Vegetarian spiders

We all know that spiders eat insects, or the occasional bird or small rodent, but it now appear that there exist a breed which is vegetarian, or at least partly vegetarian.

The 60-Second Science podcast over at Scientific American has more on this: Odd Spider Prefers Salad

Scientific American also has an article about the subject

Unusual Spider Species Passes Up Live Prey for Plants

Of the 40,000-plus spider species known, only a few nibble on plants—typically, as a dietary supplement of nectar or simply as an accidental ingestion of pollen. A new paper, published online today in Current Biology, details the natural history of Bagheera kiplingi, a jumping spider that has vegetarian leanings, and its interesting arrangement with a plant and the ants that protect it.

Certain acacia plants (Vachellia collinsii) and ants (Pseudomyrmex peperi) have developed a mutually beneficial arrangement. The plant provides hollow areas for the ants to nest, along with nutritious nuggets, called Beltian bodies, for them to eat. For their part, the ants help to fend off would-be plant eaters. The crafty B. kiplingi, however, has thwarted the system—also feasting on the plant while managing to outmaneuver attacking ants.

It's not known why the spiders prefers to eat the less nutritious plant leaves to other prey, but interestingly enough, the behavior of the spiders while the hunt is the same as it would have been if it was more traditional prey

Despite their unusual meals, these spiders still exhibit some more traditional hunting behavior. "They're like miniature cats," Meehan says. "They literally stalk and hunt the plant,"

I can't help smile at the thought of a spider stalking a plant.

The original study is behind a paywall, but can be found here.

National Geographic also writes about the spider: "Surreal" Vegetarian Spider Found -- A First

Chimpanzees get AIDS too

This is really more the area of Tara or ERV but I still thought I'd comment on this piece of news.

African primates can be infected with over 40 different simian immunodeficiency viruses (SIVs). These diseases are related to two diseases which infects our particular species of primates, Homo sapiens, human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) - indeed the two types of HIV are the result of SIVs crossing the species barrier.

HIV is considered an epidemic with more than 30 million people suffering from it worldwide (source - .pdf). As people hopefully know, HIV 1 and 2 will, if not treated by medicine, result in acquired immune deficiency syndrome (AIDS), which is fatal. 2 million people died from AIDS in 2007.

HIV and AIDS is one of the top prioritized areas of medical studies, and both the evolution of HIV from SIV and the connection between HIV and AIDS are well understood. This doesn't, however, keep some people from either claiming that HIV/AIDS is man-made, or that AIDS doesn't exist.

One of the arguments used by both groups is that SIV doesn't lead to AIDS in primates - the one group to argue that HIV couldn't have evolved from SIV, the other to argue that AIDS is not real.

Neither group makes sense. The lack of development of AIDS in SIV carrying primates is by no means evidence of there being no SIV-HIV connection, nor evidence of there being no HIV-AIDS connection.

Still, this matters even less now. Researchers have found out that some primates can get AIDS.

Nature has a new paper by Beatrice Hahn et al.

Increased mortality and AIDS-like immunopathology in wild chimpanzees infected with SIVcpz (link takes you to the abstract, the paper is behind a paywall)

African primates are naturally infected with over 40 different simian immunodeficiency viruses (SIVs), two of which have crossed the species barrier and generated human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2)1, 2. Unlike the human viruses, however, SIVs do not generally cause acquired immunodeficiency syndrome (AIDS) in their natural hosts3. Here we show that SIVcpz, the immediate precursor of HIV-1, is pathogenic in free-ranging chimpanzees. By following 94 members of two habituated chimpanzee communities in Gombe National Park, Tanzania, for over 9 years, we found a 10- to 16-fold higher age-corrected death hazard for SIVcpz-infected (n = 17) compared to uninfected (n = 77) chimpanzees. We also found that SIVcpz-infected females were less likely to give birth and had a higher infant mortality rate than uninfected females. Immunohistochemistry and in situ hybridization of post-mortem spleen and lymph node samples from three infected and two uninfected chimpanzees revealed significant CD4+ T-cell depletion in all infected individuals, with evidence of high viral replication and extensive follicular dendritic cell virus trapping in one of them. One female, who died within 3 years of acquiring SIVcpz, had histopathological findings consistent with end-stage AIDS. These results indicate that SIVcpz, like HIV-1, is associated with progressive CD4+ T-cell loss, lymphatic tissue destruction and premature death. These findings challenge the prevailing view that all natural SIV infections are non-pathogenic and suggest that SIVcpz has a substantial negative impact on the health, reproduction and lifespan of chimpanzees in the wild.

