Meteorites May Have Fostered Life on Earth
Wired.com, December 21, 2007
470 million years ago, back when our ancestors were jawless fishes and
the land was ruled by insects, Earth was pounded by a series of
enormous meteorites. The traces of that hammering still survive today
in ancient rocks in southern Sweden and central China, where scientists
have found exotic mineral grains found only in meteorites.
measuring the amount of the grains in the rocks, the scientists
calculated the rate of meteorite impacts jumped by a factor of 100
around 470 million years ago. A number of the impacts were big enough
to leave 20-mile craters. The energy unleashed was 10 million times
greater than the energy in the nuclear bomb dropped on Hiroshima.
the same time, scientists have also been putting together a chronology
of fossils from the same time, known as the Ordovician Period. They're
recording when species first emerged in the fossil record, and when
they disappeared as they became extinct. And this week in the journal Nature Geoscience, the scientists report that the impacts coincided with a drastic change in the world's biodiversity.
might expect mass extinctions. The most famous of all impacts, a
ten-mile-wide asteroid that hit the Earth at the end of the Cretaceous
Period 65 million years ago, has been linked to mass extinctions that
wiped out Tyrannosaurus rex, the other dinosaurs without wings, and about half of all other species on Earth.
470 million years ago, that's not what happened. Instead, the diversity
of life took a sharp climb right after the meteorites started falling.
Fin Whale at Feeding Time: Dive Deep, Stop Short, Open Wide
The New York Times, December 11, 2007, Link
The word “big” doesn’t do justice to whales. Humpback whales can weigh up to 40 tons. Fin whales have been known to reach 80 tons. Blue whales, the biggest animals to have ever lived, reach 160 tons--the same mass as about 2,000 grown men or 5 million grown mice.
Scientist Employs 'Circuit Theory' to Protect Endangered Species
Wired.com, December 10, 2007
we enter the wilderness, we like to leave the nonstop whir of
electronics behind. The worlds of the mountain lion and of the
integrated circuit seem to have nothing in common. But in fact, they
are similar in some profound ways. Over the years, as mountain lions
migrate and mate, their DNA flows across the landscape like electrons
flowing around a circuit.
Seymour Benzer, Geneticist, Is Dead at 86
The New York Times, December 8, 2007Link
Benzer, a geneticist who made scientific history by discovering that
genes were structured like words and who went on to do pioneering work
on the ties between genes and behavior, memory and longevity, died on
Nov. 30 in Pasadena, Calif. He was 86.
The Six Most Important Experiments in the World: Number 6, Artificial Life
Discover, December 2007Link
In the mid-1990s, Craig Venter rose to fame by claiming that he and his colleagues would decipher the human genome long before a huge team of government scientists would. He at least managed a tie: Both groups have provided increasingly accurate versions of the genome since 2000, and Venter has just published the first genome sequence from one person (himself) that includes all the chromosomes inherited from his parents. As important as sequencing the human genome has been, however, Venter is overseeing another experiment that could someday eclipse it. Scientists at the J. Craig Venter Institute and Venter’s biotech firm, Synthetic Genomics, are trying to make a genome from scratch. “I plan to show that we understand the software of life by creating artificial life,” Venter declares in his new memoir, A Life Decoded.
From Ants to People, an Instinct to Swarm
New York Times, November 13, 2007Link
If you have ever observed ants marching in and out of a nest, you might have been reminded of a highway buzzing with traffic. To Iain D. Couzin, such a comparison is a cruel insult--to the ants.
Greenup of the Planet Is Not Black Or White
Wired.com Commentary, November 9, 2007Link
Every spring, the Earth blooms. Scientists call it greenup: New buds sprout, fresh leaves unfurl, and continents turns green.
Skeletons Flesh Out Life’s Past
New York Times
, November 6, 2007
About half a billion years ago, our ancestors were slender, jawless,
fishlike creatures. Their backs were stiffened by a rod of cartilage,
along which grew bony prongs. That smattering of bone was the
forerunner of our vertebrae, and it gave us and all the other
descendants of those ancient animals our name: the vertebrates.
Vertebrates have evolved into tens of thousands of species dominating
the ocean, land and sky. Much of their success is due to the many new
forms their skeletons have taken. A new coffee-table-format book,
“Evolution” (Seven Stories Press), offers hundreds of gorgeous
photographs of those forms, as diverse as bats with fingers thinner
than pipe cleaners and rhinos with skulls as stubborn as boulders.
This man wants to control the Internet. And you should let him.
