Isegoria

By comparing ancient European genomes with recent ones from the 1000 Genomes Project, researchers have discovered how Europeans evolved from multiple disparate populations:

First, the scientists confirmed an earlier report that the hunter-gatherers in Europe could not digest the sugars in milk 8000 years ago, according to a poster. They also noted an interesting twist: The first farmers also couldn’t digest milk. The farmers who came from the Near East about 7800 years ago and the Yamnaya pastoralists who came from the steppes 4800 years ago lacked the version of the LCT gene that allows adults to digest sugars in milk. It wasn’t until about 4300 years ago that lactose tolerance swept through Europe.

When it comes to skin color, the team found a patchwork of evolution in different places, and three separate genes that produce light skin, telling a complex story for how European’s skin evolved to be much lighter during the past 8000 years. The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes. And the new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes — SLC24A5 and SLC45A2 — that lead to depigmentation and, therefore, pale skin in Europeans today.

But in the far north — where low light levels would favor pale skin — the team found a different picture in hunter-gatherers: Seven people from the 7700-year-old Motala archaeological site in southern Sweden had both light skin gene variants, SLC24A5 and SLC45A2. They also had a third gene, HERC2/OCA2, which causes blue eyes and may also contribute to light skin and blond hair. Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.

Then, the first farmers from the Near East arrived in Europe; they carried both genes for light skin. As they interbred with the indigenous hunter-gatherers, one of their light-skin genes swept through Europe, so that central and southern Europeans also began to have lighter skin. The other gene variant, SLC45A2, was at low levels until about 5800 years ago when it swept up to high frequency.

The team also tracked complex traits, such as height, which are the result of the interaction of many genes. They found that selection strongly favored several gene variants for tallness in northern and central Europeans, starting 8000 years ago, with a boost coming from the Yamnaya migration, starting 4800 years ago. The Yamnaya have the greatest genetic potential for being tall of any of the populations, which is consistent with measurements of their ancient skeletons. In contrast, selection favored shorter people in Italy and Spain starting 8000 years ago, according to the paper now posted on the bioRxiv preprint server. Spaniards, in particular, shrank in stature 6000 years ago, perhaps as a result of adapting to colder temperatures and a poor diet.

Surprisingly, the team found no immune genes under intense selection, which is counter to hypotheses that diseases would have increased after the development of agriculture.

The paper doesn’t specify why these genes might have been under such strong selection. But the likely explanation for the pigmentation genes is to maximize vitamin D synthesis, said paleoanthropologist Nina Jablonski of Pennsylvania State University (Penn State), University Park, as she looked at the poster’s results at the meeting. People living in northern latitudes often don’t get enough UV to synthesize vitamin D in their skin so natural selection has favored two genetic solutions to that problem — evolving pale skin that absorbs UV more efficiently or favoring lactose tolerance to be able to digest the sugars and vitamin D naturally found in milk. “What we thought was a fairly simple picture of the emergence of depigmented skin in Europe is an exciting patchwork of selection as populations disperse into northern latitudes,” Jablonski says. “This data is fun because it shows how much recent evolution has taken place.”

Hospitals are replacing traditional surgery preparation and recovery practices — fasting, heavy IV fluids, powerful post-op narcotics and bed rest — with enhanced recovery protocols:

Hunger and thirst from presurgical fasting can add to patients’ stress and anxiety, and cause weakness as well as postoperative nausea. Side effects of fluid retention, narcotics and immobility can interfere with getting bodily functions back to normal, resulting in longer, harder recoveries overall. With traditional regimens, patients can remain in the hospital for 10 days or more with complication rates of up to 48% and an average $10,000 in additional costs, according to researchers at Duke University School of Medicine.

With enhanced recovery protocols, patients still can’t eat after midnight before an early morning surgery, but two or three hours before surgery they do get a carbohydrate-loaded drink fortified with electrolytes, minerals and vitamins. They are pretreated for pain with nonnarcotic painkillers and epidurals that are kept in place postoperatively. With careful monitoring, patients receive only necessary levels of IV fluid during surgery. Soon afterward they get out of bed to walk and may ingest solid food, and they are discharged earlier with careful instructions for home care.

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Surgeons adopted the practice of infusing fluid, for example, after wartime studies showed it improved survival in trauma patients, but it isn’t necessary in the average patient, Dr. Thacker says. “Giving extra IV fluids to overcome the starvation we’ve imposed on patients leads to worse outcomes,” such as preventing bowel function from returning to normal, she says.

Rules on fasting before surgery are based on assumptions that anesthesia reactions might cause patients to throw up during a procedure and hamper breathing, but research has shown clear liquids within two hours actually decreases that risk, according to John Abenstein, president of the American Society of Anesthesiologists and a Mayo Clinic anesthesiologist. OR teams are sometimes reluctant to adopt the less-restrictive policies out of concern patients won’t follow directions and come in for surgery having had a glass of milk or cola, and then surgery has to be delayed, Dr. Abenstein says. But when patients consume clear liquids correctly, they feel much better after surgery, he says.

Flu is a hereditary illness:

The case Dr Casanova reports is of a then-two-year-old girl admitted to the Necker [Hospital for Sick Children, in Paris] in 2011 with severe flu. He was one of the girl’s doctors, and her symptoms were so extreme (technically, they constituted what is known as acute respiratory distress syndrome, or ARDS), that he suspected there might be something unusual about her. He therefore sequenced her genome and, in so doing, discovered she had two broken copies (one from each parent) of the gene encoding a protein called interferon regulatory factor 7.

This protein, as its name suggests, stimulates production of interferon, an antiviral molecule. Absence of interferon made the cells lining the girl’s respiratory tract more vulnerable to flu infection. It also meant that when such infection happened, her immune system, lacking its first line of defence, unleashed an inflammatory reaction so big that it was itself damaging. This inflammation caused the ARDS.

All very unfortunate for the girl concerned, then—though she survived and remains healthy (regular vaccination keeps her influenza-free). But Dr Casanova thinks her case is of wider significance, for he has now identified 30 other people with genetic faults similar to those of his first patient. He estimates, on this basis, that about one person in 10,000 has impaired interferon production caused by genetic errors.

That may not sound like much but it would, he calculates, be enough to account for the incidence rate of the most severe cases of seasonal influenza (as opposed to the epidemic sort which emerges from time to time). It could also explain accumulating evidence that some entire families seem particularly vulnerable to flu.