Category: Evolution

45,000 Year Old Human Genome Sequenced

(p. A14) Scientists have reconstructed the genome of a man who lived 45,000 years ago, by far the oldest genetic record ever obtained from modern humans. The research, published on Wednesday [October 22, 2014] in the journal Nature, provided new clues to the expansion of modern humans from Africa about 60,000 years ago, when they moved into Europe and Asia.
And the genome, extracted from a fossil thighbone found in Siberia, added strong support to a provocative hypothesis: Early humans interbred with Neanderthals.
“It’s irreplaceable evidence of what once existed that we can’t reconstruct from what people are now,” said John Hawks, a paleoanthropologist at the University of Wisconsin who was not involved in the study. “It speaks to us with information about a time that’s lost to us.”
. . .
By comparing the Ust’-Ishim man’s long stretches of Neanderthal DNA with shorter stretches in living humans, Dr. Paabo and his colleagues estimated the rate at which they had fragmented. They used that information to determine how long ago Neanderthals and humans interbred.
Previous studies, based only on living humans, had yielded an estimate of 37,000 to 86,000 years. Dr. Paabo and his colleagues have now narrowed down that estimate drastically: Humans and Neanderthals interbred 50,000 to 60,000 years ago, according to the new data.

For the full story, see:
Carl Zimmer. “Man’s Genome From 45,000 Years Ago Is Reconstructed.” The New York Times (Thurs., OCT. 23, 2014): A14.
(Note: ellipsis, and bracketed date, added.)
(Note: the online version of the story has the date OCT. 22, 2014.)

Evidence Some Flies Can Adapt to Climate Change

(p. D7) In the early 2000s, Ary A. Hoffmann, a biologist then at La Trobe University in Melbourne, Australia, wondered how the many species in tropical rain forests would cope when their humid environment dried out.
. . .
. . . at the end of the experiment, the flies were no more resistant to dry air than their forebears. The flies seemed to lack the genetic potential to evolve. Those results suggested that if the rain forest home of Drosophilia birchii loses its high humidity, the flies will die off.
. . .
Recently, two of Dr. Hoffmann’s collaborators — Belinda van Heerwaarden and Carla M. Sgrò of Monash University — decided to rerun the experiment, but with a crucial twist.
Rather than expose the flies to 10 percent relative humidity, Dr. van Heerwaarden and Dr. Sgrò tried 35 percent. That’s still far drier than the moist air of rain forests, but it’s not the aridity one might encounter on a summer day in Death Valley.
“It’s a humidity that’s more relevant to the predictions for how dry the environment would become in the next 30 to 50 years,” Dr. Sgrò said.
. . .
Unlike the flies in the earlier studies, it didn’t take long for these to start evolving. After just five generations, one species was able to survive 23 percent longer in 35 humidity.

For the full story, see:
Carl Zimmer. “MATTER; Study Gives Hope of Adaptation to Climate Change.” The New York Times (Tues., JULY 29, 2014): D7.
(Note: ellipses added.)
(Note: the online version of the story has the date JULY 24, 2014.)

The recent paper discussed above, is:
van Heerwaarden, Belinda, and Carla M. Sgrò. “Is Adaptation to Climate Change Really Constrained in Niche Specialists?” Proceedings of the Royal Society B: Biological Sciences 281, no. 1790 (2014): 1-1.

Variable Gene Expression Gives Us “Surprising Resilience”

(p. 11) As a physician who researches and treats rare genetic disorders, Sharon Moalem, the author of “Inheritance,” sees firsthand how sharply DNA can constrain our lives. Yet “our genes aren’t as fixed and rigid as most of us have been led to believe,” he says, for while genetic defects often create havoc, variable gene expression (our genes’ capacity to respond to the environment with a flexibility only now being fully recognized) can give our bodies and minds surprising resilience. In his new book, Moalem describes riveting dramas emerging from both defective genes and reparative epigenetics.
. . .
Moalem’s earthy, patient-focused account reminds us that whatever its promise, genetics yet stands at a humble place.

For the full review, see:
DAVID DOBBS. “The Fault in Our DNA.” The New York Times Book Review (Sun., July 13, 2014): 11.
(Note: ellipsis added.)
(Note: the online version of the review has the date July 10, 2014.)

Book under review:
Moalem, Sharon. Inheritance: How Our Genes Change Our Lives–and Our Lives Change Our Genes. New York: Grand Central Publishing, 2014.

