Monday, December 29, 2008
Thursday, December 11, 2008
This is an odd thing about mammalian testicles: they're often in a peculiar and very exposed place, bouncing about uncomfortably and dangerously, hanging out of the body in a scrotal sac. Other animals don't do anything so foolish; why mammals?
A couple of hypotheses have been proposed that might explain what advantage we derive from this peculiar arrangement.
- The display hypothesis. Males are flaunting their strength and health and virility and ability to protect a delicate package. Some species do make a show of it; some baboons have bright blue scrota, for instance. Most do not, however, and the idea seems unlikely to explain why this trait is preserved in mammals with widely diverse mating strategies.
- The cold storage hypothesis. It may not be so much the testis that is maintained at a cooler temperature outside the body core, but the epididymis. The epididymis is a storage organ for sperm. It may boost the longevity of the stored sperm if they are kept cool, maximizing the quantity of sperm that can be delivered. There are some good reasons that support this idea—some mammals do have internal testicles, but keep them organized so the epididymis is superficial—but personally, this hypothesis seems unlikely, and if it is sufficient to keep just the epididymis cool, it doesn't explain how the testicles ended up exposed in a bag.
- The training hypothesis. This one seems a bit of a stretch to me: the idea is that the testicle and epididymis are like boot camp, a tough, difficult environment that will weed out the unfit and allow only the strong to go on. Cool temperatures, more variable temperature, restricted blood flow...all prepare the sperm for the hostile environment they will confront upon ejaculation. There are many untested assumptions in this hypothesis, and it seems particularly improbable in species that practice sperm competition that they would sacrifice quantity for hypothetical quality, or that they would need to do something as risky as descensus and scrotal exposure to create an unpleasant cellular environment.
- The temperature hypothesis. The most likely explanation is that there is something in the function of the testis that is optimized for a lower temperature, and that the clumsy kludge that evolved to reduce that temperature was to let the organ hang out in the breeze. This seems reasonable, since fertility can be directly affected by temperature—a difference of a few degrees can be the difference between fecundity and sterility. The specific constraint in the process of sperm development that imposes this limitation hasn't been identified, however; one contributing factor (but definitely not the sole factor) may be that mutation rates increase with temperature, and the male germ line, which undergoes many more cell division than the female line, is much more sensitive to small changes in the mutation rate.
Werdelin and Nilsonne (1999) have taken a phylogenetic approach to examine this question. It may surprise some of you to learn that not all mammals have a scrotum. Many, like us people, have fully descended testicles contained in an external sac, the scrotum. Some have descended testicles, but no scrotum; the testicles are imbedded in the body wall. And some don't bother with that descensus nonsense at all, and keep their testicles high up in the dorsal body wall, near the kidneys, a condition called testicondy. If you'd asked me before I read this paper which animals have scrota and which do not, I wouldn't have had a clue (it really does seem like a rather personal thing, don't you think?), nor would I have had much of an idea of the distribution of scrota across the Mammalia. Werdelin and Nilsonne have peeked under the kilts, though, and summarized the distribution. Here is the abstract of the paper:
The adaptive significance of the scrotum and the evolution of the descent of the testicles and epididymis have been a focus of interest among biologists for a long time. In this paper we use three anatomical character states of the scrotum and descensus: (1) testicles descended and scrotal; (2) testicles descended but ascrotal; (3) testicles not descended (testicondy). These states are then mapped on an up to date phylogeny of the Mammalia. Three main points arise out of this mapping procedure: (1) the presence of a scrotum is either primitive in extant Mammalia or primitive within eutherian mammals except Insectivora; (2) evolution has generally proceeded from a scrotal condition to progressively more ascrotal; (3) loss of testicular descensus is less common in mammalian evolution than is loss of the scrotum. In the light of these findings we discuss some current hypotheses regarding the origin and evolution of the scrotum. We find that these are all incomplete in so far as it is not the presence of the scrotum in various mammal groups that requires explaining. Instead, it is the reverse process, why the scrotum has been lost in so many groups, that should be explained. We suggest that the scrotum may have evolved before the origin of mammals, in concert with the evolution of endothermy in the mammalian lineage, and that the scrotum has been lost in many groups because descensus in many respects is a costly process that will be lost in mammal lineages as soon as an alternative solution to the problem of the temperature sensitivity of spermatogenesis is available.
What they see in the phylogenetic distribution of scrota is that our common, ancestral proto-mammal had probably evolved a scrotum as a solution to its fertility requirements, and really, probably the best answer to why we have this odd scrotal arrangement is that that is the way great-great-greatn-grandpa did it. It is the primitive condition, inherited from mammal-like reptiles of the Permian, and mammalian lineages have been independently ditching the idea as fast as they can...which isn't very fast. Here's one of their summary diagrams:
Results of mapping the three character states onto a phylogeny of the Mammalia. Testicle position unordered: red, testicond; gray, descended and ascrotal; black, descended, scrotal; blue, marsupial; white, equivocal.
The black bars are us, the species that let it all hang out. The most parsimonious explanation for their distribution, the one that requires the smallest number of novel adapations, is that they represent the ancestral condition. Some lineages, such as rhinos and tapirs and bats and whales (whales and seals, by the way, still keep their gonads cool by shunting blood vessels that pass through the skin back to the testicles—they essentially have water-cooled balls), still have descended testicles but don't have scrota; these are in gray. And the rare red lineages, elephants and manatees most prominently, have dispensed with the whole silly arrangement and keep their testicles safe and deep in the body cavity. (This is very useful knowledge to have if you ever get angry at an elephant and are tempted to kick him in the nads...don't bother. He'll just laugh at you.)
Here's the rough history of the mammalian testicle, in summary:
Studies of the origin of endothermy in mammals indicate that incipient endothermy may have evolved in mammalian ancestors as early as the middle Late Permian, at least 260 million years ago, which is some 40 million years before the origin of the Mammalia and 130 million years before the origin of crown group mammals, i.e. those for which we have here demonstrated that the scrotum may be primitive. A plausible, though at present untestable, scenario is that in the course of the evolution of mammalian endothermy, core body temperatures eventually reached levels at which spermatogenesis was disrupted. At this point, the testicles had to be cooled, and descensus into a scrotum was one way of achieving this result. However, because of the various costs of descensus the evolution of the male reproductive system of mammals since then has revolved around finding alternative solutions to the original cooling problem. This means that testicondy probably evolved only once among Eutherians, strengthening the conclusions herein.
Source: The evolution of the scrotum and testicular descent in mammals: a phylogenetic view.
Opinions from Pharyngula
Monday, December 1, 2008
Monday, November 17, 2008
VIGO, Spain (25 Sep 2005) -- RESEARCH by marine scientists has shed startling new light on the secret sex life of the giant squid, one of the most mysterious monsters of the world's deepest oceans.
The breakthrough came after a recent spate of strandings on the Atlantic coast of Spain when five of the huge invertebrates - one of them 12 metres long - were washed ashore in a single week on beaches on the Bay of Biscay.
One of the two males washed ashore was found to have been accidentally inseminated - backing the findings of research in previous strandings.
And scientists now believe the males had either accidentally inseminated themselves during "violent" lovemaking sessions with females or been inseminated by other males after "bumping" into them in the dark depths of the ocean.
