlled trials to back upwards the wellness benefits of this dietary designing inwards sure enough people, peculiarly those amongst glucose intolerance or diabetes (21, 22).


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