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Posts Tagged ‘CARL ZIMMER

Female Orgasm: Where it fits in evolution?

Many aspects of the human body have obvious purposes.

But some defy easy explanation. For biologists, few phenomena are as mysterious as the female orgasm.

While orgasms have an important role in a woman’s intimate relationships, the evolutionary roots of the experience — a combination of muscle contractions, hormone release, and intense pleasure — have been difficult to uncover.

For decades, researchers have put forward theories, but none are widely accepted. Now two evolutionary biologists have joined the fray, offering a new way of thinking about the female orgasm based on a reconstruction of its ancient history.

On Monday, in The Journal of Experimental Zoology, the authors conclude that the response originated in mammals more than 150 million years ago as a way to release eggs to be fertilized after sex.

Until now, few scientists have investigated the biology of distantly related animals for clues to the mystery.

The male orgasm has never caused much of a stir among evolutionary biologists. The pleasure is precisely linked to ejaculation, the most important step in passing on a male’s genes to the next generation. That pleasure encourages men to deliver more sperm, which is evolutionarily advantageous.

For women, the evolutionary path is harder to figure out. The muscle contractions that occur during an orgasm are not essential for a woman to become pregnant. And while most men can experience an orgasm during sex, it’s less reliable for women.

In a 2010 survey, 35.6 percent of women said that they hadn’t had an orgasm the most recent time they had sex. Part of the reason for this is anatomy: the clitoris is physically separated from the vagina.

Still, a number of scientists suspect that the female orgasm serves some biological function favored by natural selection. They just need to figure out what it is.

“My gut instinct is that something that matters so much at an emotional level — the intense pleasure of orgasm — would seem to have reproductive consequences,” said David A. Puts, an evolutionary anthropologist at Pennsylvania State University.

Many hypotheses have been put forward. Dr. Puts and his colleagues have carried out studies to test the possibility that orgasms increase the odds that a woman’s eggs are fertilized by a genetically attractive male. (Many novels mention that women knew they were impregnated from the types of orgasm they experience, though impregnation does Not happens until 2 days later)

Elisabeth A. Lloyd, a philosopher at Indiana University, isn’t buying it. In 2005, she published a book called “The Case of the Female Orgasm,” in which she reviewed 18 published theories about its function.

Dr. Lloyd thinks the best explanation for the female orgasm is that it hasn’t served any evolutionary purpose at all. It’s nothing more than the by-product of the development of the male orgasm. The orgasm is to women, she believes, as nipples are to men. (Funny. I don’t buy that)

Esther Perel shared this link. August 29 at 5:00pm ·
nytimes.com|By Carl Zimmer

Dr. Pavlicev and her colleague, Günter P. Wagner of Yale University, are making the case that the human female orgasm has a deep evolutionary history that reaches back to early mammals.

They began by getting better acquainted with the sex lives of other animals, poring through obscure old journals to gather information on species ranging from aardvarks to koalas.

They noted that many female mammals release oxytocin and prolactin during sex — the hormones released by women during orgasms. What’s more, in many of those species, females use a radically different kind of reproduction.

While women release an egg each month, other female mammals, such as rabbits and camels, release an egg only after mating with a male.

Ovulatory cycles evolved in only a few lineages of mammals, including our own, Dr. Pavlicev and Dr. Wagner found. Before then, our ancient mammal ancestors originally relied on ovulation triggered by sex with a male.

Those early mammals developed a clitoris inside the vagina.

Only in mammals that evolved ovulatory cycles did the clitoris move away. Based on these findings, Dr. Pavlicev and Dr. Wagner argue that the female orgasm first evolved as a reflex to help females become pregnant.

This arrangement has worked well for mammals that rarely encounter males. It helps females make the most of each mating.

But eventually some mammals, including primates like us, started spending their lives in social groups. Females had access to regular sex with males, and orgasm as an ovulatory mechanism was no longer so useful.

Our female forebears instead evolved a new system: releasing eggs in a regular cycle.

