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Research on sex ratios from JoseFly -- Lijdrec, 10:44:34 08/25/04 Wed (ca-01.cinergycom.net/216.135.2.28)
Lij,
Saw this over on PandasThumb, and it reminded me of your idea....
Elissa Z. Cameron, "Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism" Proceedings of the Royal Society of London, Ser. B. 271, 1723 - 1728 ( DOI: 10.1098/rspb.2004.2773)
Abstract
Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios.
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Y-chromosome Adams vs Mitochondrial Eves - age differences. -- Lijdrec, 16:36:33 10/06/04 Wed (ca-01.cinergycom.net/216.135.2.28)
Now comes a fascinating new paper in press at Molecular Biology and Evolution. Scientists at the University of Arizona suspected that some of the confusion over Adam and Eve might be the result of comparing the results of separate studies on the Y chromosome and mitochondrial DNA. One study might look at one set of men from one set of ethnic backgrounds. Another study might look at a different set of women from a different set of backgrounds. Comparing the studies might be like comparing apples and oranges. It would be better, the Arizona team decided, to study Y chromosomes and mitochondrial DNA all taken from the same people. Obviously, those people had to be men. The researchers collected DNA from men belonging to three populations--25 Khosians from Southern Africa, 24 Khalks from Mongolia, and 24 highland Papuan New Guineans. Their ancestors branched off from one another tens of thousands of years ago.
The results they found were surprisingly consistent: the woman who bequeathed each set of men their mitochondrial DNA was twice as old as the man whose Y chromosome they shared. But the ages of Adam and Eve were different depending on which group of men the scientists studied. The Khosian Adam lived 74,000 years ago, and Khosian Eve lived 176,500 years ago. But the Mongolian and New Guinean ancestors were both much younger--Adam averaged 48,000 years old and Eve 93,000 years.
You wouldn't expect these different ages if a single Y chromosome had been favored by natural selection, the Arizona team argues. Instead, they are struck by the fact that Khosians represent one of the oldest lineages of living humans, while Mongolians and New Guineans descend from younger populations of immigrants who left Africa around 50,000 years ago. The older people have an older Adam and Eve, and the younger people have a younger one. The researchers argue that some process has been steadily skewing the age of Adam relative to Eve in every human population.
Now here's where things may get a little sticky for the "one-man-one-woman-is-traditional-and-natural" camp. The explanation the Arizona scientists favor for their results is polygyny--two or more women having children with a single man. To understand why, imagine an island with 1,000 women and 1,000 men, all married in monogamous pairs, just as their parents did, and their grandparents, and so on back to the days of the first settlers on the island. Let's say that if you trace back the Y chromosomes in the men, you'd find a common ancestor 2,000 years ago. Now imagine that the 1,000 women are all bearing children again, but this time only 100 men are the fathers. You'd expect that the ancestor of this smaller group of men lived much more recently than the common ancestor of all 1,000 men.
Scientists have proposed that humans have a history of polygyny before (our sperm, for example, looks like the sperm of polygynous apes and monkeys, for example). But with these new DNA results, the Arizona researchers have made a powerful case that polygyny has been common for tens of thousands of years across the Old World. It's possible that polygyny was an open institution for much of that time, or that secret trysts made it a reality that few would acknowledge. What's much less possible is that monogamy has been the status quo for 50,000 years.
People are perfectly entitled to disagree over what sort of marriage is best for children or society. But if you want to bring nature or tradition into the argument, you'd better be sure you know what nature and tradition have to say on the subject.
Posted by Carl at 5:28 PM
Read the rest...
Trackback from The Panda's Thumb, Aug 23, 2004 6:16 PM
Of course even if Pres. Bush was correct in his claim that one-man/one-woman was how it was done, it would not follow that it is preferable. And that polygyny was common in the past does not mean that it is preferable now.
It is interesting that fundamentalists who argue one-man/one-woman must do it while ignoring polygyny was fully accepted in the Old Testiment. It is amazing how changable the fundamentalists unchangable laws are.
--
Anti-spam: replace "usenet" with "harlequin2"
Posted by Mike Hopkins on August 23, 2004 09:02 PM | Permalink to Comment
Actually, if we want to take reproduction back to its biological roots, then we really should consider cloning. I mean, it was good enough a billion years ago, and I suspect it remains so to this day for the majority of individuals contributing to the world's biomass. It's just a perverse minority that uses sex for children.
Posted by oliver on August 23, 2004 10:12 PM | Permalink to Comment
Really interesting. Polygyny doesn't require one man plus multiple wives at the same time, although that explanation may be the most likely. Other possibilities: if men tended to outlive women, then serial monogamy would produce the same result. So would "monogamy" where female infidelity occurs, and multiple women tended to choose the same outside male for the extra-pair relationship.
Posted by Brian on August 24, 2004 02:31 PM | Permalink to Comment
Tell that to Mrs. Coolidge....
Excerpt: An anecdote from The Red Queen: Learning that a cockerel could have sex dozens of times a day, Mrs. Coolidge said: "Please tell that to the president." On being told, Mr. Coolidge asked, "Same hen every time?" "Oh, no, Mr....
Read the rest...
Trackback from Gene Expression, Aug 24, 2004 5:32 PM
Why is polygyny the preferred alternative to natural selection? What rules out patrilocality?
This study says the difference can be explained by patrilocality, while polygyny a factor, not the norm.
