I dedicate this blog post to all animal lovers, to those of us perpetually fascinated by the animal kingdom, especially other fellow vertebrates, and even more specially mammals and birds. This blog is a critter edition: we have necking giraffes, killer cats, co-evolving dogs, blind mole rats showcasing evolution in action, pigeon DNA, smart dolphins, and more! Sorry enthusiasts of other science fields, today you get only zoology mixed with evolution and some neuroscience.
Let’s start with something adorable:
cuddling neurons
Specialized sensory neurons that make caresses feel good. There is something that social mammals all have in common: we love to be caressed, petted, cuddled. It makes sense for social bonds to derive pleasure from the touch of our friends. Grooming is very often a component of social bonding. Given how important this behavior is for social animals, it is not entirely surprising that we have evolved specialized sensory cells to relay a sensation of pleasure when they are activated. A few years ago, neurobiologists at Caltech (California) found a specialized type of cell in mice: it was found only in areas of the skin with hair, and very spread out distribution of nerve endings. To find out what these neurons did, the scientists first try to study them in isolated patches of skin, but they could never get them to fire. They needed the animal itself. They then introduced a gene into mouse embryos, to mark these neurons. In other words, in the genetically engineered mice, the neurons will light up when activated. But in order to see them light up, they had to open a small hole in the mouse’s spine, and use a microscope to look at the end projections of these specialized neurons. They saw that these neurons lit up only in response to massage, stroking, basically cuddling, but not to pinching or poking. The researchers then made other engineered mice so that these mechanosensory (touch-sensitive) neurons would fire when the mice were given a drug. These mice learned to recognize a specific chamber out of three chambers, where they were given the drug, and if allowed to choose, they always went to that preferred chamber. The scientists concluded that the mice feel pleasure; they feel comforted, when these neurons are activated, and speculate that a drug may be developed in the future to impart a feeling of calmness and wellbeing in people, exactly when we feel caressed and comforted by our friends and family. Given the choice, I prefer the touch of my loved ones, or cuddling up with my dogs, to be given a drug to feel cuddled. But I can see how such a drug would help some people.
Your adorable kitty is a ruthless killer of wildlife. A recent meta-analysis of 21 different studies of feral and domestic cats shows that previous estimates of how many birds and small mammals cats kill were lower than they really are, by 2 to 4 times. Your cute cuddly kitty is an adorable efficient killer: in the United States alone cats kill approximately 2.4 billion birds and 12.3 billion small mammals (mice, rats, voles, squirrels, chipmunks, shrews and rabbits). One could of course argue that cats do a very good job of killing mice and rats and since these are considered pests and not wildlife, that is a good thing. But most of the small mammals they kill are wildlife and not mice and rats, according to the study. Environmentalists have long seen free-roaming domestic cats as an invasive species, a big threat to conservation efforts. The solution would be, of course, to keep all cats indoors but many people argue it is not fair to keep cats always inside. Dogs are already not allowed to be free-roaming and the same rule should apply to cats. Cats can get killed by traffic and other outdoor hazards as well too. For dogs it is different because dogs get to go out for walks, get to go to the dog park, etc. I'm of course not trying to tell cat owners what to do, bit this in t=interesting data and it should be taken into consideration.
Dogs evolved to eat pizza and pasta! No, it's not my dog Lola who says that, although she vehemently agrees, pizza, pasta, bagels and bread being some of her favorite treats. A new genomic study by Swedish researchers, comparing the DNA of dogs of 14 different breeds to the DNA of wolves, have identified some genomic regions that are common to all these dog breeds, but are not present in the wolves. Many of these regions contain genes involved in brain development and function, probably related to dog's friendliness towards humans as well as their uncanny ability to read our moods, understand our language and body language, follow our fingers pointing to stuff, etc. But they also found 10 genes that help dogs digest starches. Since we humans also evolved the capacity to better digest starches (and fats), around the time agriculture started, this is a great example of co-evolution. I think it's a beautiful story: best friends sharing meals evolved together. Tonight I'm cooking pasta and will give my dogs some too. So all those ultra-expensive dog foods claiming to mimic exactly the wolf diet and be the best for dogs, are probably a waste of money.