In other words, there is a non-trivial health cost in being infected with SIVcpz.

This is not a trivial finding. As Nature makes clear in it's news release on the story (Wild chimpanzees get AIDS-like illness) this will impact future research.

The results suggest that it will not be possible to find the key to HIV immunity in the chimpanzee genome, as scientists had hoped. However, the study, published in Nature, sets the stage for researchers to gain insight into how HIV and SIV cause disease in their hosts by studying the responses of different primates to the viruses. Wild monkeys that have coexisted with SIV for a long time — such as sooty mangabeys and African green monkeys — seem to have evolved the ability to control SIV, and so do not become ill when exposed to the virus. The new paper, however, shows that chimpanzees — which, like humans, were exposed to SIV more recently — are sickened by the virus.

NY Times also writes about this study: Chimpanzees Do Die From Simian AIDS, Study Finds

Update: Carl Zimmer has written a great blog post about this.

Social animals

Time magazine has a interesting article up about the correlation between social animals and brains size.

Social Animals: Not Necessarily Brainier

Being social isn't for dummies. Animals that gather into packs, herds or troops — never mind into cities and countries — need to be smart. How else to negotiate the complex rules and hierarchies of their cultures? It's not for nothing that sharks, among the dimmest of the large carnivores, are loners, or that humans — far and away the smartest — are so enthusiastically collectivist.

What this ought to mean is that social animals have bigger brains than solitary ones, and the research has indeed suggested as much. A landmark 2007 paper called "Social Brain Hypothesis," published in the journal Evolution, showed that increased sociality was linked to steadily bigger brains in at least three orders of mammals: primates like us, carnivores like lions and ungulates like zebras and bison.

That widely accepted truth might be coming undone, however, thanks to a new study published in the Proceedings of the National Academy of Sciences. According to the authors, evolutionary biologists John Finarelli of the University of Michigan and John Flynn of the American Museum of Natural History, there's a much murkier link than we thought between big brains and big societies. As it turns out, it was our favorite nonhuman critters — dogs — that threw off previous data.

Finarelli and Flynn only focused on carnivores when looking at this, so the study is not as broad as earlier studies (like the 2007 study mentioned), but it goes into more dept in one area, studying not only the living species but also the fossil record.

The study is unfortunately behind PNAS' paywall, but the abstract can be found here: Brain-size evolution and sociality in Carnivora

I highly recommend the Time article, which is pretty well written, and which explains the research quite well.

Undead spiders!

OK, lame title, but I couldn't help myself.

What it refers to, is an interesting piece of science news over at National Geographic, which reports on some new findings related to spiders.

Spider "Resurrections" Take Scientists by Surprise

Like zombies, spiders in a lab twitched back to life hours after "drowning"—and the scientists were as surprised as anyone.

The spiders, it seems, enter comas to survive for hours underwater, according to a new study.

The unexpected discovery was made during experiments intended to find out exactly how long spiders can survive underwater—a number of spiders and insects have long been known to be resistant to drowning.

I wasn't aware of this, but some spider species apparently take a long time to drown (we're talking 24 to 36 hours here), and the researchers were trying to find out exactly how long it took for these spiders to drown.

After the spiders had drowned, the researchers wanted to dry out the spiders, so they could weight them. This is when they found out that they spiders hadn't really drowned, but rather had gone into some kind of coma. After a fairly short while, the spiders started moving again, and after a couple of hours they were recovered.

So, just how long time does it take to really drown these things?

According to the article, the study should be in Biology Letters, but I wasn't able to locate it at the website.

Meat for sex among Chimpanzees

PLoS One has published an interesting new study on primate behavior.

Wild Chimpanzees Exchange Meat for Sex on a Long-Term Basis by Cristina M. Gomes and Christophe Boesch

It's long been known that chimpanzees share meat with each others, and that there is a tendency for male chimpanzees to share with female chimpanzees. This has lead to a hypothesis of an exchange of meat for sex, but so far there was no evidence to back this up.