"Genetic evidence for a higher female migration rate in humans"
"A higher female than male migration rate (via patrilocality, the tendency for a wife to move into her husband's natal household) explains most of this discrepancy, because diverse Y chromosomes would enter a population at a lower rate than mtDNA or the autosomes. Polygyny may also contribute, but the reduction of variation within populations that we measure for the Y chromosome, relative to the autosomes and mitochondrial DNA, is of such magnitude that differences in the effective population sizes of the sexes alone are insufficient to produce the observation."
This study indicates polygyny is a factor, but not normative.
Reduced Y-Chromosome, but Not Mitochondrial DNA, Diversity in Human Populations from West New Guinea
"We find that genetic variation in WNG is characterized by a reduced diversity of Y-chromosome DNA but not of mtDNA. This seems to reflect cultural features of these Papuan societies, such as their patrilocal residence, their patrilineal and exogamous social clan system, and the high frequency of polygyny. In addition, warfare, which existed until recently in WNG groups and mainly affected men but not women, may have contributed to a reduction of paternal but not maternal genetic lineages. Our data further provide evidence for primarily female-mediated gene flow within the highlands of New Guinea but primarily male-mediated gene flow between highland and lowland/coastal regions, both in WNG and PNG."
Posted by joel on August 24, 2004 06:10 PM | Permalink to Comment
This question may be naive but what about DNA variation in mitochondria within an individual (or cell). Presumably a mutagenic event (at the molecular level) effects only one of the thousands of mitochondria in a single cell and an oocyte contains a (mutated) copy of the population (or a subpopulation?) of the maternal mitochondria. Does this lead to different rates for the mtDNA and Y-DNA clocks and if so how accurately are these differences known.
It might be illuminating to study Y and mt-DNA ages in other great ape populatons whose sexual behaviour is known to be polygonous (Gorilla) or promiscuous (Bonobo, Chimp?).
Posted by Greyshade on August 24, 2004 09:16 PM | Permalink to Comment
If I argued for polygamy, my fiancee would kill me. I'd postulate that polygamy is more prevalent in relatively more chauvanistic societies, and from that perspective, it is progress that we've moved towards monagamy.
On a different note, has anyone attributed to chance the fact that we have common ancestors if we go far back enough in time? How similiar is human mitochondria similiar to other hominid mitochondria? If we could prove there was a time before this speciation occurred, that would irrefutably change everyone's views.
Posted by Nightmare on August 25, 2004 04:06 PM | Permalink to Comment
I am no expert on these points, but a couple well known historical facts bear on this discussion. (1) Until the 20th century childbearing age women died at a very high rate during pregnancy and labor. The result is a male might marry several women and bear children by several women frequently. (2) Until recently the usual state of society included intermitent war. In this condition, traditions often existed for the newly widowed women to either become impregnated by or marry the surviving men. Again creating a condition that led to many men having offspring from multiple women. (3) At one point, victors typically enslaved surviving women of the vanquished and at the same time as capturing them rape was normal. Again increasing the number of women a man might impregnate.
Thus, I would be hesitant to conclude whether "monogamy" was or was not the norm. I would conclude that a number of factors existed that increased the probability of men siring children by multiple wives. Also, I suspect the likelihood is that all the conditions I've highlighted and that the article underscores tend to (1) generally increase the likelihood and (2) especially increase the likelihood if social status was greater of fathering many children by mulitple mothers for the following reasons:
1) Higher ranking individuals had more wealth and power and could more easily support multiple wives or concubines.
2) Higher ranking individuals were more likely to be awarded more slaves in case of a victory.
3) Higher ranking more "heroic" individuals were likely to be more desired by surviving widows upon return from battle even if they did not marry them and they went on to other future husbands.
4) Higher ranking individuals had better access to better food and health care (rudimentary as it may have been) allowing them to continue procreating longer and increasing the chances of outliving multiple childbearing age spouses.
5) Higher ranking individuals offered better security to childbearage women increasing the possibility of continuing to have new children by
multiple spouses for a much longer span of years. On the other hand, less affluent individuals might tend to only have one spouse who upon reaching menopause effectively stopped addition to the line.
Finally, I believe the Bible offers a very good "ancient" narrative record of almost all these behavioral events occuring and their affect on procreation by men and women if carefully traced.
Posted by Blake Ratcliff on September 6, 2004 07:12 AM | Permalink to Comment
This is very intresting. But iam hearing that the mt DNA, now a yes or no question, is it true that the chance stand greater for this DNA stran to be trased back to one female in africa that maybe connected to the Anunnaqi name ninti.
Posted by JONAH MOSES on September 17, 2004 06:17 PM | Permalink to Comment
5 Jahre Erdgas Arena - JubilÄumsprty http://tickets.gelago.de/cat3396/Konzerte/Rock-pop/5-Jahre-Erdgas-Arena-JubilÄumsprty/
Posted by 5 Jahre Erdgas Arena - JubilÄumsprty on September 18, 2004 04:38 AM | Permalink to Comment
It seems more likely that a woman would evolve into a man than a monkey, and the idea that a woman would evolve into a man is ridiculous enough. GOD has designed the universe, and did not create anything by accident. Each hair on your head is numbered by GOD, and no doubt each thought is read by HIM. If each thought is read by HIM, then each man is accountable to GOD, and no amount of falty reasoning will release any from this fact. Don't believe the lie, GOD was in CHRIST reconciling the hell bound world to himself, but many have gone after vain imaginations, to thier own eternal peril.
