Science Tuesday - Old Stuff
Lactose Intolerant, Before Milk Was on Menu
By SINDYA N. BHANOO, The New York Times, March 5, 2012
Since it was discovered in 1991, preserved in 5,300 years’ worth of ice and snow in the Italian Alps, the body of the so-called Tyrolean Iceman has yielded a great deal of information. Scientists have learned his age (about 46), that he had knee problems, and how he died (by the shot of an arrow).
Now, researchers have sequenced the complete genome of the iceman, nicknamed Ötzi, and discovered even more intriguing details. They report in the journal Nature Communications that he had brown eyes and brown hair, was lactose intolerant and had Type O blood.
The lactose intolerance makes sense, said Albert Zink, an anthropologist at the European Academy of Research in Bolzano, Italy, who was one of the study’s authors.
“In early times, there was no need to digest milk as an adult because there were no domesticated animals,” Dr. Zink said. “This genetic change took hundreds of years to occur.”
But the scientists were surprised to find that Ötzi had a strong predisposition to heart disease. “If he wasn’t shot with an arrow, it would have been possible that he might have had a heart attack soon after,” Dr. Zink said.
Heart disease is often thought of as a modern problem, associated with rich food and limited physical exertion. “But obviously this disease was present already 5,000 years ago,” Dr. Zink said. “So now we can get a better understanding why such diseases develop.”
Researchers also suspect the man may have had Lyme disease, and further study could yield insight into the disease’s origins.
Today, Ötzi can be viewed at the South Tyrol Museum of Archaeology in Bolzano.
Giant Jurassic Fleas Packed a Mean Mouth
By SINDYA N. BHANOO, The New York Times, March 2, 2012
Scientists have discovered the world’s oldest fleas to date - bloodsuckers that lived among (and possibly on) dinosaurs.
Fossils found in northeastern China belong to two ancient species of fleas, the researchers report in the current issue of the journal Nature: one dating to the Middle Jurassic, about 165 million years ago, and the other to the Early Cretaceous, about 125 million years ago.
Females ranged from one-eighth to half an inch long, males from one-sixth to a third of an inch.
That makes them giants. Today’s fleas are only about one-tenth the size.
Also, although modern fleas feed primarily on the blood of mammals, the ancient fleas may have relied on that of dinosaurs.
“They had very elongated and sharp mouth parts,” said the study’s first author, Diying Huang, a paleontologist at the Chinese Academy of Sciences in Nanjing.
This sharp mouth part, known as a siphon, may have allowed the fleas to penetrate the leathery skin of reptiles like dinosaurs, Dr. Huang said.
But he added that much more remained to be uncovered to determine what animals the fleas used as hosts. Mammals did exist at the time, though they were far less common, and fleas may have fed off them.
“So we need to know more about the function and morphology of the fleas,” Dr. Huang said.
No Animals Were Harmed in the Making of This Fossil
By SARAH FECHT, The New York Times, March 5, 2012
The famous feathered dinosaur archaeopteryx seems to have had a penchant for fossilizing in painful positions, with its head cranked backward at a severe angle. The contorted posture is so common in dinosaur fossils that it has its own name: opisthotonus, from the Greek “tonos,” meaning tightening, and “opistho,” behind.
Since the 1920s, paleontologists have debated how these dinosaurs came to have such grotesque final resting positions. Some theorized that water currents moved the bones into formation, or that the muscle contractions of rigor mortis pulled the head backward. Others thought the animals must have died in pain.
New research proposes a simpler explanation.
In a paper published last month in the journal Palaeobiodiversity and Palaeoenvironments, Achim G. Reisdorf of the University of Basel in Switzerland writes that the trouble with the death-throe hypothesis is that carcasses are flexible. To fossilize in the traumatic death position, a carcass would have to be quickly buried in the exact spot where it died, without any transportation.
But that is unlikely, Mr. Reisdorf wrote. Many of the dinosaurs found in opisthotonic posture are land animals that fell into sediment at the bottom of bodies of water, and probably had to settle before reaching their final resting place.
Mr. Reisdorf thought water might be the key. So he and a colleague, Dr. Michael Wuttke, decided to try some kitchen science. They bought fresh chicken necks from a butcher and plunged them into water buckets.
Immediately, the necks bent backward by 90 degrees. After three months and significant rotting, they had twisted further backward - to 140 degrees.
These results were verified at Brigham Young University by a paleontologist, Brooks B. Britt, and an undergraduate student, Alicia Cutler.
“When you hold a carcass in your hand, it’s like a limp rag, you can move it anywhere,” Dr. Britt said. “But as soon as we put the first dead chicken in the water, we realized, ‘Holy smokes, this is amazing.’ The head immediately curved backwards.”
To test whether muscle contractions caused the spasms, both groups of researchers removed the skin and muscle from the birds, and got the same result. Only by cutting the ligaments between vertebrae could they prevent the necks from bending backward in water.
The teams independently concluded that the ligaments in chicken necks were like rubber bands - bendable, but contracted by default to hold the bird’s head upright against gravity. In the dead chicken, those ligaments still want to return to their natural, unstretched position, but the dead weight of the bird fights against it. In water, however, buoyancy and lack of friction allow the ligaments to contract into their natural shape, cranking the neck backward as they go.
The observations have been replicated in other bird species, in saltwater and fresh water, and at various depths. Because birds are living dinosaurs, the researchers think the same phenomenon may have caused opisthotonic posture in nonavian dinosaurs as well.
Kevin Padian, a paleontologist at the University of California, Berkeley, is not entirely convinced. Because similar contortions of the spine and neck occur when modern animals experience trauma, he has argued that a fossil’s opisthotonic posture could indicate that the animal died of suffocation, starvation, poisoning or other brain injuries.
Mr. Reisdorf “may be onto something, but it remains to be seen,” Dr. Padian said. The new observations don’t explain the opisthotonic fossils found in dry, non-aqueous sediments. Nor do they explain how mammals - which have a different ligament anatomy - also fossilized with these postures.
“I don’t think the two theories are mutually exclusive,” he continued. “The question is, how do you tell what’s really going on?” Like a 150-million-year-old crime scene, ancient fossils offer few clues to help paleontologists reconstruct the past.
But Mr. Reisdorf and Dr. Britt say their research reprieves most of these dinosaurs from the agonizing deaths that had been proposed for them. “A longstanding debate has been solved,” Dr. Britt said, “and it turns out to be pretty doggone simple: Just add water.”