Economy of Scales


Rock Steady patiently waiting for his lunch (and thinking that I might be it). Note the state of the wire fence from Rock Steady pulling on the mesh

Just north of Rockhampton at the end of a dirt road and across a causeway onto an island of sorts is an unusual sort of farm. This is Koorana Crocodile Farm, the first of its kind to be established in Queensland and probably the most well-known, not least because of a reality TV series called croc college.  The farm is the result of a lifetime’s work and passion of John Lever who previously worked on conservation, management and farming crocs in Papua new Guinea. John established Koorana out of a passion for crocodiles and strategic conservation, which is essentially giving people a reason to conserve something by making it valuable in some way.

Crocs are made valuable because people like to wear their skins on their feet and  hanging by a strap over their shoulders. The skins fetch a hefty price in the fashion industry and more so if they have a brand name stuck on somewhere. There’s also crocodile meat and the fascination of crocs to tourists but the skins are what makes it viable to establish a crocodile farm. They grow and mature far too slowly to be profitable in terms of meat production.

This slow growth rate and maturation are things that make crocodile farming a challenge but also things that make me wonder about the kinds of selection that are happening. In speaking with John, I bring up the subject and right away he understands what I’m getting at. John is in business and he needs to find the optimum way of making his business successful and this involves getting the most out of his crocs. This is partly why he established his farm so far south. You see during the winter, outside of breeding season, teh crocs slow down and require very little food. In fact the ideal is to breed them here in central Queensland and raise them further north where they can grow faster.

One thing that is deliberately selected for is fecundity. Females who lay lots of eggs pass this characteristic on to their progeny so these females are favoured as breeders. So to males who breed more effectively are favoured. But behaviours also figure in selection of crocs for breeding. For example a bullish male who beats up on, or chases away females is not going to last long at Koorana. He’ll more than likely be sold off to a zoo and soon be out of the breeding stock, while more peaceful males who can get along with females will be favoured. As one staff member said, we want lovers not fighters. I don’t imagine that this will result in a population of doe-eyed docile crocs, at least not in my lifetime, but I don’t doubt that this is a selection for tameness.

At the same time there’s selection for rapid growth rate. This is crucial because the faster that crocs grow, the less food they need to consume before they are killed and skinned. But this makes things complicated because it might be the case that there are linkages between growth rate which is selected for, and aggressiveness, which is selected against. It will be interesting to see which characteristic is more important and which needs to be accommodated to favour the other.

Then there’s scales. This is interesting because now we’re getting into the kind of selection that produces morphological changes. In the crocodile industry the more rows of belly scales, the finer the skin. In which case crocs which produce extra rows of scales – and this trait is heritable – are positively selected. So looking down the track we might imagine that the crocs being farmed will be quite different from their wild cousins. They should be more placid, faster growing, and with folds of skin on their bellies with countless rows of very fine scales. In the next post I’ll talk about how they might also have different responses to people.


Wingless birds of change


Ever wondered what chicken farming would be like if the chickens were six feet tall?  Emu farming comes close, only the birds have sharper claws and they don’t all scatter when you walk among them. They close in on you. Right now I’m in Marburg, Queensland to look at the particulars of emu farming and the directions that these processes are taking these birds. Is this a process of domestication or is this just the keeping of wild birds in captivity? That’s my guiding question at the moment and I’m keeping my eyes and ears open for signs that emu farming might be changing these bird populations along the lines of traditional domestication. But this is where it gets complicated. At birth emus are like many birds in that they imprint on whosoever gives them a lot of attention. So farmer Steve has to be sure to leave hatchlings well alone otherwise they imprint on humans and this causes a lot of problems down the track. Not least is that they try to mate with the human staff. So in this sense we could say that it’s essential to maintain a sort of wildness in them so that they’ll be more likely to mate with other emus rather than farmer Steve. But at the same time they can’t be too wild as some tend to get very aggressive and attack humans entering into the enclosures. These agro birds usually get removed to the ‘meat and feathers’ only paddock and are effectively out of the gene pool. But what about tame birds? Perhaps these birds are first to the feeders when farmer Steve fills them up, giving these birds a bit of an advantage over the others. Probably someone with time on their hands would be able to determine that but time I don’t have. Still, I really do think that there must be some sort of change going in the genetic makeup of the farmed emus and this is complexly woven into their developmental processes. Unsurprisingly it’s complicated. I also wonder about the wild populations if emus become domesticated. This is because a few other species that humans have domesticated – aurochsen and horses – disappeared from the wild. Some might call it extinction but on the other hand you could look at it as these animals carving out a new niche whereby they thrive in numbers far greater than their wild ancestors. And this brings me to crocodiles. The farming of these creatures has been said to be the way to save the species. I’m off to Rockhampton next to see how farming crocodiles might not just save, but alter the species.


