NOTE: there won't be a Science Fix for 2-3 weeks since I will be taking a vacation!
I will start this blog with everything human. Then interesting news regarding the natural world. I’ll throw I an arthropod or two to keep Michel happy. I will then post a pretty photo, and an interesting video. I declare today “reverse Friday”
Darwinian evolution of music by public choice. Thanks to Doone for posting this on Evolution Defenders on our site: How Evolution Works on Music Natural Selection. Here is the abstract of the original article: “Music evolves as composers, performers, and consumers favor some musical variants over others. To investigate the role of consumer selection, we constructed a Darwinian music engine consisting of a population of short audio loops that sexually reproduce and mutate. This population evolved for 2,513 generations under the selective influence of 6,931 consumers who rated the loops’ aesthetic qualities. We found that the loops quickly evolved into music attributable, in part, to the evolution of aesthetically pleasing chords and rhythms. Later, however, evolution slowed. Applying the Price equation, a general description of evolutionary processes, we found that this stasis was mostly attributable to a decrease in the fidelity of transmission. Our experiment shows how cultural dynamics can be explained in terms of competing evolutionary forces”. Go to darwintunes.org to check out the evolution of music from noise, and to participate, it’s great fun! Unfortunately I could not embed the player here! But you can go to this link to enjoy listening the evolving tunes.
Music provokes string emotions in us; I wonder what we would see if we were to look at our fellow human beings enjoying a good concert through a new little invention in eyewear:
Novel eyewear amplifies perception of emotions and health. I'm not sure how well this type of eyewear really works, but if it does what it claims it's pretty extraordinary. These glasses were designed on the basis of Mark Changizi's research on the evolution of human (primate) color vision. He thinks color vision evolved so that we could detect subtle differences in blood oxygenation (related to health and fitness), and the filters in these novel sunglass-style glasses apparently enhances this. There are also applications in medicine, to find veins or detect trauma. Here is the article on the Changizi blog.
Head Games. Discovery Channel has a new TV program about cognitive biases, called "Head Games" they run "experiments" with people on screen just to show how our perception often fool us or how we pick up unconscious clues that modify our behavior even if we're not aware of it. The host is Mark Changizi, neuroscientist and author of "The Vision Revolution", and "Harnessed." I missed the first two episodes, which I'll try to watch online; especially the second one which was about moral dilemmas and what makes us moral. I saw the third episode yesterday, called "Seeing is Believing." I thought it was pretty good and I bet most members of The Naked Ape will enjoy this show. For example, it showed how an attractive woman in a nicely fitted white dress does not get nearly the same attention from guys as the same woman, same dress, except in a red color; at some point she even asks 50 different guys (on the street, in NYC) for a dollar to buy water because she forgot her purse in the office; she gets money from 6 guys when she is wearing the white dress, and from 38 guys when she's wearing the red dress! The show also focused on "inattention blindness", how people miss weird things in their environment when they are focused on something else: the experiment was a clown on a monocycle in the middle of a college campus. He was noticed by all, except the people who were on their cell phones, engrossed in a conversation. They also did another cell phone experiment: they had volunteers assemble a little wooden stool that required a screwdriver and ~ 10 minutes of work, either by themselves, with two people chatting to each other next to them, or with one person having the same conversation next to them, but by herself and on a cell phone. Result: the volunteers took ~10 minutes on average to assemble the stool whether they were by themselves or with the two people chatting to each other on the background. But they took longer; sometimes twice as long, with the young lady on the cell phone. Our brains keep looking for the missing part of the conversation! That distracts us and our brain cannot handle to keep full attention to two things at the same time.
Nowadays we play head games, we build computer programs to evolve music through the Internet, and specialized eyeglasses to better perceive blood flow, but 7,000 years ago, simply making yogurt was a huge accomplishment.
North Africans were making yogurt 7,000 years ago. The gene variants that make some of us lactose tolerant in adulthood had not appeared 7,000 years ago, and our ancestors in North Africa had figured out how to make milk more digestible by fermenting it into yogurt, thus lowering the milk sugar content. The evidence is in traces of milk fat found in pottery shards analyzed using mass spectrometry to identify specific animal fats. The relative levels of carbon isotopes were determined to find the origin of those fats in 29 shards samples. At least half contained fats came from dairy foods. The shards come from the Takarkori rock shelter in the Acacus mountains (Libya). Now this area is a desert (actually part of the Sahara, but, 7,000 years ago it was greener and it could of support dairy animals. Rock art in the Takarkori shelter shows cows with full udders, and even pictures of people milking them. The age of the paintings has not been determined. Mark Thomas, a geneticist at University College London, says that the lactose tolerance mutation arose 6,000 years ago in Europe and then spread to Africa, perhaps as a result of a desertification that allowed lactose-tolerant people to stay hydrated better by consuming dairy. He says the shards are evidence of selective pressure for lactase persistence in Africa very early.
Yogurt evokes sour flavors, and reminds me of taste receptors. The next story will show you that taste receptors appear sometimes in weird places.