, November 2007Link
Doyle is worried about the Internet. In the next few years, millions
more people will gain access to it, and existing users will place ever
higher demands on our digital infrastructure, driven by applications
like online movie services and Internet telephony. Doyle predicts that
this skyrocketing traffic could cause the Internet to slow to a
disastrous crawl, an endless digital gridlock stifling our economies.
But Doyle, a professor of control and dynamic systems, electrical
engineering, and bioengineering at Caltech, also believes the Internet
can be saved. He and his colleagues have created a theory that has
revealed some simple yet powerful ways to accelerate the flow of
information. Vastly accelerate the flow: Doyle and his colleagues can
now blast the entire text of all the books in the library of Congress
across the United States in 15 minutes.
In Study of Human Patterns, Scientists Look to Bird Brains
New York Times
, October 23, 2007Link
month, a bird known as a bar-tailed godwit took flight from Alaska and
headed south. A day later, it was still flapping its way over the
Pacific. An airplane pilot would have a hard time staying awake after
24 hours of flight (the Federal Aviation Administration allows pilots
to fly just eight hours in a row). But the godwit kept flying for an
additional week. After eight days and 7,200 miles, it landed in New
Zealand, setting a record for nonstop flight.
“If they spend so many hours flying,” said Ruth M. Benca of the University of Wisconsin, “where do they find the time to sleep?”
Could He Live to Be 150?
Best Life, October 2007Link Two preeminent aging experts are on opposing sides of a bet that someone living today will be alive in 2150. At stake is not only a wager but also the answer to fundamental questions about the biology of aging and the ability we have to stretch our life span.
If the First Bite Doesnít Do It, the Second One Will
The New York Times, September 11, 2007Link
There are times when life imitates art. Then there are times when life imitates science fiction.
One of the most famous monsters in film history is the extraterrestrial beast of the “Alien” series. It slowly opened its glistening fangs to reveal a second set of jaws that shot forward to kill its victims.
Scientists have now discovered a fish that does the same thing.
Monkey See, Monkey Do
Forbes.com, August 28, 2007Link
McGrew spent much of the 1970s observing chimpanzees in Tanzania. One
day the chimps did something odd. As two chimpanzees groomed each
other's hair, they each lifted an arm overhead. They clasped hands,
forming a kind of primate A-frame.
McGrew and his collaborator,
Caroline Tutin, had just spent months observing another chimpanzee
community just a hundred miles away, and they had never seen that
gesture before. But at their new field site, the A-frame handshake
turned out to be common.
A special chimpanzee handshake may not
seem like much of a discovery, but McGrew realized that it could change
the way we think about human nature itself. In our own species,
handshakes are a sign of culture. Travel the world, and you'll find a
dizzying range of handshakes and other forms of greeting, from the
military salute to the cheek kiss, to the high five, to the hongi of
New Zealand--pressing noses to exchange a sacred breath. These
greetings are not hard-wired into our genomes. Each one was invented in
a particular place and time, and then spread from one person to
another. It's the same process that has given rise to all the cultural
variation that makes humans so endlessly interesting, from languages to
dances to technology.
A Daddy Longlegs Tells the Story of the Continentsí Big Shifts
The New York Times, August 28, 2007Link
Few people have heard of the mite harvestman, and fewer still would recognize it at close range. The animal is a relative of the far more familiar daddy longlegs. But its legs are stubby rather than long, and its body is only as big as a sesame seed.
To find mite harvestmen, scientists go to dark, humid forests and sift through the leaf litter. The animals respond by turning motionless, making them impossible for even a trained eye to pick out. “They look like grains of dirt,” said Gonzalo Giribet, an invertebrate biologist at Harvard.
As frustrating as mite harvestmen may be, Dr. Giribet and his colleagues have spent six years searching for them on five continents. The animals have an extraordinary story to tell: they carry a record of hundreds of millions of years of geological history, chronicling the journeys that continents have made around the Earth.
Predicting Oblivion: Are Existing Models Up to the Task?
Science, August 17, 2007Link
The most authoritative guide to today's extinction crisis is a database known as the Red List. Later this month, a group of scientists will gather in England to consider whether the Red List should be opened up to species that, for the moment, show no signs of trouble. Many scientists suspect that the next few decades of global warming could push some species toward oblivion. "The concern," says the meeting's organizer, H. Resit Akcakaya, an ecologist at ecological software company Applied Biomathematics in Setauket, New York, "is that maybe some species that are threatened by climate are not reflected on the Red List." But Akcakaya and others caution that the meeting is unlikely to come up with firm predictions of how many species will become extinct, let alone which ones will be particularly at risk.
