Declining Male Birth Rate Baffles Scientists
CHICAGO -- Once there was a kids' hockey team on the reservation of the Aamjiwnaang First Nation in Canada just across the border from Michigan.
No longer. There aren't enough boys.
This community, surrounded by dozens of pollution-spewing chemical plants, is an especially extreme example of a puzzling phenomenon playing out across the world, in countries as diverse as the United States, Sweden and Japan.
Though more boys are being born than girls in most places, their numbers are falling. And no one is sure why.
The change is small, but real. In the U.S., the number of baby boys vs. girls has been declining since 1970, translating into 17 fewer males for every 10,000 births or an estimated 135,000 fewer boys born between 1970 and 2002, according to a study last year in Environmental Health Perspectives.
Some experts suggest the shift is part of a naturally occurring, cyclical pattern in population dynamics. But others think a notable change is under way, driven by factors such as environmental contaminants and various types of stress, such as economic hardship.
These issues could affect boys more because they're actually the weaker sex _ more vulnerable than girls to illness and death from conception to grave.
Nature's way of compensating is to produce more males than females, increasing the likelihood that the sexes will survive to reproductive age in equal numbers. But recent decades have eroded the gap between the sexes.
The difference may seem tiny, but "it's important to look at the really big picture here, which is that there are global indications that something unusual is going on," said Devra Davis, director of the Center for Environmental Oncology at the University of Pittsburgh and lead author of last year's report.
The sex ratio is an indicator of population health, and unexpected changes could be an important signal that people are at risk biologically, she said.
Several Latin American nations have reported a similar shift in the sex ratio at birth, as have Finland, Norway, Wales and the Netherlands. Late last year, several Arctic communities documented a startling decline in the number of boys being born. Studies have shown changing sex ratios in Italian cities and among fish-eating women in the Great Lakes region.
None of these countries or areas has a tradition of sex selection, which in any case usually favors boys.
The puzzling phenomenon has inspired a flurry of research on what could be causing the population shifts. Davis' hypothesis is that "there is something happening after conception that is making it harder for boys to exist in the maternal fetal environment."
A growing body of research indicates that could include exposure to pollutants such as pesticides, mercury, lead and dioxin. More controversial is the idea that synthetic chemicals known as endocrine-disrupters may be damaging male fetuses during critical periods of development or affecting men's sperm counts and testosterone levels.
That thesis is "very interesting and provocative" but hasn't been proved, said Dr. Rebecca Sokol, past president of the Society of Male Reproduction and Urology.
The steepest sex ratio declines observed in the world have occurred on the 3,000-acre Aamjiwnaang (AH-jih-nahng) First Nation reservation in Canada.
The number of boys vs. girls there began dropping in the early 1990s, according to data published in 2005 in Environmental Health Perspectives. Between 1999 and 2003, researchers found, only 46 boys were born out of 132 recorded births.
"You get angry and you get worried, thinking what could be causing this," said Ada Lockridge, a member of the tribe who compiled the data and has since become an activist. "And then you want to learn more."
Dozens of petrochemical, polymer and chemical plants surround the reservation on three sides. Mercury and PCBs contaminate the creek that runs through the land, and air-quality studies show the highest toxic releases in all of Canada, said Jim Brophy, executive director of Occupational Health Clinics for Ontario Workers, based in Sarnia, the nearest city.
Several months ago, Brophy and co-worker Margaret Keith did additional calculations, finding that boys made up only 42 percent of the 171 babies born from 2001 to 2005 to Aamjiwnaang living on the reserve or nearby.
"A disruption in the sex ratio of this magnitude has to be taken seriously," Brophy said.
Still, there is no proof that pollution is responsible, and data from surrounding Lambton County don't show a similar impact. The findings represent a "short period of time and a small population" and require further study, said Dean Edwardson, general manager of the Sarnia-Lambton Environmental Association, which represents area industry.
Experts note that other factors might include diet, alcohol use, smoking and occupational exposures.
Indeed, there's strong evidence from other areas that men exposed in the workplace to pesticides, lead and solvents and in industrial accidents to toxic substances such as dioxin end up fathering fewer boys.