As the original purpose of the orgasm was lost, the clitoris moved away from its original position.

Dr. Wagner speculated that this shift was part of evolution’s dismantling of a sensor system: “You don’t want to have the old signal sending noise at the wrong time,” he said.

“Basically, we don’t know why this happened,” he added. But across mammalian species, “it’s just a very strong evolutionary pattern.”

Dr. Lloyd and Dr. Puts welcomed the new study as a provocative addition to the debate over the female orgasms.

“I’m pretty excited that it’s being published,” Dr. Lloyd said, “because people are going to start talking about female orgasms and getting a fresh look at how much we don’t know about female orgasms, and thinking hard about what we need to know.”

The new theory may shed light on how the human female orgasm first evolved, but Dr. Pavlicev and Dr. Wagner said that it doesn’t settle the debate about its current role in women. “All directions are open,” Dr. Wagner said.

Dr. Wagner said that deciphering the history of the female orgasm might improve reproductive medicine.

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Zombie Roaches?

A herd of wildebeests, a shoal of fish, a flock of birds.

Many animals gather in large groups that are among the most wonderful spectacles in the natural world. But why do these groups form?

The common answers include things like seeking safety in numbers or hunting in packs or gathering to mate or breed,

All of these explanations, while often true, make a huge assumption about animal behavior, that the animals are in control of their own actions, that they are in charge of their bodies. And that is often not the case.

0:46 This is Artemia, a brine shrimp. You probably know it better as a sea monkey. It’s small, and it typically lives alone, but it can gather in these large red swarms that span for meters, and these form because of a parasite.

These shrimp are infected with a tapeworm. A tapeworm is effectively a long, living gut with genitals at one end and a hooked mouth at the other.

As a freelance journalist, I sympathize. (Laughter) The tapeworm drains nutrients from Artemia’s body, but it also does other things. It castrates them, it changes their color from transparent to bright red, it makes them live longer.

and as biologist Nicolas Rode has found, it makes them swim in groups. Why?

Because the tapeworm, like many other parasites, has a complicated life cycle involving many different hosts. The shrimp are just one step on its journey. Its ultimate destination is this, the greater flamingo.

Only in a flamingo can the tapeworm reproduce.  So to get there, it manipulates its shrimp hosts into forming these conspicuous colored swarms that are easier for a flamingo to spot and to devour, and that is the secret of the Artemia swarm. They aren’t sociable through their own volition, but because they are being controlled.

It’s not safety in numbers. It’s actually the exact opposite. The tapeworm hijacks their brains and their bodies, turning them into vehicles for getting itself into a flamingo.

2:20 And here is another example of a parasitic manipulation. This is a suicidal cricket.

This cricket swallowed the larvae of a Gordian worm, or horsehair worm. The worm grew to adult size within it, but it needs to get into water in order to mate, and it does that by releasing proteins that addle the cricket’s brain, causing it to behave erratically. When the cricket nears a body of water, such as this swimming pool, it jumps in and drowns, and the worm wriggles out of its suicidal corpse. Crickets are really roomy. Who knew?

2:59 The tapeworm and the Gordian worm are not alone. They are part of an entire cavalcade of mind-controlling parasites, of fungi, viruses, and worms and insects and more that all specialize in subverting and overriding the wills of their hosts.

Now, I first learned about this way of life through David Attenborough’s “Trials of Life” about 20 years ago, and then later through a wonderful book called “Parasite Rex” by my friend Carl Zimmer. And I’ve been writing about these creatures ever since.

Few topics in biology enthral me more. It’s like the parasites have subverted my own brain. Because after all, they are always compelling and they are delightfully macabre.

When you write about parasites, your lexicon swells with phrases like “devoured alive” and “bursts out of its body.” (Laughter)

3:45 But there’s more to it than that. I’m a writer, and fellow writers in the audience will know that we love stories.

Parasites invite us to resist the allure of obvious stories. Their world is one of plot twists and unexpected explanations.

