////////////////////Accelerated genetic drift on chromosome X during the human dispersal out of Africa
Alon Keinan1,2, James C Mullikin3, Nick Patterson2 & David Reich1,2
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Comparisons of chromosome X and the autosomes can illuminate differences in the histories of males and females as well as shed light on the forces of natural selection. We compared the patterns of variation in these parts of the genome using two datasets that we assembled for this study that are both genomic in scale. Three independent analyses show that around the time of the dispersal of modern humans out of Africa, chromosome X experienced much more genetic drift than is expected from the pattern on the autosomes. This is not predicted by known episodes of demographic history, and we found no similar patterns associated with the dispersals into East Asia and Europe. We conclude that a sex-biased process that reduced the female effective population size, or an episode of natural selection unusually affecting chromosome X, was associated with the founding of non-African populations.
////////////////////////////////////Darwinian evolution provides a wonderful explanation for physical
pain: it has survival value, and that's pretty much the story. But
the full range of our suffering goes way beyond physical pain.
Buddhism meditation practice lets us witness the difference between
the pain that belongs to the body and the pain that is created by the
mind. And it provides a systematic, though certainly not easy,
technique for eliminating the later.
>
Even with purely physical pain, not all of it has survival value.
Examples: pain from childbirth, terminal cancer, shingles, the
various neuropathies in which irritated pain neurons fire in the
absence of any surrounding tissue damage. True, the suffering from
physical pain can be ameliorated by learning to overcome the
associated fear, to engage in various relaxation techniques and
physical therapy exercises, to persist in one's usual activities
despite pain, and probably to engage in various forms of meditation.
But people like to believe that their suffering serves some purpose.
(Giving birth is a fine purpose, but why should it be painful? And
death is not always so.)
My own general explanation of suffering is that in order for
organisms that can get around on their own to survive and evolve,
they must not only learn to avoid tissue damage; they must as well
have a biologic drive to survive. And yet in order for us to evolve,
we have to die and make way for new generations. So the biologic
drive to survive must be frustrated. This works better as an
explanation for psychic distress than it does for physical pain from
such things as childbirth, terminal cancer, shingles and
neuropathies. About the best that can be said for such conditions is
that they amount to collateral damage.
And then there is the suffering that involves neither physical pain
nor unhelpful attitudes: the punishing auditory hallucinations of a
schizophrenia, the hypervigilence, emotional numbing and flashbacks
of PTSD, the black hole of despair in severe depression. Cognitive
therapy can help in some such cases, as can medication, but these
things are not merely a matter of mistaken thinking: there is actual
tissue damage in the brain. Presumably the damage can also occur in
the part of the brain which enables us to experience insight, though
exactly where that part is located either has not been determined, or
has been and I have not yet heard about it. How does any of this
have survival value?
It was long ago discovered that the very painful, debilitating and
life-shortening disease of sicle cell anemia has survival value in
areas endemic to malaria, in that those heterozygous to the condition
are more resistant to malaria. If you are homozygous it is just
tough luck. Perhaps other diseases, whether they affect the brain or
other organ systems, will also turn out to be relics of the interplay
between genetics and environment. For example, the calorie-hoarding
propensity found in obesity has survival advantage in places like
Eastern Europe where for millenia there were frequent famines. Now
that food is more widely and consistently available, people get fat
and develop diabetes and other problems.
J
/////////////////////////////////// "Avoiding Temptation"
It is so difficult this time of the year for me to
follow my own advice with everyone bringing candy,
cakes, etc. (I have a sweet tooth.)
It is too tempting for me to leave the "goodies"
alone, so I am trying to get most of them out of
the house immediately.
As I was unbuttoning my belt after having much
too much to eat yesterday, I asked myself why I
was dealing myself such misery. I know in my heart
of hearts that I feel sooooooooo much better
when I don't eat those sweets at all.
Years ago I had a boss who had a stroke and
recovered with only a slight limp. He lost a lot
of weight and was very thin. When offered
some goodies at a party, he refused. He said that
if he ever took the first bite he would be in trouble.
He would want to eat the whole platter of goodies.
This is good advice for me and for you. Don't
get started eating the goodies in the first place!
