February 22, 2010
Our Story So Far (abridged)
- By 3.4 MYA, Australopithecus afarensis was most likely eating a paleo diet recognizable, edible, and nutritious to modern humans. (Yes, the “paleo diet” predates the Paleolithic age by at least 800,000 years!)
- The only new item on the menu was large animal meat (including bone marrow), which was more calorie- and nutrient-dense than any other food available to A. afarensis—especially in the nutrients (e.g. animal fats, cholesterol) which make up the brain.
- Therefore, the most parsimonious interpretation of the evidence is that the abilities to live outside the forest, and thereby to somehow procure meat from large animals,…
yay for another update!
great reading again, i will no doubt re-read when at home and do lots of "clicking on links" too.
One adaptation bothers me i.e. skin color variation due to sun exposure having impact over generations like Africans are black, Europeans are white and Indians are brown. I think there could be either of the two reasons for this --
a) We evolved out of Africa (Multi regional origin) so during the evolution we had varied sun exposure.
b) We started wearing clothes before this adaptation happened so we had low sun exposure during colder times.
This is again an excellent article. The two theories you mentioned are the most fundamental concepts leading to evolution. And of-course -- Optimal Foraging Theory.
Thanks for bringing them.
Excellent and thought provoking as usual! You are rapidly becoming one of my favorite writers on "pre-history".
(I put that in quotes because, as you say, human history did not suddenly begin with our learning how to build city walls or write down ledgers.)
I have been thoroughly enjoying this series.
but if an adaptation could only take as little as 5k year, by the same token, wouldn't we be adapted to grains/beans?
(i eat small amount of white rice or fermented brown rice /beans but they're not my staple; they're my intelligent & proudly "cheat" food. ^_^ )
Dude, this science shit will never get you any bloggie traction.
If you want anyone to pay attention, you're gonna have to step up the gossip and ad-hominems.
I suggest a twelve-part series on how Dr. Oz doesn't flush.
Compelling writing as always. Thank you for your posts.
February 22, 2010
Population genetics is fascinating, but you'll need a very solid math background to understand most of it. I've done my best to isolate some useful takeaways.
I think pigmentation differences postdate all migrations out of Africa, though they may have arisen independently in Neanderthals and H. sapiens. So it seems likely that they postdate clothes, though I don't know what evidence we have for clothing in the Pleistocene!
Also recall that "Native Americans" are Siberians who came from Asia. (AFAIK we're still trying to figure out if the pre-Clovis settlers were from the same population, or from somewhere else entirely.)
Population genetics is fascinating, and I didn't appreciate some of its inescapable conclusions until this series!
Human pre-history is a fascinating subject. It's rarely taught, however, for (I believe) two reasons. First, the evidence is thinner: it's much easier to make kids memorize Egyptian dynasties than it is to talk about what the artifacts in Blombos Cave might have meant. Second, because too many people in America refuse to acknowledge evolution.
5,000 years assumes several conditions:
It assumes that the selective advantage is extremely strong (10%). Even frank celiac doesn't generally kill people — certainly not before reproductive age. It makes middle and old age miserable…but lifespans in early agricultural civilizations were so low that this probably wasn't a frequent issue.
It assumes that there exists a mutation which can beneficially affect the system in question — and that it will arise when needed. For instance, there's no single mutation that would allow humans to breathe carbon monoxide or harmlessly excrete strontium-90. While it's apparent that frank celiac is genetically determined to some degree, there may not be any mutation which causes our intestines to ignore the effects of gliadin peptides on zonulin signaling…it may be too fundamental to our intestinal function. And even if there is a mutation (or sequence of mutations) that would allow us to digest gliadin peptides, such a mutation is vanishingly unlikely to arise by random chance.
Furthermore, since this would be purely a biochemical adaptation, not a behavioral adaptation, the mathematics of genetic fixation I discussed in the article would come into play — which are that most beneficial mutations are lost. Even the unrealistic 10% selective advantage is at least 80% likely to disappear, instead of reaching fixation!