Posted by Roussan on September 22, 2004 06:22 PM | Permalink to Comment
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Genetics, Evolution, Fertility and Gays -- Lijdrec, 22:54:58 10/25/04 Mon (ca-01.cinergycom.net/216.135.2.28)
Now just last night/early this morning in London comes news of a study by some Italian researchers into homosexuals and their families and how it might relate to fertility, evolution and the X chromosome --- and everything they hypothesize about seems to fit my ideas!! Here is a Google News archive of articles and the following is from the London Times Online....
http://www.timesonline.co.uk/article/0,,2-1306894,00.html
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Britain
October 13, 2004
So it is down to mother: gay gene survives because it boosts fertility
By Mark Henderson, Science Correspondent
London Times Online
THE biological enigma of how homosexuality evolved despite its obvious drawbacks for reproduction may finally have been resolved.
The genes that make men gay also help their female relatives to have bigger families, according to new research.
Scientists have discovered that gay men’s mothers, sisters and maternal aunts tend to have significantly more children than the norm — and that many of their nephews and male cousins are also gay.
The findings suggest that the same genes that trigger homosexuality in men also promote fertility in women, and that this could explain how they survive in the population when gay men themselves are unlikely to breed. The genes are instead passed on through the female line and the enhanced fertility they confer on these women ensures that they are inherited by plenty of children.
Some of these sons will grow up to be homosexual themselves. The study also revealed that gay men are more likely than heterosexuals to have a gay male relative, though only on their mother’s side of the family.
The results, from the University of Padua, in Italy, offer strong support for the theory that homosexuality is at least partly determined by a person’s genetic make-up, and is not just about personal choice or upbringing and environment. It also suggests an elegant solution to the biggest problem with this hypothesis — the “Darwinian paradox” that any genes that favour homosexuality ought to have died out through natural selection, as those that inherited them had fewer and fewer offspring.
Andrea Camperio-Ciani, who led the research, said: “Our data resolve this paradox by showing that there might be hitherto unexpected reproductive advantages associated with male homosexuality.”
The work also points to a likely location for the genes that have this effect: they almost certainly lie on the X chromosome, the package of DNA that men always inherit from their mothers.
In the study, published today in the journal Proceedings of the Royal Society, Dr Camperio-Ciani’s team interviewed 98 homosexual and 100 heterosexual men in detail about their extended families. In total, more than 4,600 individuals were thus indirectly involved. They found that both the mothers and maternal aunts of the homosexuals were significantly more fertile than those of the straight men: the mothers had an average of 2.69 children compared with 2.32, and the aunts 1.98 children compared with 1.51.
Fertility rates among paternal relatives and among male relatives on the mother’s side were similar for both groups.
All this points to genes that influence both male homosexuality and female fertility being passed down along the maternal line. “The results hypothesise that genetic factors, transmitted in the maternal line, increase both the probability of being homosexual in males and fecundity in females,” Dr Camperio-Ciani said.
The study did not investigate lesbianism. The notion that homosexuality has at least some basis in biology is not now seriously disputed by scientists, though there is little consensus on what the causes might be. Some scientists think that genetics are critical, while others believe that conditions in the womb are all-important.
The question of what causes homosexuality has long divided both the gay community and social conservatives who regard same-sex partnerships as wrong. Many gay activists think that identifying biological factors that contribute to homosexuality will prove that their sexual orientation is perfectly natural and encourage tolerance. Others fear that it will lead to greater hostility, with the risk that being gay will again be seen as a disorder that might one day be “cured”.
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Wonder what this would mean to the world view of many religions?
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Re: Final Draft -- Lijdrec, 22:52:18 11/09/04 Tue (ca-02.cinergycom.net/216.135.2.29)
Mothers' genetic skew linked to gay sons
10:26 09 November 04
There has been much debate over “gay genes”. Now an intriguing study raises another possibility: in some cases, variations in the genetic program we inherit from our parents, rather than in the genes themselves, might determine sexual preference.
Our genome is “programmed” by the addition of chemical markers called methyl groups to the DNA, which shut down genes. One of the most dramatic examples of methylation is the shutdown of one of the two X chromosomes (one from each parent) in every woman’s cells, a process called X-inactivation (New Scientist print edition, 10 May 2003).
Normally, this process is random; either of the X chromosomes can be inactivated.
But when Sven Bocklandt of the University of California, Los Angeles, compared blood and saliva samples from 97 mothers of gay men with samples from 103 mothers without gay children he found this process was extremely skewed in the mothers with gay sons, with one X chromosome being far more likely to be inactivated than the other.
"I like males"
Only 4% of the mothers without gay sons showed this skewing, compared with 14% of mothers with at least one gay son. Among mothers with two or more gay sons, the figure was 23%.
Such skewing is generally associated with genetic disorders, but the mothers all appear to be healthy. Their daughters also seemed unaffected, with only 1 out of 24 showing skewing.
Bocklandt suspects that whatever is causing the skewed methylation of the X chromosome also affects the methylation of certain genes on the chromosomes the women pass on to their sons. Mothers might not be resetting their own “I like males” program, he told a meeting of the American Society of Human Genetics in Toronto last week.
“I’m not absolutely persuaded, but it’s an interesting hypothesis,” says Ian Craig of the Institute of Psychiatry in London. “Until you’ve got some molecular way to test it, it’s just a nice idea.”