They are so hard to leave alone after that first bite.
As with many other things, they are like that old
commercial, "Bet you can't eat just one!"
Avoiding them altogether may be the best thing
you can do for yourself this season.
////////////////////////////////////Set in Our Ways: Why Change Is So Hard
Millions of us dream of transforming our lives, but few of us are able to make major changes after our 20s. Here's why
By Nikolas Westerhoff
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Key Concepts
* Studies of personality development often focus on traits such as extroversion, conscientiousness, agreeableness, neuroticism and openness to new experiences. In most people, these traits change more during young adulthood than any other period of life, including adolescence. Openness typically increases during a person’s 20s and goes into a gradual decline after that.
* This pattern of personality development seems to hold true across cultures. Although some see that as evidence that genes determine our personality, many researchers theorize that personality traits change during young adulthood because this is a time of life when people assume new roles: finding a partner, starting a family and beginning a career.
* Personality can continue to change somewhat in middle and old age, but openness to new experiences tends to decline gradually until about age 60. After that, some people become more open again, perhaps because their responsibilities for raising a family and earning a living have been lifted.
///////////////////////////////////DARK MATTER/ENERGY
By studying far-flung galaxy clusters, astronomers are able to look back in time at the state of those objects millions or even billions of years ago, when the light just now reaching us was emitted. By comparing relatively close clusters with those more distant, the physical evolution of these gargantuan structures can be traced over time. Their observed development is "exactly what's expected for a universe with a low density of matter and a high density of dark energy," Vikhlinin said. (By current estimates, dark energy makes up nearly three quarters of the universe, dark matter comprises another 20 to 25 percent, and ordinary matter—all that we can see and touch—constitutes a mere 4 percent.)
What Vikhlinin and his co-authors observed is also what was expected for a universe described by Albert Einstein's theory of general relativity, the reigning theory of gravity. At the news conference, Princeton University astrophysicist David Spergel, who did not contribute to the research, called this further confirmation of dark energy "a triumph of general relativity."
Study co-author William Forman, a CfA astrophysicist, noted that although general relativity fit well with his team's observations, Einstein's vision may still require future adjustments. Livio agrees, but believes that the galaxy-cluster result nonetheless provides an important test for relativity. "There was the potential here, with this method," he says, "to tell us whether we had to modify our theory of gravity."
/////////////////////////////The fossil record tells us that the oldest member of our own species lived 195,000 years ago in what is now Ethiopia. From there it spread out across the globe. By 10,000 years ago modern humans had successfully colonized each of the continents save Antarctica, and adaptations to these many locales (among other evolutionary forces) led to what we loosely call races. Groups living in different places evidently retained just enough connections with one another to avoid evolving into separate species. With the globe fairly well covered, one might expect that the time for evolving was pretty much finished.
But that turns out not to be the case. In a study published a year ago Henry C. Harpending of the University of Utah, John Hawks of the University of Wisconsin–Madison and their colleagues analyzed data from the international haplotype map of the human genome [see “Traces of a Distant Past,” by Gary Stix; Scientific American, July 2008]. They focused on genetic markers in 270 people from four groups: Han Chinese, Japanese, Yoruba and northern Europeans. They found that at least 7 percent of human genes underwent evolution as recently as 5,000 years ago. Much of the change involved adaptations to particular environments, both natural and human-shaped. For example, few people in China and Africa can digest fresh milk into adulthood, whereas almost everyone in Sweden and Denmark can. This ability presumably arose as an adaptation to dairy farming.
////////////////////////////1. He´s got the whole world in His hands,
|: He´s got the whole world in His hands, :|
He´s got the whole world in His hands.
2. He´s got the wind and the rain in His hands,
|: He´s got the wind and the rain in His hands, :|
He´s got the whole world in His hands.
3. He´s got the the tiny little baby in His hands,
|: He´s got the the tiny little baby in His hands, :|
He´s got the whole world in His hands.
4. He´s got you and me, brother, in His hands,
|: He´s got you and me, brother, in His hands, :|
He´s got the whole world in His hands.
5. He's got ev'rybody here in His hands.
|: He's got ev'rybody here in His hands. :|
He's got the whole world in His hands.
/////////////////////////////////////
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