The new discovery is reported by a team of Spanish scientists at the Institute of Marine Research in Vigo in the latest edition of the monthly magazine of the International Council for the Exploration of the Seas.
The researchers state: "The giant squid, Architeuthis, is not only a cultural and media icon, but also a scientific enigma. Although it is among the largest living invertebrates ... most of our knowledge of its biology and ecology is still fragmented. So each time a giant squid is washed ashore or gets brought up in a fishing net, it provides a gold mine of information. A recent spate of strandings along the Spanish Atlantic coast has shed new light on their unique sexual behaviour in the ocean depths."
The report goes on: "Although mating has never been observed in giant squid, it is thought that what happens is that the male injects his sperm packages into the female's arms. The process is likely to be a fairly violent affair as the female is probably not that keen on being injected. This is a problem for the amorous male as females are normally a third bigger than they are.
"But males get round their inferior size by being endowed with a particularly long penis, which means they can inject the female without having to get too close to her chomping beak. The male's sexual organ is actually a bit like a high-pressure fire hose and is normally nearly as long as his body - excluding legs and head.
"But having such a big penis does have one drawback: it seems that co-ordinating eight legs, two feeding tentacles and a huge penis, whilst fending off an irate female, is a bit too much to ask, and one of the two males stranded on the Spanish coast had accidentally injected himself with sperm packages in the legs and body. And this does not seem to have been an isolated incident since two of the eight males that had stranded in the north-east Atlantic before had also accidentally inseminated themselves.
"It is also possible that the sperm packages had come from other males that they had 'bumped' into, in the dark depths of the ocean. However, the sperm packages ended up in the squid - it is just another part of the mysterious lives of these creatures of the deep sea."
Fewer than 600 specimens of giant squid have been recorded around the world since the 16th century, with the majority of landings and strandings in the north-east Atlantic and off the coasts of New Zealand and Australia. The giant squid can reach up to 18 metres in length and weigh up to 900kg.
The researchers state: "For many years the race has been on to try to film a giant squid going about its business in the ocean depths, and many marine scientists are vying to get the first video footage. So far all expeditions have been unsuccessful, but a new Spanish expedition is currently being planned and maybe this time we will be lucky."
GIANT squid are not the only members of the natural world to display unusual sexual behaviour. In Australia, the male Yellow-footed Antechinus - a mouse-like marsupial - goes through such a frenzy of mating that they die of sexual stress. The female praying mantis often eats her partner during or after sex, while homosexual behaviour is also known in geese, ostriches, cichlid fish, rats and monkeys.From CDNN
Tuesday, October 28, 2008
Wednesday, September 17, 2008
Enhanced Partner Preference in a Promiscuous Species by Manipulating the Expression of a Single Gene
A team of scientists observed the arginine vasopressin receptor 1a gene in prairie voles (Microtus ochrogaster) who are socially monogamous animals. This is a largely unique behavior among rodents. Prairie voles form long-lasting pair bonds and both parents partake in raising their young. It is thought that two hormones, oxytocin and vasopressin, are essential in the development of monogamy. The scientists observed a gene that regulates vasopressin output in the brain to see if, when transplanted into a close promiscuous relative species, the meadow voles (Microtus pennsylvanicus), it would have the same effect in forming pair bonds. The scientists genetically modified meadow voles by transferring the viral vector V1aR gene into test subjects’ forebrain. Additionally, they isolated adult males for 24 hours with a receptive female and sought to find out whether the males preferred to return to the female with whom he had spent the previous day. After male meadow voles were given the opportunity to access new partners, would they prefer to return to the old one? They measured this empirically by timing how long affected males huddled with the female with whom they had previously been isolated. They also hoped to show that by changing a single gene they would be able to provide “a potential molecular mechanism for the rapid evolution of complex social behaviour.”
They found that males possessing the V1aR gene would go back to the females with whom they were isolated for 24-hours and huddle. Males who hadn't been genetically modified were found uniformly distributed among females after the 24-hour isolation with one female.
Monogamy is a rarely observed phenomenon in mammals. Unlike birds that lay eggs, parental investment can just as easily come from the mother as it can from the father. Female mammals, on the other hand, tend to have long gestation periods followed by long lactation periods before they can mate again. From a male perspective, if the objective is to pass your genes on to as many offspring as possible, it seems maladaptive to stay with one female when there are many other females you could potentially inseminate.
If females are the limiting factor, from an evolutionary perspective mammals should be largely polygynous. Polygyny is a mating system where one male mates with many females. From a female perspective, it may be in her best interest to be polygynous because “loser” females, or those with unattractive genetic material, would be able to mate with high quality males. Polygyny may also ensure superior habitat and resources supplied by the male.
Promiscuity is another viable option for mammals. It may be in males’ and females’ best interest to be promiscuous like the meadow voles and let sperm competition and cryptic female choice determine which males are successful in providing the gamete for the female’s egg. Given the severity of the many negative aspects of monogamy- and the advantages of other mating systems - why do certain species still engage in this behavior?
Polygyny and promiscuity favor few “winner” males, and the many “loser” males do not mate at all. This is not an argument for group selection, but if a loser male can hook a female into mating with him, it is in his best interest to invest all of his time and resources into her and not attempt to sequester many females. From a female perspective, monogamy may be the best choice because it provides ensured support for the female and her offspring. Gestation and lactation are incredibly energy-consuming and difficult if pursued solitarily.
Olivia Judson wrote about this paper in her blog, The Wild Side, and concluded with "it does raise the tantalizing prospect that, one day, it might really be possible to concoct love potions or pills that would alter brain chemistry and enhance the odds of a man forming a strong attachment to his lover." A tantalizing prospect, indeed!
Lim, M. M., Wang, Z., Olazabal, D. E., Ren, X., Terwillinger, E. F., Young, L. J. 2004. Enhanced Partner Preference in a Promiscuous Species by Manipulating the Expression of a Single Gene. Nature: 429.
Wednesday, August 27, 2008
Well, it appears to be for sexual selection. The standard story about why giraffes have evolved their incredibly long necks states that this trait has helped them in reaching to higher leaves. This story, however, is probably wrong. Observations of giraffes have shown that over 50 percent of the time, they feed with their necks horizontal and that during the food-scarce dry season, they feed in low bushes rather than in tall trees. The giraffes are obviously capable of feeding on higher leaves than other animals but this advantage doesn't seem to be sufficiently great to justify the costs of having such a long neck.
The giraffes' head is about 3 meters above the heart which makes it very difficult for the heart to pump blood to the brain. The giraffe has the highest blood pressure of all mammals and its heart weighs up to 10 kg. The largest giraffe on record was almost 6 meters tall and weighed about 2 tons. In spite of their size, the giraffe can run very fast, up to 60 km/h (aprox. 35 mph). Their heart seems to cope with such effort. Their front legs are 10 percent longer than the back legs which might also help them run.
Another reason why it is unlikely that the giraffe's neck has evolved due to feeding habits is that its closest relatives, although big, had short necks. The discovered fossils reveal large animals with long legs rather than long necks. The largest giraffe relative discovered insofar had legs almost twice as long than those of modern giraffes but a short neck. Other giraffe relatives have had impressive horns - while the giraffes have only two small horns. The giraffe evolved around 1 million year ago in the African savannah at the time when our ancestor Homo Erectus had already spread from Africa throughout Asia. The giraffe ancestor was significantly smaller in size and had a shorter neck than today's giraffes. So, what favored the growth of that incredible neck in a relatively short time?
