Posts about evolution

Human Gene Origins: 37% Bacterial, 35% Animal, 28% Eukaryotic

The percent of human genes that emerged in various stages of evolution: 37% bacterial, 28% eukaryotic, 16% animal, 13% vertebrate, 6% primate. The history that brought us to where we are is amazing. Eukaryotes include animals, plants, amoebae, flagellates, amoeboflagellates, fungi and plastids (including algae). So eukaryotic genes are those common to us and other non-animal eukaryotes while those classified as animal genes are shared by animals but not non-animal eukaryotes.

We are living in a bacterial world, and it’s impacting us more than previously thought by Lisa Zyga

Bacterial signaling is not only essential for development, it also helps animals maintain homeostasis, keeping us healthy and happy. As research has shown, bacteria in the gut can communicate with the brain through the central nervous system. Studies have found that mice without certain bacteria have defects in brain regions that control anxiety and depression-like behavior. Bacterial signaling also plays an essential role in guarding an animal’s immune system. Disturbing these bacterial signaling pathways can lead to diseases such as diabetes, inflammatory bowel disease, and infections. Studies also suggest that many of the pathogens that cause disease in animals have “hijacked” these bacterial communication channels that originally evolved to maintain a balance between the animal and hundreds of beneficial bacterial species.

Scientists have also discovered that bacteria in the human gut adapts to changing diets. For example, most Americans have a gut microbiome that is optimized for digesting a high-fat, high-protein diet, while people in rural Amazonas, Venezuela, have gut microbes better suited for breaking down complex carbohydrates. Some people in Japan even have a gut bacterium that can digest seaweed. Researchers think the gut microbiome adapts in two ways: by adding or removing certain bacteria species, and by transferring the desired genes from one bacterium to another through horizontal gene transfer. Both host and bacteria benefit from this kind of symbiotic relationship, which researchers think is much more widespread than previously thought.

We want badly for the message in ‘Animals in a bacterial world,’ to be a call for the necessary disappearance of the old boundaries between life science departments (e.g., Depts of Zoology, Botany, Microbiology, etc.) in universities, and societies (e.g., the American Society for Microbiology, etc.). We also want the message disseminated in college and university classes from introductory biology to advanced courses in the various topic areas of our paper.”

Very cool stuff. This amazing facts scientists discover provide an amazing view of the world we live in and how interconnected we are to other life forms in ways we don’t normally think of.

Related: People’s Bodies Carry More Bacterial Cells than Human CellsMicrobes Flourish In Healthy PeopleTracking the Ecosystem Within UsForeign Cells Outnumber Human Cells in Our BodiesBacteria Beneficial to Human Health

Evolution Follows a Predictable Genetic Pattern

Far from random, evolution follows a predictable genetic pattern

The researchers carried out a survey of DNA sequences from 29 distantly related insect species, the largest sample of organisms yet examined for a single evolutionary trait. Fourteen of these species have evolved a nearly identical characteristic due to one external influence — they feed on plants that produce cardenolides, a class of steroid-like cardiotoxins that are a natural defense for plants such as milkweed and dogbane.

Though separated by 300 million years of evolution, these diverse insects — which include beetles, butterflies and aphids — experienced changes to a key protein called sodium-potassium adenosine triphosphatase, or the sodium-potassium pump, which regulates a cell’s crucial sodium-to-potassium ratio. The protein in these insects eventually evolved a resistance to cardenolides, which usually cripple the protein’s ability to “pump” potassium into cells and excess sodium out.

Andolfatto and his co-authors examined the sodium-potassium pump protein because of its well-known sensitivity to cardenolides. In order to function properly in a wide variety of physiological contexts, cells must be able to control levels of potassium and sodium. Situated on the cell membrane, the protein generates a desired potassium to sodium ratio by “pumping” three sodium atoms out of the cell for every two potassium atoms it brings in.

Cardenolides disrupt the exchange of potassium and sodium, essentially shutting down the protein, Andolfatto said. The human genome contains four copies of the pump protein, and it is a candidate gene for a number of human genetic disorders, including salt-sensitive hypertension and migraines. In addition, humans have long used low doses of cardenolides medicinally for purposes such as controlling heart arrhythmia and congestive heart failure.