When a July 1976 chemical plant explosion in Seveso, Italy sent a cloud of dioxin over the area, researchers discovered that no boys were born for seven years to parents who had the highest levels of the toxin in their blood.
In another study, men exposed to the pesticide dibromochloropropane fathered three times as many daughters as expected.
Some evidence also suggests stress can reduce the motility or viability of Y-bearing sperm, reducing the likelihood that boys will be conceived. This may help explain why fewer boys are born after natural disasters such as earthquakes and floods _ a finding well documented in the scientific literature.
Moms are thought to have a different set of responses to stress, which also could favor girls over boys.
When pregnant women struggle with adverse circumstances _ economic hardship, poor food supply _ a biological mechanism that "culls" weak male fetuses may be inadvertently deployed, said Ralph Catalano, a professor of public health at the University of California, Berkeley.
From an evolutionary standpoint, this would make sense, since boys require more parental effort to raise while also dying at a higher rate, Catalano explained. When times are tough, it's more advantageous to give birth to a girl, he said.
Among Catalano's thought-provoking findings: The number of boys born in New York City relative to girls fell significantly after the Sept. 11 terrorist attacks.
That result, reported in 2006 in the journal Human Reproduction, applied primarily to women in their second trimester at the time of the attacks. In the paper, Catalano suggests that "fetal response to maternal stressors appears strongest in the second half of gestation" and "mothers may use that response as a test of male fetal robustness."
Separately, in 2003 Catalano reported that the proportion of boys born in East Germany dropped sharply in 1991, when that nation's economy collapsed.
The world's leading expert on the science of sex ratios, William H. James, who spent his career at University College in London, offers another possible explanation: Hormones in both parents at the time of conception affect the sex of offspring.
Higher levels of testosterone and estrogen are associated with the birth of sons, James says, while elevated levels of gonadotropins and progesterone are associated with daughters. These hormones are internally regulated but also are subject to external influences such as alcohol, cigarette smoke, radiation, chemicals, and illnesses in parents.
A spinoff of the theory is the notion that the timing of conception can help determine the sex of offspring because hormone levels fluctuate during a woman's fertile period.
James observed that women who conceive early or late in their fertile periods are more likely to have boys. Couples who have lots of sex have a higher probability of bearing sons, he concluded, because they're more likely to conceive early on, he concluded.
This ties in to the stress hypothesis: If adults have less sex when enduring adversity, then they'd be less likely to conceive male children.
Another notable finding conforms to James' research: Women receiving ovary-stimulating drugs (including gonadotropins) during assisted reproduction give birth to more girls.
On the Aamjiwnaang reservation, it took people a while to recognize the trend toward fewer boys. Families were more concerned about how many babies they were losing: The miscarriage rate for women on the reservation is about 40 percent, much higher than Ontario's average.
Even when there were three girls' baseball teams and only one boys' team, "people just thought there were girls running in their families," Lockridge said.
It still isn't a subject that people talk about much, said Stephanie Stone, 37, who lives on the reservation with her husband, Paul, and three young daughters.
Stone has an 18-year-old son from a previous marriage but said "it hurts my heart" that she hasn't been able to have another. "We have tried and tried to have a baby boy," she said.
http://www.redorbit.com/news/science/1412472/declining_male_b...
Source: Chicago Tribune
No longer. There aren't enough boys.
This community, surrounded by dozens of pollution-spewing chemical plants, is an especially extreme example of a puzzling phenomenon playing out across the world, in countries as diverse as the United States, Sweden and Japan.
Though more boys are being born than girls in most places, their numbers are falling. And no one is sure why.
The change is small, but real. In the U.S., the number of baby boys vs. girls has been declining since 1970, translating into 17 fewer males for every 10,000 births or an estimated 135,000 fewer boys born between 1970 and 2002, according to a study last year in Environmental Health Perspectives.
Some experts suggest the shift is part of a naturally occurring, cyclical pattern in population dynamics. But others think a notable change is under way, driven by factors such as environmental contaminants and various types of stress, such as economic hardship.
These issues could affect boys more because they're actually the weaker sex _ more vulnerable than girls to illness and death from conception to grave.