One proposal is that the neck helped the giraffe spot predators from the distance, but most biologists reject this explanation as being much too ad hoc. Instead, the most widely accepted hypothesis is that the neck evolved under the pressure of sexual selection. Thus, the giraffe's neck is similar to the peacock's tail or to the moose's horns.
This explanation is in no way obvious, especially because the female giraffes also have long necks, while sexual selection usually favors such "wild" traits only in males. Nonetheless, observations of giraffes' behavior seem to support this view.
The first clue is quite direct: male giraffes, unlike female giraffes, use their necks to fight each other. Moreover, before an actual fight, they point their noses upwards as if they are trying to create the impression that their necks are higher. Researchers have discovered that this is indeed a sign of domination as some males run away from a dominant bull that does such a sign.
"An average male giraffe's neck weighs 90.72 kg. and can stretch 1.83 meters long. Giraffes fight over females by swinging their necks and heads like a medieval ball and chain. The longer and heavier the neck, the more momentum behind the often bone-shattering head slams," Kathy Wollard remarked.
A study in the 1980s by Pratt and Anderson had shown that the main criterion that determines the dominance among bulls is neck size. They classified the giraffes in three classes, A, B, C according to neck size and horns lengths and discovered that neck length is what counted. "The larger-necked A bulls were consistently dominant over B and C bulls, and they courted females significantly more often than B or C did. Ranking also appeared to be important in female mate choice: females allowed themselves to be urine tested (a test of their sexual receptiveness) by A bulls more often than B bulls, and they refused to be urine tested by C bulls in two-thirds of all encounters," wrote Robert Simmons and Lue Scheepers who first argued in favor of the sexual selection theory in the 1990s.
But why do female giraffes also have long necks? Simmons and Scheepers argued that the neck, unlike the tails or the horns, is a trait much too heavily integrated in the organism to be controlled only by a small number of genes. Therefore, the females necessarily inherit the same "neck genes" as the males.
There are however differences between males and females - exactly as one would expect from the theory of sexual selection. Female giraffes do have smaller necks than the males because their necks stop growing in their "adolescence", when they are around 6 years old. This probably happens because females have a gene that silences the neck-growing genes. The males' necks on the other hand grow constantly throughout their lives (giraffes live about 20 years). The largest males are about 53 percent heavier than the largest females.
The fact that the neck is a hindrance and has a large survival cost has been demonstrated by other studies, conducted since the late 1960s, which have shown that male giraffes were about twice as likely as females to be killed by a predator - mostly lions. This kind of difference, again, is a hallmark of sexual selection.
Finally, there is another interesting fact that can explain the long necks of female giraffes. The male giraffes are among the most homosexual mammals. Bruce Bagemihl has discovered that in some areas, 94% of mounting incidents were between two males. Males don't just fight with their necks - in one in 20 cases they engage in affectionate behavior. On the other hand, female giraffes engage in homosexual behavior only in one percent of the time. It thus seems that female giraffes have sexually selected males with longer and longer necks, but the males themselves find long necks sexy. So, in order to still get males, females also had to grow long necks.
Friday, August 1, 2008
This article generated some question marks for me. I tend to see the world and observe human behavior from a evolutionary perspective, so the content of this article seemed obvious. Of course we are narcissists!
Within the spheres of ethics that exist in individuals, the very first is that of self-love. How are we to pass our genes on to subsequent generations (arguably the purpose of life) if we are more concerned about others? Does altruism exist in nature? Not likely. Most cases in which one could argue selflessness as a motive for an organism to act in the interest of another have been proved wrong. Ultimately, these "altruistic" behaviors benefit the seemingly thoughtful animal in the long run, as opposed to the alternative route that would appear to benefit it in the short-term.
An obvious example of misdiagnosed altruism can be found in male anubis baboons (Papio anubis) who may willingly assist other males in copulating with sexually receptive females. And does this really surprise you? I have heard countless laments from our own male species about a "friend," or one with whom he has formed an alliance, who exploits friendships only to bolster his own chances of mating with the opposite sex.
While the helper baboon appears to willingly eliminate his own chances of mating with the female of interest, the act is not necessarily altruistic. This mating strategy can subvert the normal age and size sexual dominance hierarchy. As males patiently scale the hierarchy, they heighten their own chances of mating successfully by using this behavior. The assumption is that the helper baboon will eventually become the helpee. By assisting another with whom he has formed an alliance, he will in the long run be rewarded with a better chance of mating successfully than had he not helped at all.
Thursday, May 8, 2008
Anglerfish, a deep sea fish named for the spiny appendage on its head that it uses as bait to "fish" its prey, has an unusual mating habit. As it spends its time in the bottom of the ocean, finding a mate is a problem - but the species solved this evolutionary challenge beautifully.
At first, scientists were perplexed because they’ve never caught a male anglerfish. Also, all female anglerfish have a lump on their body that looks like a parasite. Only later did scientists discover that the lump is the remain of the male fish.
The tiny male anglerfish are born without any digestive system, so once they hatch, they have to find a female quickly. When a male finds a female, he quickly bites her body and releases an enzyme that digests his skin and her body to fuse the two in an eternal embrace. The male then wastes away, becoming nothing but a lump on the female anglerfish’s body!
When the female is ready to spawn, her "male appendage" is there, ready to release sperms to fertilize her egg.
Taken from Journal of Ichthyological Research
Monday, April 21, 2008
Previously the only four-limbed creatures known to lack lungs were salamanders.
A species of earthwormlike, limbless amphibian called a caecilian is also lungless.
Tetrapods, or four-limbed creatures, that develop without lungs are rare evolutionary events, Bickford and colleagues write.The researchers suggest lunglessness in B. kalimantanensis may be an adaptation to the higher oxygen content in fast-flowing, cold water.
"Cold water can hold more dissolved oxygen than warm water," Bickford explained.
The frog also has a low metabolic rate, which means it needs less oxygen.
What's more, the species is severely flat compared to other frogs, which increases the surface area of the skin.
"Along with the fact that having lungs makes you more likely to be swept away in a fast-flowing stream—because you would float—this [is] a very strong context for the evolution of loss of lungs," Bickford said.
(Article from National Geographic Website)
Thursday, April 3, 2008
Divers have spotted a new type of fish off Ambon Island in Indonesian waters. The striped fish, which is about the size of a human fist, is believed to be an anglerfish because it crawls along the ground and into crevices using leglike pectoral fins. But unlike most anglerfish, this species does not have a "lure" dangling from its head to attract prey, so it probably represents a family of fish previously unknown to science, says Ted Pietsch, a professor of aquatic and fishery sciences at the University of Washington.
Three scuba divers first spotted and photographed one of the fish in late January. In search of international experts to identify the fish, they found Pietsch, who says the fish is unmistakably an anglerfish because of the leglike fins on its sides. Anglerfish are also known as frogfishes and toadfishes.
The new fish appears to be fleshy with tough skin, because it is able to squeeze itself into very small cracks in coral reefs without getting scratched. That may be how it has escaped human attention for so long.