Theory Said Giant Bird Could Not Fly, But It Flew Anyway

(p. A3) Scientists have identified the largest flying bird ever found–an ungainly glider with a wingspan of 21 feet or more that likely soared above ancient seas 25 million years ago.
Until now, though, it was a bird that few experts believed could get off the ground. By the conventional formulas of flight, the extinct sea bird–twice the size of an albatross, the largest flying bird today–was just too heavy to fly on its long, fragile wings.
But a new computer analysis reported Monday [July 7, 2014] in the Proceedings of the National Academy of Sciences shows that the bird apparently could ride efficiently on rising air currents, staying aloft for a week or more at a stretch.
. . .
“You have to conclude that this animal was capable of flapping its wings and taking off, even though it is much heavier than the theoretical maximum weight of a flapping flying bird,” said Luis Chiappe, an expert on flight evolution at the Los Angeles County Natural History Museum, who wasn’t involved in the project. “Our modern perspective on the diversity of flight is rather narrow,” he said. “These were very unique birds.”
. . .
“This was a pretty impressive creature,” said avian paleontologist Daniel T. Ksepka at the Bruce Museum in Greenwich, Conn., who conducted the analysis of the bird’s biomechanics. “Science had made a rule about flight, and life found a way around it.”

For the full story, see:
ROBERT LEE HOTZ. “U.S. NEWS; Giant Bird Was Able to Fly, Scientists Find; Computer Analysis Shows Ancient Glider Could Get Off the Ground, Defying Conventional Theories of Flight.” The Wall Street Journal (Tues., July 8, 2014): A3.
(Note: ellipses, and bracketed date, added.)
(Note: the online version of the article has the date July 7, 2014.)

Reigning Intellectual Orthodoxy on Race Is Wrong

ATroublesomeInheritanceBK2014-06-05.jpg

Source of book image: http://ecx.images-amazon.com/images/I/41BYpEQumNL._.jpg

(p. C5) The reigning intellectual orthodoxy is that race is a “social construct,” a cultural artifact without biological merit.

The orthodoxy’s equivalent of the Nicene Creed has two scientific tenets. The first, promulgated by geneticist Richard Lewontin in “The Apportionment of Human Diversity” (1972), is that the races are so close to genetically identical that “racial classification is now seen to be of virtually no genetic or taxonomic significance.” The second, popularized by the late paleontologist Stephen Jay Gould, is that human evolution in everything but cosmetic differences stopped before humans left Africa, meaning that “human equality is a contingent fact of history,” as he put it in an essay of that title in 1984.
Since the sequencing of the human genome in 2003, what is known by geneticists has increasingly diverged from this orthodoxy, even as social scientists and the mainstream press have steadfastly ignored the new research. Nicholas Wade, for more than 20 years a highly regarded science writer at the New York Times, has written a book that pulls back the curtain.
It is hard to convey how rich this book is. It could be the textbook for a semester’s college course on human evolution, systematically surveying as it does the basics of genetics, evolutionary psychology, Homo sapiens’s diaspora and the recent discoveries about the evolutionary adaptations that have occurred since then. The book is a delight to read–conversational and lucid. And it will trigger an intellectual explosion the likes of which we haven’t seen for a few decades.
The title gives fair warning: “A Troublesome Inheritance: Genes, Race and Human History.” At the heart of the book, stated quietly but with command of the technical literature, is a bombshell. It is now known with a high level of scientific confidence that both tenets of the orthodoxy are wrong.

For the full review, see:
CHARLES MURRAY. “The Diversity of Life; A scientific revolution is under way–upending one of our reigning orthodoxies.” The Wall Street Journal (Sat., May 3, 2014): C5 & C7.
(Note: ellipses added.)
(Note: the online version of the review has the date May 2, 2014, and has the title “Book Review: ‘A Troublesome Inheritance’ by Nicholas Wade; A scientific revolution is under way–upending one of our reigning orthodoxies.”)

The book under review is:
Wade, Nicholas. A Troublesome Inheritance: Genes, Race and Human History. New York: The Penguin Press, 2014.

Some Birds “with Higher Radiation Exposure May Show Greater Adaptation”

MousseauTimothyStudiesBatsAtChernobyl2014-05-31.jpg With an unfinished cooling tower at the Chernobyl plant in the background, Timothy Mousseau, right, and an assistant set out microphones to study bats in the contaminated area.” Source of caption and photo: online version of the NYT article quoted and cited below.

