Archive for the ‘Evolution’ Category

Charles Darwin, proponent of the theory of evolution by natural selection.

Nature has a brief and fascinating interview with evolutionary biologist David Sloan Wilson of New York’s Binghamton University. Dr. Wilson is a full time researcher, yet he also spends time injecting evolution into public policy debates. He advocates engaging the general public with evolutionary ideas, and giving evolutionary theories real world relevance for society.

Dr. Wilson’s ideas couldn’t come at a better time. Among Western nations, Americans are famously skeptical of evolution. It was only four years ago that a comprehensive review of surveys on public perceptions of evolution determined that less than half of Americans agreed with the assertion that human beings evolved from other animal species. A mere 14% of the general public believes that evolution is “definitely true.” Of all the Western countries surveyed, only Turkey had a population that was more wary of evolution, while Scandinavian countries had over three-quarters of their citizens accepting evolutionary theory.

Americans have unique historical and sociological reasons for their skepticism and hostility toward evolution. Many have theorized that the strong presence of Protestant fundamentalism in the American tradition decoupled religious learning from the major universities. As a result, whole Protestant groups educated and cultivated clergy and congregations hostile to mainstream Western education ideals and standards, especially in regard to the natural sciences. In addition, in recent decades, the political climate in the United States has added fuel to the notion of evolution as a dangerous, foolhardy, and heretical falsehood. President Reagan famously littered some campaign speeches with the line, “I have no chimpanzees in my family,” to ridicule a whole field of biological study. Some argue that the link between the political right in the United States with hostility toward evolutionary theory was cemented to curry favor among religious fundamentalists. If so, it is an alliance that is noticeably absent in other Western countries. In much of Europe and Japan, far-right political groups are just as a likely to accept evolutionary theory as other segments of the population.

Another reason the American public is so hostile to evolution may be the poor state of scientific literacy in general in the United States. Most Americans have only a minimal scientific education up through high school, barely touching on subjects like evolution, genetics, and inheritance. Beyond high school, most Americans don’t further their scientific education at all. Dr. Wilson’s group at Binghamton University is researching ways to inject evolution back into the day-to-day lives of ordinary Americans. It will be interesting to see if these methods bear fruit, especially since Dr. Wilson himself believes his methods of engagement may not please a prominent pro-evolution group: atheists.

Dr. Wilson is an atheist himself, but does not agree with many “new atheists” who take an openly hostile view to all religious belief. In fact, part of Dr. Wilson’s work looks at the group benefits of religious belief from an evolutionary perspective.

To learn more, read Dr. Wilson’s whole interview with Nature.

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The orca, Orcinus orca, is the “official marine mammal of the State of Washington.” It’s status is even preserved in the Revised Code of Washington. Orcas obtained this rare honor as a symbol of the State of Washington in 2005, when a group of second grade students from Oak Harbor, Washington successfully lobbied the Washington Legislature.

When I was a little kid in the American south and midwest, everyone called them “killer whales.” In the Pacific Northwest, the name orca is preferred in the zeitgeist. However, these marine mammals are not just known in my current home. They swim in every ocean, from the tropics to the polar seas.

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Scientists from the Maryland and California-based J. Craig Venter Institute announced today that they successfully created a partially synthetic lifeform. <a href="Their efforts appear in the journal Science, and include a detailed description of the steps they took to create life.

The lifeform in question is a single-celled bacterium called Mycoplasma mycoides. A bacterial cell, like all living organisms, stores “instructions” or “blueprints” for making and maintaining itself in the form of DNA (deoxyribonucleic acid). DNA is the genome of an organism — it is a long strand of chemicals stored within living cells. In single-celled organisms like bacteria, each cell is an individual, and each cell contains a copy of the genome. The instructions for making and maintaining the cell are “read” from the genome by the cell. Thus, the complex chemicals and molecules that cells make to do work, maintain integrity, survive, and reproduce are all made using these DNA-based “instructions.” When a cell divides, DNA is copied, so that each daughter cell has a complete copy of the genome.

A colony of Mycoplasma mycoides cells.