==============================================================================
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Survival of genetic homosexual traits explainehttp://www.newscientist.com/news/news.jsp?id=ns99996519d http://www.newscientist.com/news/news.jsp?id=ns99996519
13 October 2004
Homosexuality is biological, suggests gay sheep study http://www.newscientist.com/news/news.jsp?id=ns99993008
05 November 2002
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Oh boy.... now the "god gene" -- Lijdrec, 00:35:27 11/14/04 Sun (ca-02.cinergycom.net/216.135.2.29)
'God gene' discovered by scientist behind gay DNA theory
By Elizabeth Day -- telegraph.co.uk - (Filed: 14/11/2004)
Religious belief is determined by a person's genetic make-up according to a study by a leading scientist.
After comparing more than 2,000 DNA samples, an American molecular geneticist has concluded that a person's capacity to believe in God is linked to brain chemicals.
His findings were criticised last night by leading clerics, who challenge the existence of a "god gene" and say that the research undermines a fundamental tenet of faith - that spiritual enlightenment is achieved through divine transformation rather than the brain's electrical impulses.
Dr Dean Hamer, the director of the Gene Structure and Regulation Unit at the National Cancer Institute in America, asked volunteers 226 questions in order to determine how spiritually connected they felt to the universe. The higher their score, the greater a person's ability to believe in a greater spiritual force and, Dr Hamer found, the more likely they were to share the gene, VMAT2.
Studies on twins showed that those with this gene, a vesicular monoamine transporter that regulates the flow of mood-altering chemicals in the brain, were more likely to develop a spiritual belief.
Growing up in a religious environment was said to have little effect on belief. Dr Hamer, who in 1993 claimed to have identified a DNA sequence linked to male homosexuality, said the existence of the "god gene" explained why some people had more aptitude for spirituality than others.
"Buddha, Mohammed and Jesus all shared a series of mystical experiences or alterations in consciousness and thus probably carried the gene," he said. "This means that the tendency to be spiritual is part of genetic make-up. This is not a thing that is strictly handed down from parents to children. It could skip a generation - it's like intelligence."
His findings, published in a book, The God Gene: How Faith Is Hard-Wired Into Our Genes, were greeted sceptically by many in the religious establishment.
The Rev Dr John Polkinghorne, a fellow of the Royal Society and a Canon Theologian at Liverpool Cathedral, said: "The idea of a god gene goes against all my personal theological convictions. You can't cut faith down to the lowest common denominator of genetic survival. It shows the poverty of reductionist thinking."
The Rev Dr Walter Houston, the chaplain of Mansfield College, Oxford, and a fellow in theology, said: "Religious belief is not just related to a person's constitution; it's related to society, tradition, character - everything's involved. Having a gene that could do all that seems pretty unlikely to me."
Dr Hamer insisted, however, that his research was not antithetical to a belief in God. He pointed out: "Religious believers can point to the existence of god genes as one more sign of the creator's ingenuity - a clever way to help humans acknowledge and embrace a divine presence."
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Re: Final Draft -- Lij, 17:03:23 01/23/05 Sun (ca-01.cinergycom.net/216.135.2.28)
And another.....
Gene Scan Suggests Homosexuality Origin
David Ryan Alexander, PlanetOut Network
Friday, January 21, 2005 / 04:27 PM
A new genetic study released Jan. 12 claims to "help explain why some men are gay and other men are heterosexual." The study, published in the biomedical journal Human Genetics, analyzed 456 individuals from 146 unrelated families with two or more gay brothers and claims to be the first full genome scan of sexual orientation in men.
"We found three chromosomal regions that are likely to have genes within them that influence sexual orientation," said Brian Mustanski of the University of Illinois, one of the six scientists from a number of institutions who conducted the study.
"I think we essentially found these regions that are likely to influence sexual orientation," Mustanski said. "We found some genes that influence hormones and brain development. The next step is to look at specific genes in a new family sample to see if those are the exact genes that affect sexual orientation."
The study also stated that "given the complexity of sexual orientation, numerous genes are likely to be involved, many of which are expected to be autosomal (or of a non-sex chromosome) than sex-linked." In previous studies regarding gay male twins, the report said, only limited connection could be made showing male sexual orientation as being inherited from the X-chromosome, or sex chromosome.
"Previous research had looked exclusively at the X-chromosome," Mustanski said, "and found that the region right at the tip of the X-chromosome may influence sexual orientation."
The current study sought to provide a scan analyzing both sex and non-sex chromosomes to identify all genes that potentially contribute to variation in sexual orientation.
Mustanski compared the study to finding one person in a town of 40,000 people. "You make some assumptions about where they might be, knocking on one door on every street," he said. "You're going to narrow it down considerably."
According to Mustanski another study exploring the genetics of sexual orientation is currently being conducted, and he assumed its researchers would incorporate these new findings into their study, but it will still probably be years until that report is completed.
As for exactly what locating these genes would mean, Mustanski said, "Finding the specific genes would have implications beyond uncovering the cause of homosexuality. Their identification would also greatly advance our understanding of human variation, evolution and brain development."
