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When was the first language? When was the first human?

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Reading a new book of mine, Steven Pinker’s The sense of style, 2014, I was bemused by his casual remark on the first page of the first chapter, ‘The spoken word is older than our species…’. Hmmm. As Bill Bryson put it in A short history of nearly everything, ‘How do they know that?’. And maybe I should dispense with ‘they’ here – how does Pinker know that? My previous shallow research has told me that nobody knows when the first full-fledged language was spoken. Furthermore, we’re not sure about the first full-fledged human either. Was it mitochondrial Eve? But what about her mum? And her mum’s great-grandad? Which raises an old conundrum, one that very much exercised Darwin, and which creationists today love to make much of, the conundrum of speciation.

Recently, palaeontologists discovered human-like remains that might be 300,000 years old in a Moroccan cave. Or, that’s the story as I first heard it. Turns out they were discovered decades ago and dated at about 40,000 years, though some of their features didn’t match with that age. They’ve been reanalysed using thermoluminescense dating, a complicated technique involving measuring light emitted from escaping electrons (don’t ask). No doubt the dating findings will be disputed, as well as findings about just how human these early humans – about 100,000 years earlier than the usual Ethiopian suspects – really are. It’s another version of the lumpers/splitters debate, I suspect. It’s generally recognised that the Moroccan specimens have smaller brains than those from Ethiopia, but it’s not necessarily the case that they’re direct ancestors, proof that there was a rapid brain expansion in the intervening period.

Still there’s no doubt that the Moroccan finding, if it holds up, is significant, as at the very least it pushes back findings on the middle Stone Age, when the making of stone blades began, according to Ian Tattersall, the curator emeritus of human origins at the American Museum of Natural History. But as to tracing our ancestry back to ‘the first humans’, we just can’t do this at present, we can’t join the dots because we have far too few dots to join. It’s a question whether we’ll ever have enough. Evolution isn’t just gradual, it’s divergent, bushy. Where does Homo naledi, dated to around 250,000 years ago, fit into the picture? What about the Denisovans?

Meanwhile, new research and technologies continue to complicate the picture of humans and their ancestors. It’s been generally accepted that the last common ancestor of chimps and humans lived between 5 and 7 million years ago in Africa, but a multinational team of researchers has cast doubt on the assumption of African origin. The research focused on dental structures in two specimens of the fossil hominid Graecopithecus freybergi, found in Greece and Bulgaria. They found that the roots of their premolars were partially fused, making them similar to those of the human lineage, from Ardepithecus and Australopithecus to modern humans. These fossils date to around 7.2 million years ago. It’s conjectured that the possible placing of the divergence further north than has previously been hypothesised has much to do with environmental factors of the time. So, okay, African conditions were more northerly in those days…

So these new findings and new dating techniques are adding to the picture without clarifying it much, as yet. They’re like tiny pieces in a massive jigsaw puzzle, gradually accumulating, sometimes shifted to places of better fit, and so tantalisingly offering new perspectives on what the whole history might look like. I can imagine that in this field, as in so many others, researchers are chafing against their own mortality, as they yearn for a clearer, more comprehensive future view.

Meanwhile, speculations continue. Colin Barras offers his own in a recent New Scientist article, in which he considers the spread of H sapiens in relation to H naledi and H floresiensis. The 1800 or so H naledi fossil bones, discovered in a South African cave four years ago by a team of researchers led by Lee Berger, took a while to be reliably dated to around 250,000 years (give or take some 50,000), just a bit earlier than the most reliably dated H sapiens (though that may change). Getting at a precise age for fossils is often difficult and depends on many variables, in particular the surrounding rock or sediment, and many researchers were opting for a much earlier period on the evidence of the specimens themselves – their small brain size, their curved fingers and other formations. But if the most recent dating figure is correct (and there’s still some doubt) then, according to Barras, it just might be that H sapiens co-existed, in time and place, with these more primitive hominids, and outcompeted them. And more recent dating of H floresiensis, those isolated (so far as we currently know) hominids from the Indonesian island of Flores, has ruled out that they lived less than 50,000 years ago, so their extinction, again, may have coincided with the spread of all-conquering H sapiens. Their remote island location may explain their survival into relatively recent times, but their ancestry is very much in dispute. A recent, apparently comprehensive analysis may have solved the mystery however. It suggests H floresiensis descended from an undiscovered ancestor that left Africa over 2 million years ago. Those who stayed put evolved into H habilis, the first tool makers. Those who left may have reached the Flores region more than 700,000 years ago. The analysis is based on detailed comparisons with many other hominid species and earlier ancestors.