The divers who discovered the fish kept quiet about it for a while. But now that another adult, two juveniles, and a mass of eggs have been seen, the word is out.
(Article from PopularScience)
Wednesday, April 2, 2008
Two evolutionary biologists — P. Z. Myers of the University of Minnesota, Morris, and Richard Dawkins of Oxford — tried to go to the movies at the Mall of America in Minneapolis Thursday evening. Dr. Dawkins got in. Dr. Myers did not.
On those facts, everybody agrees. After that, things break down.
The movie the two scientists wanted to see was “Expelled,” whose online trailer asserts that people in academia who see evidence of supernatural intelligence in biological processes — an idea called “intelligent design” — have unfairly lost their jobs, been denied tenure or suffered other penalties as part of a scientific conspiracy to keep God out of the nation’s laboratories and classrooms.
Dr. Myers asserts that he was unfairly barred from the film, in which both he and Dr. Dawkins appear, and that Dr. Dawkins would have been, too, if people running the screening had realized who he was — a world leader in the field of evolutionary biology.
But Walt Ruloff, a partner in Premise Media, the film’s producer, said the screening was one of a series the producers have organized for the film, which opens April 18, in hopes of building favorable word-of-mouth among people likely to be sympathetic to its message. People like Dr. Myers and Dr. Dawkins would not have been invited, he said.
Mark Mathis, a producer of the film who attended the screening, said that “of course” he had recognized Dr. Dawkins, but allowed him to attend because “he has handled himself fairly honorably, he is a guest in our country and I had to presume he had flown a long way to see the film.”
Actually, Dr. Myers and Dr. Dawkins said in interviews that they had long planned to be in Minneapolis this week to attend a convention of atheists. Dr. Dawkins, an vocal critic of religion, is on the convention program.
And both had earlier complained that they originally agreed to appear in the movie — then called “Crossroads” — because producers told them it would be an examination of religion and science, not a defense of intelligent design, an ideological cousin of creationism. People who have seen the movie say it also suggests that there is a link between the theory of evolution and ideas like Nazism, something Dr. Dawkins called “a major outrage.”
In an interview, Dr. Myers said he registered himself and “guests” on a Web site for the film’s screening. A security guard pulled him out of the line but admitted his wife, daughter and guests — including Dr. Dawkins, who, Dr. Myers said, no one seemed to recognize. Dr. Dawkins, who like everyone was asked to present identification, said he offered his British passport, which lists him as Clinton Richard Dawkins.
Mr. Mathis said in an interview that he had confronted Dr. Dawkins in the question and answer period after the screening and that Dr. Dawkins withered. “These people who own the academic establishment and who have great friends in the media — they are not accustomed to having a level, open playing field,” Mr. Mathis said. “I watched a man who has been a large figure, an imposing figure, I watched this man shrink in front of my eyes.”
That is not how Dr. Dawkins recalls it. He said Mr. Mathis said “enemies” were attempting to interfere with the film.
“It is impossible to imagine what Mathis is afraid of,” Dr. Dawkins said. “It is impossible to credit such bungling and inept public relations.”
Eugenie Scott, director of the National Center for Science Education, a group that opposes the teaching of creationist ideas in public school classrooms, said in an interview that her organization was setting up a Web site to counter the arguments made in the film.
She said it was “just tacky” that the producers barred Dr. Myers from the screening, but added, “I don’t think it’s inappropriate for us to have a good laugh at the creationists’ expense.”
Dr. Dawkins said the hoopla has been “a gift” to those who oppose creationism. “We could not ask for anything better,” he said.
This article was taken from The New York Times
Meyers responded to what he deemed a "hilarious" experience. Understandably!
"There is a rich, deep kind of irony that must be shared. I'm blogging this from the Apple store in the Mall of America, because I'm too amused to want to wait until I get back to my hotel room.
I went to attend a screening of the creationist propaganda movie, Expelled, a few minutes ago. Well, I tried … but I was Expelled! It was kind of weird — I was standing in line, hadn't even gotten to the point where I had to sign in and show ID, and a policeman pulled me out of line and told me I could not go in. I asked why, of course, and he said that a producer of the film had specifically instructed him that I was not to be allowed to attend. The officer also told me that if I tried to go in, I would be arrested. I assured him that I wasn't going to cause any trouble.
I went back to my family and talked with them for a while, and then the officer came back with a theater manager, and I was told that not only wasn't I allowed in, but I had to leave the premises immediately. Like right that instant.
I'm still laughing though. You don't know how hilarious this is. Not only is it the extreme hypocrisy of being expelled from their Expelled movie, but there's another layer of amusement. Deep, belly laugh funny. Yeah, I'd be rolling around on the floor right now, if I weren't so dang dignified.
You see … well, have you ever heard of a sabot? It's a kind of sleeve or lightweight carrier used to surround a piece of munition fired from a gun. It isn't the actually load intended to strike the target, but may even be discarded as it leaves the barrel.
I'm a kind of sabot right now.
They singled me out and evicted me, but they didn't notice my guest. They let him go in escorted by my wife and daughter. I guess they didn't recognize him. My guest was …
He's in the theater right now, watching their movie.
Tell me, are you laughing as hard as I am?"
(Taken from his blog: Pharyngula)
The following is a trailer for the film:
Monday, March 31, 2008
This quote is taken from the website of the Creationist Museum.
The following is taken from our friend, Wikipedia:
"The Creation Museum is a 60,000 square foot museum in the United States designed to promote young Earth creationsim. The museum presents an account of the origins of the universe, life, mankind, and man's early history according to a literal reading of the book of Genesis. Its exhibits reject evolution and assert that the earth and all of its life forms were created in 6 days just 6000 years ago and that man and dinosaurs once coexisted. These views disagree with well in excess of 99% of the scientists in relevant fields. Also, the museum exhibits are at odds with the vast majority of scientists who accept that the Earth is approximately 4.5 billion years old, and that the dinosaurs became extinct 65.5 million years before human beings arose.The museum has generated criticism by the scientific community, several groups of educators, Christian groups opposed to young Earth creationism, and in the general press.
The museum, which is said to have cost $27 million, is privately-funded through donations and opened its doors to the public on May 28, 2007. Based on projections, the museum anticipated 250,000 paying visitors in its first year of operation.Total attendance at the museum surpassed 100,000 visitors on July 21, 2007 and 200,000 visitors on September 20, 2007. Visitor attendance also exceeded first year expectations only 5 months and 5 days after opening, with a total of 250,000 visitors on November 2, 2007."
The BBC covered the grand opening of this facility:
This is a video about the evolution of a complex eye structure. It explains how a group of light-sensitive cells could be favored in primitive animals and, over time, develop into the complex eye we now possess (though it pales in comparison to many other critters like raptors). Given millions of years, I think it's pretty feasible.
Monday, March 24, 2008
"The magic of the microscope is not that it makes little creatures larger, but that it makes a large one smaller. We are too big for our world. The microscope takes us down from our proud and lonely immensity and makes us, for a time, fellow citizens with the great majority of living things. It lets us share with them the strange and beautiful world where a meter amounts to a mile and yesterday was years ago."
-From the book “Mites of Moths and Butterflies”
This is an animal I wouldn’t want to meet if I were tiny. Though they are small — a fully-grown adult has a shell just 2 centimeters (three quarters of an inch) across — they can see off a lizard that intrudes on their plant, and they can kill large centipedes, so they’d make mincemeat of little me.