Why, for example, does this caterpillar start violently thrashing about when another insect gets close to it and those white cocoons that it seems to be standing guard over? Is it maybe protecting its siblings? No.

This caterpillar was attacked by a parasitic wasp which laid eggs inside it. The eggs hatched and the young wasps devoured the caterpillar alive before bursting out of its body. See what I mean? Now, the caterpillar didn’t die. Some of the wasps seemed to stay behind and controlled it into defending their siblings which are metamorphosing into adults within those cocoons. This caterpillar is a head-banging zombie bodyguard defending the offspring of the creature that killed it.

4:52 We have a lot to get through. I only have 13 minutes. (Laughter)

4:56 Now, some of you are probably just desperately clawing for some solace in the idea that these things are oddities of the natural world, that they are outliers, and that point of view is understandable, because by their nature, parasites are quite small and they spend a lot of their time inside the bodies of other things.

Parasites are easy to overlook, but that doesn’t mean that they aren’t important.

A few years back, a man called Kevin Lafferty took a group of scientists into 3 Californian estuaries and they pretty much weighed and dissected and recorded everything they could find, and what they found were parasites in extreme abundance.

Especially common were trematodes, tiny worms that specialize in castrating their hosts like this unfortunate snail.

Now, a single trematode is tiny, microscopic, but collectively they weighed as much as all the fish in the estuaries and three to nine times more than all the birds.

And remember the Gordian worm that I showed you, the cricket thing? One Japanese scientist called Takuya Sato found that in one stream, these things drive so many crickets and grasshoppers into the water that the drowned insects make up some 60% of the diet of local trout.

Manipulation is not an oddity. It is a critical and common part of the world around us, and scientists have now found hundreds of examples of such manipulators, and more excitingly, they’re starting to understand exactly how these creatures control their hosts.

6:23 And this is one of my favorite examples. This is Ampulex compressa, the emerald cockroach wasp, and it is a truth universally acknowledged that an emerald cockroach wasp in possession of some fertilized eggs must be in want of a cockroach. When she finds one, she stabs it with a stinger that is also a sense organ.

This discovery came out three weeks ago. She stabs it with a stinger that is a sense organ equipped with small sensory bumps that allow her to feel the distinctive texture of a roach’s brain. So like a person blindly rooting about in a bag, she finds the brain, and she injects it with venom into two very specific clusters of neurons.

Israeli scientists Frederic Libersat and Ram Gal found that the venom is a very specific chemical weapon. It doesn’t kill the roach, nor does it sedate it. The roach could walk away or fly or run if it chose to, but it doesn’t choose to, because the venom nixes its motivation to walk, and only that.

The wasp basically un-checks the escape-from-danger box in the roach’s operating system, allowing her to lead her helpless victim back to her lair by its antennae like a person walking a dog. And once there, she lays an egg on it, egg hatches, devoured alive, bursts out of body, yadda yadda yadda, you know the drill. (Laughter)

7:48 Now I would argue that, once stung, the cockroach isn’t a roach anymore. It’s more of an extension of the wasp, just like the cricket was an extension of the Gordian worm. These hosts won’t get to survive or reproduce. They have as much control over their own fates as my car. Once the parasites get in, the hosts don’t get a say.

8:09 Now humans, of course, are no stranger to manipulation.

We take drugs to shift the chemistries of our brains and to change our moods, and what are arguments or advertising or big ideas if not an attempt to influence someone else’s mind?

But our attempts at doing this are crude and blundering compared to the fine-grained specificity of the parasites.

Don Draper only wishes he was as elegant and precise as the emerald cockroach wasp. Now, I think this is part of what makes parasites so sinister and so compelling.

We place such a premium on our free will and our independence that the prospect of losing those qualities to forces unseen informs many of our deepest societal fears.

Orwellian dystopias and shadowy cabals and mind-controlling supervillains — these are tropes that fill our darkest fiction, but in nature, they happen all the time.