Cool stuff. It makes sense to me which is nice (it is nice to get confirmation that I find what actually exists is sensible). When things that are true just seem crazy it is a bit disconcerting – like quantum mechanics. It is fun to read stuff that totally shakes up preconceived notions, but even then it is nice once I think understand it to find it sensible.

Related: All present-day Life on Earth Has A Single AncestorCambrian Explosion SongBacteriophages: The Most Common Life-Like Form on EarthMicrocosm by Carl Zimmer

Learning About Life over 200 Million Years Ago From Samples Trapped In Amber

230-Million-Year-Old Mite Found in Amber by Charles Choi

One way to learn more about prehistoric life is amber — fossilized tree resin. Before it hardened, this ooze often dripped over bugs and other wildlife perched on its tree’s bark, entombing them for millions of years.

“Amber is an extremely valuable tool for paleontologists because it preserves specimens with microscopic fidelity, allowing uniquely accurate estimates of the amount of evolutionary change over millions of years,” Grimaldi said.

Scientists have now revealed arthropods trapped in 230-million-year-old amber from northeastern Italy, which appears to hold the most abundant outcrops of Triassic amber in the world. These are the oldest amber-trapped arthropods by about 100 million years, and are the first arthropods to be found in amber from the Triassic.

These mites are unexpectedly similar to their closest relatives, modern gall mites, creatures that feed on plants and cause abnormal growths known as galls to form around them.

“You would think that by going back to the Triassic you’d find a transitional form of gall mite, but no,” Grimaldi said. “Even 230 million years ago, all of the distinguishing features of this family were there — a long, segmented body; only two pairs of legs instead of the usual four found in mites; unique feather claws.”

These discoveries are very cool. The process of the discovery is often fairly tedious.

“The challenge for us, personally, is the tedious work required to screen through so many tiny droplets of amber — 70,000 droplets for three specimens, in this case!”

Related: Marine Plankton From 100 Million Years Ago Found in AmberDino-Era Feathers Found Encased in AmberAmber Pieces Containing Remains from Dinosaurs and Birds Show Feather Evolution

Our Dangerous Antibiotic Practices Carry Great Risks

Our continued poor antibiotics practices increase the risk of many deaths. We are very poor at reacting to bad practices that will kill many people in the future. If those increased deaths happened today it is much more likely we would act. But as it is we are condemning many to have greatly increased odds of dying from bacterial causes that could be prevented if we were more sensible.

Resistance to antibiotics is becoming a crisis

Increasingly, microbes are becoming untreatable. Margaret Chan, director general of the World Health Organization, warned in March of a dystopian future without these drugs. “A post-antibiotic era means, in effect, an end to modern medicine as we know it,” she said. “Things as common as strep throat or a child’s scratched knee could once again kill.”

evidence is mounting that antibiotics are losing efficacy. Through the relentless process of evolution, pathogens are evading the drugs, a problem known broadly as antimicrobial resistance.

Europe has launched a $741 million, seven-year, public-private collaborative research effort to accelerate drug development.

Seeking new antibiotics is wise but the commentary completely ignores our bad practices that are causing the problem to be much worse than it would be if we acted as though bad practices that will lead to many deaths should be avoided.

Previous posts about practices we taking that create great risk for increased deaths: Antibiotics Too Often Prescribed for Sinus Woes (2007)Meat Raised Without Antibiotics is Sadly Rare Today (2007)Overuse of Antibiotics (2005)CDC Urges Increased Effort to Reduce Drug-Resistant Infections (2006)FDA May Make Decision That Will Speed Antibiotic Drug Resistance (2007)Antibacterial Soaps are Bad (2007)Waste Treatment Plants Result in Super Bacteria (2009)Antibiotics Breed Superbugs Faster Than Expected (2010)Antibiotics Use in Farming Can Create Superbugs (2010)What Happens If the Overuse of Antibiotics Leads to Them No Longer Working? (2011)Dangerous Drug-Resistant Strains of TB are a Growing Threat (2012)

Obviously bacteria evolve to survive the counter measures we currently have. The foolish practices of promoting ignorance of evolution leads to a society where the consequences of actions, and the presence of evolution, lead to bad consequences. We find ourselves in that society.