All the same, I like them because they are unusual in two ways. First: their habitat. Most crabs live in the ocean or, if they’re really adventurous, in burrows they dig on a beach; a few live in (or near) streams and lakes. But M. depressus has evolved to exploit the bromeliad pools, and as far as anyone knows, they do so exclusively.
And here’s the other oddity: in this species, mothers look after their young.
Crabs aren’t famous for paying attention to their offspring. In most species, the female carries her eggs until they are ready to hatch, then releases the larvae into the ocean, where they fend for themselves. The numbers can be enormous — female blue crabs (Callinectes sapidus), for instance, can release two million larvae in one go. (After fertilizing all those eggs, the male needs 15 days to replenish his sperm supplies, poor fellow.)
M. depressus is different. The female lavishes attention on her young. She chooses her plant carefully — she prefers plants with larger volumes of water — and then prepares the pool that will be the nursery. She fishes out any dead leaves that may have fallen in, and drops them onto the ground. (If a sneaky experimenter puts leaves back in, she’ll remove them.) And she drops empty snail shells into the water, often after capturing and feasting on the owners.
These behaviors have two effects. Removing the leaves increases the amount of oxygen in the water; crab larvae need high levels of oxygen in order to breathe. The added snail shells increase the levels of calcium, a mineral without which baby crabs can’t make shells of their own. Unimproved pools can’t sustain baby crabs.
And the hard work doesn’t stop there. For several weeks, the mother feeds her young — perhaps as many as 90 of them (which sounds a lot — but is a lot less than two million) — on cockroaches and millipedes that she catches. And she protects them from being eaten by predators, especially hungry damselfly larvae.
Damselfly larvae generally live in streams, ponds, and lakes; but some have evolved to inhabit bromeliad pools. Among them: Diceratobasis macrogaster. Given a chance, one of these larvae will eat as many as five baby crabs a day. The mother crab does not give them that chance; but an orphaned brood will perish quickly.
Even more unusual, the young crabs don’t disperse immediately, but remain with mom; sometimes you’ll find a couple of generations living together. This is probably because small crabs are more vulnerable to attack as they search for plants of their own, and so it makes sense to grow up before leaving. But whatever the reason, living in family groups is the first evolutionary step towards complicated social arrangements, such as those common among termites and the ants, bees and wasps, but rare for other insects or crustaceans. Perhaps one day, if the evolutionary pressures are right, crabs might join the list of highly social creatures.
-Taken from Olivia Judson's Blog
Saturday, March 22, 2008
The mantis shrimp (which oddly is neither a mantis nor a shrimp, but a crustacean that resembles both) has arguably the most complicated visual system of any animal on Earth. Its compound eyes sit on independently moving stalks and can see colors ranging from ultra-violet to infra-red. Each eye is divided into three regions for tracking motion, forms, depth, and color. All of this, it is theorized, is done without the aid of its tiny brain. (It’s also got claws that can smash through glass, but that we’ll save for another article). Now add to this an entirely new kind of vision previously unknown: the mantis shrimp can see circular polarized light.
We humans can see the effects of linear polarized light when we put on polarized sunglasses and go out on a boat. Linear polarization is observed when transparent materials reflect light, so on a sunny day, the ocean’s surface will look glassy to us. Put on polarized sunglasses and the glare is eliminated. Circular polarization is a bit more complicated. It has to do with out-of-phase stereo imaging, which can best be explained by the effect you get when you put on 3-D glasses and watch a movie in 3-D. That’s circular polarization.
Why the mantis shrimp has the ability to, in effect, put on 3-D glasses is still a mystery. But Professor Justin Marshall (the researcher who discovered it), from the Queensland Brain Institute, surmises it has something to do with sex. Only the males are able to see this way, so his theory is it is some as of yet unknown communication for mating. "[We] humans only have three color channels," he said. "These little guys have 12, and can see both linear and circular polarized light—it is remarkable."
Peacock Mantis Shrimp
(Article by PopSci.com)
Wednesday, March 12, 2008
Sunflower sea stars are large predators of the sea floor, reaching arm spans of up to three feet. They are surprisingly fast, voracious hunters for clams, urchins, snails, abalone, sea cucumbers, and other sea stars. Adult sunflower sea stars can move at the astonishing speed of one meter per minute using 15,000 tube feet which line the undersides of their bodies.
The following video uses time-lapse photography to capture this beautiful animal in hot pursuit of lunch. Sea stars have two stomachs - one is used for digestion, and the other stomach can be extended outward to engulf and digest prey. The latter is highly specialized, and uses digestive enzymes to liquefy its prey before complete digestion. After protruding from the mouth, the stomach can be stretched so thin that it can fit into the thin opening of a mussel or clam shell! Once the stomach has entered the shell, the digestive enzymes liquefy the prey within its own shell. The liquids are fully digested when the stomach retracts back into the body of the sea star.
Wednesday, March 5, 2008
Bushbabies and many other primates have monstrous penises – many of them look like medieval torture instruments. They have spikes and knobs and bristles and are often twisted into weird and sinister shapes. By comparison, the human penis is dull, notable only for its girth.
Among primates as among insects, it is a rule of thumb that in species where females consort with one male at a time, penises are small and uninteresting. Take the gorilla – a huge guy with a little teeny weenie. A male gorilla can weigh 210kg (460lbs), but his penis is a measly 5cm (2in) long and entirely devoid of knobs and spikes. The Argentine lake duck puts him to shame. The duck is small, but his penis, which rivals that of the ostrich, is 20cm (8in) long – and it has spines. But then a male gorilla generally presides over a small group and does not often have to worry about other fellows’ sperm.
Damselflies, on the other hand, have evolved some of the fanciest penises around. A typical damselfly penis has a balloon – an inflatable bulb – and two horns at the tip, plus long bristles down the sides. In the black-winged damselfly, Calopteryx maculate, the male uses this device to scour sperm from inside a female before depositing his own. But in the related Calopteryx haemorrhoidalis asturica, he uses his penis as an instrument of persuasion: by stimulating her in the proper manner, he can induce her to eject sperm from previous lovers.
Meanwhile, the moth Olceclostera seraphica has genitals that resemble a musical instrument: the male rubs one part of his privates against another, producing vibrations with which to thrill his mate.
In contrast, among termites the female typically mates with only one male – and male termites have plain, unadorned genitalia that do not differ much from one species to the next.
Bar the doors and break out the chastity belts, boys, because girls of most species sleep around, and it's for their own good, if not yours.
For generations, biologists had assumed females to be naturally chaste, while males were renowned for their promiscuity. Even Charles Darwin, who invented the idea of sexual selection, didn't dare challenge the Victorian morals of his day. Man evolved from ape, fine. But an immodest and lustful Mother Nature? Heaven forbid!
Now, hundreds of studies and a spate of books are challenging that conventional wisdom. Females of many species, it turns out, have evolved strategies for passing on their genes that involve copulating with multiple males -- and recognition of that fact is literally changing our view of the birds and the bees.
"Natural selection, it seems, often smiles on strumpets," says evolutionary biologist Olivia Judson, author of "Dr. Tatiana's Sex Advice to All Creation," the most recent and entertaining book exploring the variety of female harlotry.