Mustanski also placed importance on studies focusing on women. "As with many things," he said, "females tend to be studied last and it would be important to start looking at female sexuality."
http://www.planetout.com/news/article.html?2005/01/21/5
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URL for Mothers' genetic skew linked to gay sons / methylation -- Lij, 17:16:30 01/23/05 Sun (ca-01.cinergycom.net/216.135.2.28)
Mothers' genetic skew linked to gay sons
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Zimmer on Hamer's God Gene -- Lij, 12:06:10 02/12/05 Sat (ca-01.cinergycom.net/216.135.2.28)
SCIENTIFIC AMERICAN, October, 2004 - A review of The God Gene: How Faith Is Hard-wired Into Our Genes, a book by Dean Hamer. Review by Carl Zimmer
By page 77 of The God Gene, Dean H. Hamer has already disowned the title of his own book. He recalls describing to a colleague his discovery of a link between spirituality and a specific gene he calls “the God gene.” His colleague raised her eyebrows. “Do you mean there's just one?” she asked. “I deserved her skepticism,” Hamer writes. “What I meant to say, of course, was 'a' God gene, not 'the' God gene.”
Of course. Why, the reader wonders, didn't Hamer call his book A God Gene? That might not have been as catchy, but at least it wouldn't have left him contradicting himself.
Whatever you want to call it, this is a frustrating book. The role that genes play in religion is a fascinating question that's ripe for the asking. Psychologists, neurologists and even evolutionary biologists have offered insights about how spiritual behaviors and beliefs emerge from the brain. It is reasonable to ask, as Hamer does, whether certain genes play a significant role in faith. But he is a long way from providing an answer.
Hamer, a geneticist at the National Cancer Institute, wound up on his quest for the God gene by a roundabout route. Initially he and his colleagues set out to find genes that may make people prone to cigarette addiction. They studied hundreds of pairs of siblings, comparing how strongly their shared heredity influenced different aspects of their personality. In addition to having their subjects fill out psychological questionnaires, the researchers also took samples of DNA from some of them. Hamer then realized that this database might let him investigate the genetics of spirituality.
He embarked on this new search by looking at the results of certain survey questions that measured a personality trait known as self-transcendence, originally identified by Washington University psychiatrist Robert Cloninger. Cloninger found that spiritual people tend to share a set of characteristics, such as feeling connected to the world and a willingness to accept things that cannot be objectively demonstrated. Analyzing the cigarette study, Hamer confirmed what earlier studies had found: heredity is partly responsible for whether a person is self-transcendent or not. He then looked at the DNA samples of some of his subjects, hoping to find variants of genes that tended to turn up in self-transcendent people. His search led him to a gene known as VMAT2. Two different versions of this gene exist, differing only at a single position. People with one version of the gene tend to score a little higher on self-transcendence tests. Although the influence is small, it is, Hamer claims, consistent. About half the people in the study had at least one copy of the self-transcendence boosting version of VMAT2, which Hamer dubs the God gene.
Is the God gene real? The only evidence we have to go on at the moment is what Hamer presents in his book. He and his colleagues are still preparing to submit their results to a scientific journal. It would be nice to know whether these results can withstand the rigors of peer review. It would be nicer still to know whether any other scientists can replicate them. The field of behavioral genetics is littered with failed links between particular genes and personality traits. These alleged associations at first seemed very strong. But as other researchers tried to replicate them, they faded away into statistical noise. In 1993, for example, a scientist reported a genetic link to male homosexuality in a region of the X chromosome. The report brought a huge media fanfare, but other scientists who tried to replicate the study failed. The scientist's name was Dean Hamer.
To be fair, it should be pointed out that Hamer offers a lot of details about his study in The God Gene, along with many caveats about how hard it is to establish an association between genes and behavior. But given the fate of Hamer's socalled gay gene, it is strange to see him so impatient to trumpet the discovery of his God gene. He is even eager to present an intricate hypothesis about how the God gene produces self-transcendence. The gene, it is well known, makes membrane covered containers that neurons use to deliver neurotransmitters to one another. Hamer proposes that the God gene changes the level of these neurotransmitters so as to alter a person's mood, consciousness and, ultimately, self-transcendence. He goes so far as to say that the God gene is, along with other faith-boosting genes, a product of natural selection. Self-transcendence makes people more optimistic, which makes them healthier and likely to have more kids.
These speculations take up the bulk of The God Gene, but in support Hamer only offers up bits and pieces of research done by other scientists, along with little sketches of spiritual people he has met. It appears that he has not bothered to think of a way to test these ideas himself. He did not, for example, try to rule out the possibility that natural selection has not favored self-transcendence, but some other function of VMAT2. (Among other things, the gene protects the brain from neurotoxins.) Nor does Hamer rule out the possibility that the God gene offers no evolutionary benefit at all. Sometimes genes that seem to be common thanks to natural selection turn out to have been spread merely by random genetic drift. Rather than address these important questions, Hamer simply declares that any hypothesis about the evolution of human behavior must be purely speculative. But this is simply not true. If Hamer wanted, he could have measured the strength of natural selection that has acted on VMAT2 in the past. And if he did find signs of selection, he could have estimated how long ago it took place. Other scientists have been measuring natural selection this way for several years now and publishing their results in major journals.
The God Gene might have been a fascinating, enlightening book if Hamer had written it 10 years from now-after his link between VMAT2 and self-transcendence had been confirmed by others and after he had seriously tested its importance to our species. Instead the book we have today would be better titled: A Gene That Accounts for Less Than One Percent of the Variance Found in Scores on Psychological Questionnaires Designed to Measure a Factor Called Self-Transcendence, Which Can Signify Everything from Belonging to the Green Party to Believing in ESP, According to One Unpublished, Unreplicated Study.
