 can produce a strong stock of offspring all on her own. )
SANS SEX: This checkered whiptail lizard (Aspidoscelis tesselata) can produce a strong stock of offspring all on her own.
Image: PETER BAUMANN
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Since the 1960s scientists have known that some species of whiptail lizards need a male even less than a fish needs a bicycle. These all-lady lizard species (of the Aspidoscelis genus) from Mexico and the U.S. Southwest manage to produce well-bred offspring without the aid of male fertilization.
But how do they—and the other 70 species of vertebrates that propagate this way—do it without the genetic monotony and disease vulnerability that often results from asexual reproduction? "It has remained unclear" and "has been the topic of much speculation," report a team of researchers who aimed to answer just that question. Their results were published online February 21 in the journal Nature. (Scientific American is part of Nature Publishing Group.)
These lizards and other "parthenogenetic species are genetically isolated," explains Peter Baumann, an associate investigator at the Stowers Institute for Medical Research in Kansas City, Mo., and co-author of the study. Species as diverse as Komodo dragons and hammerhead sharks do it asexually if necessary, but some species, like these little lizards, don't have a choice. "They can't exchange genetic material, and this loss of genetic exchange is a major disadvantage to them in a changing environment," he says. Unless an animal can recombine the DNA they already have, they will produce an offspring with an identical set of chromosomes, in which any genetic weakness, such as disease susceptibility or physical mutation, would have no chance to be overridden by outside genetic material from a mate.
The new research by Baumann and his team reveal that these lizards maintain genetic richness by starting the reproductive process with twice the number of chromosomes as their sexually reproducing cousins. These celibate species resulted from the hybridization of different sexual species, a process that instills the parthenogenetic lizards with a great amount of genetic diversity at the outset. And the researchers found that these species could maintain the diversity by never pairing their homologous chromosomes (as sexual species do by taking one set of chromosomes from each parent) but rather by combining their sister chromosomes instead. "Recombination between pairs of sister chromosomes maintains heterozygosity" throughout the chromosome, noted the authors of the study, which was led by Aracely Lutes, a postdoctoral researcher in Baumann's lab.
This discovery, which had until now been unconfirmed in the reptile world, means that "these lizards have a way of distinguishing sister from homologous chromosomes," Baumann says. How do they do it? That's something the group is now investigating.
Another big unknown is precisely how the lizards end up with double the amount of chromosomes in the first place. Baumann suspects that it could happen over two rounds of replication or if two sex cells combine forces before the division process starts.
Although asexual reproduction might seem like a bore—and one that can have questionable genetic outcomes unless done right—it has its benefits, too, Baumann notes. "You're greatly increasing the chances of populating a new habitat if it only takes one individual," he says, citing the example of the brahminy blind snake (Ramphotyphlops braminus), another parthenogenetic species. "If she has a way of reproducing without the help of a male, that's an extreme advantage." Indeed it is—the brahminy has already colonized six continents.
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34 Comments
Add CommentOnce human females learn how to do this, they will no longer have a use for men.
Reply | Report Abuse | Link to thisThank Gawad. It's about bloody time.
Awwww....You'd miss us. Who would take out the trash and check the oil in the car? And males can be handy in other ways too. 'Spose you get an itch where you can't reach?
Reply | Report Abuse | Link to thisIt bothers me that whenever we discover a species that reproduces asexually, women all start thinking that they should eliminate men and the world would be better. Since men were originally the only ones who practiced any form of science it should go to reason that men are the ones to created the sciences. If history has taught us anything its that men would be the first to eradicate a gender. Both genders are essential to human survival and thus neither should ever discuss the idea of erasing the other.
Reply | Report Abuse | Link to thisI think we should discuss everything, regardless of how uncomfortable it seems.
Reply | Report Abuse | Link to thisPersonally, I could do without women entirely.
@hotblack,
Reply | Report Abuse | Link to thisI always find your gay comedy routine, really quite funny and refreshing after reading all the serious cranks on this site.
o_o ... -_- o_o -_- o_o -_- o_o ... O_O
Reply | Report Abuse | Link to thisCrap! Don't tell the woman! Don't tell the woman!