Those sharp claws make for hazardous farming at times. Especially as emus show almost no fear of humans. See above.


Emu eggs are very heavy, dark green, and taste like egg. Interestingly the emus lay them beside the fences  and (to my great relief) don’t defend the eggs when you collect them.

There are none so cortically blind as cannot see

In the last post I talked about the bits of the brain that (normally) cooperate to make the rest of our bodies react fearfully to things like snakes. I highlighted the thalamus-amygdala pairing and how one send information to the other in advance of our conscious knowledge of whatever it is we’re reacting fearfully to. But in the end we do get to process the fear-relevant information and take control of our fear response, don’t we? Well, that depends on who this ‘we’ is that I’m referring to. If ‘we’ is the small percentage of the population who have brain injuries that cut the connection between the thalamus and the visual cortex, then think again. Or don’t think as the case may be, because what the eyes perceive will never reach the part of the brain that thinks about things that the eyes perceive. But that’s not to say it won’t be acted upon.

Here again is the picture of the see-through head that I used in the last post just to make this easier to follow:

High Low Roads

As you can see there are two pathways along which fear-relevant visual stimuli travel. Both go through the thalamus and amygdala but only one pathway goes through the visual cortex for conscious processing. So in cases where the pathway from the thalamus to the visual cortex is damaged, we should still expect the visual information to reach the amygdala, right? After all the eyes are good, the thalamus and amygdala are fine and the pathway isn’t damaged. Well, it just so happens that the information does travel the low road intact and this folks, is called blindsight.

There’s someone who is famous in cognitive neuroscience although I don’t know his name. All I know is that his initials are G.Y. and he’s probably English. G.Y. is famous because he straddles the line between those who are cortically blind and those who can see normally. Following a car accident he suffered damage to only the right hemifield of his visual cortex, meaning that he is only  ‘bind in one eye’ although technically both his eyes can see. Consequently G.Y. is much sought after by cognitive neuroscientists because he is a test case and a control all in the one neat package.

In one experiment G.Y was shown images of male and female faces with fearful and happy expressions. These were shown separately to his left and right hemifields and he was required to push a button to identify whether the face was male or female. Throughout the trial G.Y. denied visual perception of anything presented to his right visual field, but still reported the feeling that ‘something happened’ when he was presented with the images. Something certainly did happen. In fact he correctly identified the sex of faces presented to his right (blind) side more than he did those presented to his left side – 76% compared to 63%.

In the second experiment G.Y. was presented with pictures of males and females with happy or angry faces and the angry female faces presented to his left visual field were accompanied with a loud noise – an unconditioned stimulus. The expectation was that the  angry female faces would elicit a fear response in his right (blind) hemifield because they should be associated with an aversive stimulus. But anyone who is human should know not to expect brains to act predictably. In contrast to the first experiment G.Y. identified the female faces presented to his right hemifield only 34% of the time. In fact he was significantly more likely to identify an ‘unseen’ aversively conditioned face as male. We can only guess what is going on although the fMRI showed the amygdala firing on all cylinders while G.Y. was shown the angry faces indicating a fear response. There was also activity in the superior colliculus and our old friend the thalamus indicating that some subconscious decision making was going on. So it looks like the bits of the brain that decide what is fearful and how to act make assumptions based on the nature of the stimuli. In fearful faces they seem to identify sex quite easily but with angry faces they seem to assume that if an angry person is making them fearful it must be a male. On balance it’s a pretty wise assumption.



The Organisational Structure of a Fear Corporation

I should begin this post with an advisory message: the following should be read while secured to a strong anchor point as it will turn your world upside down. I can’t overstate the awesomeness of what is revealed below. There’s also a fair wad of toilet humour which might be unpleasant as your world is being turned upside down.

In the previous post I discussed Snake Detection Theory and the experiments that showed people have a perceptual bias toward detecting snakes. Fair enough, I’ve had a few snake detection experiences and I certainly detect them better than I do my car keys when I’m in a hurry to go out. But what is the neurological basis for this detection bias? What happened in my brain when I found myself jumping in the air in response to a snake I didn’t even know was there?

The psychologist Joseph LeDoux explained all this when he mapped out the neural pathways that cause us humans to express fear. There are two different pathways that have become known as DeDoux’s High and Low Roads. Here’s a picture to give you a better idea of how these pathways transform visual information into fear responses:

High Low Roads

As you can see, before it reaches the visual cortex, visual information travels through a primitive part of the brain called the thalamus. This overgrown soybean is like the front desk of your consciousness. It filters every bit of information and decides on where it should be sent. If it’s something from the peripheral vision that has no relevance to you it is hastily sent out the door. If it’s something that the upstairs department – consciousness central – is dependent on, then it’s sent along the high road to the visual cortex for conscious processing. If it’s something dangerous, i.e. a snake, the information is immediately copied and the equivalent of a red button is pushed at the front desk.