(p. D1) In dozens of papers over the years Dr. Mousseau, his longtime collaborator, Anders Pape Moller of the National Center for Scientific Research in France, and colleagues have reported evidence of radiation’s toll: . . .

(p. D2) But their most recent findings, published last month, showed something new. Some bird species, they reported in the journal Functional Ecology, appear to have adapted to the radioactive environment by producing higher levels of protective antioxidants, with correspondingly less genetic damage. For these birds, Dr. Mousseau said, chronic exposure to radiation appears to be a kind of “unnatural selection” driving evolutionary change.
. . .
The findings . . . suggest that in some cases radiation levels might have an inverse effect — birds in areas with higher radiation exposure may show greater adaptation, and thus less genetic damage, than those in areas with lower radiation levels.
Like almost all of the studies by Dr. Mousseau and his colleagues, the latest one takes advantage of the unique circumstances of the Chernobyl exclusion zone as a real-world laboratory. “Nature is a much more stressful environment than the lab,” Dr. Mousseau said.

For the full story, see:
HENRY FOUNTAIN. “Adapting to Chernoby.” The New York Times (Tues., MAY 6, 2014): D1 & D2.
(Note: ellipses added.)
(Note: the online version of the story has the date MAY 5, 2014, and has the title “At Chernobyl, Hints of Nature’s Adaptation.”)

The research discussed above is more fully elaborated in:
Galván, Ismael, Andrea Bonisoli-Alquati, Shanna Jenkinson, Ghanem Ghanem, Kazumasa Wakamatsu, Timothy A. Mousseau, and Anders P. Møller. “Chronic Exposure to Low-Dose Radiation at Chernobyl Favours Adaptation to Oxidative Stress in Birds.” Functional Ecology (Early View published online on May 17, 2014).

More Evidence that Humans May Not Have Killed Off the Woolly Mammoth After All

On April 20, 2014 I posted an entry citing research that humans may not have been the main cause of the extinction of the mammoths. The article quoted below provides further evidence:

(p. D2) Many woolly mammoths from the North Sea had a superfluous rib attached to their seventh vertebra, a sign that they suffered from inbreeding and harsh conditions during pregnancy, researchers report.

This may have contributed to their eventual extinction, say the scientists who looked at fossil samples that date to the late Pleistocene age, which ended about 12,000 years ago.
. . .
Woolly mammoths died out 12,000 to 10,000 years ago, when flowery plant covers disappeared from the tundra. Human hunting may also have contributed to their demise.
But the cervical ribs are a clear indication that “they were already struggling before that,” Dr. Galis said.

For the full story, see:
SINDYA N. BHANOO. “Observatory; In Extra Rib, a Harbinger of Mammoth’s Doom.” The New York Times (Tues., April 1, 2014): D2.
(Note: ellipsis added.)
(Note: the online version of the commentary has the date MARCH 31, 2014.)

The mammoth research summarized above was published in:
Reumer, Jelle W.F., Clara M.A. ten Broek, and Frietson Galis. “Extraordinary Incidence of Cervical Ribs Indicates Vulnerable Condition in Late Pleistocene Mammoths.” PeerJ (2014).

Humans May Not Have Killed Off the Woolly Mammoth After All

MammothTusk2014-04-10.jpg “A mammoth tusk.” Source of caption and photo: online version of the NYT article quoted and cited below.

(p. D2) A 50,000 year analysis of Arctic vegetation history reveals that a change in diet may have led to the demise of the woolly mammoth, the woolly rhinoceros and other large animals, according to a study in the journal Nature. About 10,000 years ago in the Arctic steppe, grasslands began to replace forbs, a flowery plant cover. Animals may have relied on forbs as a source of protein.