You posit that men created science -- but in a world once ruled by men, how could any female that dabbled in the sciences receive any recognition? If you want to talk about history here, it was practically blasphemous for a woman to even think until the past hundred years or so. Your claim that men created the sciences is not backed by any superior intelligence on the part of men -- the only reason this occurred is due to the oppression they practiced, not science. Women didn't even enter the WORKFORCE until World War II.
Reply | Report Abuse | Link to thisAnd if we're looking at the historical importance of women in the sciences, here's a few (although history might neglect to tell you about them, so very typical indeed):
Gerty Radnitz Cori
Rosalyn Sussman Yalow
Barbara McClintock
Rita Levi-Montalcini
Gertrude Elion
Christiane Nusslein-Volhard
Linda B. Buck
Francoise Barre-Sinoussi
Elizabeth H. Blackburn
Carol W. Greider
Marie Sklodowska Curie
Irene Joliot-Curie
Dorothy Crowfoot Hodgkin
Ada E. Yonath
Marie Sklodowska Curie
Maria Goeppert Mayer
And if you'd like the real history of male achievement, here you are:
http://en.wikipedia.org/wiki/History_of_women_in_the_United_States
http://www.mincava.umn.edu/documents/herstory/herstory.html
And let's not forget how Watson bragged about stealing Rosalind Franklin's research.
Reply | Report Abuse | Link to thisAnd Florence Nightingale who was not only a nurse but also a statistician and of course Ada Lovelace
Reply | Report Abuse | Link to thisGuys Guys, no need to feel threatened. We still need you. Remember the “Brave New World”?
Reply | Report Abuse | Link to thisWomen don’t really want to eliminate men. I don’t think there will be any human left if the world is ruled by Wonder Woman and Cleopatra. If you live in New Your you’ll know what I mean. Women are practically “fighting” and attacking each other just to get a guy’s phone number (no matter how unattractive he might be).
"Women dont really want to eliminate men." - Sense
Reply | Report Abuse | Link to thisWell they should.
"I dont think there will be any human left if the world is ruled by Wonder Woman and Cleopatra." - Sense
Oh I don't know. Wonder woman is pretty hot.
"Women are practically fighting and attacking each other just to get a guys phone number ." - Sense
Where is this New Your? I'll print up some business cards.
Quite interesting! Quite interesting! I have heard about parthenogenesis but not to the extent that it is mention in this article. I think even Merriam-Websters will have to modify the definition given to the word in that dictionary. Very interesting the long list of girls given by a reader that have accomplished something worthwhile in science. I have heard only about Marie Sklodowska Curie. It would be interesting to read the story of all of them. Girls certainly are very amazing. They are so beautiful and can do such an amazing array of things! Some times they do extremely useful thing for the benefit of all of us, sometimes they do extremely harmful thing that put in danger our very life. But I tend lightly to trust women more than men; but I think generally women mean to be good and nice if they do not feel offended or betrayed. I believe in the good nature of mankind as a whole. We can not compare women with men. We are not equals; we complement each other. But, to avoid misunderstandings, in many abilities we men and women are probably identical. The article is extremely interesting and research should of course go on. I can probably do without men; no man is an island. But definitively I can not do without women. We need each other and it is futile to try to deny it.
Reply | Report Abuse | Link to thisThe difference is the drive. Yes. Many women have contributed to science in the past. Many are now. However, most are not as aggressive to look beyond the horizon to see what's new. Even though there will ALWAYS be someone claiming it's because of discrimination, even if the playing field is even, the fact remains that regardless of what anyone thinks--men and women are different! There, I said it. Now I get flamed. Testosterone and genetic disposition make men more aggressively look for new horizons than most women. I wish to give great credit where credit is due and say that it's not because women overall cannot do science, it's because fewer women than men wish to. Men also tend to be more obsessive about their work to a fault. Anyone that claims there is no difference between men and women should start parthenogenisis right away, heh. Be sure to read exactly what I'm saying before you flame me, please. Conversly, one can say there are more failed male scientists than there are failed female scientists--so be sure to address that when you flame me. Oh, and be sure to call me a chauvinist even though you don't know what sex I am...