Gomes and Boesch, however, observed a group of wild chimpanzees, and found that over a 22 month period, female chimpanzees more frequently had sex with male chimpanzees which had shared meat with them, than with other similar chimpanzees.

Humans and chimpanzees are unusual among primates in that they frequently perform group hunts of mammalian prey and share meat with conspecifics. Especially interesting are cases in which males give meat to unrelated females. The meat-for-sex hypothesis aims at explaining these cases by proposing that males and females exchange meat for sex, which would result in males increasing their mating success and females increasing their caloric intake without suffering the energetic costs and potential risk of injury related to hunting. Although chimpanzees have been shown to share meat extensively with females, there has not been much direct evidence in this species to support the meat-for-sex hypothesis. Here we show that female wild chimpanzees copulate more frequently with those males who, over a period of 22 months, share meat with them. We excluded other alternative hypotheses to exchanging meat for sex, by statistically controlling for rank of the male, age, rank and gregariousness of the female, association patterns of each male-female dyad and meat begging frequency of each female. Although males were more likely to share meat with estrous than anestrous females given their proportional representation in hunting parties, the relationship between mating success and sharing meat remained significant after excluding from the analysis sharing episodes with estrous females. These results strongly suggest that wild chimpanzees exchange meat for sex, and do so on a long-term basis. Similar studies on humans will determine if the direct nutritional benefits that women receive from hunters in foraging societies could also be driving the relationship between reproductive success and good hunting skills.

Given the fact that earlier research has shown that chimpanzees can understand the concept of bartering, I think the findings sounds plausible, but nevertheless I can't help pointing out that the meat sharing and the more frequent sex might both be symptoms of an already existing bond between the chimpanzees.

Short news, endangered species edition

While browsing around on National Geographic I came across two pieces of news related to endangered species.

Guantanamo's Wild Side: Huge Boas, "Banana Rats," More

It turns out that the US military base at Guantanamo Bay is the home of a lot of wildlife, much of which is endangered, or at least threatened. They obviously don't live in the prison camp, but in the military base as a whole, specially the more remote parts.

6,000 Rare, Large River Dolphins Found in Bangladesh

A previously unknown population of Irrawaddy dolphins discovered in Bangladesh has given scientists "great hope" for the survival of the rare species, conservationists said Wednesday.

A research team estimated that 6,000 Irrawaddy dolphins thrive in the country's Sundarbans mangrove forests and nearby waters of the Bay of Bengal.

This is obviously great news as well, and we can hope it's possible to protect this population, to ensure the survival of the species.

Polar regions contain identical animals

The Census of Marine Life project, which has looked at both Arctic and Antarctic marine life, and have found a surprisingly large number which appears to live in both places, even though they are at opposite ends of the globe.

According to their press release (full pdf can be found here) researchers found "at least 235 species live in both polar seas". The species they could seems to be quite diverse.

The scientists found marine life that both poles apparently share in common include marathoners such as grey whales (www.eol.org/pages/328569) and birds, but also worms, crustaceans, and angelic snail-like pteropods, the latter discoveries opening a host of future research questions about where they originated and how they wound up at both ends of the Earth. DNA analysis is underway to confirm whether the species are indeed identical.

The census of polar marine life, made during the 2007-2008 Polar Year, have yielded many interesting results, and this newest press release shows us that there are many more to come.

Social anxiety among macaques (and humans?) explained

ScienceDaily reports this interesting story

Genetic Variation Cues Social Anxiety In Monkeys And Humans

A genetic variation involving the brain chemical serotonin has been found to shape the social behavior of rhesus macaque monkeys, which could provide researchers with a new model for studying autism, social anxiety and schizophrenia. Humans and macaques are the only members of the primate family to have this particular genetic trait.

The original study was published in PLoS One

Serotonin Transporter Genotype Modulates Social Reward and Punishment in Rhesus Macaques

Background

Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonin transporter gene (5-HTTLPR) has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans.

Methodology/Principal Findings

In contrast to monkeys with two copies of the long allele (L/L), monkeys with one copy of the short allele of this gene (S/L) spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a “pay-per-view” task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos.