I doubt there will ever be agreement on the first humans, or a very precise date. We’re not so easily defined. But what about the first language? Is it confined to our species?

Much of the speculation on this question focuses on our Neanderthal cousins as the most likely candidates. Researchers have examined the Neanderthal throat structure as far as possible (soft tissue doesn’t fossilise, which is a problem), and have found one intriguing piece of evidence that makes Neanderthal speech plausible. The semi-circular hyoid bone is located high in the human throat, and is found in the same place in the Neanderthal throat. Given that this bone is differently placed in the throat of our common ancestors, this appears to be an example of convergent evolution. We don’t know the precise role of the hyoid in speech, but it certainly affects the space of the throat, and its flexible relationship to other bones and signs of its ‘intense and constant activity’ are suggestive of a role in language. Examination of the hyoids of other hominids suggests that a rudimentary form of language may go back at least 500,000 years, but this is far from confirmed. It’s probable that language underwent a more rapid development between 75,000 and 50,000 years ago. It’s also worth noting that a full-fledged language doesn’t depend on speech, as signing proves. It may be that a more or less sophisticated gestural system preceded spoken language.

a selection of primate hyoid bones

Of course there’s an awful lot more to say on the origin of language, even if much of it’s highly speculative. I plan to watch all the best videos and online lectures on the subject, and I’ll post about it again soon.

References

https://www.sciencedaily.com/releases/2017/05/170523083548.htm

https://www.vox.com/science-and-health/2017/6/7/15745714/nature-homo-sapien-remains-jebel-irhoud

Did Neanderthals Speak?

http://www.isciencetimes.com/articles/6557/20131220/neanderthals-speak-like-humans-hyoid-bone-study.htm

https://www.newscientist.com/article/2128483-mystery-human-hobbit-ancestor-may-have-been-first-out-of-africa/

https://www.newscientist.com/article/2128834-homo-naledi-is-only-250000-years-old-heres-why-that-matters/

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Written by stewart henderson

July 9, 2017 at 11:14 am

why are our brains shrinking?

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my own brain, squeezed of alcohol

my own brain, squeezed of alcohol

Jacinta: So you know that the average human brain mass, or is it volume, has reduced by  – is it 15%, I can’t remember – over the past 20,000 years or so, right? And there’s this theory that it’s somehow related to domestication, because the same thing has happened to domesticated animals…

Canto: How so..?

Jacinta: Well, we don’t know how so, we just know it’s happened.

Canto: How do we know this? Who says?

Jacinta: Well I’ve heard about it from a few sources but most recently from Bruce Hood, the well-known psychologist and skeptic who was talking on the SGU about a recent book of his, The Domesticated Brain. 

Canto: So the idea is that humans have somehow domesticated themselves, in the same way that they’ve domesticated other species, with a corresponding decrease in brain mass in all these species, which signifies – what?

Jacinta: Well it raises questions, dunnit? What’s going on?

Canto: It doesn’t signify dumbing down though – I read in Pinker’s big book about our better angels that our average IQ is rising in quite regular and exemplary fashion.

Jacinta: Yes, the Flynn effect. Though of course what IQ measures has always been controversial. And they do reckon size isn’t the main thing. I mean look at all those small critters that display so many smarts. For example, rats, octopuses and corvids (that’s to say crows, ravens and some magpies). They all seem to be fast learners, within their limited spheres, and very adaptable. But getting back to the human brain, it seems to be something known mainly to palaeontologists, who have a variety of theories about it, including the ‘we’re getting dumber’ theory, but I’m not convinced by that one. It seems more likely that our brains are getting more organised, requiring less mass.

Canto: So this has happened only in the last 20,000 years?

Jacinta: Or perhaps even less – between 10 and 20 thousand.

Canto: Isn’t that a phenomenally short time for such a substantial change?