Reply | Report Abuse | Link to thisThe difference is the drive. Yes. Many women have contributed to science in the past. Many are now. However, most are not as aggressive to look beyond the horizon to see what's new. Even though there will ALWAYS be someone claiming it's because of discrimination, even if the playing field is even, the fact remains that regardless of what anyone thinks--men and women are different! There, I said it. Now I get flamed. Testosterone and genetic disposition make men more aggressively look for new horizons than most women. I wish to give great credit where credit is due and say that it's not because women overall cannot do science, it's because fewer women than men wish to. Men also tend to be more obsessive about their work to a fault. Anyone that claims there is no difference between men and women should start parthenogenisis right away, heh. Be sure to read exactly what I'm saying before you flame me, please. Conversly, one can say there are more failed male scientists than there are failed female scientists--so be sure to address that when you flame me. Oh, and be sure to call me a chauvinist even though you don't know what sex I am...
Reply | Report Abuse | Link to thisThe difference is the drive. Yes. Many women have contributed to science in the past. Many are now. However, most are not as aggressive to look beyond the horizon to see what's new. Even though there will ALWAYS be someone claiming it's because of discrimination, even if the playing field is even, the fact remains that regardless of what anyone thinks--men and women are different! There, I said it. Now I get flamed. Testosterone and genetic disposition make men more aggressively look for new horizons than most women. I wish to give great credit where credit is due and say that it's not because women overall cannot do science, it's because fewer women than men wish to. Men also tend to be more obsessive about their work to a fault. Anyone that claims there is no difference between men and women should start parthenogenisis right away, heh. Be sure to read exactly what I'm saying before you flame me, please. Conversly, one can say there are more failed male scientists than there are failed female scientists--so be sure to address that when you flame me. Oh, and be sure to call me a chauvinist even though you don't know what sex I am...
Reply | Report Abuse | Link to thisCrud, so sorry. I had problems logging in. someone plz delete a couple of my dupe posts.
Reply | Report Abuse | Link to thisUnfortunately, I do not buy the notion that differences in the behavior of the sexes is exclusively linked to biology, nor do any scientists today. The fact of the matter is, culture impacts biology and vice versa, and the two evolve simultaneously. You cannot disregard culture as a tremendously powerful force in the shaping of human beings.
Reply | Report Abuse | Link to thisYou also misunderstand the attribute known as aggression, which testosterone does, indeed, impact. Aggressive behavior, which is strengthened with increased levels of testosterone, is characterized by hostile, often destructive behavior.
http://www.essortment.com/all/whatisaggress_rxeo.htm
Aggression, as defined in both psychology and in the hard sciences, is not the same as "drive." Aggression does not account for one's motivation or seeking out of new avenues, but rather, aggression is a LASHING out.
Therefore, the premise that women are not as likely to "look beyond the horizon" because of lower testosterone levels is a laughable suggestion. Testosterone has nothing to do with one's drive.
It is true that hormones can greatly impact a human being's behavior, and it does create differences in the sexes to VARYING degrees, but this does not produce definitive differences in the sexes. In terms of behavior, nearly all phenotypes have *many* underlying genes and chemical interactions that produce a SPECTRUM of individuals.
So to say that women are passive and men are aggressive is to ignore this *gradation* of unique individuals, shaped not only by biology which varies from individual to individual, but it blatantly ignores the culture which surrounds them, as well as evolution itself -- which consists of interactions between culture and biology... they are not mutually exclusive, and impossible to separate.
All of that aside, going so far as to say that a single hormone impedes one's desire to expand or grow, or one's intellectual capacity and creativity... that is incredibly an absolutely bogus statement which any credible scientist would discount.
LOL, I was right about the flames. Okay, look up aggressive at http://dictionary.reference.com/browse/aggressive. I wasn't making a reference to animal aggression and that insinuation was ridiculous. An aggressive tumor doesn't lash out.
Reply | Report Abuse | Link to thisI thought I was clear that I wasn't claiming men have a corner on the market for science or frontiers, but I've learned that regardless of what I say here, there's always someone looking for a reason to be offended. I knew it was a mistake typing the word "testosterone" because that always gets a flame. I know no single hormone is responsible but it's a primary hormone in the cocktail--it is a definite contributing factor to the differences between men and women. I'm always fascinated in certain types of people who claim there is NO difference between males and females when it's so plain in the biology of the animal kingdom. Yes, social influences have an effect. I think it is "absolutely bogus" to claim it's only social influences that determine the differences.