"As a rule, loose females have more and healthier children."
To be sure, biologists are examining these questions in the dispassionate light of scientific inquiry. In describing their theories, they prefer the more neutral term "polyandry," meaning many males, instead of "promiscuity." And they caution laypeople not to look to nature's own apparent infidelities for any justification of their own behavior.
The misbegotten idea that males evolved to make love and females to demur gained scientific currency in the late 1940s in fruit fly experiments by Angus Bateman, a British scientist who reached his erroneous conclusions in part because his experiments lasted only three or four days.
Had he run his experiments longer, he might have discovered that male black- bellied fruit flies secrete an anti-aphrodisiac in their semen that's relatively short lived. As soon as it runs out, females become interested in copulating again.
On the surface, the conventional view made sense. Sperm seemed to come cheap to males, while eggs were expensive to females, which have to invest the time to raise offspring. Scientists could not fathom any possible benefit of multiple partners of females, and they could come up with plenty of potential costs, such as sexually transmitted diseases.
BIRDS DO IT
Then came DNA paternity testing. In one species after another, it turned out that biologists were as cuckolded as the males they had been observing. The first and most extensive examples of polyandry were found among avian species, which was quite a shock to scientists because birds had appeared to be paragons of traditional family values.
"The way the male and female rush back and forth to their demanding brood of chicks seems like nature's model of good parenting," says Marlene Zuk, biology professor at UC Riverside and author of "Sexual Selections: What We Can and Can't Learn About Sex From Animals."
"Now, we find that they're actually in the same situation as millions of modern-day husbands and wives, eyeing a child warily and making uneasy jokes about the milkman," she says.
DNA testing in chicks of seemingly monogamous females showed a wide range of extra mates. In one study, for example, as much as 90 percent of the offspring of the brilliantly colored Australian fairy wren were from mates other than the presumed father.
Biologists have struggled to come up with broad theories for why females benefit from playing the field, but so far the reasons seem to vary widely according to species. A lot of complex theory boils down to this: A gal's got to do what's necessary to ensure the survival of her genes.
In some cases, females may get more help around the home. Among bronze- winged jacana, for example, harems of up to four males do all the child care, enabling a female to have four times as many broods. Male greater rheas, flightless South American birds that resemble ostriches, receive eggs from several females, incubate them and rear all the chicks, while females go off to mate and lay other clutches.
In other cases, females swap sex for food -- the more sex, the more food and the healthier their offspring.
Among green-veined white butterflies, for example, a virgin male ejaculates a sperm packet roughly 15 percent of his weight that also contains nutritious substances. Females that have sex with several virgins lay more and bigger eggs than those that do it with only one or with males that have lost their virginity and consequently make sperm packets only half the size of their virgin glory.
SURVIVAL OF THE LOOSEST
In other cases, promiscuity is simply a matter of survival. Male chimpanzees, for example, have been known to kill infants not their own. Frequent sex with several males -- in one 15-minute period, a female was observed having sex with eight males -- can heroically confuse paternity and act as insurance against harm to her offspring.
But while females are busy ensuring their genetic survival by sleeping around, males have not been idle. After all, female promiscuity puts the genes of males at risk. It's no good being Don Juan, seducing all the females in sight, if none of them uses your sperm, Judson says. So males have developed counterstrategies to ensure their genetic survival.
"This is perhaps the most significant discovery of the past two decades, that male and female attributes coevolve," writes Tim Birkhead, professor of behavioral ecology at the University of Sheffield in Britain and author of "Promiscuity: An Evolutionary History of Sperm Competition."
(From the San Francisco Chronicle)
Monday, March 3, 2008
I'm a European praying mantis, and I've noticed I enjoy sex more if I bite my lovers' heads off first. It's because when I decapitate them they go into the most thrilling spasms. Somehow they seem less inhibited, more urgent - it's fabulous. Do you find this too?
I Like 'Em Headless in Lisbon
Males of your species are boring lovers. Beheading them works wonders: whereas a headless chicken rushes wildly about, a headless mantis thrashes in a sexual frenzy. Why can't he be that way when he's whole? Well, it's hard to have wild sex if you're trying to keep your head.
A male praying mantis is in danger during his approach and his departure, but while he's actually on your back-the position in which intact males have sex- you cannot attack him. However, you do not need him intact to have sex with him. If you rip his head off on the approach, his body will go into spasms that allow his genitalia to connect with yours. Unsurprisingly, though, he does not want to have his head removed. Put yourself in his place - you'd be trembling to the tips of your antennae.
(From Dr. Tatiana's Sex Advice to all Creation)
Saturday, March 1, 2008
Eusocial animals are an anomaly within Kindgom Animalia because an individual will put its energy towards helping another reproduce instead of placing that energy towards the perpetuation of its own genes. Within a colony of naked mole-rats, only one female will mate with her few chosen consorts, and the young from previous litters maintain and defend the colony and assist in rearing newborns. They essentially sacrifice their own opportunities to survive and reproduce for the good of other colony members.
The naked mole-rats are the only known mammal to display this odd behavior. We see eusocial systems in Class Insecta, Order Hymenoptera: bees, wasps, and ants. Why be eusocial? The reason is that by helping the queen reproduce offspring, it may contribute more to future generations of the species than actually reproducing themselves.
Is eusociality altruistic? Certainly not. Guidelines governing eusociality are as follows:
1. Reproductive division of labor
2. Overlap of generations
3. Cooperative care of young
Naked mole-rats’ native range is in
(They also regularly practice coprophagy, the reingestion of feces, which allows them to maximize their uptake of nutrients from their food.)
"When the rains come, the eusocial mole rats cooperate and teams of animals dig like the fury," said Dr. Paul W. Sherman, a behavioral ecologist and Cornell professor of neurobiology and behavior. "Together, they are more likely than a solitary mole rat to find a bonanza of tubers to sustain the colony until the next rain. Alone, individuals would starve in that environment. And with a 'super mom' to produce more helpers, individuals willingly give up personal reproduction for indirect reproduction through relatives."
This video feature this odd rodent: hairless, with sensory hairs on their nose and tail (which allows them to move deliberately backwards and forwards) . Their large incisor teeth sit outside their lips so they can gnaw comfortably through the toughest tuber. They are adorable. Enjoy!
Tuesday, February 26, 2008
“A shade-loving snail has been invaded by worms. These parasites take over the snail’s brain, and push into his tentacles, transforming them into swollen, colorful, pulsating targets…”
This parasite is apparently called Leucochloridium paradoxum.
There are many other “mind-controlling” parasites such as the Spinochordodes Tellinii which infect grasshoppers and forces them to drown themselves. The animal develops inside land-dwelling grasshoppers and crickets until the time comes for the worm to transform into an aquatic adult. Somehow mature hairworms brainwash their hosts into behaving in way they never usually would – causing them to seek out and plunge into water.
Once in the water the mature hairworms – which are three to four times longer that their hosts when extended – emerge and swim away to find a mate, leaving their host dead or dying in the water.