Conclusions/Significance

These data indicate that genetic variation in serotonin function contributes to social reward and punishment in rhesus macaques, and thus shapes social behavior in humans and rhesus macaques alike.

Since there are so big similarities between humans and macaques in this regard, they probably serve as a good animal model for human behavior, which makes this finding very interesting indeed.

One interesting thing about this, is that there are quite different frequencies of the different genetic variation among different human populations, which could help explaining different social behavior in different cultures.

Preventing extinction

National Geographic has a good article about how preventing extinction requires protection of habitats.

Last One

In the United States as elsewhere, stopping the countdown to extinction means preserving healthy habitats—the aim of the celebrated and scorned Endangered Species Act.

The focus of the article is the US Endangered Species Act, which is aimed at protecting the habitats of endangered species, but the problems it mentions are global.

One of the things the article mentions is that the more iconic animals are easier to protect than the less "sexy" animals. Panda bears are cute, and an icon for animals close to extinction, yet there are other animals who are as close to extinction as they are, without receiving any focus whatsoever.

A thing I would have liked the article to mention, is the role of invasive species, when it comes to driving plants and animals to extinction. One way of loosing your habitat is for someone else to take it over, and while this might not be the worst problem in the US, it has had serious impact in other countries, including Australia, where imported animals such as rabbits, foxes, rats, and cats, is a huge problem.

Water, water, every where, Nor any drop to drink.

I found this new finding interesting. ScienceDaily reports on a new study that shows that sea snakes drink fresh water.

Sea Snakes Seek Out Freshwater To Slake Thirst

Sea snakes may slither in saltwater, but they sip the sweet stuff. So concludes a University of Florida zoologist in a paper appearing this month in the online edition of the November/December issue of the journal Physiological and Biochemical Zoology.

Harvey Lillywhite says it has been the “long-standing dogma” that the roughly 60 species of venomous sea snakes worldwide satisfy their drinking needs by drinking seawater, with internal salt glands filtering and excreting the salt. Experiments with three species of captive sea kraits captured near Taiwan, however, found that the snakes refused to drink saltwater even if thirsty — and then would drink only freshwater or heavily diluted saltwater.

So, saltwater sea snakes can literately dehydrate while swimming in their natural environment. That means that they need to live fairly close to fresh water, which limits their possible habitat.

This is why I love the scientific process. It was thought that we knew how sea snakes slake their thirst, but someone still make sure to investigate the subject, and thus proved the common assumption wrong.

The study can be found here (unfortunately behind a pay-wall)

For more information about the sea snakes, I recommend the wikipedia entry on the subject

Disease genes older than previously thought

The New Scientist brought my attention to some recent research with some interesting results.

The disease legacy of our distant ancestors

GENETIC diseases such as diabetes and Huntington's disease may be an evolutionary hangover from our primitive ancestors. This surprising discovery might make it possible to study human diseases in fish and insects - unlikely as that seems - as well in the more usual mice.

To discover when disease-related genes emerged in humans, Tomislav Domazet-Loao from the Ruder Boakovic Institute in Zagreb, Croatia, and colleagues compared our genome with that of organisms as diverse as bacteria and primates, which come from different stages in the evolution of living species.

The team found that we have inherited a far greater proportion of disease-related genes from organisms that evolved early on than from our closer relatives, such as rodents or other primates, although they don't yet know why. For example, while a massive 40 per cent of our genes come from bacteria, the proportion of disease genes that come from bacteria is even larger, at 60 per cent.

So, if there is an intelligent designer involved, we have to conclude that he, she, or it, wants us to suffer, and has been working on this for a long time.

No, seriouslty, this might result in some good changes on how research is done, as it would indicate that it's possible to do research on species that are further from our species than previously thought. Currently, mice is often the species of choice, but instead species like zebrafish, or perhaps even bacteria, can be used.

The study is published in Molecular Biology and Evolution as An ancient evolutionary origin of genes associated with human genetic diseases by Tomislav Domazet-Loso and Diethard Tautz, and is accessible for download.

Many new species found in the Great Barrier Reef

Yet again we see an example of new species getting found when scientists start looking through an area systematically.