For the original story, see:
“‘Observatory; Tiny Plants’ Loss May Have Doomed Mammoths.” The New York Times (Tues., FEB. 11, 2014): D2.
(Note: Sindya N. Bhanoo is listed as the author of the second “Observatory” short entry, but it is not at all clear if that is intended to imply that she also is author of the first “Observatiory” short entry on the “Tiny Plants Loss . . . ” Her name does not appear anywhere in the online version.)
(Note: the online version of the interview has the date FEB. 10, 2014, and has the title “‘SCIENCE; Tiny Plants’ Loss May Have Doomed Mammoths.” )

The study in Nature mentioned above, is:
Willerslev, Eske, John Davison, Mari Moora, Martin Zobel, Eric Coissac, Mary E. Edwards, Eline D. Lorenzen, Mette Vestergård, Galina Gussarova, James Haile, Joseph Craine, Ludovic Gielly, Sanne Boessenkool, Laura S. Epp, Peter B. Pearman, Rachid Cheddadi, David Murray, Kari Anne Bråthen, Nigel Yoccoz, and Heather Binney. “Fifty Thousand Years of Arctic Vegetation and Megafaunal Diet.” Nature 506, no. 7486 (Feb. 6, 2014): 47-51.

Dinosaurs Show that Size Does Not Assure Success, or Even Survival

(p. 504) If the Museum of Natural History was going to be, as Carnegie intended, a world-class institution, it needed more than mummies, ana-(p. 505)tomical models, and Appalachian minerals. It had to have a dinosaur or two. The dinosaur was more than simply a crowd-pleaser. For Carnegie and other devotees of evolutionary science, it was an apt symbol of the unpredictability of a universe in which species and races fell into extinction when they failed to adapt to new environments. For men of slight stature, such as Carnegie, there must have been something quite enthralling about this most vivid demonstration that size and power did not guarantee survival.

Source:
Nasaw, David. Andrew Carnegie. New York: Penguin Press, 2006.
(Note: the pagination of the hardback and paperback editions of Nasaw’s book are the same.)

Some Dogs, Like Humans, Thrive If They Have a Project

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Source of book image: http://www.stephthebookworm.com/wp-content/uploads/2013/12/What-the-Dog-Knows.jpg

(p. 40) Warren, a science journalism professor at North Carolina State University, never dreamed of becoming a cadaver dog handler, searching woods and rubble for dead bodies. She just wanted a new German shepherd puppy after the death of her saintly dog Zev. What she got was Solo: “a maniacal clown,” loving and intensely smart, but “an unpredictable sociopath with other dogs.” . . .

. . . Fortunately, Warren understood behavior issues are rarely the dog’s fault. They often just mean humans haven’t found the right way to channel their pet’s energy.
. . . it’s . . . a moving story of how one woman transformed her troubled dog into a loving companion and an asset to society, all while stumbling on the beauty of life in their searches for death.

For the full review, see:
REBECCA SKLOOT. “Release the Hounds.” The New York Times Book Review (Sun., December 8, 2013): 40.
(Note: ellipses added.)
(Note: the online version of the review has the date December 6, 2013.)

Book under review:
Warren, Cat. What the Dog Knows: The Science and Wonder of Working Dogs. New York: Touchstone, 2013.

M.R.I. Evidence that Emotions Are Similar in Dogs and Humans

HowDogsLoveUsBK2014-01-18.jpg

Source of book image: http://2.bp.blogspot.com/-VIlNHG9gZ4M/Uo6zpfJTahI/AAAAAAAAU9U/9ASa-7VHHKc/s1600/a0c2a640e1085a57e07c368bfe5151f0_XL.jpg

(p. 40) Gregory Berns wasn’t sure if his pug Newton really loved him. Newton wagged his tail and gave kisses, but that wasn’t enough. Berns, a neuroscientist, wanted hard data. He also hoped to uncover “what makes for a strong dog-human bond” and how that might improve canine welfare. So he built a special M.R.I. machine, and trained dogs to lie still inside it, allowing him to study their brains. Though the results may seem obvious to dog lovers (that humans and dogs experience emotions similarly), they’re not a given for science. Berns’s book is a beautiful story about dogs, love and neurology that shows how nonhuman relationships are inspiring researchers to look at animals in new ways, for their benefit and ours.

For the full review, see:
REBECCA SKLOOT. “Release the Hounds.” The New York Times Book Review (Sun., December 8, 2013): 40.
(Note: the online version of the review has the date December 6, 2013.)

Book under review:
Berns, Gregory. How Dogs Love Us: A Neuroscientist and His Adopted Dog Decode the Canine Brain. New York: Houghton Mifflin Harcourt Publishing, 2013.

CallieDogMRI2014-01-18.jpg “After training and hot dog treats, Callie is ready for an MRI.” Source of caption and photo: online version of the NYT review quoted and cited above.