Jacinta: I really don’t know. They say it might be partly related to a decrease in overall body size, so that the brain to body ratio remains much the same.

Canto: A decrease in body size? What about the obesity epidemic? And I remember way back when I was a kid reading about how we’d been getting taller with each generation since the Great Depression – or was it the Industrial Revolution? Anyway our improved diet, our era of relative abundance, has led to a change in height, and presumably in mass, in only a few generations.

Jacinta: So now you’re saying that substantial changes can occur in a few generations, let alone 10,000 years?

Canto: Uhhh, yeah, okay, but I wasn’t talking about brain size.

Jacinta: Well why not brain size? Anyway, although there have been those recent changes, at least in the west, the story goes that the planet has warmed since the last ice age, favouring less bulky bodies, less fat storage, more gracile frames.

Canto: So what about domestication, why has this led to decreased brain sizes?

Jacinta: Well this is very complex of course…

Canto: I can think of a reason, though it might not be called domestication, more like socialisation, and outsourcing. You can see it in very recent times, with smart phones – it’s even become an already-stale joke, you know phones are getting smarter so we’re getting dumber. But then we always tend to exaggerate the short-term and the present against the longer view. And yet…. I was on the tram the other night, sitting across from this couple, locked into their phone screens, I mean really locked in, earplugs attached, heads bent, utterly fixated on their little screens, completely oblivious, of each other as well as of the outside world. I was reading a book myself, but I became distracted by my irritation with these characters, while wondering why I should be irritated. It just went on so long, this locked-in state. I leaned forward. I waved my hand in front of their bowed heads. I wanted to tell them that the tram had rattled past all the stations and was heading out to sea…

Jacinta: There are some problems with the whole argument. How do we know that domesticated animals have smaller brains? Domesticated cats have a wide range of brain sizes no doubt, but what wild cats are you comparing them with? Even more so with dogs and their immense varieties. Okay they’re descended from wolves so you compare a wolf brain with its modern doggy-wolfy counterpart, but who’s going to agree on type specimens?

Canto: So you brought the subject up just to dismiss it as a load of rubbish?

Jacinta: Well if we shelve the domestication hypothesis for the moment – I’m not dismissing it entirely – we might consider other reasons why human brains are shrinking – if they are.

Canto: So you’re not convinced that they are?

Jacinta: Well let’s be sceptical until we find some solid evidence. In this Scientific American site, from November 2014, palaeontologist Chris Stringer states that ‘skeletal evidence from every inhabited continent’ suggests – only suggests – that our brains have become smaller in the past 10 to 20 thousand years. No references are given, but the article assumes this is a fact. This piece from Discovery channel or something, which dates back to 2010, relies in part on the work of another palaeontologist, John Hawks, whose website we link to here. Hawks also talks about a bucketload of evidence, but again no references. The original research papers would likely be behind a paywall anyway, and barely intelligible to my dilettante brain….

Canto: Your diminishing brain.

Jacinta: Okay I’m prepared to believe Hawks about our incredible shrinking brains, but is domestication the cause, and what exactly is domestication anyway? Hawks doesn’t go with the domestication hypothesis. In fact the Discovery article usefully covers a number of alternative hypotheses, and of course the shrinking may be due to a combo. In fact that’s more than likely.

Canto: So what’s Hawks’ hypothesis, since we’re supposedly admirers of his?

Jacinta: Well Hawks decided to look more closely at this brain contraction – which is interesting because I was thinking along the same lines as he was, i.e. has it been a uniform contraction, or was there a sudden, quick development, followed by a stagnant period, as you would expect?

Canto: Anyway isn’t brain organisation more important than brain mass? Sorry to interrupt, but haven’t we already established that?

Jacinta: We haven’t established anything, we’re just effing dilettantes remember. Hawks started looking at more recent data, over the past 4000 years or so, to see if he could detect any difference in the encephalisation quotient (EQ) – the ratio of brain volume to body mass – over that time. He found that indeed there has. The picture is complicated, but overall there has been a reduction in the brain compared to the body. His explanation for this though is quite different. He reckons that a series of mutations over recent history have resulted in the brain producing more out of less…

Canto: Right, just as a series of modifications have allowed us to produce smaller but more powerful and fuel-efficient cars.