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Report in Nature details disease density of sex chromosome and surprises about X inactivation -- Lijdrec, 17:20:31 03/18/05 Fri (ca-02.cinergycom.net/216.135.2.29)
X Sequence Published
Report in Nature details disease density of sex chromosome and surprises about X inactivation | By Stephen Pincock
An international collaboration led by Britain's Wellcome Trust Sanger Institute will publish on Thursday (March 17) an almost complete sequence of the human X chromosome that offers, among many new insights, a better picture of how sex chromosomes evolved. A second paper in the same issue reveals some surprises about X inactivation of genes.
The Sanger Institute's Mark Ross and colleagues in the US and Germany determined 99.3% of the chromosome's euchromatic sequence and found 1,098 genes, including 399 "new" genes and 99 cancer-testis antigen genes.
But more than simply improving our understanding of individual genes, the sequence offers a powerful insight into the evolution of the chromosome itself, Ross told reporters at a press conference in London. "We can see the way evolution has shaped the chromosomes that determine our gender to give them their unique properties," he said. "The X chromosome is definitely the most extraordinary in the human genome."
Ross and colleagues offer some comparison of the sequence with that of the chicken to explore the development of the X chromosome from an autosome, which is thought to have occurred something like 300 million years ago. "Comparing the sequence of human X as it is with what is known about the sequences of other animal chromosomes allows you to tell where the X chromosome came from," said Robin Lovell-Badge from the National Institute for Medical Research, who wasn't involved in the study. "They've done some of that, but there's a lot more to be done."
Looking at more recent evolutionary history, the authors compared the human X chromosome with other mammalian sequences, finding nine major blocks of homology between human and mouse X chromosomes and 11 between human and rat. "The homology blocks occupy almost the entirety of each X chromosome, confirming the remarkable degree of conserved synteny of this chromosome within the eutherian mammalian lineage," they write.
The team's analysis revealed what coauthor Richard Gibbs from Baylor College of Medicine called "a lot of interesting local stories." "But maybe the message is not so much about surprise findings as the wealth of data," Gibbs told The Scientist. "It's mind-blowing the amount of biochemical data that has been generated."
The X chromosome has revealed itself to be quite different to autosomes, Lovell-Badge told The Scientist. "Compared with the autosomes that have been sequenced, it is relatively gene poor, which is interesting. It looks different to other chromosomes, so that's going to be interesting to study further."
One other difference is the relative density of disease related genes on the X, said Nature senior editor Chris Gunter, who wrote a News and Views article on the results. "It is the case that it is overrepresented with known disease genes," she told The Scientist. The sequence will be invaluable for identifying the genes for other known X-linked diseases, speakers at the press conference said.
The authors also note that LINE1 repeat elements cover a third of the X chromosome, "with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation."
In the second paper, Laura Carrel from Pennsylvania State University College of Medicine, and Huntington Willard from Duke University, Durham, North Carolina, present a comprehensive profile of X-chromosome inactivation, the process by which genes on one X chromosome in female mammals are silenced in individual cells.
They found that about 75% of X-linked genes are permanently silent and about 15% permanently escape inactivation and are thus expressed at twice the level in women as in men. An additional 10% show variable patters of inactivation, they write.
"This suggests a remarkable and previously unsuspected degree of expression heterogeneity among females," Carrel and Willard write, and could explain some sexually dimorphic traits.
This finding also points to the future direction genomics should take, said Steve Jones, professor of genetics at University College London, who was not involved in the research. "All the action in genetics in the future will not be in the anatomy of the genome, which this sequencing is, but in physiology."
"It's not the structure that's important," he told The Scientist. "It's the regulation and the function."
Links for this article
M.T. Ross et al. "The DNA sequence of the human X chromosome." Nature 2005; 434:325-337.
http://www.nature.com
L. Carrel, HF Willard. "X-inactivation profile reveals extensive variability in X-linked gene expression in females," Nature 2005; 434:400-404.
http://www.nature.com
C. Holding, "Spreading key to X inactivation," The Scientist, February 23, 2004.
http://www.biomedcentral.com/news/20040223/01
Mark Ross
http://www.sanger.ac.uk/Teams/Team61/
Robin Lovell-Badge
http://www.nimr.mrc.ac.uk/devgen/
Richard Gibbs
http://www.bcm.edu/pa/gibbs.htm
C. Gunter. "She moves in mysterious ways," Nature 2005;434:279-280.
http://www.nature.com
Laura Carrel
http://fred.hmc.psu.edu/ds/retrieve/fred/investigator/lcarrel
Huntington Willard
http://www.genome.duke.edu/people/faculty/willard
Steve Jones
http://www.ucl.ac.uk/biology/new/admin/staffpages/jones/jones.h tm
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ok -- Lijdrec, 18:37:59 06/14/05 Tue (ca-01.cinergycom.net/216.135.2.28)
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The Fawn Year... -- Lij, 19:47:38 09/07/05 Wed (ca-01.cinergycom.net/216.135.2.28)
A Fleeting First Appearance....
It was only a short peak out from the woods that had been its security blanket. With the setting sun upon its face the fawn tentively stepped out onto the lawn at the urging of its mother. Its sun-dappled back almost camoflaged its own natural spotted camoflage. But the security of the woods beckoned this years nervous young fawn and he was soon finding his way back to the grounds that had seen so many other fawns nurtured these last 30 plus years.