Sunday, February 24, 2008
The adult worms live in the colons (large intestines) of human children and apparently feed on human fecal matter.NEJM -- Enterobius vermicularis -- Data Supplement - Video
When adult male and female worms copulate, each female pinworm produces about 10,000 fertilized eggs. At night, the pregnant female migrates from the colon, out through the child's anus and onto the skin of the buttocks. There she violently expels all of her eggs and dies. Some of the eggs become airborne and land elsewhere in the child's room, but the great majority of the fertilized eggs stay on the skin of the child's buttocks. The eggs mature within six hours of being laid.
The adult worms and the eggs on the skin of the buttocks can cause intense itching in the child. When the sleeping child scratches, the eggs often get on the fingers and under the fingernails. If the child sucks his or her thumb or otherwise brings his or her hand to the mouth (perhaps while eating breakfast), the pinworm eggs are swallowed. They usually hatch within the small intestine and mature there. When they become adults, they move to the colon where they take up residence. The entire life cycle lasts four to six weeks.
One idea is that gene exchange [among early microbes similar to our modern day bacteria] facilitated the repair of damaged DNA: an intact string of DNA received from a partner could perhaps be used to replace or repair genes that had been broken.
A second, more exotic idea is that sex was simply infectious. In other words, it arose because a segment of DNA promoted gene exchange in order to spread itself through the population. To use an analogy, it's as though the common cold caused humans to be promiscuous - an effect that would clearly enhance its transmission. One reason a modern bacterium will be moved to have sex is because it's become infected with a particular segment of DNA known as the F plasmid. An individual who's got the F plasmid is then driven to mate with an individual who hasn't, and so spreads the sex habit around.
Mysteries of the maleWhy do males exist? If you look at any standard biology textbook, you will probably read that the point of having males as well as females is to promote variation by the exchange of different mutations, and hence to increase the chances of species survival. Unfortunately, most evolutionary biologists stopped believing in this explanation over 20 years ago. From a reproductive point of view, no individual is interested in anything beyond donating genes to the next generation, while species survival happens more or less at random, according to the whims of climate and geology. You don't actually need sexes in order to mutate and produce variation. In any case, most mutations have no effect, or mainly deleterious ones. John Maynard Smith talks of ‘the twofold cost of males’. Firstly, it is incomprehensible that any female should want to chuck away half her genome. Secondly, the males of many species are useless at doing anything except sitting around, getting fat at the females’ expense, and—in the words of Richard Dawkins—duffing up other males. Among some animals, such as elephant seals, the vast majority die as wasteful, disappointed virgins.
Given the cost of males, it is perhaps not surprising that there are at least 40 species where the female kills the male during or after sex. In the case of the praying mantis, she literally bites his head off as part of foreplay, and he carries on in a delighted reflex of posthumous orgasm. Females of other species are equally imaginative: male scale insects have been demoted to microscopic excrescences on their females’ legs, while female angler fish carry their mates on their backs as tiny dwarves. More pertinently, there are many effective ways of reproducing apart from sex as we understand it. These include simple division and gene exchange, which have served prokaryotes so well that they have produced the longest-enduring of all species on the planet, as well as comprising the greatest number of species, and probably constituting most of the biomass as well.
Among other organisms, alternative methods of reproduction include budding, hermaphroditism and isogamy (i.e. two individuals, not distinguished as males and females, combining their genes). There are asexual variants among all sorts of creatures, including jellyfish, dandelions, lichens and lizards. Of the creatures who do reproduce sexually, some species have two sexes, but others have three, or thirteen, or 10 000, if you are a fungus. Many species alternate between sexual and asexual reproduction, either on a regular basis or occasionally, as the circumstances require. Bdelloid rotifers—tiny invertebrates who live in drains and puddles—went off sex about 80 million years ago, and have cheerfully diversified into several hundred species since then, without regaining the inclination. Maynard Smith described them an ‘an evolutionary scandal’.
The various current theories about why males evolved and still remain in existence are nicely set out in Matt Ridley's book ‘The Red Queen’. They are also covered in Olivia Judson's racy and wonderfully informative book ‘Dr Tatiana's Sex Advice to All Creation’. Different theories rejoice in names like Muller's ratchet, Kondrashov's hatchet, and the eponymous red queen of Ridley's book (named after the character in Alice in Wonderland who perpetually runs without getting very far because the landscape moves with her). This last theory seems to be the front runner at the moment. It is based on W.D. Hamilton's idea that sex is part of a continual race to outwit external pathogens. What is clear, however, is that the consensus that existed on this topic from Darwin until the 1980s has totally broken down. The purpose of males has instead become one of the biggest unanswered questions in science. My guess is that we will eventually come to understand fertilization by males in a similar way to how we now understand the appearance of ancient autonomous organisms such as mitochondria or chloroplasts in the eukaryotic cell. In other words, we will see it as an evolutionary compromise poised half way between invasion and alliance, parasitism and symbiosis, or genetic rape and informed consent. There is already much evidence to show how females resist the process physiologically (for example by stripping male gametes of all extra-nuclear DNA) and how males try to control reproduction against their females’ will (for example, by killing off competitor sperm or genetic material in the female genital tract, or alternatively killing the competitors and their offspring directly).
If the status of males in evolutionary terms is an equivocal one, the consequences of sexual dimorphism are not reassuring for males either. In a review of the evidence relating to human males, my colleague and mentor Sebastian Kraemer has set out the scale of the problem. Throughout life, men are more vulnerable than women on most measures. This starts with the biological fragility of the male foetus, leading to ‘a greater risk of death or damage from almost all the obstetric catastrophes that can happen before birth’. If they survive these catastrophes, boys then have a far greater susceptibility to developmental disorders than girls. These are magnified in turn by our cultural assumptions about masculinity, and by our low expectations of males. The toxic interaction of biological and social ingredients shows itself in far higher rates of suicide and deaths through violent crime. Males also do worse in (among other things) scholastic achievement, emotional literacy, alcoholism, substance abuse, circulatory disorders, diabetes, and of course in longevity. Kraemer looks at how male disadvantage is ‘wired in’ from infancy and persists to the grave, but he suggests that we shouldn't necessarily conclude that maleness is a genetic disorder. Instead, he argues, we should show more curiosity about the reasons for boys and men being so vulnerable, and should pay more attention to redressing this in child-rearing and in medicine.
It may be no coincidence that questions about the ‘raison d’etre’ for males, and concerns about their relative deficiencies, should have arisen at this point in history; enough of the relevant information behind them would probably have been available to an observer in Darwin's time. The recent appearance of these scientific preoccupations may well be the consequence of understandable male anxiety. In the last few generations of our species, female control over fertility has developed at a rate so phenomenal that it may justify comparison with the sudden emergence of male-female reproduction itself, around a thousand million years ago. In evolutionary terms, it has taken only the twinkling of an eye from the introduction of the vaginal diaphragm and the contraceptive pill in the middle of the last century, to the widespread use of frozen sperm and extracted eggs, and hence to the actualization of human oocyte cloning. Within the span of just one lifetime, women have advanced through several enormous stages of biological liberation and have reached the threshold of elective parthenogenesis.Assuming that the minor technical problems of gene damage during cloning can soon be overcome, and that legal constraints will in time be removed—assumptions that seem reasonable by any standard—it is possible that the women of our species will soon have the overall choice of doing with very few men, or with none at all. If, in the mean time, they can prevent males from destroying any environment in which to survive, they might be forgiven if they choose to follow the path that has already been pioneered by the bdelloid rotifers. Attempts to understand maleness or to redress its difficulties will then become entirely academic.