Jacinta: Uhh, yeah, something like that.

Canto: But we know what those modifications were, we can name them. Can we name the mutations?

Jacinta: Clever question, but we know about cars, we built them and they’ve only been around for a bit more than a century. We know vastly less about the brain and we’re still getting our heads around natural selection, give us a break. Hawks points out that it’s a rule about population genetics well-known in principle to Darwin, that the larger the population the more numerous the mutations, and there was a surge in the human population back when agriculture was developed and large settlements began to form. So a number of brain-related mutations led to streamlining and, as you suggest, fuel efficiency.

Canto: But isn’t this compatible with the domestication hypothesis? I imagine that, if there really is a brain reduction for domesticated animals, it’s because they don’t have to rely on their brains so much for survival, and we don’t either, the collective has sort of magically taken care of it through farming and infrastructure and supermarkets.

Jacinta: Yes but they all have their own complicated networks and issues we have to wrap our brains around. The domestication hypothesis is really about aggression apparently. The argument goes that all animals under domestication become more varied in size, coloration and general build, with a tendency to become more gracile over all. Selection against aggression, according to the primatologist Richard Wrangham, favours a slowly developing brain – one that is, in a sense, in a perpetually juvenile state (think of cute cat and dog videos). Of course, all this assumes that juvenile brains are less aggressive than adult brains, which some might see as a dubious assumption.

Canto: Yes, think of school bullying, Lord of the Flies, youth gangs, the adolescent tendency to extremes…

Jacinta: Well, both Wrangham and Hood offer a particularly interesting example of ‘super-fast’ domestication to illustrate their hypothesis:

In 1958 the Russian geneticist Dmitri Belyaev started raising silver foxes in captivity, initially selecting to breed only the animals that were the slowest to snarl when a human approached their cage. After about 12 generations, the animals evidenced the first appearance of physical traits associated with domestication, notably a white patch on the forehead. Their tameness increased over time, and a few generations later they were much more like domesticated dogs. They had developed smaller skeletons, white spots on their fur, floppy ears, and curlier tails; their craniums had also changed shape, resulting in less sexual dimorphism, and they had lower levels of aggression overall.

Now, how does this relate to juvenilism? Well, in the wild, offspring grow up quickly and have to fend for themselves, which requires a certain ruthless degree of aggression. Cats and dogs, yes, they abandon their offspring soon enough, but those offspring continue to be tutored, tamed, domesticated under their human owners. We hear a lot about school bullying and gangs of youths, but they’re actually the exception rather than the rule, or a last ditch rebellion against the domestication pressure that’s exerted by the whole of society, and they’ll either succumb to that pressure or end up in jail, or worse. It’s a bit like the Freudian concept of sublimation, you channel your aggressive energies into creativity, competitive problem-solving, sports achievements and the like.

Canto: So you’re in favour of the domestication hypothesis?

Jacinta: Well, I’m not against it. It sounds plausible to me. Human domestication, or self-domestication if you want to call it that, is a social-contract sort of thing. You agree to outsource and comply with certain arrangements – laws, government, taxation and so forth, in return for certain benefits in terms of security and resources. So you don’t have to fend for yourself. And that affects the brain, obviously. Though it might not be the whole story.

Written by stewart henderson

April 15, 2016 at 8:42 am

the biggest dinosaur?

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5-17-14-Giant-femur-of-saurpod-discovered-in-Patagonia_full_600

Okay I was going to write about the intriguing and tragic figure Ludwig Boltzmann, in keeping with my plan to write connected pieces, but today’s ‘wow’ news reports about ginormous dinosaur bones found in Argentina – already the domain of the largest dino ever found, the sauropod Argentinosaurus – have proved just too irresistible. Ludwig will have to wait. I learned about Argentinosaurus earlier this year while researching dinosaurs for another post, but this recent discovery is of what’s believed to be a new species of titanosaur or giant herbivore. You’ll see pics of the giant thigh bone all over the net, usually with some dusty palaeontologist or farm worker snuggled against it, but scientists are cautioning against too much speculation about this beast’s proportions in comparison to that of Argentinosaurus, from the relatively scant remains found so far. We do love to see records broken, don’t we? In any case the animal’s femur looks like taking the record of biggest bone ever found.