I tried to use your essortment.com to see what they said about testosterone, but there was no article specifically about that. They were mostly articles about testosterone injections and a large part were for the purpose of changing one's sex. Why do this if there's no difference? Honestly, I don't know what your problem was with what I said. You latched on to "aggressive" and "testosterone" and ignored the fact that I did refer to the gradation you say I ignored. I just didn't say it in crayon.
...so, why are there more failed male scientists than failed female scientists?
As far as I can tell, I think we both agree except for the fact I used "aggressive" as a social reference rather than an animal survival reference as your link does, and that I used the word testosterone as an example of one of the major differences between the sexes. Men have more of it than women. You somehow got the idea that I believe testosterone is the one chemical that makes men superior in all ways to all the lower creatures or some bogeyman idea like that. Read the intent of the article and see the articles before it that I may have been responding to.
Ah, the men vs women debate, always a fun one. I have heard, from a very smart person, but one who arguably did not conduct the studies (as he was only 18 when he told me about them), that men have a greater variation in terms of intelligence than women, as in men dominate the Nobel Prizes and the Darwin Awards, while women tend to be closer to the average. However, there have been some changes in that breakdown more recently, and cultural influences undeniably have a powerful impact. For example, right now girls tend to outperform boys academically in school in most categories, with the possible exception of math and hard science; I saw this myself in high school, the first three years our Vals and Sals were female dominated, although my year was exclusively male. But that hasn't always been the case, 50 years ago it was reversed, and from what I've read the reason the switch happened is that our education system went from being optimized for boys to being optimized for girls. I must say though that not all the differences are culturally-based, there are some things that are simply different between men and women. This was confirmed by studies that were done with baby chimpanzees, who are absolutely unaffected intellectually by our cultural preferences. In the study the male chimps preferred the color blue and played with toy trucks, while female chimps preferred pink and played with dolls, showing that there are some fundamental hard-wired differences. I'm male (if you hadn't figured that out yet), and I really don't care who is smarter on average, they are close enough it doesn't matter. But, I am very strongly against ultra-feminism, that brand of it that blames everything from lower pay to menstrual cramps to poor housing markets on those of us with "outdoor plumbing", to use my Grandpa's euphemism. Did you know that women with MBAs tend to work a few hours less per week than men at what should be equivalent points in their careers? Or that these women are also less productive per hour worked than their male counterparts? I'm completely fine with "equal work equal pay", but these women don't do equal work, so why should they get equal pay? Now I know there are other things to consider, but feminazis see a pay gap, declare discrimination, sue and get tons of money when there was nothing there. How many collegiate sports programs has Title IX destroyed? I'm fine with equality, but some of the stuff that has come up because of feminazis should be disposed of, it has done more harm than good.
Reply | Report Abuse | Link to thisWomen ! You can't help liking most of them, but they don't notice me, and I can't afford one anyway - which s probably why they don't notice me. I have even got to the extent of building a "Tadfrey" atop the house with two bays to take a "TAD" each. These wind Turbine-Alternator devices readily provide annually 5% of their cost, in a windy place, but they are not aware of ANY of this !
Reply | Report Abuse | Link to thisMeanwhile, they cannot help but notice the superbly Big "Turbines" of "Windfarms" which - allthough they re-coop annually, only a fraction of one percent of their cost, are Very Big, and even have rotating things on the top - Wow ! who cares if their worth it - "I want one !" So kind of governments to invest our resources and effort so phallicly.
So - while oil - and next nuclear energy (and the Biosphere) - lasts, there would appear to be an evolutionary advantage to being a politician. It seems to me that how one reproduces is almost irrelevat anyway - you can allways get the mess fixed-up somewhere - if you can pay.
Maybe this issue can only be explained by Darwin.
Reply | Report Abuse | Link to thisMaybe the best man to argue this issue is Darwin.
