Maybe I've been a bit unclear. That may be because I'm no native writer of English.
The point I wanted to make was just "Be very, very careful if you start messing with your feelings of hunger."
Self inflicted eating disorders are no fun.
(Also, there are a lot of people with eating disorders out there. Knowledge about starving more effective can be harmful to some people.)
And just to make it clear no one in their right state of mind would start taking ECA while being at BMI 18, the bit about my BMI was just anecdotal to make my point clearer. The nonanecdotal knowledge is in the link I provided, and a short search at Pubmed or Google Scholar should unearth more facts about hunger and it's psychic and physical effects.
Messing with your feelings of hunger is seriously dangerous.
Starvation leads to a massive biochemical response, among other things a excretion of endorphines, so you can get kicks from hunger. (That seems to be one of the ways anorexia works - http://www.ncbi.nlm.nih.gov/pubmed/22036318)
So, if you want to test the ECA- theory for yourself, be very, very careful.
(I speak as a person with weak feelings of hunger which tends to forget to eat. I constantly battle against my tendency to lose weight, especially if stressed. That's no classical eating disorder - I'm very aware that I'm much to thin (BMI around 18). After approx. 2-3 days of low caloric intake (say, only breakfast and nothing else) hunger goes away completely and is replaced by feelings of euphoria and happiness. I suppose, this could happen to anyone who switches of his feelings of hunger. So, be careful, make and keep a timetable for meals!)
Because it works something like this, in a grossly oversimplified explanation:
Human genes are organized on 23 chromosomes, 2 complete sets of them, so 46 in all, with 50% being redundant.
Your DNA is fragmented in 46 stripes of neatly ordered DNA.
Information on these two sets of chromosomes aren't identical, just redundant: On one set could for example be the information to make fair hair, on the other the information for brown hair, with the carrier of those genes getting brownish hair.
If a human produces gametes (cells used for reproduction, sperm and eggs), each gamete will get half of the set of chromosomes.
So, to oversimplify even more, your daddy will put one of its two sets of chromosomes into his sperm, yielding sperms with each half of his whole set of chromosomes. For the sake of clarity, lets call the sets of sperms he can produce D1 and D2.
Mommy will do the same, just getting M1 and M2.
If they procreate, the embryo will get chromosomes from 2 randomly chosen gametes, which can be M1 or M2, and D1 and D2.
That leads to following possible genotype-mixtures:
The outcome is completely random, so you would have a chance to get a sibling with identical genes 25%, with half of your genes 50% and with none of your genes also 25%. Which gets to an average of 50% of identical genes per sibling.
Evolution works with huge numbers and enormous timescales, so it is save to assume that this statistic works out true and is safe enough to bet on.
Less simplified, each the chromosomes which is put into a gamete is randomly chosen. So, each gamete gets 23 completely randomly chosen chromosomes from the whole set of 46 chromosomes. (Keyword here is meiosis, biologogenes for "making gametes").
And, to complicate matters further, in one step of the meiosis the DNA-strands which make up the chromosomes are broken randomly (but at the correct places) and joined. (This process is called crossover.)
So, the body does it's best to make the genetic makeup of any gamete to a very randomly chosen set of all genes in the body.
(That's because the body does not know and isn't able to find out which of his genes make him fit in an evolutionary sense. So, randomness is the best chance. Again, that's very simplified.)
That boils down to the fact, that siblings share approximately 50% of their genes, give or take a few.
If you want to know that a bit better, read Dawkins "The selfish gene" (no atheism in there, just good old biology). Really good book, which clarifies many things regarding evolution and genetics with just traces of chemistry.
Or, if you want to know it really good, read a book about genetics, I would recommend the tome "Genes IX" by Benjamin Lewin or similar.)
(Serious biologenes and chemistry there, though.)
Hope that helped.
Then you are suffering strongly from the Bystander-effect.
One could translate this effect as "the warm fuzzy feeling that there are enough people around which will do the job and oneself doesn't need to bother".
The effect is very strong. So, adjust your thoughts:
The barbarians will kill you either way. There aren't enough people which care, so you yourself have to rise to do something.
(That also applies to everyday life: If you want something done, especially in a busy and people-rich environment, do it yourself.)
The point of banned goods is not that they are banned because of the hazards for the people alone who buy them but for everyone else also.
Sulphuric acid for example is easily usable as a weapon especially in concentrated form.
(It grows very hot if it touches water. And it is very acidic. So, by using a simple acid proof squirt gun one can do serious damage.)
And, that's not really all:
Suppose I could go into such a shop, proof that I'm sufficiently intelligent to handle dangerous stuff without being a danger for myself and buy
a) a PCR machine
b) a flu virus genome sequence
c) a HIV genome sequence
d) some assorted chemicals
e) some literature about virology
f) lungs tissue cell cultures
g) some pigs/monkeys to test it
and wipe out Japans population just for the sake of it?
(Contagious like flu and deadly as AIDS. It would take some months or even years to clone it but it would be manageable.)
Well, Japan wouldn't actually a sensible target for that. To much risk of travelers spreading the virus worldwide. Choose your own isolated country to test.
I sleep better in my bed each night because I know it is not that easy to get really dangerous stuff in Shops.
You write "The evolutionary reasons for this are so obvious as to be worth belaboring: In the ancestral environment, politics was a matter of life and death."
Is there any evidence for that? That sounds much like the typical sort of sociobiologistic hypothesis which sounds so convincing that no one really thinks about it and just nods in agreement. So, are there any papers, experiments, mathematical models to back it up?
I would rather more suggest a hypothesis that it was (and is) very favorable for humans in terms of fitness to belong to a certain group of people and stick to that group - whether that group is a sports team, a class at school or a political party.
Well, I wouldn't dare to disagree with the rest of your article.
Just that choosing of a political party has nothing to do with actual politics, just with sticking to a group.