A smart dolphin asks for help? I’m sure you guys have seen this video that is all over the internet this week (it was posted on our site by a couple of us previously). The video is astonishing because it shows an adult male wild bottlenose dolphin with a fishing line wrapped around one its fins who swims up to a diver, seemingly asking for help, and remains calm while the diver disentangles the fishing line by cutting it.
This video was uploaded by a Hawaiian ecotourism company that does manta ray tours in off the coast of Kailua-Kona. Everything occurs with such calmness and deliberation, that I confess that my first thought was that it was staged and the dolphin was a trained animal. Incredibly, at one point, the dolphin returns to the surface for a breath before re-approaching the divers. It sure seems like the animal is asking for help. A dolphin scientist, Justin Gregg, thought this event was remarkable because wild dolphins are scared of scuba divers bubbles, and the animal in the video is very relaxed. He speculates that the animal could have been weak or sick, therefore appears calm. He also suggests that perhaps the dolphin, who was seeing rubbing against mooring lines to try to disentangle itself, saw the divers are simply another thing to rub himself against. This seems far-fetched to me, but it is always difficult to know for sure what is going on in the head of animals. It is very tempting to say the dolphin was asking for help. That’s what it looks like. The explanation I like best is that the dolphins in the area off the coast are used to seeing humans and have been fed by humans, so they already view humans as “helpful.” It is illegal to feed wild dolphins therefore nobody is going to asmit to the behavior, but it seems the best explanation to me.
Evolution in action in blind mole rats. Evolutionary biologists love to fight about speciation. Speciation is the process that allows two species to arise from one. Speciation happens when the members of what was once one species can no longer interbreed. There are two types: allopatric speciation and sympatric speciation. Allopatric speciation occurs when a physical barrier, such as a river, mountain chain, etc., separate two populations and after a long time, if they met again, they would not be able to interbreed because by then, the two populations would be genetically distinct. There are evolutionary biologists that say the speciation can be sympatric, that is, occur in the same place, without obvious physical barriers, due to natural variation. Sympatric speciation is controversial. Now Israeli scientists caught two populations of the Middle East blind mole rat in the act of sympatric speciation. They found that two blind mole rat (Spalax galili) populations, even though separated by a few feet of easily excavated soil, are very different based on their mitochondrial DNA, showing they are not interbreeding much. In this area, igneous basalt rock has been pushed against the chalk bedrock by past geological activity. The plants that grow above each area are different, because the soil is different, so it creates a sort of barrier even though the two populations could easily meet in their underground tunnels. The researchers have preliminary evidence that female and male mole rats taken from one soil type prefer to mate with each other even in the presence of mole rats from the other soil type. The scientists think that given enough time, these would evolve into separate species, and claims this as an example of sympatric speciation. Not so fast, says Jerry Coyne. Definitive proof would be if the animals were no longer capable of interbreeding. The Israeli scientists are expanding their observation and if they confirm that the mating preferences have changed, this could be clearly considered an example of sympatric speciation. Observable sympatric speciation events are rare, so evolutionary biologists get very excited when they can see this type of evolution in action.
Sexual selection is not responsible for the giraffe’s long neck. Observations about giraffe biology and behavior led many zoologists to propose that the giraffe’s impossibly long neck was the result of sexual selection. Male giraffes battle each other using their necks as sledgehammers, thus, sexual selection would favor those with the most powerful neck, which would win more battles and thus leave more offspring. Before sexual selection was proposed, most zoologists thought that the long neck resulted from competition for food: giraffes with longer necks would be able to reach higher into the trees and thus have access to more resources. A new study about how giraffes’ heads and necks grow points back in the direction of food competition. They examined 65 male and 71 female giraffes from two different populations, and found very small differences between male and female giraffes in terms of skull and neck mass. This goes against the sexual selection explanation, because in that case males would have ended up having longer, heavier necks than females (similar to the antlers of some male deer). In addition, the “necking” battles occur mostly in younger males, and they are contests of dominance and not really to directly gain access to females. The researchers also found no correlation between dominance and neck morphology. Ultimately more data from the fossil record will be needed to give us more clues as to why giraffes ended up with such a long neck. And no, it was not so that they could look out for land on Noah’s arc.