Reply | Report Abuse | Link to thisGood job :). Drosophila melanogaster like that genus. I m amazing because we learn today at genetic study. It s edifice. thx
Reply | Report Abuse | Link to thisFisixisfun- are you referring to this article? http://www.nytimes.com/2009/04/29/business/global/29iht-riedgenper.html?_r=2&adxnnl=1&adxnnlx=1266948567-TZeWAkeV+wCTzUpMrvX+rg
Reply | Report Abuse | Link to thisBecause they make it pretty clear that women work less not because they're lazy, but because they have children, and after going on maternity leave their careers don't quite recover. Do some women work less because they're lazy? Absolutely. Just like some men. People are lazy because they're human, not because they belong to a certain sex.
Munkiy- someone disagreeing with you isn't flaming. And you can be a chauvinist without being male.
Reply | Report Abuse | Link to thiswell, my wife is gonna be happy...
Reply | Report Abuse | Link to thisKotor, I agree. However, insinuating I said things that are "laughable" and "bogus" is inflammatory language. Also, picking at the edges of my reply and not addressing the overall statement is a poor tactic I see too much in politics and lawyers in an effort to degrade integrity without addressing an issue.
Reply | Report Abuse | Link to thisI do love the comment someone made earlier that men top the Nobel and Darwin awards. It's kinda one of the points I was making, but not nearly as clearly! Hahah!
Yes, Cultural (non) Sense please tell that to the thousands of young men in India and China that don't seem to find a girl friend or wife. Just because in the west there is apparently a higher proportion of women with respect to men doesn't mean that it reflects the whole proportion for the entire planet.
Reply | Report Abuse | Link to thisFrom what I have read and observed it is not so much that there is a difference between men and women in the LEVEL of intelligence so much as in the TYPE.
Reply | Report Abuse | Link to thisMen tend to be very narrow focused and will become obsessed with what they are doing and so tend to drill down to more depth of a single project. Women have a wider focus and are more aware of the inter-connection of subjects and how they relate to each other. So while a man might get to a greater depth of the project he is working on a woman will see more opportunities for research and applications. The best team is a mix of both sexes. Where the males may bring their narrower focus to bear the females would be quicker to realize if they needed to change the projects focus or even start up parallel lines of research. Of course this is all general/stereotype individuals vary greatly and may not fit the usual profile.
As for the claim that men work more than women; I don't know what the global average is but in the company where I work (a custom electronics engineering company) it is very noticeable that the women spend a great deal more time socializing both with their fellow workers and on their cell phones. So much so that we had to pass a rule banning cell phone use outside of breaks/lunch. This was true from the officers down to the assemblers.
Reply | Report Abuse | Link to thisIt seems somewhat hypocrite: the idea that these sisters should be able to live in celibacy without problems. These asexual species originate by hybridization of different sexual species. So this start indeed is a good investment in heterozygosity and in rich genetic diversity. Recombination with the different homologous chromosome is avoided by some trick. This maintains not only the heterozygosity, but prevents also the enviable recombinations that makes offspring of interspecific mating so often infertile. This may be the cause why here has been evolutionary selected for the recombination with the copy DNA. Nevertheless these asexual species will accumulate genetic mutations, unfavorable for survival and so will die out sooner or later. If new asexual species ever arise by hybridization of the sexual species the repeatedly extinction of the asexual sisters will not be noticed.
Reply | Report Abuse | Link to thisfemale humans aren't even smart enough to drive let alone accomplish this feet. lets face it you need a male to point you in the right direction otherwise our species would wind up dead from stupidity. i like to call it the where is my butthole syndrome since most of you can't find it.
Reply | Report Abuse | Link to this@abarel
Reply | Report Abuse | Link to thisOh calm down, we're just having a bit of fun. With males believing that they are "God's gift" to women, can you blame us when we feel a little justified when we find out in nature males can be obsolete? It doesn't mean we're going to get rid of you.
Men created the sciences? If that statement has any truth to it, do you know why? It's because the women weren't allowed to do anything but be breeders and housekeepers. It's hard to do any type of scientific discoveries when you're a house servant...
Testosterone also promotes rigidity. We do not advance by having an idea noone else has, we do it by getting rid of an idea that HAS been had before:dogma, misconceptions, idiosyncracies. If the great ideas had been generated by women, they would have been generated before. They couldn't have, because they were saervants! The ones that have, you've never even heard of. Interesting stuff, huh?
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