Science is Cool!

A new study finds that genes for diet, behavior, and disease in dogs and humans have evolved together.

Researchers from the University of Chicago and several international institutions found that several groups of genes in humans and dogs—including those related to diet and digestion, neurological processes, and disease—have been evolving in parallel for thousands of years.

This parallel evolution was likely driven by the shared environments of humans and dogs, wrote the authors in a study published May 14, 2013 in the journal Nature Communications.

"As domestication is often associated with large increases in population density and crowded living conditions, these 'unfavorable' environments might be the selective pressure that drove the rewiring of both species," the authors surmise.

For example, living in crowded conditions with humans may have conferred an advantage on less aggressive dogs, leading to more submissive canines and eventually to the pets whose puppy-dog eyes gaze at us with unconditional affection.

The study authors suggest that dogs were domesticated 32,000 years ago; that's much earlier than current estimates, which place domestication at around 15,000 to 16,000 years ago.

"Thirty-two thousand is a little bit old," said Bob Wayne, an evolutionary biologist at the University of California, Los Angeles. Although he does acknowledge that the timing of a split between wolves and dogs has varied widely—ranging between 6,000 and 120,000 years ago.

The cultural diversity of culinary practice, as illustrated by the variety of regional cuisines, raises the question of whether there are any general patterns that determine the ingredient combinations used in food today or principles that transcend individual tastes and recipes. We introduce a flavor network that captures the flavor compounds shared by culinary ingredients. Western cuisines show a tendency to use ingredient pairs that share many flavor compounds, supporting the so-called food pairing hypothesis. By contrast, East Asian cuisines tend to avoid compound sharing ingredients. Given the increasing availability of information on food preparation, our data-driven investigation opens new avenues towards a systematic understanding of culinary practice.

As omnivores, humans have historically faced the difficult task of identifying and gathering food that satisfies nutritional needs while avoiding foodborne illnesses. This process has contributed to the current diet of humans, which is influenced by factors ranging from an evolved preference for sugar and fat to palatability, nutritional value, culture, ease of production, and climate. The relatively small number of recipes in use (∼10E6, e.g. http://cookpad.com) compared to the enormous number of potential recipes (>10E15), together with the frequent recurrence of particular combinations in various regional cuisines, indicates that we are exploiting but a tiny fraction of the potential combinations. Although this pattern itself can be explained by a simple evolutionary model or data-driven approaches, a fundamental question still remains: are there any quantifiable and reproducible principles behind our choice of certain ingredient combinations and avoidance of others?

Although many factors such as colors, texture, temperature, and sound play an important role in food sensation, palatability is largely determined by flavor, representing a group of sensations including odors (due to molecules that can bind olfactory receptors), tastes (due to molecules that stimulate taste buds), and freshness or pungency (trigeminal senses). Therefore, the flavor compound (chemical) profile of the culinary ingredients is a natural starting point for a systematic search for principles that might underlie our choice of acceptable ingredient combinations.

A hypothesis, which over the past decade has received attention among some chefs and food scientists, states that ingredients sharing flavor compounds are more likely to taste well together than ingredients that do not (for more info, see http://www.foodpairing.com). This food pairing hypothesis has been used to search for novel ingredient combinations and has prompted, for example, some contemporary restaurants to combine white chocolate and caviar, as they share trimethylamine and other flavor compounds, or chocolate and blue cheese that share at least 73 flavor compounds. As we search for evidence supporting (or refuting) any ‘rules’ that may underlie our recipes, we must bear in mind that the scientific analysis of any art, including the art of cooking, is unlikely to be capable of explaining every aspect of the artistic creativity involved. Furthermore, there are many ingredients whose main role in a recipe may not be only flavoring but something else as well (e.g. eggs' role to ensure mechanical stability or paprika's role to add vivid colors). Finally, the flavor of a dish owes as much to the mode of preparation as to the choice of particular ingredients. However, one hypothesis is that, given the large number of recipes we use in our analysis (56,498), such factors can be systematically filtered out, allowing for the discovery of patterns that may transcend specific dishes or ingredients.

In the middle of the South Atlantic, there's a patch of sea almost devoid of life. There are no birds, few fish, not even much plankton. But researchers report that they've found buried treasure under the empty waters: ancient DNA hidden in the muck of the sea floor, which lies 5000 meters below the waves.

The DNA, from tiny, one-celled sea creatures that lived up to 32,500 years ago, is the first to be recovered from the abyssal plains, the deep-sea bottoms that cover huge stretches of Earth. In a separate finding published this week, another research team reports teasing out plankton DNA that's up to 11,400 years old from the floor of the much shallower Black Sea. The researchers say that the ability to retrieve such old DNA from such large stretches of the planet's surface could help reveal everything from ancient climate to the evolutionary ecology of the seas.

