2013年02月15日

発見 人類はネズミのひ孫だった


Found: Humanity’s Great-Grand-Rat
( TIME )

Most of us think we know exactly what we mean when we use the word
“mammal” -- and most of us are wrong. Typically, we think only of
the sub-group of mammals like us, the so-called placental mammals.
There are two other kinds, however: the egg-laying monotremes, which
include the duck-billed platypus; and the marsupials, which count
kangaroos, opossums and wombats among their ranks. But unless you
live in Australia and a few other spots, the vast majority of mammals
you run into, even at the zoo, are placentals, a group that
encompasses everything from rats to rhinos, gerbils to giraffes,
chipmunks to chimps, and, of course humans as well.

It wasn’t always thus, however. Mammals have been around for
hundreds of millions of years, but placentals for only tens of
millions. Now a new paper just published in Science purports to
pinpoint their, or rather, our, origins with impressive specificity.
The great-great grandfather of us all, argue the authors, was a
small, scurrying, insect-nibbling creature that arose a mere 200,000
to 400,000 years after the cataclysmic extinction event 65 million
years ago that wiped out the dinosaurs (or, more precisely, the non-
avian dinosaurs, since birds are now considered the one branch of the
dinosaur family that survived).

This may seem like just a number to you and me but for
paleontologists and evolutionary biologists, it’s something of a
bombshell. The prevailing wisdom since the 1990’s, based on
assumptions about how quickly mutations arise in DNA, was that the
placentals emerged and began to diversify a whopping 35 million
earlier, spurred by the breakup of the giant continent Pangea into
the smaller landmasses that exist today. They didn’t really flourish
until the dinosaurs went away -- but then, who could, with huge,
voracious lizards towering overhead?

All that impressive brainwork led us back to a rather humbling place:
You, your loved ones and your friends, not to mention Abe Lincoln,
Winston Churchill, Napoleon, Babe Ruth, Marilyn Monroe -- all of us,
in other words -- are the multi-multi-generational grandkids of a rat-
like, half-pound, furry-tailed bug-eater. Like it or not. The work,
Novacek promises, will go on. “This thing will continue to grow like
an organism. We have this important new result, but we also have a
playground for future research.” The science may advance, but our
egos may never recover.

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年12月04日

相手の感情を読み解きたいなら、顔ではなく体を見よ


To Really Read Emotions, Look at Body Language, Not Facial Expressions
( TIME )

We like to think we can read people like a book, relying mostly on
tell-tale facial expressions that give away the emotions inside: the
way the brows lift slightly with alarm, or the crow’s feet that
crinkle with a wide smile. But when it comes to the strongest
emotions, we read much less from facial expressions than we think we
do. In fact, even though we believe it’s the face that tells the
story, we’re typically reading something very different: body
language and social cues.

That’s the new, counterintuitive finding from a study published this
week in the journal Science. Researchers from Princeton, New York
University, and the Hebrew University of Jerusalem presented
volunteer study participants with a series of pictures showing people
experiencing extreme emotion, either positive or negative. The images
included professional tennis players who had just won or lost a point
in a major match, as well as people undergoing nipple piercing, and
those in the throes of orgasm.

In some of the images, researchers would only show the study
participants a face; in others, only a body; and in others still,
both the body and the face. You might think it’d be obvious from a
face whether someone is in pain (having a nipple pierced) or whether
he has just won Wimbledon. But it turns out it isn’t.

“The striking finding was that our participants had no clue if the
emotion was positive or negative, when they were judging isolated
faces,” says lead study author Hillel Aviezer from Hebrew University
in an email response discussing the findings. “By contrast, when
they were judging the body (with no face), or the body with the face,
they easily differentiated positive from negative expressions.”

He adds that we do, of course, read a great deal of salient day-to-
day emotional information from faces -- but only in certain
situations. The reliability of that transmission, for example,
appears to break down when emotions are at their strongest. The face
contorts. We can tell that something major has happened, but it’s
tough to tell that something is dramatically positive or
devastatingly negative.

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年10月12日

2人の幹細胞科学者がノーベル生理学・医学賞に輝く


Stem Cell Scientists Awarded Nobel Prize in Physiology and Medicine
( TIME )

In a testament to the revolutionary potential of the field of
regenerative medicine, in which scientists are able to create and
replace any cells that are at fault in disease, the Nobel Prize
committee on Monday awarded the 2012 Nobel in Physiology or Medicine
to two researchers whose discoveries have made such cellular alchemy
possible.

The prize went to John B. Gurdon of the University of Cambridge in
England, who was among the first to clone an animal, a frog, in
1962, and to Shinya Yamanaka of Kyoto University in Japan who in 2006
discovered the four genes necessary to reprogram an adult cell back
to an embryonic state.