Nature's way of compensating is to produce more males than females, increasing the likelihood that the sexes will survive to reproductive age in equal numbers. But recent decades have eroded the gap between the sexes.
The difference may seem tiny, but "it's important to look at the really big picture here, which is that there are global indications that something unusual is going on," said Devra Davis, director of the Center for Environmental Oncology at the University of Pittsburgh and lead author of last year's report.
The sex ratio is an indicator of population health, and unexpected changes could be an important signal that people are at risk biologically, she said.
Several Latin American nations have reported a similar shift in the sex ratio at birth, as have Finland, Norway, Wales and the Netherlands. Late last year, several Arctic communities documented a startling decline in the number of boys being born. Studies have shown changing sex ratios in Italian cities and among fish-eating women in the Great Lakes region.
None of these countries or areas has a tradition of sex selection, which in any case usually favors boys.
The puzzling phenomenon has inspired a flurry of research on what could be causing the population shifts. Davis' hypothesis is that "there is something happening after conception that is making it harder for boys to exist in the maternal fetal environment."
A growing body of research indicates that could include exposure to pollutants such as pesticides, mercury, lead and dioxin. More controversial is the idea that synthetic chemicals known as endocrine-disrupters may be damaging male fetuses during critical periods of development or affecting men's sperm counts and testosterone levels.
That thesis is "very interesting and provocative" but hasn't been proved, said Dr. Rebecca Sokol, past president of the Society of Male Reproduction and Urology.
The steepest sex ratio declines observed in the world have occurred on the 3,000-acre Aamjiwnaang (AH-jih-nahng) First Nation reservation in Canada.
The number of boys vs. girls there began dropping in the early 1990s, according to data published in 2005 in Environmental Health Perspectives. Between 1999 and 2003, researchers found, only 46 boys were born out of 132 recorded births.
"You get angry and you get worried, thinking what could be causing this," said Ada Lockridge, a member of the tribe who compiled the data and has since become an activist. "And then you want to learn more."
Dozens of petrochemical, polymer and chemical plants surround the reservation on three sides. Mercury and PCBs contaminate the creek that runs through the land, and air-quality studies show the highest toxic releases in all of Canada, said Jim Brophy, executive director of Occupational Health Clinics for Ontario Workers, based in Sarnia, the nearest city.
Several months ago, Brophy and co-worker Margaret Keith did additional calculations, finding that boys made up only 42 percent of the 171 babies born from 2001 to 2005 to Aamjiwnaang living on the reserve or nearby.
"A disruption in the sex ratio of this magnitude has to be taken seriously," Brophy said.
Still, there is no proof that pollution is responsible, and data from surrounding Lambton County don't show a similar impact. The findings represent a "short period of time and a small population" and require further study, said Dean Edwardson, general manager of the Sarnia-Lambton Environmental Association, which represents area industry.
Experts note that other factors might include diet, alcohol use, smoking and occupational exposures.
Indeed, there's strong evidence from other areas that men exposed in the workplace to pesticides, lead and solvents and in industrial accidents to toxic substances such as dioxin end up fathering fewer boys.
When a July 1976 chemical plant explosion in Seveso, Italy sent a cloud of dioxin over the area, researchers discovered that no boys were born for seven years to parents who had the highest levels of the toxin in their blood.
In another study, men exposed to the pesticide dibromochloropropane fathered three times as many daughters as expected.
Some evidence also suggests stress can reduce the motility or viability of Y-bearing sperm, reducing the likelihood that boys will be conceived. This may help explain why fewer boys are born after natural disasters such as earthquakes and floods _ a finding well documented in the scientific literature.
Moms are thought to have a different set of responses to stress, which also could favor girls over boys.
When pregnant women struggle with adverse circumstances _ economic hardship, poor food supply _ a biological mechanism that "culls" weak male fetuses may be inadvertently deployed, said Ralph Catalano, a professor of public health at the University of California, Berkeley.
From an evolutionary standpoint, this would make sense, since boys require more parental effort to raise while also dying at a higher rate, Catalano explained. When times are tough, it's more advantageous to give birth to a girl, he said.