ScienceDaily has the story

Explorers Find Hundreds Of Undescribed Corals, Other Species On Familiar Australian Reefs

Hundreds of new kinds of animal species surprised international researchers systematically exploring waters off two islands on the Great Barrier Reef and a reef off northwestern Australia -- waters long familiar to divers.

As the paragraph shows, my headline was a little misleading. It's not only the Great Barrier Reef which the scientists looked at, and found new species.

Interestingly enough, these species have been under our noses all the time, we just haven't looked properly.

The effort that lead to these discoveries are part of the Census of Coral Reefs

Genetic engineering in the NY Times

A little late, so many people have probably already seen this, but the NY Times have a (so far) two-part series about genetic engineering by Olivia Judson. The really interesting part about these articles are that they are not dealing with crops, as so many other articles on this issue are.

The first article is Braking the Virus from September 2nd, which clearly states the scope of this series of articles

Most of the time, talk of genetic modification revolves around crops, with claims and counterclaims as to the relative risks and benefits. Such questions are obviously important, but they have been so much discussed I don’t want to consider them again here (at least, not at the moment). Instead, I want to spend the next couple of weeks looking at other possible uses of genetic engineering.

The second article is from September 9th, and is titled A Genetically Engineered Swat

Both of these articles are great reads, and I'm looking forward to the rest of the series.

Invasive species implicated in killing prehistoric animals

New findings show that it's likely that an invasive species killed off large marsupial species in prehistoric Australia.

What invasive species would that be? Home sapient, the most invasive around.

ScienceDaily has the story.

Humans Implicated In Prehistoric Animal Extinctions With New Evidence

Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The new study provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived.

The findings suggest that the mass extinction of Tasmania's large prehistoric animals was the result of human hunting, and not climate change as previously believed.

While the ScienceDaily article makes it sound like this is amazing news, but the idea of a human cause of the megafauna's extinction is hardly a novel idea, and it has certainly been investigated before. PNAS had a good overview article on it back in 2002 Explaining the Pleistocene megafaunal extinctions: Models, chronologies, and assumptions by Brook and Bowman.

The focus of these investigations have mostly focused on whether there were an overlap of human and megafauna inhabitation of Australia, but other studies have shown that even if there were, the extinction might still be at least partly caused by climate changes - see e.g Prolonged coexistence of humans and megafauna in Pleistocene Australia (.pdf) by Trueman et al.

According to the ScienceDaily article, new findings puts humans as the culprits.

Previous research by Professor Flannery and Professor Bert Roberts of the University of Wollongong, Australia, has shown that 90 per cent of mainland Australia's megafauna disappeared about 46,000 years ago, soon after humans first settled the continent. But humans did not reach Tasmania until a few thousand years later, when the island became connected to the mainland by a land bridge as sea levels fell during the last glaciation. "The Tasmanian results echo those on mainland Australia, putting humans squarely back in the frame as the driving force behind megafaunal extinction", said Professor Roberts.

It should perhaps be pointed out that human driven extinction could be cause indirectly, e.g. through changes to the living habitats by the burning of forests etc. or by animals brought along by the humans (e.g. dingos).

Unfortunately it appears that the study the ScienceDaily article refers to haven't appeared online yet - it should be published in the Proceedings of the National Academy of Sciences of the USA (PNAS), so I expect it to be only a matter of time before it's available (though probably behind a paywall).

While looking after the article, however, I did come across to one that's seems somewhat related:
Species invasions and extinction: The future of native
biodiversity on islands (.pdf) by Sax and Gaines. It does address the role of humans in the recent extinction of species.

Evolution - it works!

One of my friends was kind enough to send me a link to the following article, thinking it would be of interest to me. He was quite right.

Bacteria make major evolutionary shift in the lab

A major evolutionary innovation has unfurled right in front of researchers' eyes. It's the first time evolution has been caught in the act of making such a rare and complex new trait.

And because the species in question is a bacterium, scientists have been able to replay history to show how this evolutionary novelty grew from the accumulation of unpredictable, chance events.

Simply put, 20 years ago, a scientist started an experiment, where he created 12 populations of Escherichia coli, all cultivated from a single bacterium. After more than 30 thousand generations, they have evolved some new and interesting traits.

I could write more about it, but instead I would suggest that you go read PZ's post about it.