I harp so much on DNA because much of the work done by the J. Craig Venter Institute centers on the Mycoplasma mycoides genome. Scientists had already “read” the full chemical sequence of the DNA strand (also known as the complete genome sequence) from Mycoplasma mycoides. Researchers at the Venter Institute set out to use that known Mycoplasma mycoides genome sequence to create their own Mycoplasma mycoides cell from scratch.

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Scientists from the University of Utah and Qinghai University Medical School in China’s Qinghai Province have discovered some of the genetic changes that have allowed ethnic Tibetans to survive in the high altitudes of their homeland.

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This image shows a fossil specimen of Archaeopteryx, one of the first birds. Archaeopteryx (“ancient wing”) thrived 145-150 million years ago during the time of the dinosaurs. In fact, all living birds are dinosaur descendants! This particular Archaeopteryx specimen is on display in a Berlin museum.

Several Archaeopteryx fossil specimens (including the specimen pictured above) famously show brilliant impressions of the proto-bird’s elaborate feathers. However, new research has shown that at least one specimen contains more than just impressions of the feathers. There are small chemical traces of the feathers themselves. The specimen in question was discovered in Germany in 2005, and later donated to the Wyoming Dinosaur Center in Thermopolis, Wyoming. Thus, it is often called the “Thermopolis” specimen.

Scientists borrowed the Thermopolis specimen and bombarded it with x-rays at the Stanford Linear Accelerator in California. The x-ray data provided new data on the fossil’s chemical composition, and revealed those unexpected chemical traces of the specimen’s feathers and bone. The findings, published recently in the Proceedings of the National Academy of Sciences of the United States of America, has revealed many more bird-like characteristics of Archaeopteryx. Scientists announced that Archaeopteryx and modern birds both have similar bone chemistry, and likely similar nutritional needs. Owners of pet birds, for example, might know that copper and zinc are essential minerals in pet bird diets. Archaeopteryx may have had similar nutritional needs.

These new findings are as amazing as they are tragic. Traditionally, fossils weren’t thought to contain chemical traces of the original organism. Thus, curators preparing fossil specimens for display typically didn’t treat fossils to preserve these chemical signatures. Thus, for many other Archaeopteryx specimens that have been studied and put on display, handlers and curators have likely inadvertently swept away these chemical traces. It was only by luck that a few portions of the Thermopolis specimen of Archaeopteryx had not been handled too roughly.

This new look at Archaeopteryx fossils is breathing new live into paleontology — but from a chemical perspective. Expect chemical analyses of other fossil specimens in the future. Some even speculate that the right fossil sample may even preserve another mystery about this early bird: the color of its feathers. Stay tuned.

Image provided courtesy of H. Raab.

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New analyses of genes from modern humans and extinct neanderthals have revealed something remarkable: some of us have a tiny amount of neanderthal ancestry.

Neanderthals were a group of hominids (human-like great apes) who last shared a common ancestor with all modern humans over 500,000 years ago. Based on fossil records, neanderthals lived primarily in Europe and some parts of Asia. For most of neanderthal history, we humans occupied parts of Africa. However, a small group of humans left Africa in a series of migration waves starting 50,000 to 80,000 years ago. As humans migrated out of Africa, neanderthal numbers declined. Neanderthals ultimately died out sometime around 30,000 years ago. However, the timing and cause of our robust cousin’s disappearance is a matter of intense debate, as is their interaction with modern humans as they left Africa and spread to Eurasia, Oceania, and the Americas.

  • As humans migrated out of Africa, did they interact with neanderthals?
  • Did ancient humans breed with neanderthals?
  • If ancient humans bred with neanderthals, did this breeding extend to human populations who remained in Africa?
  • (more…)

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New research published in the journal Nature Genetics is shedding more light on adaptations that allowed woolly mammoths to thrive in frigid latitudes during our planet’s recent ice ages. Woolly mammoths (Mammuthus primigenius) inhabited extreme northern latitudes starting about 150,000 years ago, and died out approximately 10,000 years ago. To study the cold adaptations of this mammal, scientists had to do something remarkable: they rebuilt a blood protein from this extinct species.