QJM: An International Journal of Medicine
We often think of animals hunting and fighting for food, but many flatworms appear to hunt and fight for mates. Each worm is hermaphroditic, containing both ovaries with eggs and testes with sperm. Some even have two penises and one or more genital pores for receiving a unique, two-tailed sperm delivered during copulation.
Using new camera technology, Marine Biologist Leslie Newman of Australia's Southern Cross University participated in filming the marine flatworm Pseudobiceros hancockanus engaging in some odd reproductive behavior -- referred to as penis fencing.
During penis fencing, each flatworm tries to pierce the skin of the other using one of its penises. The first to succeed becomes the de facto male, delivering its sperm into the other, the de facto female. For the flatworms, this contest is serious business. Mating is a fight because the worm that assumes the female role then must expend considerable energy caring for the developing eggs.
The Shape of Life . The First Hunter | PBS
(Article found at The Shape of Life)
Remember the infamous gay penguin scare of 2006, when it was revealed that gay mating behavior among penguins was not at all unusual? It wasn't just the two male penguins at the Central Park Zoo taking care of an egg and acting as a family, it turned out that this sort of thing was commonly observed in penguin populations in captivity all over the world. Well a couple of authors wrote a children's book about it and people are trying to ban it from libraries all over the country.
The latest instance is in Loudon County, Virginia, where a parent is complaining and trying to get the book removed from an elementary school library, presumably on the theory that if their child happens to stumble upon the fact of the existence of gay penguins, they will turn out to be interior decorators or gym teachers.
"And Tango Makes Three" by Peter Parnell and Justin Richardson is based on the true story of two male penguins who took turns sitting on an orphaned egg at the Central Park Zoo. In the story, the penguins, Roy and Silo, start their family when the chick, Tango, is hatched.
A parent at Sugarland Elementary in Sterling filed a request with the school principal that the book be reviewed. The principal and several staff members deemed the book appropriate for general circulation.
The parent appealed the school's decision with the Loudoun County Public Schools administration. According to David Jones, the LCPS library media supervisor, a district-level committee was formed with teacher, parent, school librarian and administrative representatives who reviewed the book and offered a recommendation to Superintendent Edgar B. Hatrick III, who ultimately decided on the book's status.
Dr. Hatrick determined that "And Tango Makes Three" should be taken out of general circulation at the elementary level and placed in each school's professional library. Teachers may reference and share the book with students at their own discretion. Children and parents may not check the book out of the library.
The American Library Association says that this book is one of the most challenged books of the last couple years all over the country. All because there are people ridiculous enough to believe that if you even acknowledge the existence of gays, whether human or some other species, their kids will turn out to be gay. I love the smell of irrationality in the morning.(Article found at Science Blogs)
(Roy and Silo, a now famous same-sex penguin couple who successfully raised a penguin chick, Tango)
A new paper about the reproductive behaviour of the spiny anteater, to be published in the December issue of American Naturalist, makes for fascinating - if slightly disturbing - reading.
The spiny anteater (Tachyglossuss aculeatus) is a primitive mammal with an unusual four-headed penis. The animal is difficult to observe in the wild, and does not readily copulate when in captivity, so exactly how the male uses its penis was a mystery.
Stephen Johnston of the University of Queensland and his colleagues obtained a male spiny anteater which regularly produced erections when handled during public viewing sessions at a zoo, and had been "conditioned to develop an erection to the point where it would ejaculate." Johnston's team were therefore able to make the first observations of the animal's erection and ejaculatory mechanism.
They discovered that the anteater's ejaculatory mechanism is very strange - it is unique among mammals, and actually cloesly resembles the form of ejaculation observed in some reptile species. Further, they found that the anteater's sperm forms bundles which consist of up to 100 cells (above right).
The spiny anteater's penis is bilaterally symmetrical, and the glans is subdivided into four "rosettes", all of which remain displayed during the early stages of an erection. But as the erection continues, the two rosettes on one side become engorged with blood, and the two on the opposite side retract.
Because the two unused rosettes retract, the erection is symmetrical in appearance (right). The erect penis - which is one-quarter the anteater's body-length - is therefore fully compatible with the female, which has only two reproductive tracts.
Observation of consecutive ejaculations showed that the left and right sides of the penis are used alternately. But it remains whether or not ejaculation becomes restricted to one side of the penis during copulation; it is possible that sperm travels to the vas deferens on the unused side of the penis without being discharged.
When semen samples were examined using a scanning electron microscope, they were observed to contain bundles of up to 100 spermatozoa. This apparently increases the motility of the cells - although the precise velocities were not measured, large sperm bundles were found to swim more quickly than smaller bundles or individual cells.
Female anteaters sometimes copulate with up to 11 males in quick succession, so bundling may have evolved as a form of sperm competition. Alternatively, it could be a means of storing sperm within the female reproductive tract, or of preventing the cells on the inside of the bundle from maturing before fertilization can occur. A better understanding of sperm bundling should be possible now that the researchers have the ability to collect semen samples regularly.
This is the first time such ejaculatory behaviour has been described in a mammal. The ejaculation mechanism of the spiny anteater is reminiscent to that of the squamate reptiles (lizards and snakes), which have two alternately-used hemipenes that otherwise remain inverted inside the tail.
This study therefore supports the theory that monotremes (the mamalian order to which anteaters belong) have a close evolutionary relationship with reptiles. And further studies of the spiny anteater's reproductive behaviour may provide useful information about how all mammals evoloved.
(Article from Science Blog)
First, she describes why we have not yet answered this question based on good 'ol fossil evidence:
"The reason we don’t know whether T. rex had one is that the organ is generally too soft to leave a fossil trace. (There’s an exception to this: some mammals have a bone in their penis, the os penis or baculum. This can fossilize. Humans are unusual among primates in not having one; in case you’re wondering, it’s not clear whether the bone plays a role in maintaining erections.)"
To summarize the article: yes, she thinks they did. She bases her opinion on a few key evolutionary pieces of evidence. First, the two extant groups most closely related to dinosaurs are the crocodiles and birds.
Male crocs (of Class Reptilia) have a penis they keep tucked inside their cloacae. Unlike mammalian penises, that of the crocodile transports the sperm along an external groove, as opposed to through an internal tube.
The other group related to dinosaurs is the birds (of the violently disputed Class Aves). Birds can be divided into two main groups: those of the palaeognathous and those of the neognathous.
"The palaeos comprises the big flightless birds such as ostriches, emus, rheas, and cassowaries, as well as kiwis and an obscure (but flying) group of south American birds, the tinamous; the neos covers everything else. The palaeos have penises; like crocodiles, they keep them tucked into their cloacae. Again like crocodiles, the organ has an external groove for sperm. What’s more, the lineage leading to the other endowed birds, the ducks, geese, and swans, appears to have split off from that of the other neos relatively early."
All of this informations points to the conclusion that the ancestor of all birds in fact had a penis. At some point early in the evolution of neognathous birds, the penis was lost (and regained in many types of waterfowl in what probably was an independent event. Waterfowl often mate in the safety of the water, and a penis assists in steering the sperm and balance). So crocodiles have one, and ancestral birds probably did, and since the two groups have a very similar genital morphology - it may be safe to infer that T.rex probably had one too!