9:06 Which leads me to an obvious and disquieting question: Are there dark, sinister parasites that are influencing our behavior without us knowing about it, besides the NSA? If there are any — (Laughter) (Applause) I’ve got a red dot on my forehead now, don’t I? (Laughter)

9:29 If there are any, this is a good candidate for them.

This is Toxoplasma gondii, or Toxo, for short, because the terrifying creature always deserves a cute nickname.

Toxo infects mammals, a wide variety of mammals, but it can only sexually reproduce in a cat. And scientists like Joanne Webster have shown that if Toxo gets into a rat or a mouse, it turns the rodent into a cat-seeking missile. If the infected rat smells the delightful odor of cat piss, it runs towards the source of the smell rather than the more sensible direction of away. The cat eats the rat. Toxo gets to have sex. It’s a classic tale of Eat, Prey, Love. (Laughter) 

10:18 You’re very charitable, generous people. Hi, Elizabeth, I loved your talk.

10:24 How does the parasite control its host in this way? We don’t really know. We know that Toxo releases an enzyme that makes dopamine, a substance involved in reward and motivation. We know it targets certain parts of a rodent’s brain, including those involved in sexual arousal.

But how those puzzle pieces fit together is not immediately clear. What is clear is that this thing is a single cell. This has no nervous system. It has no consciousness. It doesn’t even have a body. But it’s manipulating a mammal?

We are mammals. We are more intelligent than a mere rat, to be sure, but our brains have the same basic structure, the same types of cells, the same chemicals running through them, and the same parasites.

Estimates vary a lot, but some figures suggest that one in three people around the world have Toxo in their brains. Now typically, this doesn’t lead to any overt illness. The parasite holds up in a dormant state for a long period of time. But there’s some evidence that those people who are carriers score slightly differently on personality questionnaires than other people, that they have a slightly higher risk of car accidents, and there’s some evidence that people with schizophrenia are more likely to be infected.

Now, I think this evidence is still inconclusive, and even among Toxo researchers, opinion is divided as to whether the parasite is truly influencing our behavior. But given the widespread nature of such manipulations, it would be completely implausible for humans to be the only species that weren’t similarly affected.

11:53 And I think that this capacity to constantly subvert our way of thinking about the world makes parasites amazing.

They’re constantly inviting us to look at the natural world sideways, and to ask if the behaviors we’re seeing, whether they’re simple and obvious or baffling and puzzling, are not the results of individuals acting through their own accord but because they are being bent to the control of something else. And while that idea may be disquieting, and while parasites’ habits may be very grisly, I think that ability to surprise us makes them as wonderful and as charismatic as any panda or butterfly or dolphin.

12:32 At the end of “On the Origin of Species,” Charles Darwin writes about the grandeur of life, and of endless forms most beautiful and most wonderful, and I like to think he could easily have been talking about a tapeworm that makes shrimp sociable or a wasp that takes cockroaches for walks.

12:51 But perhaps, that’s just a parasite talking.

Patsy Z and TEDxSKE shared a link.
In this fascinating, hilarious and ever-so-slightly creepy talk, science writer Ed Yong tells the story of his favorite parasites —
animals and organisms that live on the bodies (and brains!) of other organisms, causing them to do their bidding. Do…
ted.com|By Ed Yong

Scientific Retractions: Sharp Rise Prompts Calls for Reform

CARL ZIMMER published on April 16, 2012 under “A Sharp Rise in Retractions Prompts Calls for Reform”:

“In the fall of 2010, Dr. Ferric C. Fang made an unsettling discovery.  Editor in chief of the journal Infection and Immunity, and professor at the University of Washington School of Medicine, Dr. Fang found that one of his authors had doctored several papers.

Fang said in the interview: “Prior to that time the journal “Infection and Immunity” had only retracted nine articles over a 40-year period. The journal wound up retracting six of the papers from Naoki Mori of the University of the Ryukyus in Japan. And it soon became clear that Infection and Immunity was hardly the only victim of Dr. Mori’s misconduct. Since then, other scientific journals have retracted two dozen of his papers, according to the watchdog blog Retraction Watch.