Lessons From an Insectís Life Cycle: Extreme Sibling Rivalry
New York Times, August 14, 2007Link
understand the rules that govern life, biologists often seek out the
weird extremes. And when it comes to family life, it is hard to find a
weirder example than that of a common wasp known as Copidosoma
“You couldn’t dream up a more surreal life cycle
than these guys have,” said Mike Strand, a professor at the University
Scientist at Work | Martin Nowak: In Games, an Insight Into the Rules of Evolution
New York Times, July 31, 2007
When Martin Nowak was in high school, his parents thought he would be a
nice boy and become a doctor. But when he left for the University of
Vienna, he abandoned medicine for something called biochemistry. As far
as his parents could tell, it had something to do with yeast and
fermenting. They became a little worried. When their son entered
graduate school, they became even more worried. He announced that he
was now studying games.
The Meaning of Life
Seed Magazine, August 2007 (cover story)Link
It's hard to think of a word more charged with meaning--or meanings--than "life." Some of the most passionate debates of our day, over stem cells or the right to die, genetically modified food, or wartime conduct, revolve around it. Whether we're talking about when life begins or when it ends, the sanctity of life, or the danger of playing God, we all have an idea of what we mean when we talk about life. Yet, it often turns out, we actually mean different things. Scientists, despite their intimacy with the subject, aren't exempt from this confusion.
"There is no one definition that we agree upon," says Radu Popa, geobiologist and the author of Between Probability and Necessity: Searching for the Definition and Origin of Life. In the course of researching his book, Popa started collecting definitions that have appeared in the scientific literature. He eventually lost count. "I've found at least three hundred, maybe four hundred definitions," he says.
Scientists Urge a Search for Life Not as We Know It
The New York Times, July 7, 2007 Link
A panel of scientists convened by the country’s leading scientific advisory group says the hunt for extraterrestrial life should be greatly expanded to include what they call “weird life”: organisms that lack DNA or other molecules found in life as we know it.
Aliens Among Us
Discover, July 2007 Link
Every living thing on Earth shares a long, colorful history. Our planet was born into a maelstrom 4.5 billion years ago, and for the next 600 million years a steady bombardment of primordial debris made the surface uninhabitable. The blitz finally tapered off 3.8 billion years ago. Then within about 50 million years later--practically an instant in geologic time--life irrevocably established itself. Since then, it has evolved into everything from bacteria to toadstools to mudskippers to humans. Outwardly these species vary wildly, but at the molecular level they are staggeringly uniform. They all use DNA to encode genetic information. They all use RNA molecules as messengers to transfer the information from DNA to cellular factories called ribosomes, which then build proteins, which in turn drive our metabolisms and form the structures of our cells. In short, every species seems descended from a common ancestor whose attributes define what scientists mean when they say “life as we know it.”
But what about life as we don’t know it? What if other, completely distinct forms of biology also took root on the early Earth? After all, the swiftness with which life appeared might mean that it could easily do so anytime, anywhere the conditions are right. If so, maybe life arose more than once at different locations on the early Earth. Those other organisms might have their own biochemistry and a separate evolutionary history. They might not even use DNA--they could be, in essence, alien beings that just happened to emerge on the same planet. Which leads to the big question: What if one (or more) of those alternative forms of life is still around?
Fast-Reproducing Microbes Provide a Window on Natural Selection
New York Times, June 26, 2007 Link
In the corner of a laboratory at Michigan State University, one of the longest-running experiments in evolution is quietly unfolding. A dozen flasks of sugary broth swirl on a gently rocking table. Each is home to hundreds of millions of Escherichia coli, the common gut microbe. These 12 lines of bacteria have been reproducing since 1989, when the biologist Richard E. Lenski bred them from a single E. coli. “I originally thought it might go a couple thousand generations, but it’s kept going and stayed interesting,” Dr. Lenski said. He is up to 40,000 generations now, and counting.
Keys to a Long Life; Take It Slow, Don't Have Many Kids and Enjoy Cold Water
New York Times, June 17, 2007 (Week In Review)
Eskimo hunters killed a bowhead whale off the coast of Alaska last
month and began to chainsaw their way into its blubber. They stopped
when the saw hit the tip of an old harpoon lodged deep inside the
whale. Historians identified it last week as part of a bomb lance, a
harpoon manufactured for only a few years in the late 1800s in New
Bedford, Mass. Whalers probably fired it at the bowhead around 1890,
when the whale was probably a teenager, and it carried the harpoon for
the next 115 years before finally being killed by a modern one.