"We have been able to show that the deep sea is the largest long-time archive of DNA, and a major window to study past biodiversity," says Pedro Martinez Arbizu, a deep-sea biologist of the German Centre for Marine Biodiversity Research in Wilhelmshaven.

The new studies are "very exciting," says micropaleontologist Bridget Wade of the University of Leeds in the United Kingdom, who was not connected to the research. Until now, it wasn't clear "how far back in time you could take these DNA studies. … These records are telling you new information that wasn't found in the fossil record."

The South Atlantic team went looking for DNA in plugs of silt and clay coaxed out of the ocean floor hundreds of kilometers off the Brazilian coast. The researchers were after genetic material from two related groups of marine organisms, the foraminifera and the radiolarians. Both are single-celled, and both include many species with beautiful pearly shells that fossilize nicely, making them a favorite target of researchers studying the prehistoric oceans.

The researchers used special pieces of DNA specific to radiolarians and foraminifera to fish out DNA from those groups. Then they sequenced the DNA and compared the results to known foraminifera and radiolarian DNA sequences. Their analysis showed they'd found 169 foraminifera species and 21 radiolarian species, many of which were unknown. What's more, many of the foraminifera species belonged to groups that don't form fossils

Unlike most exoplanet discoveries, which are inferred from analysis of data, the planets of the HR8799 system are directly visible from Earth. The planets were discovered in 2008 using the Keck and Gemini telescopes in Hawaii. The star HR8799, about 1.5 times the size of the sun and about five times brighter, lies 130 light years from Earth. Each of the star's four known planets is larger than any planet in our solar system. The star formed only 30 million years ago and is a variable star, meaning that its luminosity changes over a period of about half a day. By studying light reflected from planet HR8799c, astronomers have found water and carbon monoxide in its atmosphere.

The story of the Neandertals may need a new ending, a controversial study suggests. Using improved radiocarbon methods, scientists redated two of the youngest known Neandertal cave sites and concluded that they are at least 10,000 years older than previous studies have found.

The findings cast doubt on the reliability of radiocarbon dates from other recent Neandertal sites, the researchers suggest online February 4, 2013, in the Proceedings of the National Academy of Sciences. This means the last Neandertals might have died out much earlier than previously thought, which could cause anthropologists to rethink how and why these hominids vanished. Researchers have long debated whether the harsh Ice Age climate, the appearance of modern humans migrating out of Africa, or some other factor drove Neandertals to extinction.

“The paper is simply excellent,” says archaeologist Olaf Jöris of the Romano-Germanic Central Museum in Mainz, Germany. The new research supports Jöris’ own review of Neandertal dates, in which he concluded that the most-recent Neandertals probably lived around 42,000 years ago. The standard view suggests that the last of these hominids occupied Europe as recently as about 28,000 years ago.

But other archaeologists are not convinced by the new work. “We shouldn’t get too carried away over results that amount to a few radiocarbon dates from two sites,” says Paul Pettitt, an archaeologist at Durham University in England.

ENLARGE This Neandertal jaw from a cave in southern Spain may be at least 10,000 years older than previously estimated, a new dating analysis suggests. 

Over the last couple of decades, archaeologists have determined that the Iberian Peninsula was one of the last Neandertal refuges. Neandertals throughout much of Europe appear to have gone extinct around the same time that modern humans reached the continent, at least 42,000 years ago. But the favorable climate of southern Spain and Gibraltar may have helped Neandertals hang on in for another 10,000 years or so. Getting a precise chronology is crucial to understanding what factors played a role in the Neandertals’ demise and the degree to which Neandertals and humans interacted and possibly interbred, researchers say.

This is how Neptune's Great Dark Spot and rings may have looked in 1989 from a position just beneath Neptune's ring plane. The outermost Adams ring is near the top of the frame, and beneath that is the much broader and diffuse Lassell ring. Further in toward Neptune and abutting the Lassell ring is the thin LeVerrier ring, and beyond that is the diffuse Galle ring.

The Great Dark Spot is believed to be a storm similar to, but only half the size of, Jupiter's Great Red Spot. While Jupiter's Great Red Spot has been raging for at least 400 years, subsequent observations of Neptune's Great Dark Spot in 1994 by the Hubble Space Telescope revealed that this storm has since disappeared.

The Great Dark Spot was a very dynamic weather system, generating massive, white clouds similar to high-altitude cirrus clouds on Earth. Unlike cirrus clouds on Earth however, which are composed of crystals of water ice, Neptune's cirrus clouds are made up of crystals of frozen methane. Neptune's clouds are driven by winds of 1,200 mph, the fastest winds of any planet in the Solar System. How such high-velocity winds come to be on a planet so far from the Sun is still a mystery.