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Scientists Singing About Science

Fun video with scientists singing about science.

More scientists singing science songs: Friday Fun, Large Hadron RapCambrian Explosion SongThe Sun is a Miasma of Incandescent PlasmaProtein Synthesis: 1971 Video

Friday Fun: Exercise Wheels for Dogs and Cats

This would certainly give dogs that don’t have big enough yards to run in some good exercise.

Cats don’t seem to take to the wheels as naturally as a few dogs do. While the wheel is odd no matter what I would also wager the evolution of the animals is at play. Cats are use to stalking animals. You can see that trait play out in the kitten video above (and lots of other similar videos – so while this one is partially the kittens short attention span it also seems common that cats don’t just run for a long time). While dogs are evolved to wear our their prey in log distance chases. I’m sure getting dogs to use a wheel isn’t likely to be super easy but I think it will be easier than getting cats to do so.

Related: Kittens Reminding You to Thank Your MotherFriday Escape Dog FunFriday Cat Fun: Treadmill CatsDog and Duckling Fun

Our Genome Has Adopted Virus Genes Critical to Our Survival

Mammals Made By Viruses by Carl Zimmer

Viruses have insinuated themselves into the genome of our ancestors for hundreds of millions of years. They typically have gotten there by infecting eggs or sperm, inserting their own DNA into ours. There are 100,000 known fragments of viruses in the human genome, making up over 8% of our DNA. Most of this virus DNA has been hit by so many mutations that it’s nothing but baggage our species carries along from one generation to the next. Yet there are some viral genes that still make proteins in our bodies. Syncytin appeared to be a hugely important one to our own biology. Originally, syncytin allowed viruses to fuse host cells together so they could spread from one cell to another. Now the protein allowed babies to fuse to their mothers.

The big picture that’s now emerging is quite amazing. Viruses have rained down on mammals, and on at least six occasions, they’ve gotten snagged in their hosts and started carrying out the same function: building placentas.

Some mammals that scientists have yet to investigate, such as pigs and horses, don’t have the open layer of cells in their placenta like we do. Scientists have come up with all sorts of explanations for why that may be, mainly by looking for differences in the biology of each kind of mammals. But the answer may be simpler: the ancestors of pigs and horses might never have gotten sick with the right virus.

More amazing facts from science. This stuff is so interesting. Carl Zimmer is a fantastic science writer and he has written several great science books.

Related: Amazing Science, RetrovirusesMicrocosm by Carl ZimmerTen Things Everyone Should Know About ScienceParasite Rex

Amber Pieces Containing Remains from Dinosaurs and Birds Show Feather Evolution

Dinosaur feather evolution trapped in Canadian amber

a study of amber found near Grassy Lake in Alberta – dated from what is known as the Late Cretaceous period – has unearthed a full range of feather structures that demonstrate the progression. “We’re finding two ends of the evolutionary development that had been proposed for feathers trapped in the same amber deposit,” said Ryan McKellar of the University of Alberta, lead author of the report.

The team’s find confirms that the filaments progressed to tufts of filaments from a single origin, called barbs. In later development, some of these barbs can coalesce into a central branch called a rachis. As the structure develops further, further branches of filments form from the rachis.

“We’ve got feathers that look to be little filamentous hair-like feathers, we’ve got the same filaments bound together in clumps, and then we’ve got a series that are for all intents and purposes identical to modern feathers,” Mr McKellar told BBC News.

“We’re catching some that look to be dinosaur feathers and another set that are pretty much dead ringers for modern birds.”

a picture is emerging that many dinosaurs were not the dull-coloured, reptilian-skinned creatures that they were once thought to be. “If you were to transport yourself back 80 million years to western North America and walk around the forest… so many of the animals would have been feathered,” said Dr Norell.

“We’re getting more and more evidence… that these animals were also brightly coloured, just like birds are today.”

Very cool. Science really is great.