Matthew Ryan Williams for The New York Times

Retraction of papers increased 10 fold in the last ten years, while published papers increased just 44%. The chart shows the trend of the drastic increases in fraudulant scientific papers (196), scientific mistakes (235) and faulty experimental design, procedure and data acquisition (311):

Source: Journal of Medical Ethics

“Nobody had noticed the whole thing was rotten,” said Dr. Fang. To find out, he teamed up with a fellow editor at the journal, Dr. Arturo Casadevall of the Albert Einstein College of Medicine in New York.

And before long they reached a troubling conclusion: not only that retractions were rising at an alarming rate, but that retractions were just a manifestation of a much more profound problem — “a symptom of a dysfunctional scientific climate,” as Dr. Fang put it.

Dr. Casadevall, now editor in chief of the journal mBio, said he feared that science had turned into a winner-take-all game with perverse incentives that lead scientists to cut corners and, in some cases, commit acts of misconduct.

“This is a tremendous threat,” Casadevall said.

Last month, in a pair of editorials in Infection and Immunity, the two editors issued a plea for fundamental reforms. They also presented their concerns at the March 27 meeting of the National Academies of Sciences committee on science, technology and the law.

Members of the committee agreed with their assessment. “I think this is really coming to a head,” said Dr. Roberta B. Ness, dean of the University of Texas School of Public Health. And Dr. David Korn of Harvard Medical School agreed that “there are problems all through the system.”

No one claims that science was ever free of misconduct or bad research. Indeed, the scientific method itself is intended to overcome mistakes and misdeeds. When scientists make a new discovery, others review the research skeptically before it is published. And once it is, the scientific community can try to replicate the results to see if they hold up. (All that is in theory of the procedures: How many do replicate experiments?)

But critics like Dr. Fang and Dr. Casadevall argue that science has changed in some worrying ways in recent decades — especially biomedical research, which consumes a larger and larger share of government science spending.

In October 2011, for example, the journal Nature reported that published retractions had increased tenfold over the past decade, while the number of published papers had increased by just 44 percent.

In 2010 The Journal of Medical Ethics published a study finding the new raft of recent retractions was a mix of misconduct and honest scientific mistakes.

Several factors are at play here, scientists say:

1. One may be that because journals are now online, bad papers are simply reaching a wider audience, making it more likely that errors will be spotted. “You can sit at your laptop and pull a lot of different papers together,” Dr. Fang said.

2. Other forces are more pernicious. To survive professionally, scientists feel the need to publish as many papers as possible, and to get them into high-profile journals. And sometimes they cut corners or even commit misconduct to get there.

To measure this claim, Dr. Fang and Dr. Casadevall looked at the rate of retractions in 17 journals from 2001 to 2010 and compared it with the journals’ “impact factor,” a score based on how often their papers are cited by scientists. The higher a journal’s impact factor, the two editors found, the higher its retraction rate.

The highest “retraction index” in the study went to one of the world’s leading medical journals, The New England Journal of Medicine. In a statement for this article, it questioned the study’s methodology, noting that it considered only papers with abstracts, which are included in a small fraction of studies published in each issue. “Because our denominator was low, the index was high,” the statement said.

Monica M. Bradford, executive editor of the journal Science, suggested that the extra attention high-impact journals get might be part of the reason for their higher rate of retraction. “Papers making the most dramatic advances will be subject to the most scrutiny,” she said.

Dr. Fang says that may well be true, but adds that it cuts both ways: the scramble to publish in high-impact journals may be leading to more and more errors.

Each year, every laboratory produces a new crop of Ph.D.’s, who must compete for a small number of jobs, and the competition is getting fiercer. In 1973, more than half of biologists had a tenure-track job within six years of getting a Ph.D. By 2006 the figure was down to 15 percent.


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