All that being said, there is evidence that humans have adapted in some measure (though incompletely) to the consumption of birdseed ("cereal grains") and beans. The longer one's ancestors have been practicing agriculture, the less common celiac disease is in a population…and on the other hand, diabetes and metabolic syndrome is rampant amongst native populations newly introduced to "Western" foods (e.g. grains and sugar).
However, there is no evidence that zonulin signaling and intestinal permeability remains unaffected by gliadin peptides in anyone (see my second point, above) — and the nutritional profile of grains and beans is so lousy compared to animal foods that I see no reason to eat them even if they were harmless. Also, my points about anti-nutritionism from last week's article still stand.
What's been going on at paleohacks, and in the comments of some blogs, reminds me of junior high school. (To your list of "gossip and ad hominems" let me add "sweeping generalizations and vitriolic attacks".) I want no part of this race to the bottom, and I'm glad that my readers want no part of it either.
Please keep spreading articles you find helpful, thought-provoking, or otherwise interesting, so that gnolls.org can continue to be a place of learning and thoughtful discussion. And you'd be surprised how many others are reading "this science shit": it's just that my readers, like yourself, aren''t inclined to start or encourage drama. I greatly appreciate that.
Thank you for the support and encouragement!
J.S. By Indians I mean people from India not native Americans. In the first migration out of Africa our ancestors didn't took path through higher latitude so the resident of south India should not have acquired the pigmentation gene. But they do show pigmentation variation depending on sun exposure. In last 50 years color of South Indians have become less dark. If the gene was acquired through other population then it should have got lost because of the same principle you mentioned i.e. Most Mutations Are Lost.
June 14, 2011
Looks like we can add sleep in to the mix!
The period that hominins began sleeping on the ground may have been pivotal for their cognitive development, says Thomas Wynn at the University of Colorado in Colorado Springs. It allowed them to spend more of the night in REM sleep, which he says is important for memory consolidation and cognition. A common feature of REM sleep is muscle paralysis, which makes it precarious for apes that sleep in trees, says Wynn.
Since you said "pigmentation differences postdate all migrations out of Africa". It is possible that living in huts may have caused this adaptation.
"and on the other hand, diabetes and metabolic syndrome is rampant amongst native populations newly introduced to “Western” foods (e.g. grains and sugar). "
This is sommething I see quite alot aand it really interests me. Do Native people (presumable Native Americans) eat good diets or lousy cheap subsidised diets. Do Native peoples have diabetes/obesity rates similar to the low income population of America?
No western society even historically rich ones like England have been exposed to sugar for more than a few hundred years and the whole population frequently far less.
It is a true shame that Evolution is contested in the United States though according to a Dawkins documentary some new schools have been teaching it as an alternative theory here in the UK, changes in the education system might make it more common too.
It would be nice to see prehistory taught more in schools (in the UK history starts with the Romans and that is where school history can start) but I think teaching is about exposing children to sources of information and research for which history can expose children, not only, to all the archaeological techniques but other sources as well.
That said history subjects I see taught to tend to concentrate on Empires and civilisation.
@Neal - I can't find any good studies (in the time I'm stealing from work, lol!) making a comparison of diabetes/metabolic syndrome rates between Native Americans and low income households. But I grew up next door to a reservation, and my mother is a nurse who worked with a lot of NA patients... according to her those who were hospitalized were mostly there for obesity-related illnesses and heart disease. And according to my own observation (I apologise for the plain language if it offends anyone) the adults were pretty much all fat, and everyone I knew ate vending machine crap and sodas at the same rate as Americans generally do. Now, this is in no way a generalization to the entire Native American population... simply an observation of the conditions on one reservation during a decade or so. They were mostly poor, and a lot of people - especially the young - embraced "progress" by eating the commercial stuff over traditional dishes.
My complaint with history classes - and school in general - is that they spend too much time teaching you WHAT to think and none at all teaching you HOW to think. Deductive reasoning should be one of the first things anyone learns! And after it's been drilled into your head for so many years, Rome and Egypt become BORING.
February 22, 2010
If by "first migration out of Africa" you mean Homo erectus, they didn't contribute a significant proportion of the genome to India. (The Denisovans seem to have contributed to Pacific Islanders and Australian aboriginals.)
