Interesting. I've got a semi-relevant story, but I get long winded so feel free to skip to the next comments if you like.

My wife (Thai) and I (American) had our first daughter this year. When she first got pregnant, one of the doc's first priorities was to get us both tested for "Thalassemia", which I had never heard of before. Apparently it is a blood disorder that affects hemoglobin production and therefore red blood cells -- if both parents carry the (rather rare) recessive gene, it can be a pretty bad deal.

It turned out that my wife is in the 1% or so of Thais that carry the gene (but she doesn't express / suffer from it, it is recessive and she has the dominant gene also). I had to get tested as well, but they said it would be incredibly unlikely that I'd be positive and I wasn't. So, our daughter has a 25% chance of being a carrier like my wife but zero chance of suffering from the effects of it.

Anyway, I was curious about the disease and asked the doc why it is a big deal here (every pregnant couple MUST get screened for it here when getting hospital/prenatal care) but I'd never even heard of it in the US. It turns out that the disease / genetic mutation arose only in places with high rates of malaria. As it happens, the genetic effect on your blood cells that the mutation has makes you more resistant to malaria -- full-on exhibitors of it (two recessive genes) are far less likely to die of malaria than people that don't have the gene. That is, assuming that you don't have the extreme variants of it that make it very unlikely to survive early childhood. Basically, if you have the disease and yet are healthy enough to survive to adulthood, you're close to malaria immune (that's overstating it, but ballpark). The malaria parasite can't survive and reproduce properly on your funky Thalassemia-affected red blood cells.

I thought that was a pretty interesting evolutionary response that must have arisen from some populations being pretty much decimated by malaria back in pre-recorded history. Current carriers like my wife are probably the descendants of lucky folks that survived a deadly outbreak in history by virtue of having a disease/mutation that is, under normal circumstances, slightly or even extremely bad in species survival / reproductive fitness terms. I thought that was kinda cool -- but I'm glad that neither my wife nor my daughter are/can be full-on expressors of the gene.

http://en.wikipedia.org/wiki/Dinosaur#Soft_tissue_and_DNA

One of the best examples of soft-tissue impressions in a fossil dinosaur was discovered in Petraroia, Italy. The discovery was reported in 1998, and described the specimen of a small, very young coelurosaur, Scipionyx samniticus. The fossil includes portions of the intestines, colon, liver, muscles, and windpipe of this immature dinosaur.[45]

In the March 2005 issue of Science, the paleontologist Mary Higby Schweitzer and her team announced the discovery of flexible material resembling actual soft tissue inside a 68-million-year-old Tyrannosaurus rex leg bone from the Hell Creek Formation in Montana. After recovery, the tissue was rehydrated by the science team.[46]

When the fossilized bone was treated over several weeks to remove mineral content from the fossilized bone-marrow cavity (a process called demineralization), Schweitzer found evidence of intact structures such as blood vessels, bone matrix, and connective tissue (bone fibers). Scrutiny under the microscope further revealed that the putative dinosaur soft tissue had retained fine structures (microstructures) even at the cellular level. The exact nature and composition of this material, and the implications of Schweitzer's discovery, are not yet clear; study and interpretation of the material is ongoing.[46]

Newer research, published in PloS One (30 July 2008), has challenged the claims that the material found is the soft tissue of Tyrannosaurus. Thomas Kaye of the University of Washington and his co-authors contend that what was really inside the tyrannosaur bone was slimy biofilm created by bacteria that coated the voids once occupied by blood vessels and cells.[89] The researchers found that what previously had been identified as remnants of blood cells, because of the presence of iron, were actually framboids, microscopic mineral spheres bearing iron. They found similar spheres in a variety of other fossils from various periods, including an ammonite. In the ammonite they found the spheres in a place where the iron they contain could not have had any relationship to the presence of blood.[90]

The successful extraction of ancient DNA from dinosaur fossils has been reported on two separate occasions, but, upon further inspection and peer review, neither of these reports could be confirmed.[91] However, a functional visual peptide of a theoretical dinosaur has been inferred using analytical phylogenetic reconstruction methods on gene sequences of related modern species such as reptiles and birds.[92] In addition, several proteins, including hemoglobin,[93] have putatively been detected in dinosaur fossils.[94]

That is very *EIA .
This is why you do not take those instant cold ICE Packs and bang them around and shit.

You crack the water module, and then shake the liquid down onto the ammonium nitrate pellets.

http://home.howstuffworks.com/refrigerator7.htm

This house hold product is an interesting item, much like non dairy coffee creamer. These are both very dangerous, in the hands of idiots.

http://www.jtbaker.com/msds/englishhtml/a6048.htm

Inhalation:
May cause irritation to the respiratory tract; symptoms may include coughing, sore throat, and shortness of breath. At high temperatures, exposure to toxic nitrogen oxides decomposition products can quickly cause acute respiratory problems. Inhalation of large amounts causes systemic acidosis and abnormal hemoglobin.
Ingestion:
Large oral doses of nitrates may cause dizziness, abdominal pain, vomiting, bloody diarrhea, weakness, convulsions, and collapse. Harmful if swallowed. May cause methemoglobinemia resulting in cyanosis.
Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain.
Eye Contact:
Causes irritation, redness, and pain.
Chronic Exposure:
Small repeated oral doses of nitrates may cause weakness, depression, headache, and mental impairment.
Aggravation of Pre-existing Conditions:
No information found.

/\ interesting note, smibbo.

Reminds me of the genetic trait for sickle-shaped red blood cells; millions die from malaria every year, but a simple alteration of the shape of blood cells confers some resistance, making what would generally be a "bad" genetic mutation (less efficient hemoglobin) actually a slight advantage in particular environments (areas with malaria, like the lowlands of central Africa).
(google searched my facts... check!: http://sickle.bwh.harvard.edu/malaria_sickle.html )

Selective pressure is always there, even in human society. Look around! I have friends with slightly different skin color, eye color, hair texture, facial features, hand shapes, head shape, etc., from my own. Recorded history is almost nothing in the scale of time scientific theories often attempt to describe.

An interesting fact I picked up the other day, just in case you wondered why your shit is typically brown:

The brown colour of feces is due to the action of bacteria on bilirubin, which is the end product of the breakdown of hemoglobin (red blood cells)

Bilirubin is a useless and toxic breakdown product of hemoglobin, which also means that it is generated in large quantities. In the time it takes you to read this sentence aloud, roughly 20 million of your red blood cells have died and roughly 5 quintillion (5 x 1015) molecules of hemoglobin are in need of disposal.

In the liver cells (hepatocytes) the bound bilirubin reacts with glucuronic acid to form conjugated bilirubin. Most of the conjugated bilirubin is secreted into the small intestine with the bile. In the large bowel, bacteria convert bilirubin into the yellow-brown pigment (urobilinogen) that gives feces its characteristic color. Some of this pigment re-enters the blood from the colon and is removed by the kidney into the urine (characteristic color).

Cool. Reminded me of Disney's Amazing Mr. Hemoglobin.