The first copy is very hastily made and the rather rough information is sent to another primitive part of the brain that we share with all vertebrates: the amygdala. Yes, lizards have these, as do fish and it’s as crucial to your survival as your seat belt . The amygdala quickly holds the information up against a bunch of templates of things that should be feared, such as snakes, heights, my dad, and if it finds a match the amygdala initiates a fear response. This is the physiological equivalent of an evacuation of the building. Hair is raised, heart rate increased, blood supply directed to the muscles, and if the information is sufficiently fearful, bowels voided. A literal evacuation.

But remember I said the information is quick and dirty. It has to be, as speed is of the essence and in terms of things like snakes, ignoring a potential danger can be a lot more costly than an over-reaction. Meanwhile the thalamus sends a better picture upstairs via the high road to the visual cortex for conscious processing. This is the copy from the good printer that has more detail to go on. And if the conscious processing confirms the presence of a danger then another signal is sent to the amygdala to keep on voiding those bowels. But if the information proves to be non-threatening. i.e ‘Oh it’s just a damaged power-lead lying across the ground,’ then a signal is sent to the amygdala to cancel the fear-response. Heart rate decreases, hair flattens, sphincter closes, and you calmly step on the power-lead, getting an electric shock from hell.

Now here is the awesome bit: Sometimes the amygdala doesn’t trust the information from the visual cortex and says, nope, I’m going to keep on voiding those bowels. No matter how hard you try to control your fear response you only have limited conscious control over your amygdala and literally none over your thalamus down there at reception. What this means is that there is no singular mind in a singular body. Our minds are actually bunches of connected parts, usually cooperating to get us through the challenges of day-to-day survival but not entirely trusting each other to send the right information. What’s more is that there is no separation between the mind and the body in this sense because there is no mind. Our eyes are no more separated as our thalamuses and amygdalae (my spell check is going crazy). So while you might think your upstairs department is quite special and separate from the rest of the organisation, it’s actually just another level of cognitive processing that is often at the mercy of the other departments. This is mind-body pluralism.

How does this relate to your own experience? Have you ever had your amygdala take over and send you scurrying? In the next post I’ll finally get around to the subject of blindsight. This is where the lines to the upstairs department are damaged but the rest of the organisation keeps on operating.




The snake in the grass, not in the tree, made us human

In the last post I described some conditioning experiments in which researchers tested whether it was harder to extinguish peoples’ fear of snakes as opposed to fear of innocuous things or modern dangers. These experiments eventually gave way to a new paradigm in which researchers tested whether people had a perceptual bias toward detecting snakes. In other words they wanted to know whether people more easily detected a snake in the grass than say, a daffodil.

To test this they set people in front of monitors, showed them sets of pictures, and recorded the time it took to identify the odd one out. So among a set of flower pictures they included a snake picture or among snake pictures they included a single flower picture. What they found was that people more quickly spotted the snake among flowers than the flower among snakes. What’s more, it made no difference whether it was a 2 x 2 matrix of pictures or 3 x 3. The time to detect a snake was equally as fast. This suggested that yes, people do have a bias toward detecting snakes over other things.

Snake Matrix

Source: LoBue and Deloache 2008

At the same time a primatologist named Lynne Isbell theorised that this perceptual bias is a very ancient thing among us primates. Isbell’s Snake Detection Theory holds that the threat from snakes, whether as predators or things stepped upon, was a key driver in primate evolution, and by extension human evolution, fostering key attributes such as orbital convergence, trichromacy, and even declarative pointing. In other words, it was snakes moreso than brightly coloured fruits that set us on our current evolutionary pathway.

In the next installment, I’ll describe how this evolved adaptation to the danger from snakes is expressed physically in our overgrown primate brains.


Learning to un-fear snakes

In February I wrote a post about an encounter with a snake and an explanation for my reaction to said snake. Well, I’ve been thinking about this a lot and I think it warrants more attention. In that previous post I mentioned Seligman’s Preparedness Theory as an explanation for my reaction. The theory goes that humans are prepared or more inclined to fear evolutionary relevant things such as snakes and heights in comparison to modern  dangers such as cars and power outlets. Consequently the part of my brain that is evolved to initiate a reaction to snakes sprang into action as I perceived a harmless tree snake in my peripheral vision and made me jump in the air before I even realised that there was a snake beneath my feet.