The genome of the domestic pigeon: Darwin was right once again. Charles Darwin was a pigeon fancier, and he maintained that all fancy domestic pigeon breeds derived from the wild rock dove (Columba livia), which is the animal that we mostly call simply "pigeon" (see photo to the left). The traits of fancy domestic pigeon breeds are sometimes so remarkable (see photos below) that many people have argued that other Columba species, in particular Columba rupestris. Scientists have just published in Science a big study sequencing the genomes of street pigeons from the US, and of 36 different fancy breeds. They are al more closely related to each other than to C. rupestris. Basically they are all C. livia. Another interesting discovery from this genetic study is that the head crests (basically feathers that grow in the reverse direction), from the smallest to some outrageously big ones, are all caused by the same recessive mutation, suggesting that the mutation evolved just once within the species.
An experiment with rhesus macaques revealed that they would "pay" to look at pictures of the faces and bottoms of high-ranking females, by forfeiting their usual reward of a glass of cherry juice. With low-ranking females, however, the researchers had to bribe them with an even larger glass of juice before they would pay any attention.
And you ladies think it's just US! We've been telling you for years, it's in our jeans - uh, genes!
Image credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team.
This image obtained by the Hubble Space Telescope shows the galaxy NGC 4526 and its supernova 1994D (lower left).
“Night, when words fade and things come alive. When the destructive analysis of day is done, and all that is truly important becomes whole and sound again.” -Antoine de Saint-Exupery
When you look out into the Universe, what is it that you typically think of? Do you think of reliable, fixed stars and constellations? The vast expanse of the Milky Way, with its memorable dust lanes and amorphous shapes?
The unchanging nature of the points of light in the sky?
Image credit: Roth Ritter (Dark Atmospheres), of the double cluster in Perseus.
Maybe you think deeper and farther than that. Maybe you think about the distant galaxies and clusters, and the deepest deep-sky objects we know of. How the light took millions or even billions of years to reach us, and yet how every time we look at them, we see them exactly the same way.
Image credit: Misti Mountain Observatory.
I couldn’t fault you for thinking like this; from mankind’s point of view, the Universe — for all intents and purposes — doesn’t change at all as we view it from one night to the next.
But does that really mean the Universe isn’t changing?
Let me flip this around on you: how much does anything here on Earth — you, your surroundings, even an entire, vibrant city — change in half-a-millisecond?
Image credit: DC User Forum, of a short-exposure shot with a Sony A900 DSLR.
Not a whole lot, that’s for certain. You only change with the passage of time, and half-a-millisecond is just 0.00000000002% of a typical human lifetime. It’s too short of a timespan to notice any but the most catastrophic changes, and even then you have to look very closely.
So why should you expect the Universe to change substantially over just 0.00000000002% of itslifetime? That’s how much of the Universe’s lifetime passes between one night on Earth and the next. And yet, if you looked at the right objects, you would be able to see meaningful changes from one night to the next.
Image credit: Tunc Tezel.
The objects within our Solar System, for example, are close enough that we can see them moving from night-to-night. Objects closer to us — like Mars, in the foreground — appear to move more substantially than more distant objects like Uranus, visible in the background.
The great cause of all this motion, of course, is our largest nearby clump of matter: the Sun. Objects like planets move at tens of kilometers-per-second relative to the Sun thanks to its gravity, while Sun-grazing comets can be accelerated up to speeds in the hundreds of kilometers-per-second. If you’re in the southern hemisphere, you may be able to get a good view of one now: Comet Lemmon.
Image credit: Rolf Wahl Olsen from Auckland, New Zealand.
Green because of the carbon and nitrogen interacting with sunlight, this photo does an excellent job of tracking the stars from the Earth along with the Earth’s rotation. What you probably can’t tell is that the comet — with a photo exposure time of over an hour — is blurred.
If instead of tracking the stars perfectly, we tracked the comet perfectly, know what we’d see?