Among Catalano's thought-provoking findings: The number of boys born in New York City relative to girls fell significantly after the Sept. 11 terrorist attacks.
That result, reported in 2006 in the journal Human Reproduction, applied primarily to women in their second trimester at the time of the attacks. In the paper, Catalano suggests that "fetal response to maternal stressors appears strongest in the second half of gestation" and "mothers may use that response as a test of male fetal robustness."
Separately, in 2003 Catalano reported that the proportion of boys born in East Germany dropped sharply in 1991, when that nation's economy collapsed.
The world's leading expert on the science of sex ratios, William H. James, who spent his career at University College in London, offers another possible explanation: Hormones in both parents at the time of conception affect the sex of offspring.
Higher levels of testosterone and estrogen are associated with the birth of sons, James says, while elevated levels of gonadotropins and progesterone are associated with daughters. These hormones are internally regulated but also are subject to external influences such as alcohol, cigarette smoke, radiation, chemicals, and illnesses in parents.
A spinoff of the theory is the notion that the timing of conception can help determine the sex of offspring because hormone levels fluctuate during a woman's fertile period.
James observed that women who conceive early or late in their fertile periods are more likely to have boys. Couples who have lots of sex have a higher probability of bearing sons, he concluded, because they're more likely to conceive early on, he concluded.
This ties in to the stress hypothesis: If adults have less sex when enduring adversity, then they'd be less likely to conceive male children.
Another notable finding conforms to James' research: Women receiving ovary-stimulating drugs (including gonadotropins) during assisted reproduction give birth to more girls.
On the Aamjiwnaang reservation, it took people a while to recognize the trend toward fewer boys. Families were more concerned about how many babies they were losing: The miscarriage rate for women on the reservation is about 40 percent, much higher than Ontario's average.
Even when there were three girls' baseball teams and only one boys' team, "people just thought there were girls running in their families," Lockridge said.
It still isn't a subject that people talk about much, said Stephanie Stone, 37, who lives on the reservation with her husband, Paul, and three young daughters.
Stone has an 18-year-old son from a previous marriage but said "it hurts my heart" that she hasn't been able to have another. "We have tried and tried to have a baby boy," she said.
http://www.redorbit.com/news/science/1412472/declining_male_b...
Source: Chicago Tribune
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So which causal theory do you believe - environmental or stress?
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enviromental mostly... I tend to believe our planet as well as biology itself is more intellegent than we realize (such as the cells of our bodies) and if a gender, species or whatever places to much burden on the rest of the enviorment, its own species and or those species around them,,, nature begins to select for traits that are less abusive or damaging. This isnt an insult to men, its the truth,,,, the male gender more so than the female, have put great enviormental stress on the planet, on other species as well as on its own species via wars, rape, and various other 'abuses' of what is available.
Perhaps mother nature is simply going to eventually switch our species to asexual reproduction, science has already figured out how to. -
Thanks, while I had some awareness that chemical pollution had depleted male populations in the north, I was completely unfamiliar with Brian Sykes work until reading your posts. At least he gives us fellows another 5000 generations, so maybe we'll sort it out before we're gone.
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very interesting...why dont you make it a poll?
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oh, this one... email me back about the 255 characters if you know the answer and I will! I have anouther one thats simliar that says the male gene is breaking down..
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Ah,, here it is.....
Imagine a world without men: Lauren Bacall but no Bogie, Hillary Clinton but no Bill, no Starsky or Hutch.
This isn't just an unlikely sci-fi scenario. This could be reality, according to Bryan Sykes, an eminent professor of genetics at Oxford University and author of "Adam's Curse: A Future Without Men."
"The Y chromosome is deteriorating and will, in my belief, disappear," Sykes told me. A world-renowned authority on genetic material, Sykes is called upon to investigate DNA evidence from crime scenes. His team of researchers is currently compiling a DNA family tree for our species.
Y Chromosome 'Fatally Flawed'
The Y chromosome is passed from father to son, it's what makes babies into boys. Basically the human template is a female: the Y chromosome kicks in a few weeks after conception and makes a boy. "Men are genetically modified women," explained Sykes. But unlike other chromosomes, the Y chromosome can't repair itself and will, says Sykes, disappear altogether in about 125,000 years.