We would expect people to show pigmentation variation based on sun exposure within a "race"...there's a difference in skin color between the average Irishman and the average Italian, though both are "white".
The hut question is interesting: one wonders how much time pre-agricultural humans would have spent in their shelters. In the case of Bushmen the answer is "not much"...they mostly just sleep in them at night. I think time spent indoors is mostly a post-industrial thing for anyone but the ruling elite...agricultural labor is still mostly outdoors.
As the conclusion states, "This topic is far into the realm of speculation." It's certainly entertaining speculation, though!
One central point is that fire isn't necessary to ground sleeping -- a point reinforced by accounts of the Kalahari Bushmen, who didn't require continual fire to keep lions at bay. (This is another thorn in the side of Richard Wrangham, who maintains that we needed fire to sleep on the ground.)
Kassandra's observations are in line with everything I've seen and heard. Weston A. Price's "Nutrition and Physical Degeneration" was all about the problems resulting from natives adopting Western diets, and all the statistics with which I'm familiar show native populations suffering from diabetes, metabolic syndrome, and heart disease at far greater a rate than the white settlers selling it to them.
Rome and Egypt would be a lot less boring if they taught the real history instead of the sanitized version, which basically involves memorizing a lot of names and dynasties and laughing at the paintings of people with animal heads.
The fundamental problem with our school system is that it was designed from the start to produce compliant manual laborers, not smart, independent thinkers -- because a nation of compliant laborers was what the ruling class thought we needed back in 1900.
"We want one class to have a liberal education. We want another class, a very much larger class of necessity, to forego the privilege of a liberal education and fit themselves to perform specific difficult manual tasks." -Woodrow Wilson
"Ninety-nine [students] out of a hundred are automata, careful to walk in prescribed paths, careful to follow the prescribed custom. This is not an accident but the result of substantial education, which, scientifically defined, is the subsumption of the individual." -William Torrey Harris, US Commissioner of Education from 1889 to 1906
By "first migration out of Africa" I mean first migration by humans around 70-80 thousand years back. I got what you mean -- so difference of sun exposure between middle east (Iran) and South India may be good enough for this adaptation over the long period.
J.S. these modern diseases (diabetes, metabolic syndrome, and heart disease) are also rising in India. Historically wheat was only consumed in western part of India but with Green revolution (Happened in 1950s and 60s) most farmers moved from millet to wheat farming) and wheat consumption is still growing due to health and fiber craze.
also vizeet you need to consider socialogical reasons as well.
my understanding, which may be inaccurate of course, is that in India they have developed a view that paler skin is better or more attractive than darker skin.
how long this has been in place would make a difference, but it could explain a shift in pigmentation over the last 50 years as those with paler skin produce children with ever paler skin?
February 22, 2010
Re: skin color, I think so. Remember that the population genetics figures and times I cite are only applicable to the case of a mutation arising in one individual. If there is significant genetic variation within a population in general, selection can occur much more quickly, and the variation won't go extinct due to random chance.
I've heard the same thing about India: modern diseases are rising with the introduction of modern foods.
It depends on the reproductive rate of those with paler vs. darker skin. I can easily see social stratification occurring, especially with the caste system (the rich get lighter, the poor get darker or stay the same)...but in America, the rich reproduce less than the poor.
as countries get access to antibiotics and similar medicines infant mortality plummets so the need for lots of children to ensure some survive is reduced.
India is only recently in that situation when looking at the big picture i believe.
also this http://www.eurekalert.org/pub_releases/2012-04/uot-sfe_1032812.php
fire 1 million years ago?
@Eddie, I think it is not just about India. There was a study that people prefer Beta-Carotene tan over sun tan and Indian are normally yellow or brown not grey and white. This might be because of our Beta Carotene rich vegetarian diet. Another reason could be that many people who moved in from Persian region or Europe were light skinned and were also dominating class so darker people looked up-to them.
But if sociology had significant contribution then dark would have become more dark and pale may have become more pale but we haven't seen this happening in India (This might be true for US though).
Shift in diet may have also played an important role. In earlier days people from South India which were darker and were eating less vegetables then now so their skin may be becoming more yellow and less black.
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