Bartering among chimpanzees

Somewhat related to my last post, PLoS One also has an interesting article, this one about bartering among chimpanzees.

Chimpanzee Autarky by Sarah F. Brosnan et al.

Background

Economists believe that barter is the ultimate cause of social wealth—and even much of our human culture—yet little is known about the evolution and development of such behavior. It is useful to examine the circumstances under which other species will or will not barter to more fully understand the phenomenon. Chimpanzees (Pan troglodytes) are an interesting test case as they are an intelligent species, closely related to humans, and known to participate in reciprocal interactions and token economies with humans, yet they have not spontaneously developed costly barter.

Methodology/Principle Findings

Although chimpanzees do engage in noncostly barter, in which otherwise value-less tokens are exchanged for food, this lack of risk is not typical of human barter. Thus, we systematically examined barter in chimpanzees to ascertain under what circumstances chimpanzees will engage in costly barter of commodities, that is, trading food items for other food items with a human experimenter. We found that chimpanzees do barter, relinquishing lower value items to obtain higher value items (and not the reverse). However, they do not trade in all beneficial situations, maintaining possession of less preferred items when the relative gains they stand to make are small.

Conclusions/Significance

Two potential explanations for this puzzling behavior are that chimpanzees lack ownership norms, and thus have limited opportunity to benefit from the gains of trade, and that chimpanzees' risk of defection is sufficiently high that large gains must be imminent to justify the risk. Understanding the conditions that support barter in chimpanzees may increase understanding of situations in which humans, too, do not maximize their gains.

I was under the impression that chimpanzees traded somewhat similar to humans (though without the use of money), but obviously this not the case. From what I got out of the article, the chimpanzees didn't quite seem to grasp the concept of money when introduced to it, and often traded in non-beneficial ways because of this. While this is not too surprising, given that they don't use money themselves, observation of other forms of bartering showed similar behavior.

Development of the human species' mathematical ability

PLoS biology has an incredible interesting article up on the study of the Evolutionary and Developmental Foundations of Mathematics by Michael J. Beran.

Understanding the evolutionary precursors of human mathematical ability is a highly active area of research in psychology and biology with a rich and interesting history. At one time, numerical abilities, like language, tool use, and culture, were thought to be uniquely human. However, at the turn of the 20th century, scientists showed more interest in the numerical abilities of animals. The earliest research was focused on whether animals could count in any way that approximated the counting skills of humans [1,2], though many early studies lacked the necessary scientific controls to truly prove numerical abilities in animals. In addition, both the public and many in the scientific community too readily accepted cases of “genius” animals, including those that performed amazing mathematical feats. One such animal still lends its name to the phenomenon of inadvertent cuing of animals by humans: Clever Hans. Hans was a horse that seemed to calculate solutions to all types of numerical problems. In reality, the horse was highly attuned to the subtle and inadvertent bodily movements that people would make when Hans had reached the correct answer (by tapping his hoof) and should have stopped responding [3]. One consequence of this embarrassing realization was a backlash for the better part of the 20th century against the idea that animals could grasp numerical concepts. The second, more positive consequence, however, was that future researchers would include appropriate controls to account for such cues.

Beran goes on to explain how the current research shows that animals operate on approximations, rather than concrete numbers, much the same way that humans do when prevented from counting while comparing two sets of items. What's more interesting, in my opinion, is how much our symbolic representation of numbers actually mean for our math ability. Not only on the grand scale, but also on smaller problems.

Human mathematical abilities, of course, are highly dependent on symbolic representations of number. A recent paper by Diester and Nieder published in PLoS Biology shows that brain areas critical to processing symbolic and analogue numerosities in humans also support numerical processing in monkeys [38]. After monkeys learned to associate Arabic numerals with specific numbers of items, the researchers recorded from single neurons in the PFC and IPS when monkeys judged whether two successive analog arrays were the same in number or whether an analog array matched a numeral in a pairing. PFC neurons were selectively responsive to given numerical values, presented in either analog or symbolic formats. In other words, the PFC in monkeys seems to be involved in the association between symbols and numerical concepts, and it builds upon the capacities of the IPS to encode approximate numerical information early in quantity processing. By four years of age, the IPS in human children is already responsive to changes in the numerosity of visual arrays [39], but the parietal cortex shows a more protracted developmental trajectory for the representation of symbolic numbers. Specifically, children who have not yet become proficient with numerals show elevated PFC activity in response to numerals, whereas parietal areas seemingly take over as proficiency with symbols emerges [40,41]. In adult humans, representation of numerical information across many formats (numerals, analog stimuli, number words) relies substantially on parietal areas [42].