Dad and I had drained that spot. Back in 1970 below where the house is now located, it had been a small mud-hole of a pond, which was meant to water cattle in the pasture that was here. I remember when the dam broke from under the blade of dad's bulldozer, the pond had been full of 6 inch catfish. And then they were all trying to go down the small woodland stream to Mariah Creek with the flood from the pond. I doubt many of them made it; we probably gave the coons in our woods a feast that night.
Dad had wanted to build a larger pond in that hollow, so he and I could walk out of the house he was planning and catch a mess of bluegill for dinner. But it wasn't to be; dad died of cancer at the age of 58 in that next year. Mom and I later built the house in 1974. But the hollow and the pastures beyond we replanted in walnut trees for a future sale. They, along with the ash, oaks, tulip poplar, and maple that volunteered there, have had 30 years growth now.
We didn't really plant the pond. It was still wet in parts and willows grew up there. The old pond bottom got to be grassy with the fescues of our late pastures. Around the edge of the pond bottom a thicket of blackberries grew up in a circle. But inside, that was different; it remained a small 50 foot circle of fescue grass and the favorite of a succession of does for raising their fawns. The thicket provided protection and the grass surely good bedding. And even now there is grass there despite the surrounding forest having grown up around it. For nearly 30 years now, does and fawns have lived there just below our house, outside of our lawn. And for those same years the fawns have taken their first tentative steps out of the woods into the light of our backyard lawn. One of the truest signs of summer around here.
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Lessee.....
-At least a half-dozen Eastern Kingbirds darting out of the trees to catch flying insects.
-About a dozen Chipping Sparrows sharing forage in the lawn 'neath the trees with a pair of Northern Flickers.
-A male and female Baltimore Orioles are out thrashing around the honeysuckle sucking up nectar.
-About three dozen or more American Robins out front foraging in the open lawn.
-4 or 5 Ruby-throated Hummingbirds vying for the nectar feeder.
-Four or so Carolina Chickadees and a pair of Tufted Titmouses visiting the sunflower seed feeder.
-Another half dozen or so American Goldfinches and a pair of Purple Finches staked out on the thistle feeders.
-A couple of White-breasted Nuthatches chasing each other around the oak tree by the feeder.
-While the half dozen or so Downy Woodpeckers snack on the suet cakes....
-A pair of Carolina Wrens chase each other around the brick of the house.
-The Indigo Buntings holding sway along the driveway near the house, while....
-Overhead sitting on the electric wire a dozen or so Barn Swallows sit waiting for their late afternoon meal.
-Further on down the lane a Killdeer rules its part of the lawn.
-While a gaggle of Warblers - Cerulean, Kentucky, and Yellow - hold sway along the edges of the forest.
-And overhead a pair of Red-tailed Hawks lazily soar on the thermals.
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About 150 Bushels of Corn per Acre in a Fair Year....
Project a price of about $2.17/bushel of corn, 20 ears of corn per deer per hour. I watched one eat tonight at dusk. LOOK! There's another cornstalk shaking! Sorta funny looking, a deer with a yellowish-white, pointy cob sticking out of its mouth - funny that it will never be in the corn hopper.
But also about 20-30 deer eating over a period of 2-3 weeks (baby corn phase when the cob is edible) plus about 200 squirrels, 50 or so groundhogs, etc... etc... etc... well, it adds up to about one acre in every 35 that feeds the wildlife (they should consider themselves lucky we didn't plant soybeans!). That means for mom's 140 acres of cornfields about 4 acres go to feed the wildlife. That comes to about 600 bushels of corn or about $1300.00 in lost income that goes to feeding wildlife.
I think a corn-fed doe or two in the freezer this fall/winter is in order. Venison salami is really tasty! Wonder how my 250 acres of corn in the bottoms is fairing.... lessee... that's about 2 or 3 more deer!
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Betwixt the Cornfield, the Lawn and the Woods....
At the junction of the cornfield, the lawn, and the woods lies the salt block put out for the wildlife. Tonight as the sun started to retreat the doe made one of her longest appearances there with her single fawn. The mother spent quite a while lapping at the salt block and the fawn paced around tentatively, never far from her side. Returning at times to nuzzle at her breast. But as time went on the fawn became bolder and wandered out into the open lawn to nibble at plantains and dandelions. There in the waning light of the sun one could see the fading lighter spots of its fawn-dom.
Momma doe eventually left the salt block and started down the cornfield along the edge of the lawn. She paused every so often to test the tendernous of a corn cob along the way. The fawn did not follow at first; prefering to stay in the protection of the V made by the lawn bordered on the right by the woods and the left by the tall corn. But mom kept turning back as she moved down the row. I could just hear the faint bleat that a mother doe makes to call her fawn. And soon her fawn responded and trotted towards her; but only to be stopped as a large truck drove by on the state highway further off to the left. Still the doe beckoned the fawn on and they finally joined with her.
But a car and then another truck drove by, and the doe could evidently see the apprehension in her fawn. So she turned and took a step back towards the woods. The fawn was suddenly exhuberant. It kicked up its heels, raised the white flag of its tail and expertly bounded down the lawn alongside the cornfield towards the trailhead at the woods. The fawn slowed and looked back for its mother; but she prefered just to mosey along and eventually caught up. When she did, she changed their direction. Mother and fawn walked in the lawn along the woods and up the rise towards our side yard.
I knew where she was going. All that salt would surely have made the doe thirsty; and that was the way to the big hollow in the woods with the permanent spring in it. But even mom was a bit wary; this was perhaps the longest her fawn had been out in the open this summer. So as she neared the more open side lawn the doe led her fawn into the woods to take the more guarded route to the stream.