Related: Dino-Era Feathers Found Encased in Amber (2008)Dinosaur Remains Found with Intact Skin and TissueMarine Plankton From 100 Million Years Ago Found in AmberGiant Duck-Billed Dinosaur Discovered in Mexico

Evolution in New York City Wildlife

Evolution Right Under Our Noses by Carl Zimmer

White-footed mice, stranded on isolated urban islands, are evolving to adapt to urban stress. Fish in the Hudson have evolved to cope with poisons in the water. Native ants find refuge in the median strips on Broadway. And more familiar urban organisms, like bedbugs, rats and bacteria, also mutate and change in response to the pressures of the metropolis. In short, the process of evolution is responding to New York and other cities the way it has responded to countless environmental changes over the past few billion years. Life adapts.

Dr. Wirgin and his colleagues were intrigued to discover that the Hudson’s population of tomcod, a bottom-dwelling fish, turned out to be resistant to PCBs. “There was no effect on them at all,” Dr. Wirgin said, “and we wanted to know why.”

In March, he and his colleagues reported that almost all the tomcod in the Hudson share the same mutation in a gene called AHR2. PCBs must first bind to the protein encoded by AHR2 to cause damage. The Hudson River mutation makes it difficult for PCBs to grab onto the receptor, shielding the fish from the chemical’s harm.

The AHR2 mutation is entirely missing from tomcod that live in northern New England and Canada. A small percentage of tomcod in Long Island and Connecticut carry the mutation. Dr. Wirgin and his colleagues concluded that once PCBs entered the Hudson, the mutant gene spread quickly.

Carl Zimmer again does a good job of explaining science in an engaging way. It is interesting to learn about science and evolution in urban environments. Lots of life manages to survive the challenges of urban life and it is interesting to learn what scientists are finding about that life.

Related: Trying to Find Pest Solutions While Hoping Evolution Doesn’t Exist Doesn’t WorkMicrocosm by Carl ZimmerNew Yorkers Help Robot Find Its Way in the Big CityParasite RexBackyard Wildlife: Great Spreadwing Damselfly

Cambrian Explosion Song

via Smithsonian’s Surprising Science:

What does a music teacher do when he ends up teaching science? He teaches about evolution and the geologic timeline with music, of course, and that’s what Canadian elementary school teacher John Palmer did. He originally played “Cambrian Explosion” as a rock/hip hop creation in class but has since recorded an acoustic version. (The trio is called Brighter Lights, Thicker Glasses and consists of Palmer on the guitar/vocals, Michael Dunn on the dobro and Brian Samuels [from UBC civil engineering department] on the cello.)

The video was filmed in the Beaty Biodiversity Museum (Canada) atrium with the blue whale exhibit in the background.

Related: Test it Out, Experiment by They Might Be GiantsHere Comes Science by They Might Be GiantsLobopodians from China a Few Million Years AgoGoogle Art Project: View Art from the Hermitage, the Met, etc.

Evolution of Altruism in Robots

The webcast explores robots evolving cooperative behavior. A Quantitative Test of Hamilton’s Rule for the Evolution of Altruism (open access paper)

One of the enduring puzzles in biology and the social sciences is the origin and persistence of altruism, whereby a behavior benefiting another individual incurs a direct cost for the individual performing the altruistic action. This apparent paradox was resolved by Hamilton’s theory, known as kin selection, which states that individuals can transmit copies of their own genes not only directly through their own reproduction but also indirectly by favoring the reproduction of kin, such as siblings or cousins. While many studies have provided qualitative support for kin selection theory, quantitative tests have not yet been possible due to the difficulty of quantifying the costs and benefits of helping acts. In this study, we conduct simulations with the help of a simulated system of foraging robots to manipulate the costs and benefits of altruism and determine the conditions under which altruism evolves.

By conducting experimental evolution over hundreds of generations of selection in populations with different costs and benefits of altruistic behavior, we show that kin selection theory always accurately predicts the minimum relatedness necessary for altruism to evolve. This high accuracy is remarkable given the presence of pleiotropic and epistatic effects, as well as mutations with strong effects on behavior and fitness. In addition to providing a quantitative test of kin selection theory in a system with a complex mapping between genotype and phenotype, this study reveals that a fundamental principle of natural selection also applies to synthetic organisms when these have heritable properties.

Related: Robots That Start as Babies Master Walking Faster Than Those That Start as AdultsFriday Fun: Robocup 2010, Robot FootballToyota Develops Thought-controlled Wheelchair
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