Taste receptors in unexpected places: your intestines, and sperm. We are all well aware of the taste receptors present in our tongue, but how about taste receptors in other places? We have them in our nasal epithelium (have you ever noticed how when we have a cold our ability to taste is dampened?), and this sort of makes sense. But we also have taste receptors in our stomach, pancreas, and intestines! It is clear that the function of taste receptors goes far beyond giving us pleasure when we eat something tasty, or even warning us of potentially toxic foods. The stomach, pancreas and intestines have sweet, bitter and umami receptors. The function of the taste receptors in the gut is to aid the digestive process by influencing appetite and regulating insulin production. For example, “tasting” the sugar a second time in the stomach triggers glucose transport into the cells and bloodstream, and the faster this happens, the more insulin will be released. This explains why eating glucose triggers more insulin release than if it’s given intravenously. Interestingly, artificial sweeteners, which were thought to influence only the tongue, also trigger changes in the gut. Using brain-imaging techniques, neuroscientists have found that the brain processes taste in “hotspots”, in other works, specific clusters of neurons in specific areas that respond to sweet, salty and umami. Sour taste apparently does not have a “hotspot”. There is a logic for this type of organization: separating the bitter hotspot from the sweet, for example, means that bitterness can be wired to a brain area that drives aversion, whereas sweetness can be wired to attraction. Perhaps sourness, which is perceived in a similar way to pain, does not need a hotspot because it’s perception is associated with pain and it could be more useful to perceive pain more extensively throughout the brain. By now you are probably asking: what are taste receptors doing in sperm? Sperm cells have umami receptors, and it is believed that they aid in fertilization, by triggering the release of DNA from the sperm into the ovum. One cannot help but wonder: does the ovum taste savory to the sperm?
And while we are on the subject of fertilization, the Internet this week was abuzz with news of ancient, really ancient, actually fossil sex.
47 million year old turtle fossil sex. Nine pairs of aquatic turtles were found in the Messel pit, a fossil quarry in Germany. These turtles died while mating, about 47 million years ago. They are the first confirmed vertebrate sex act to survive 47 million years. How do paleontologists know these turtles were actually copulating when they died? For starters, each pair includes a male and a female (the female is the larger specimen seen in the image). Male turtles of this species, like many of their modern relatives, have longer tails than females (no jokes allowed here). Also, the turtles are in direct contact along the edge of their shells just above their tails, and in two of those pairs, the male's tail wraps below the female's shell in mating position, as modern turtles do. What caused the lovers to die at such intimate moment? One possibility is that while surface waters of the ancient lake were oxygenated, deeper layers were oxygen-poor and possibly saturated with carbon dioxide or other toxic substances, as it happens in some modern lakes. The lack of oxygen could explain the excellent preservation of creatures that died at the bottom. Aquatic turtles mate in open waters and often sink when they're copulating, since mating in turtles is often a strenuous and protracted deal. In most lakes, sinking is not a problem because turtles can absorb oxygen through their skin, but in the Messel pit lake, it led to asphyxiation.
Other animals die or suffer bodily harm during copulation, especially some arthropods, but self-castration? It seems a strange reproductive strategy.
Self-castration in male spiders increase reproductive success. Spiders are known for complex mating rituals, involving ritualized dances, etc. Since the males are much smaller than the females, they need to signal their intentions clearly and pacify the dangerous females. And some male spiders have arrived at extreme strategies to ensure the success of their genetic line: self-castration. Males of the orb-web spider Nephilengys malabarensis castrate themselves by leaving behind, inserted in the female, either both of their copulatory appendages or just one. Castrated males are 10% lighter than intact males; they stand guard next yo the female and are more successful at fending off invading males because of their increased agility. The strategy pays off also because females are aggressive and males can usually mate only once or twice before being eaten by the female.
If you think this is weird, well, quantum physics is even weirder.
Theory Explains the Quantum Weirdness of Exotic Materials. How is this for weird: superfluids are bizarre liquids that can flow straight up walls, Bose-Einstein condensates are gasses that will vibrate eternally, and neutron stars are essentially subatomic particles the size of New York City. A new mathematical theory explains the strangeness of these materials through quantum mechanics. The theory works well for all these disparate materials. Here it is in a nutshell: the behavior of these materials depends on a phenomenon known as spontaneous symmetry breaking. This occurs when a group of particles that once had no preferred alignment or direction suddenly create a collective behavior. For example, when iron cools down, it forms a magnet because each atom points their own magnet in the same direction as neighboring atoms, instead of randomly like in hot iron. With this new theory, physicists don’t have to look at the details of each specific system, and instead can focus on the number of symmetries broken. In the image: individual rubidium atoms form into a single super-atom in a Bose-Einstein condensate.
FEATURED IMAGE: Xenopus laevis oocytes
VINCENT PASQUE, UNIVERSITY OF CAMBRIDGE
This confocal micrograph shows stage V-VI oocytes (800-1000 micron diameter) of an African clawed frog (Xenopus laevis), a model organism used in cell and developmental biology research. Each oocyte is surrounded by thousands of follicle cells, shown in the image by staining DNA blue. Blood vessels, which provide oxygen to the oocyte and follicle cells, are shown in red. The ovary of each adult female Xenopus laevis contains up to 20 000 oocytes. Mature oocytes are approximately 1.2 mm in diameter, much larger than the eggs of many other species. Go to the link above to see all 16 images that won the Welcome Image Award of 2012
Since we discuss green solutions and sustainability very often, how about a music festival powered totally by…bicycles!
This is the 6th annual San Francisco Bicycle Music Festival, where all amplification for the music is Pedal Powered, literally. The audience generates electricity for the sound system by pedaling bicycles. Every material aspect of the Festival – sound equipment, instruments, gear, personnel, musicians, and fans – is transported by bicycle.