So while our brains are hardwired to math, we can only utilize it fully when using symbolic representations.

Evolution is not random

We all know that a lot of people misunderstand the concept of evolution, and believes it to be random ("pure chance"), but this is not what the theory states at all.

Now, a new international study shows that the theory is right, and evolution is not random.

Via ScienceDaily:
New Findings Confirm Darwin's Theory: Evolution Not Random

According to Darwin’s theory of evolution, individuals in a species pass successful traits onto their offspring through a process called “deterministic inheritance.” Over multiple generations, advantageous developmental trends – such as the lengthening of the giraffe’s neck – occur.

An opposing theory says evolution takes place through randomly inherited and not necessarily advantageous changes. Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones.

Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits. The collaborative study by researchers at the Technion-Israel Institute of Technology in Israel, the U.S, France and Germany is published in the November 2007 issue of Current Biology (vol. 17, pp. 1925-1937).

To settle the question about whether evolution is deterministic or random, the researchers used various tools – including DNA strand analysis and electronic microscopy – to study female sexual organ development in 51 species of nematode, a type of worm commonly used to better understand evolutionary processes.

The findings showed similar development in the species, which falsifies the idea that the development is random.

The Current Biology article about the study, can be found here:
Trends, Stasis, and Drift in the Evolution of Nematode Vulva Development. It's quite technical, and much of it went over my head. Still, it's worth taking a look at.

I've heard about omnipresent but omnidirectional?

PLoS Biology brings us the news about a discovery of an omnidirectional fish. The black ghost knifefish (Apteronotus albifrons) uses a weak electric field to actively monitor its surrounding. This sort of monitoring is different from the ones that we usually see in that it's active, rather than passive (which we humans engage in).

PLoS Biology has been nice enough to write an synopsis about this discovery. That makes it a lot easier for us non-biologists to understand the meaning of the original article (excellent as that might be). The articles own authors' summary isn't too bad though

Most animals, including humans, have sensory and motor capabilities that are biased in the forward direction. The black ghost knifefish, a nocturnal, weakly electric fish from the Amazon, is an interesting exception to this general rule. We demonstrate that these fish have sensing and motor capabilities that are omnidirectional. By combining video analysis of prey capture trajectories with computational modeling of the fish's electrosensory capabilities, we were able to quantify and compare the 3-D volumes for sensation and movement. We found that the volume in which prey are detected is similar in size to the volume needed by the fish to stop. We suggest that this coupling may arise from constraints that the animal faces when using self-generated energy to probe its environment. This is similar to the way in which the angular coverage and range of an automobile's headlights are designed to match certain motion characteristics of the vehicle, such as its typical cruising speed, turning angle, and stopping distance. We suggest that the degree of overlap between sensory and movement volumes can provide insight into the types of control strategies that are best suited for guiding behavior.

So, we're dealing with a fish that can sense in all directions, and then move in any direction where it might locate prey. That sounds like a pretty good advantage to have while hunting (or escaping for that matter). So, why doesn't all, or at least a large number, of animals have this ability? Well, first of all, they would have to been maritime, as they need water for the electric field. Second of all, such things comes at a cost. As the summary clearly states.

Although it's certainly useful to be able to sense in all directions, active sensing comes at a cost; energetically, it's very expensive to generate a good-sized electric field, since the signal falls off rapidly with distance.

Obviously, this leads to a shorter detection range - according to the findings, the black ghost knifefish had a averagee estimated prey detection distance of about 3.5 cm from the fish's body. Hardly a substitute for good eyes in areas with sparse food resources.

Giant bug fossil found

A fossilized claw of a 8 feet long sea scorpion, living 390 million years ago, has been discovered. This is the largest insect ever discovered according to the article, though it's speculated that Arthropleuridae could be as long as 10 feet.

The paper about the discovery can be found at the Royal Society's Biology Letters (link to abstract), which unfortunately is behind a pay-wall.