Just as Gurdon was facing his critics in England, a young boy was
born in Osaka, Japan, who would eventually take Gurdon’s finding to
unthinkable extremes. Initially, Shinya Yamanaka would follow his
father’s wishes and become an orthopedic surgeon, but he found
himself ill-suited to the surgeon’s life. Intrigued more by the
behind-the-scenes biological processes that make the body work, he
found himself drawn to basic research, and began his career by trying
to find a way to lower cholesterol production. That work also wasn’t
successful, but it drew him to the challenge of understanding what
makes cells divide, proliferate and develop in specific ways.

In 2006, while at Kyoto University, Yamanaka stunned scientists by
announcing he had successfully achieved what Gurdon had with the frog
cells, but without using eggs at all. Yamanaka mixed four genes in
with skin cells from adult mice and turned those cells back to an
embryo-like state, essentially erasing their development and turning
back their clock. The four genes reactivated other genes that are
prolific in the early embryo, and turned off those that directed the
cells to behave like skin.

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2012年10月09日

引っ込んでいてください、部長 子猫の動画で仕事が捗るんです


Back Off, Boss: Cute Kitten Videos May Improve Work Performance
( TIME )

Got caught at work playing Kittenwar or cooing over a puppy cam? No
problem: tell your manager you were only trying to improve your
attention to detail. In a series of experiments, a new study shows
that viewing cute images enhances performance on tasks that require
careful focus and dexterity.

Researchers at Japan’s Hiroshima University found that after people
looked at adorable kitten and puppy pictures -- but not images of
adult cats and dogs -- they significantly increased their accuracy on
an agility task, namely the children’s game Operation. The game
involves using tweezers to extract plastic body parts from tiny
compartments in the game-board patient, without hitting the edges and
triggering a loud buzzer.

To many, cuteness itself seems like a trivial distraction. But
researchers now believe it is an essential emotional trigger, evolved
over eons to help new parents engage in a care-taking task that is
often difficult and always demanding. The reason babies, kittens and
puppies bring us such pleasure -- and millions of hits to thousands
of websites -- is that characteristics associated with infancy cue
our brains to feel warm and caring. And that can change the rest of
our behavior.

The features of cuteness are universal, but not just anything can be
cute: the key characteristics involve disproportionately large heads
and eyes, clumsy behavior and apparent but endearing helplessness. In
short, features shared by young animals.

Japan, of course, is an excellent place to study cuteness. More than
most cultures, the Japanese have elevated cuteness on their cultural
stage: it’s not a coincidence that Hello Kitty and the big-eyed
girls of anime come from Japan. As the study’s authors note, the
etymology of the word for cute in Japanese, kawaii, is telling. The
word’s root originally meant blushing with shame, being unable to
bear to see something pitiful. That shifted to a notion of
unbreakable attachment, of being involuntarily compelled to help and
care, suggesting that cuteness is the drug that addicts parents to
children, a heavy bond hidden in fuzzy cuddliness. And indeed, modern
neuroscience is demonstrating that brain systems first explored for
their roles in addiction actually evolved at least in part to compel
love and caregiving.

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2012年10月05日

宦官は本当に長生きなのか?


Do Eunuchs Really Live Longer?
( TIME )

Talk about a longevity strategy no man wants to pursue. A recent
study published in the journal Current Biology finds that Korean
eunuchs -- castrated men -- lived 14 to 19 years longer than other
men, suggesting that male sex hormones play a role in life span.

In the study, the researchers used a genealogy record called the Yang-
Se-Gye-Bo that tracked eunuchs who worked in the Korean imperial
court during the Chosun Dynasty, which ruled from the 14th to early
20th centuries. Researchers were able to identify 81 eunuchs, who
were castrated as boys, and determined that they lived to an average
age of 70, significantly longer than other men of similar social
status. Even kings didn’t typically make it to age 50.

Three of the 81 eunuchs lived to 100, a centenarian rate that’s far
higher than would be expected in modern society. The current
incidence of centenarians is 1 per 3,500 people in Japan, and 1 per
4,400 people in the United States, for instance; thus, the incidence
of centenarians among Korean eunuchs was at least 130 times higher
than that of present-day developed countries, according to the paper.

“Our study supports the idea that male sex hormones decrease the life
span of men,” the authors write. Based on earlier research, the
authors argue that one explanation for this could be that male sex
hormones may negatively influence the immune system and “predispose
men to adverse cardiovascular attacks.” They note further that the
theory helps explain why females -- in many species -- live longer
than males.

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