In Sudan, an Animal Migration to Rival Serengeti
New York Times, June 12, 2007
The first aerial survey of southern Sudan in 25 years has revealed vast
migrating herds, rivaling those of the Serengeti plains, that have
managed to survive 25 years of civil war, the Wildlife Conservation
Society and Southern Sudan will announce today at a news conference in
J. Michael Fay, a conservationist at the Wildlife Conservation Society
and explorer-in-residence at the National Geographic Society, who has
participated in the surveys, said in a telephone interview from Chad
that southern Sudan's herds of more than a million gazelle and antelope
may even surpass the Serengeti's herds of wildebeest, making the newly
surveyed migration the largest on earth.
''It's so far beyond anything you've ever seen, you can't believe it,'' Dr. Fay said. ''You think you're hallucinating.''
Forbes, June 2007 (originally published on Forbes.com March 2, 2007)
make partner. You get tenure. You conquer the known world. You achieve
greatness in your lifetime. But in the great scheme of things, how much
does any of that really matter? After you die, they come to empty your
desk. They take down your plaques from the wall. The grand statues you
had built for yourself crumble in the desert winds.
Discover, May 2007
The town of Bar Harbor, just off the rockbound coast of Maine, is home to spectacular granite cliffs, herds of barking seals, and about 5,000 human residents who live there year-round. Like the rest of us, some of these humble citizens will enjoy long, happy lives, and some will die all too young. According to national statistics, about 1,400 of them will die of heart disease, and 1,100 will die of assorted cancers. Others will struggle with chronic, debilitating diseases. About 1,600 of them are obese. Some 500 suffer from diabetes, and another 150 have osteoporosis. Environment and behavior have their roles, of course, but the different fates of people in Bar Harbor have a lot to do with the different kinds of genes they carry.
In Ducks, War of the Sexes Plays Out in the Evolution of Genitalia
The New York Times
, May 1, 2007Link
Litchfield, Conn.-- “This guy’s the champion,” said Patricia Brennan, a behavioral ecologist, leaning over the nether regions of a duck--a Meller’s duck from Madagascar, to be specific--and carefully coaxing out his phallus.
Time and the Animal Mind
The New York Times,
April 3, 2007Link
Humans are born time travelers. We may not be able to send our bodies into the past or the future, at least not yet, but we can send our minds. We can relive events that happened long ago or envision ourselves in the future.
Scientists Explore Ways to Lure Viruses to Their Death
The New York Times,
March 27, 2007Link
There are only a few basic ways to fight viruses. A vaccine can prime the immune system to attack them as soon as they invade the body. If a virus manages to establish itself, a doctor may be able to prescribe a drug to slow down its spread. And if all else fails, a doctor may quarantine a patient to head off an epidemic."
In the Marmoset Family, Things Really Do Appear to Be All Relative
The New York Times,
March 27, 2007Link
"Well, I'll be a monkey's uncle" has now taken on a new meaning. Scientists studying marmosets have discovered that over half the males carry their brother's sperm.
March 9, 2007Link
Tyrannosaurus rex, it turns out, had a pretty small genome. A team of American and British scientists estimates that it contained a relatively puny 1.9 billion base pairs of DNA, a little over half the size of our own genome.
A Biological Hot Spot in Africa, With New Species Still to Discover
The New York Times,
March 6, 2007Link
The Eastern Arc Mountains of Tanzania may not be terribly tall -- only half the height of their famous neighbor, Mount Kilimanjaro. But to scientists who tally the planet's biodiversity, they tower over the rest of the world. The forests that cover their flanks contain the highest density of endangered animals anywhere on earth.
Evolved for Cancer?
, January 2007 Link
(Reprinted in the Best American Science Writing 2008
Natural selection is not natural perfection. Living creatures have evolved some remarkably complex adaptations, but we are still very vulnerable to disease. Among the most tragic of those ills--and perhaps most enigmatic--is cancer. A cancerous tumor is exquisitely well adapted for survival in its own grotesque way. Its cells continue to divide long after ordinary cells would stop. They destroy surrounding tissues to make room for themselves, and they trick the body into supplying them with energy to grow even larger. But the tumors that afflict us are not foreign parasites that have acquired sophisticated strategies for attacking our bodies. They are made of our own cells, turned against us. Nor is cancer some bizarre rarity: a woman in the U.S. has a 39 percent chance of being diagnosed with some type of cancer in her lifetime. A man has a 45 percent chance.
The Genome: An Outsiderís View
Public Library of Science Computational Biology 2(12): e156 (doi:10.1371/journal.pcbi.0020156) Link
The Buddha once told a story about a king who ordered a group of blind men to be presented with an elephant. Each man touched a different part of the animal. The king then asked them what an elephant is like.
A Radical Step to Preserve a Species: Assisted Migration
New York Times,
January 23, 2007Link
The Bay checkerspot butterfly's story is all too familiar. It was once a common sight in the San Francisco Bay area, but development and invasive plants have wiped out much of its grassland habitat.