Of course, even if this unnamed beastie was 77 tonnes, as some pundit has calculated it, compared to 70 tonnes for Argentinosaurus, that doesn’t prove that one species in general was larger than the other. Argentinosaurus’ weight has been based on even more scant remains. Take a look at a range of websites, including Wikipedia’s entry on dinosaurs, and you’ll find quite a range of values for the weight of Argentinosaurus. It’s not quite wild speculation, but it’s speculation nonetheless. I’m also wondering, from my profoundly non-expert perspective, if these bones from what is now Argentina reveal the limited range of those creatures or if they’re largely a result of a combination of the right kinds of preservatives – soil type, climatic conditions and so forth – prevailing in that region.

It’s a great time for dinosaur fans. A new species of long-snouted tyrannosaur, named Pinocchio rex, has recently been unearthed, ‘remarkably well-preserved’, in southern China. It’s estimated to have lived about 66 mya, in the late Cretaceous, the last period of the dinosaurs. Not quite the size of T rex, it may have been faster and nimbler. One expert described it as a cheetah to T rex’s lion, because the two tyrannosaurs lived and hunted in the same regions, chasing different prey.

Our new Titanosaur also hails from the Late Cretaceous, though probably earlier than P rex (the Late Cretaceous extends more than 30 million years, from 100 to 66mya).

Incidentally, the record for the smallest dinosaur goes to a birdie from 120 mya called Quiliana, weighing in at 15 grams. Well, that’s according to this site. Wikipedia describes the smallest dinosaur as weighing about 110 grams and measuring about 35 cms but they don’t include ‘avialan’ dinosaurs (i.e. birds). In fact, just about every site I’ve checked out describes a different species. But if you accept, as many do, that birds are dinosaurs, then the smallest dinosaur ever is still with us. The bee hummingbird is only about 5 centimetres long and weighs about 2 grams.

bee hummingbird

Written by stewart henderson

May 21, 2014 at 12:08 am

who fought who in the upper cretaceous?

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Pachyrhinosaurus

Pachyrhinosaurus

So here I am at lovely Victor Harbour on Encounter Bay where England’s Matt Flinders and co encountered France’s Nick Baudin and co most unexpectedly over 200 years ago as each expedition was sailing round this great south land in opposite directions, mapping and exploring and discovering, but I’m not going to tell that story, I’m going to explore a much earlier era, as we spent a little over an hour in the heat of the day in the local cinema, watching a thing called Walking with dinosaurs – the movie. I think this was a companion-piece to Walking with dinosaurs – the real thing, or something like that. Anyway, it was aimed largely at kids, with a horribly anthropomorphised storyline replete with Yank cliches, in Yank accents, in spite of its being a BBC production. The animation was fine though, and hey it was dinosaurs, so more or less bearable.

 

But what about historical accuracy? Wouldn’t want to be leading kids up the garden path. The story, we’re told, takes place 70mya, in what’s now Alaska. Our hero starts life as the runt of the litter, and of course ends up as the leader of a herd of hundreds if not thousands. He’s a pachyrhino or something, and they headbutt for control of the females, and other males, and have to fight off their natural predators, the omnivorous gorgosauri. He also at one stage gets adopted by a wandering herd of gigantic edmontosauri, a herbivorous bunch. I’m no dinosaur expert but I’ve never heard of any of these beasties, whose names are presented to us with an air of scientific authenticity.

 

Well, as it turns out they’re all quite real (what was I thinking, BBC and all). Gorgosaurus (‘fierce lizard’) is known to have roamed about the region of modern Alberta, Canada some 75mya (the late or upper Cretaceous). Weighing in at more than 2 tonnes, it was an apex predator, a genus of tyrannosaurid therapod dinosaur, and is one of the best-represented tyrannosaurid therapods, with dozens of specimens found, so shame on me for my ignorance. Smaller than Tyrannosaurus, to which it’s distantly related, it’s often confused with Albertosaurus, and they may simply be variants. As with all tyrannosaurids, its massive head is crammed with teeth, though not so many, and not so blade-like, as T rex. The Wikipedia article on gorgosaurus is incredible detailed and overwhelmingly rich for dilettantes comme moi, but it’s well worth a visit.