Image credit: Peter Ward (Barden Ridge Observatory).
That comet is moving relative to the stars behind it, and our ultra-close proximity to the comet makes it abundantly clear.
But what you may not realize is that these “fixed” stars are also moving at tens-to-hundreds of kilometers-per-second relative to us, and relative to one another! It’s only the vast distances between us — measured in many light-years — that make it impossible to detect these changes from night-to-night.
But we can’t really detect changes in ourselves from millisecond-to-millisecond; you simply need to look on longer timescales!
Image credit: Martha Haynes of Cornell University.
The stars in our night sky shift positions by many kilometers each second. From night-to-night we might not be able to tell the difference, but just as you or I look different when we go weeks without cutting our hair, we can see just how the Universe changes over long enough timescales.
There are gas clouds and stellar remnants tearing through the interstellar medium at these same speeds, including some that move at thousands of kilometers-per-second, even approaching 1% the speed of light!
Image credit: NASA/ESA/Hubble Heritage Team and CTIO.
There are new stars being born — where nuclear fusion ignites for the first time — and stars that run out of fuel, dying in either a planetary nebula or a supernova explosion, depending on the properties of the star.
And on the largest scales, galaxies merge together, triggering star formation and some fabulous cosmic mashups, in processes taking upwards of hundreds-of-millions of years.
Image credit: Hubble Space Telescope, NASA, STScI and ESA.
And in some of the fastest and most spectacular changes, catastrophic stellar events — like supernovae — can literally appear from nothing over the timescale of just a few nights!
Image credit: Peter Nugent/Palomar Transient Factory.
When you look up at the Universe, it may appear static and unchanging, but that’s only because these objects are so far away and our human experiences are so short in comparison with the age of the Universe.
But stick around for a while, and even the most mundane of objects will change for you. Fuel burns, elements fuse, gravity pulls, and physics happens. Just give it time, and you’ll see it for yourself.
We may only be around for a snapshot of it, but make no mistake, it’s never the same from moment-to-moment. From the way I look at it, there isn’t any doubt about it: the Universe is alive.
In tomorrow’s New York Times, I write about what pigeons taught Darwin about evolution, and what they can teach.... The spur for the story is a new paper in which scientists analyze the genomes of forty different pigeon breeds to understand the molecular secrets behind their remarkable diversity. My story is accompanied by some wonderful photosas well as a podcast in which I talk to my editor, David Corcoran, about the research.
Those who have ever been in earshot of me may find this story a bit puzzling. I have ranted many times about all the hoopla that bursts upon us every time the genome of yet another species is sequenced. Eventually my rants crystalized into a self-diagnosis: I realized that I suffered from YAGS, short for Yet-Another-Genome Syndrome. I first identified this disorder here on the Loom, and when I was asked to give a keynote talk at a genome science meeting last year, I explained it at more length. You can see the lecture in this video:
I got the sense from some of the scientists I talked to afterwards that my talk came off a bit nasty. That wasn’t my intention–I was just trying to convey just how exhausted I (and some other journalists I’ve spoken to) have gotten with the endless barrage of press releases that tout new papers on newly sequenced genomes.
It is unquestionably useful for scientists to do this work. The growing database of genomes has become a new territory for biological exploration. In some cases genomes turn out to be especially messy, and in these cases the scientists involved should be commended for their high pain threshold. Some genome studies even lead to fundamentally new methods of DNA sequencing, which is all for the good.
But the mere appearance of a new genome paper is not in itself reason for major news coverage. Nor are promissory notes for how valuable the genome sequences will be in the future. (Let’s wait till the future comes before we start reporting on it, shall we?)
Yet there is, in fact, lots of news about genomes worth reporting. Genome sequencing is getting so ubiquitous that scientists can fold it into their explorations of interesting questions about life. The mere existence of one pigeon genome won’t lead me to write a story. But a study that uses forty pigeon genomes to probe the evolution of new forms? Sign me up. The same goes for my recent Wired feature about using genome sequencing to track hospital outbreaks. The antidote to YAGS, in other words, is witnessing genomes in action.
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