Preparedness theory was initially tested to death by Arne Öhman and associates from the University of Uppsala Sweden. There they created a conditioning paradigm in which research subjects were shown pictures of snakes, spiders, flowers and mushrooms, while at the same time given electric shocks for particular pictures. The electric shocks were thus the unconditioned stimuli, or the stimuli that would require no conditioning for people to fear them. The pictures were the conditioned stimuli; the idea being that an electric shock administered with a particular picture would condition the subject to fear that picture. The measure of a person’s fear in this case was skin conductance. If skin conductance was higher then that indicated a fear response. Sweaty palms are a pretty good indicator of fear.

Interestingly the researchers found that where people were given a shock they readily acquired a fear – recorded as an increase in skin conductance – in association with the photograph type with which the shock was associated. So in that sense, preparedness theory was not supported because it predicts a difference between pictures of snakes and spiders as compared to pictures of flowers and mushrooms with regard to how easily people acquire a fear of them. But the theory was not a write off just because of that finding. After conditioning the subjects to fear particular types of photographs, the researchers switched off the electrodes so that the subjects no longer received shocks in association with any types of photographs. They were interested in how quickly the conditioned fear was extinguished when an unconditioned stimulus was no longer associated with the conditioned stimulus.

As for the flower and mushroom photographs, once people no longer received a shock in association with such photos, the subjects’ conditioned fears were quickly extinguished. But surprise surprise, where subjects were conditioned to fear images of snakes and spiders, their fear responses took longer to extinguish. Even though they knew they were no longer going to receive an electric shock in association with a picture of a snake or spider, they still gave a higher skin conductance reading for longer. What’s more the reseachers found this effect not only in cases where pictures of snakes and spiders were compared with pictures of flowers and mushrooms, but where they were compared with pictures of modern fear-relevant dangers such as guns, knives, and power outlets. So Seligman’s theory was not disproven. But this is not the end of the story. In the next installment I’ll describe the visual search test that took the theory further.

Unseen and ill considered

I’ve been going over the photos from the camera traps and gee there’s a lot of what you might call ‘noise.’ First and foremost is the inevitable consequence of setting up camera traps on a farm: photos of livestock. About 99.9 percent of the tens of thousands of photos are of cows and horses. There are cows and horses passing by the cameras, cows and horses grazing near the cameras, cows and horses investigating the cameras.


And then there are sequences of photos of cows and horses parked in front of the cameras. Here’s one of a cow who decided to have a lie down near to camera trap number four. Look at the time the photo was taken:


And here is a photo of the same cow at the time she decided to get up (again look at the time):


So over the space of 48 minutes during which this cow had a nice lie down, the camera trap shot over a thousand photos of her preparing to lie down, lying down, still lying down, and then getting back up. All of which I had to scroll through later, pulling a hamstring on my index finger. In fact there would have been more such photos had it not been for the unwitting arrival of a certain researcher who disturbed her:


My index finger thanks me.

But among the countless images of livestock animals and farm vehicles are little tidbits of other animals’ lives being lived in parallel to those of the domesticated ones. There are lots of birds: ducks and plovers magically appearing after the rain:



And this kookaburra divebombing  an unsuspecting grub:


And there is the occasional mammal. This wallaby gets around the farm a bit, making an appearance at several of the camera traps:


And this cat with interesting markings did a drive-by during the day. No coincidence that most of the wildlife was photographed at the top of the ridge where the cows and farmers seldom go:


And a fox making nightly visits. This fox was later trapped and collared by the DPI guys:


As far as dogs, most of the dog photos are of the farm hounds racing around. This one looks like an act of predation but it is in fact Rover giving one of the bulls a bit of exercise. Not welcome in 33 degree heat.


As far as wild dogs, there’s is only one individual visiting the farm:


He’s a shy fellow and as soon as the camera flashed in his face he shot off to the side. In fact I think the flashes from the camera traps disturb him quite a bit as the flashes startle him and he is rarely photographed by the same trap twice. So either he’s an infrequent visitor or else he’s avoiding places with camera traps. The only way to determine this would be with camera traps with infrared flashes, but it’s not one of the questions I need to answer. What does interest me is what the farmer here knows about what’s going on. He mentioned that he’d seen one dog but that he thought there were very few wild dogs visiting compared to in the past. He was right.

Why only one dog? Well up to the north, some farmers were recently laying baits for dogs and it seems that the dogs from our farm must have gone and taken those baits and died. So this boy is either the last of the pack or the first of the next wave. This is cattle farming in Australia: inevitably more dogs will come, calves will be killed, poison distributed and the cycle of life and death will continue. Unless that is, they sell off the cows and plant more blueberries. Apparently there’s more money to be made from the latter and dogs actually control the rats who are attracted to the millet used to stabilise the ground around the blueberries. I wonder if making dogs useful to farmers that way would make them less ‘invasive’.