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Note to Self: Do Not.....
Do not have soup flavored with cilantro (Chinese parsely) for lunch followed by a dinner of a burrito made with green salsa! You ain't 29 anymore!
Also... I've got about a dozen ruby-throated hummingbirds mobbing the one 4-place feeder. They are sucking down half a quart of nectar a day now - the red-trumpet flowers and honeysuckle must be letting up. But sometimes two hummingbirds will suck from the same floret on the feeder. One will come hover in from the bottom and the other will hover above that one. I wonder what happens when their tongues touch while lapping it up? Is that Hoosier kissing for a hummingbird?
I better see if I have that other feeder around....
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Are the Macintosh Apples Getting Ripe?
It was late August and I was walking down the length of the family-room/kitchen and you can look through the doorway to the laundry room and out the laundry room window to our side yard and mini-orchard. The Macintosh apples are getting rosey red and I've been wondering about their ripeness, though I know that they won't be ready until the second week of September or so. So to my surprise, I just catch sight of a rosey-red Macintosh tumble to the ground and come to a rest. And I think to myself, 'well, maybe I should go get that apple and see how they are coming along.'
So I was keeping my eye on the apple as I continued my walk towards the laundry room. And then to my surprise I see the apple bounce! Bounce? How can it bounce after it had come to a rest below the tree? But then it bounced again! And again! And again!! And then it did a very unapple-like thing, it flew off!!
I started laughing my head off at myself; my Macintosh apple was a red-breasted robin....
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Wildlife Notes for this Labor Day...
For two days in a row a blue-tailed skink has climbed up the chimney just outside of the sliding glass doors to the patio and within view of where I sit at the computer. I wonder what it finds up there? I guess what I call a blue-tailed skink is more properly called a five-lined skink. Just like the red-headed lizards that I see around the house are more properly called a broadhead skink, though they are known also as a "red-headed scorpion!" I don't know how a person could confuse a blue-tailed... excuse me... five-lined skink with a red-headed, broadhead skink. That blue tail is pretty bright on the skinks we have and the red-heads, excuse me again, the broad heads are just that - broader in head and body and a duller, less-irridescant color.
Yesterday we watched the doe, a yearling and the fawn walk out of the woods were the lawn and cornfield meet it at the salt block. They walked up the hill beside the house and out to the orchard where the doe and yearling began to chow down on some dropped apples. The fawn had another idea and it was racing around the orchard, quickly darting back and forth. The fawn's antics got to be contagious after a while and the yearling and doe joined in the game, though to a lesser degree. But they all sure looked as if they were having fun. The doe even kicked up her back heals bucking like a donkey and with her head down, playing at butting the yearling. That might have been a bit of mothering, trying to drive away the yearling. All the while the fawn was doing wind-sprints in the lawn from the edge of one woods to the other. It might have been the family's Labor Day vacation!
But today I caught sight of the doe and yearling down along the cornfield. They were nibbling on grass in the lawn and every so often the doe would try an ear of drying corn. But the fawn was nowhere in sight. Eventually they started up the hill as if they were going to the orchard again. They were picking at browse along the edge of the woods as went and got about a third of the way up the hill. It was then that the doe pricked up her ears and started looking about. Was she looking for her fawn? Perhaps she heard her fawns bleating for her? Whatever it was she quickly made an about face and disappeared into the cornfield along the woods. The yearling soon followed her. So I am wishing the best for the fawn tonight.
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Sometimes You Live.....
I saw the doe and what might have been the fawn out in the orchard just this dusk, two days from when I saw the doe and yearling alone. But they walked behind the one peach tree that is all bushed out - I really have to trim that tree late this winter.
Ten minutes later I still wasn't sure they were still there so I walked out the front door to go down the lane for the newspaper. Immediately, after I got around the corner of the house and could see the orchard I caught sight of what was probably the yearling behind the orchard at the woodsline; and he caught sight of me - I froze. The wind was on my face, so they shouldn't get a wiff of me.
He was staring at me rather intently for about a minute while I remained as steady as I could, when the doe walked into view between us in front of the orchard, nibbling on grass as she went. The yearling lost his caution and bent to graze on some grass for himself. I took the opportunity to take two steps closer to them when the yearling looked up and stomped its foot. Now the doe looked at the yearling concerned about what was going on. She turned to look at me; but I was again as steady as I could be in somewhat mid-stride. The doe took a short while to look in my direction, but then went on about her browsing on a nearby apple tree.
The yearling kept looking my way, though, and, well, I couldn't stay still for long. So I let out a soft 'baa-aah' without even opening my mouth. The doe immediately whirled around and looked my way, stomped her foot, and gave that loudest sound that a deer can make, a loud snort, that indicates she's really nervous. Even so the doe just started to amble back to the yearling, trying to make a sneaking get-away. All this time, I am really trying to find the fawn, so I let out another 'baa-aah.' That got things going a little more, the doe bounded back to the yearling, then took a right, and both bounded off to the safety of the big hollow's woods.
I walked on down the lane and retrieved the evening paper. There was no fawn, sometime, I guess, you are a meal for the coyotes. The doe, understandably still nervous, snorted loudly twice from the woods as I walked back to the house. She has a right to be nervous; this year she lost her child.
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The Fawn's Year (revised)... -- lij, 22:28:52 09/07/05 Wed (ca-01.cinergycom.net/216.135.2.28)
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