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One of the fascinating puzzles of evolutionary biology is how old structures change over time to acquire new functions or features. We can ask the “how” on multiple levels:

  • What genetic changes occurred?
  • What physiological changes occurred?
  • Did ecological factors contribute?
  • How quickly did the new function or feature arise?

The list of questions can go on and on.  However, scientists don’t always have tools at their disposal to answer everything.  For extinct organisms, we have only the fossil record.  Molecular biologists like me don’t get DNA to play with in those cases (usually). Physiologists don’t get muscle and bone samples. Thus, we can’t fully answer how whale fins developed from an ancestor who walked on solid ground. Though we have whales here today, all those walking ancestors died millions of years ago.

But, even with these limitations, we can still learn something about how older structures can change to acquire new functions. Recently, two biologists published an account of a “new” feature derived from an “old” structure: the cobra’s hood. In cobras and several other groups of snakes, the ribs, muscles, and skin near the head and neck (as much as snakes have a neck) can spread out away from the body’s core, forming an elaborate display hood when the animal is startled or threatened.

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In 2007, a reindeer herder and his two sons found this remarkably well-preserved baby woolly mammoth frozen solid in the Yamal-Nenets Autonomous Okrug (District) in northern Russia. The herder named her (for it is indeed a she) Lyuba, after his wife. The International Mammoth Committee, a consortium of scientists dedicated to the preservation and study of mammoth remains, has safeguarded and studied Lyuba ever since. Usually quartered at the Shemanovsky Yamal-Nenets Museum and Exhibition Centre in Salekhard, Russia, she is beginning a tour across the United States. Her first stop is Chicago’s Field Museum of Natural History.

Scientists report that Lyuba lived a tragically short life. Yet, the unique circumstances of her death have permitted us to learn a great deal about her mammoth kin, who roamed the planet as recently as ten millennia ago. Some 42,000 years ago, when Lyuba was just one month old and still nursing on her mother’s milk, fell into a muddy river bank. Struggling in vain to free herself, she sank and suffocated in the muck. Her remains froze in the permafrost, slowing decay and preserving soft tissue, skin, hair, and even stomach contents.

In short, Lyuba (pronounced Lee-OO-bah) is a rare and Earth-shattering find. As far as mammoth remains go, we’re used to finding skeletons, occasionally clumps of hair or tissue, or one or two mummified remains. A whole frozen animal can (and in this case, has) revealed a lot. CAT and MRI scans of her soft tissues have shown us how her innards are arranged. Stomach contents revealed that she’d still been nursing when she died. Hair and skin samples have even given molecular biologists like me something to drool over: a rare specimen of intact mammoth DNA!

Lyuba’s tour of the United States will hopefully draw attention to the problems faced by the International Mammoth Committee. Most woolly mammoth specimens (skeletal or otherwise) that have been recovered frozen and relatively well-preserved in permafrost. However, as Siberian permafrost melts for good, no one knows how many undiscovered mammoth specimens there are that will begin to thaw and decay. The International Mammoth Committee is racing against time to unearth mammoth remains and preserve them for study. Otherwise, we’ll only have a handful of samples like Lyuba to help us understand these elephant relatives that roamed the northern latitudes with our ancestors.

If you find yourself in Chicago up through 6 September 2010, head on over to the Field Museum and see Lyuba for yourself. The exhibit will also go to Boston, Jersey City, Saint Louis, Denver, San Diego, and Anchorage.

Image of Lyuba, a one-month old female woolly mammoth (Mammuthus primigenius) preserved by Siberian permafrost, is provided courtesy of the International Mammoth Committee and Francis Latreille.

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I’ve been so busy this past week that I completely missed the exciting news from the world of biology: a second bird genome has been sequenced. A genome is the sum of all the genetic material in an individual or organism — all the genes, all the regulatory sequences that control when and where genes are turned on, and all the other DNA sequences that might have a purpose we don’t yet know about. While a good number of genomes of vertebrates (backboned animals) have been sequenced1, up until now the chicken had been the sole bird to have its genome sequenced.

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