"Every generation one percent of men will have a mutation which reduces their fertility by 10 percent," explained Sykes. Unlike most chromosomes, the Y does not travel through the generation in pairs, so can never repair itself from a mirror. Flaws are never repaired. "So if that goes on for generation after generation," Sykes argued, "eventually there are no functioning Y chromosomes left."
So no more men … sparsely populated sports bars, Ferrari would lose the lion's share of its business, and Hooters would probably go out of business.
It's a long time, 125,000 years. But we men have a far more immediate problem: sperm counts have fallen by an incredible 20 percent in the past 50 years. Stress? Alcohol? Environmental pollution? Who knows, but it's deeply concerning for those of us with a vested interest in the survival of the male.
Sykes has received hate mail. "To seem to be saying that men will become extinct, which is what I am saying," he mused. "I've had all kinds of messages from male groups saying, 'how can you betray your gender?'"
But would the absence of men make the world a better place? There would be far fewer wars without men on the planet, and the U.S. prison population would drop a colossal 97 percent. Road deaths in the U.S. would fall 70 percent. The Olympics would be half as long, which some people might view as a good thing.
Female-Only Reproduction
But surely, flawed Y chromosome or not, bad behavior or not, we are needed for procreation. Women can't have babies without us … right? I'm afraid, pretty soon they won't need our sperm, our chromosomes, our anything.
Until now, female-only reproduction has been limited to the plant and animal kingdom. So-called parthenogenesis, observed in the Cape Honey Bee, the Kimono Dragon and the hammerhead shark. In humans: confined to 1950s B movies. But Sykes says the technology for women to procreate without us is just around the corner.
"Within the next few years you will get two women having a child who is the biological child of both of them," Sykes said. "And entirely normal in every respect, but always female."
They've already done it with mice. Two mothers: the genetic material from one used to fertilize the egg of the other.
Two Mommies
The picture that Professor Sykes is painting is of a nuclear family without a man in sight. We went in search of what could be the template for the survival of our species. Laura and Natalie are a lovely couple who live in South London with their 13-month-old daughter Sanne. They agreed to let our all-male crew take a peek into their lives. Natalie actually gave birth to Sanne. The sperm came from an anonymous donor. She's raised by two moms.
"That the child will be well balanced with just two moms: Well, that's been proven back in the 40s," explained Natalie, who is also a child psychologist. "It's the care giving and the relationship between the care-giver and the infant that is the important part."
Laura, who right now is the bread winner, thinks any family will work as long as the child is, "getting the attention, the affection, the discipline." Looking at her very contented daughter, Laura told me, "She's obviously confident. She's very stable and secure. So I think so far we're doing okay."
Laura attended both the dads' and the moms' prenatal classes. I asked Natalie if having Laura as the partner was better than having a man? "I had actually a couple of mothers saying, 'Well, at least Laura's a woman she will understand better.'" Natalie told me. "And I said, 'no.' … She was exactly the same as the dads!"
Could Laura mount a defense? "I would like to think that I separate from the dads in that I'm not hooked on the ball games and things like that," she explained. And I must say, she was knee-deep in diaper changing and feeding time while we were hanging out.
So judging by this family, two moms aren't necessarily better, but can be just as good. But surely they must need a burly man for some things? I offered to put up some shelves, or change some light bulbs. "Actually, Laura is very, very handy," Natalie told me, trying not to hurt my feelings.
"My father's a mechanic, so there's nothing about a car that disturbs me," explained Laura. "I've also … I renovated a house. So, I'm really not concerned about that either."
Maybe our only hope as men is that women decide to keep us alive for their own amusement. For the pop music, perhaps, or maybe the dancing. We can be good at that.
For more details on Professor Sykes' work, check out http://www.oxfordancestors.com/
article from ....
http://abcnews.go.com/Health/...
Does not surprise me at all, the whitetail deer herd does the same thing and IMHO, I would guess there is more money spent studing deer herds than any other thing out there...that's where the money is, so that's where the studies are...stress of any kind changes the doe to buck birth ratio.
On apersonal note dealing with premies, the black females were the toughest, the white males were the long shots.