 

Gorgosaurus libratus

Gorgosaurus libratus

The protagonist of the movie was a Pachyrhinosaurus. They inhabited the Alberta and Alaska regions from 79 t0 66mya. They’re a genus (of which 3 separate species have been recognised) of centrosaurine ceratopsid dinosaurs. They were gentle giants (when they weren’t headbutting), weighing up to 4 tonnes, and their presentation in the film as herd animals is backed up by the most important find of pachyrhinosaurus fossils, a bone-bedalong Pipestone Creek in Alberta, where some 3500 bones and 14 skulls have been found, apparently the site of a mass mortality, possibly a failed river crossing.

 

Pachyrhinosaurus has become a popular dino since being relatively recently discovered, in the forties. I’ve mentioned it’s a centrosaurine ceratopsid, the centrosaurinae being a subfamily of ceratopsid dinosaurs (which doesn’t include Triceratops, the most well-known ceratopsid). The centrosaurines are divided into two tribes, the centrosaurins and the pachyrhinosaurins. Ceratopsids all have these fearsome-looking great horny heads, like elephantine frill-necked lizards, but they’re all quadrupedal herbivores, so not only are we safe from being eaten by them, we might be able to eat them ourselves if we could bring them back to life. And I’m sure their horns would have aphrodisiac qualities.

 

edmontosaurus-regalisThe other dinosaur type featured, Edmontosaurus, was a hadrosaurid or duck-billed dinosaur, some 12 metres long and 4 tonnes in weight. There are two known species, one of which is known to have lived right up to the Cretaceous-Paloegene extinction event (the one that killed off all non-avian dinosaurs). They were coastal-dwelling herbivores, from North America (so-named because first found near modern Edmonton), and if the general rule is – and I’m largely guessing here – that the herbivorous dinos roamed about in herds, like modern-day bison, antelopes and kangaroos, then the scenario in Walking with dinosaurs, in which our young pachyrhino and his bro hook up with a herd of edmontosauri for a while, and were savaged by scavenging is almost plausible for the time and place.

 

So, with the help of Wikipedia mainly – it’s very comprehensive on this stuff – I managed to get quite a lot out of Walking with dinosaurs, though I have to say, some of it was strictly for the birds.

 

 

Written by stewart henderson

January 28, 2014 at 2:58 pm

Should we be lumpers or splitters over our hominid ancestors?

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D4500 on the right

D4500 on the right

As I’m overwhelmed and a bit stressed by work issues, I’ve not posted here for a while, or to be precise I’ve got three or four posts going which I’ve not been able to finish. So I’ve decided to throw something down and push it out today no matter what.

A fascinating post on the John Hawks blog, alerted to me by Butterflies and Wheels. He goes into much detail on an issue that has fascinated me, in my dilettantish way. My general reading on human ancestry, which turned up names such as Homo erectus, Homo habilis, Homo ergaster, Homo rudolfensis, Homo heidelbergensis et al, together with the information that the remains of these hominids or hominins were scanty and their precise identities disputed, made me wonder from my distant armchair whether they all represented different species or just variants of the one. Of course I have no expertise at all, and I don’t know the difference between a species and a subspecies, but my reading did make me aware that this was a genuine issue amongst paleoanthropologists.

The Hawks post, which takes its departure from a paper published on a recently revealed specimen of Homo erectus, goes into some detail on all this. The cranial specimen, D4500, from Dmanisi in Georgia, is the best-preserved of any so far discovered. The writers of the paper take the opportunity to put forward the view that the early Homo finds, such as D4500 and remains from the Malapa fossil site in South Africa, and by inference a number of others, represent a single lineage, a view with which Hawks largely concurs. So there, I told you so.

Of course Hawks goes into a lot of detail, and expresses his views with the diffidence we generally find in true scientists, but I’m delighted to find my vague sense of things so thoroughly supported. i must be a lumper, but of course I’m prepared to change my mind at the slightest change in the winds of research. Now I just need to work out where all those Australopithecines fit into the general picture, without moving too far from my armchair, of course.

Written by stewart henderson

November 4, 2013 at 4:26 pm