Tasmanian Devils And The Evolution Of a New Species Of Parasitic Tumour

Creationists love to misrepresent evolution and have an inordinate fondness for strawmen. These include:

1. Evolutionary change requires in increase in “genomic information”
2. Evolution only occurs within “kinds”
3. Speciation does not occur (incompatible with 2).

Number 1 would imply that genome size correlates with complexity. It does not. The largest known genome belongs to the single celled Amoeba dubia at about 600 billion base pairs. This is 200 times larger than our own genome. Even the lungfish Protopterus aethiopicus has a genome 50 times larger than ours. See here for phyletic comparisons .

This strawman also ignores the reality that some genes such as Abd-a can inhibit the development of complex structures such as abdominal appendages in invertebrates. Furthermore, subtle changes in regulatory sequences can affect morphological development that is controlled by genes already present. An example would be the expression of Bmp2 in the developing forelimb of bats .

One final problem for creationists is that natural or experimental deletions of parts (or the whole) of Alx-4 (loss of “information”) increases digit number in mammalian limbs – ie, less “information”, greater “complexity”.

Number 2 is just absurd as the spatio-temporal distribution of any number of transitional fossils shows. The creationist concept of “kind” is also confused.

Number 3. It happens! Deal with it creationists!

Now to the point, Jerry Coyne has posted this fascinating summary of work on tumours of Tasmanian Devils. It is significant because the tumours seem to have originated in an individual Tasmanian Devil and are now transferred from individual to individual by bite. Thus, making it a new species of parasite that is derived from the host species. It has obvious implications for all three points above. It is well worth a read.

Jumbo Dinosaur Jobbies

Having a degree in Parasitology tends to familiarise you with the value of Jobbies; as one of my tutors said, “shit is tour bread and butter as a parasitologist”. This is because many parasites produce cysts or lay eggs that pass out the body in the faeces. These infect the next host and this spreads the disease. The eggs are often characteristic to a particular species or genus. So, you can work out infection rates and parasite loads of particular species in individual hosts. One quarter of the world population is infected by just one parasite – Ascarais lumbricoides. One of my class mates became infected with this and the first she knew of it was when she saw 20 one foot long worms thrashing in the toilet bowl. If you want to feel uncomfortable (or lucky) check out this picture out of someone who has just been "wormed"
Another thing that shit can tell you about diet. I remember one gross practical class where we had to sift through someone’s fudge. It was supposedly collected in the Dominican republic, but contained saw dust- turns out, it had been supplemented with veterinary material. What I remember most though is the huge chunk of onion in it. The person obviously ate onions, but didn’t chew properly or process their food that much either (probably the prof). Apparently, the prof had just discovered that not processing food properly can contribute to severe malnutrition in areas where intestinal parasites are prevalent. He found lots of unprocessed and therefore indigestible corn in the crap.

So, shit can tell you a lot about living animals. Now, to the main point of the post – dino poo. Fossil jobbies are called coprolites. We know for example that pines were on the menu of some dinosaurs, and they were clearly capable of grinding it down – as would be inferred from the structure of the teeth batteries of some herbivores. What is particularly interesting though is the Jumbo Jobbie shown below. It is a possible Tyrannosaurus turd, and measures about 17 inches long.

This majestic Bondi cigar even contains bone fragments belonging to a sub adult herbivore. The large quantity of bone in the meal suggests that the dinosaur was not careful about butchering its meal. We know that Tyrannosaurs were capable of biting through bone, as fossils showing pre-mortem Tyrannosaur bites have been found. These include Hadrosaurs with “healed” wounds that were excised by T. rex bites (about 4 minutes in), and even a T. rex with another T. rex’s tooth embedded in its rib- with an abscess formed around it. Those wanting a laugh (or to annoy themselves) should listen to creationist nincompoop Ken Ham’s short talk on the matter here. I don’t know which is the bigger pile of shite, but at least he knows the consequences of a meat eating dinosaur for his creationist myth that all animals ate fruit and veg before two mythical human beings ate a mythical fruit, and that supposedly caused death, volcanoes, earthquakes and the Mc Chicken Sandwich. That’s why he has to deny evolution. I touch on the absurdity of this claim here (incidentally, that is a Carcharodontosaurus skull at the top of the page).

The other thing that I want to mention is that parasite eggs have been found in fossil shit too (below from left to right Entamoeboides cyst, and two Ascarid eggs). I find this fascinating, and it tells us something about the health of these animals, as well as their ecological interactions with parasites. This is not the first time evidence has popped up for dinosaur parasite interaction, but is certainly the best – and all before man “polluted” creation – yet more evidence that the creationists need to go to farcical lengths to deny.

Finally, we know that some dung beetles even used dino poo – shit’s not that shit after all.

Wasp Stings Young Earth Creationism In The Bum

Over at the Mac Gafraidh blog, I questioned Chelsea on whether she took the following verses literally:

“And God said, Behold, I have given you every herb bearing seed, which [is] upon the face of all the earth, and every tree, in the which [is] the fruit of a tree yielding seed; to you it shall be for meat. And to every beast of the earth, and to every fowl of the air, and to every thing that creepeth upon the earth, wherein [there is] life, [I have given] every green herb for meat: and it was so.” (Genesis 1:29-30).

Like all biblical literalists, she said that she does believe this. These verses basically says that all animals were created to be vegetarian - an absurd position to hold. We need only think about carnivores and their killing adaptations like the canines of big cats that that are so good a piercing flesh – and just happen to be at the right spacing to dislocate the cervical (neck) vertebrae of their main prey species. Then there are species of fish specifically adapted to eat scales and fins (eg Perissodus sp and Exodon paradoxus). One species, the Sabre tooth blenny (Aspidontus taeniatus) even mimics that Cleaner wrasse (Labroides dimidiatus). Cleaner wrasse pick parasites, which are themselves highly specialised non vegetarians (see my article on Trypanosomes for an complex example of adaptation to living inside and off of another species). Fish approach cleaner wrasse to be serviced and the wrasse signals back. This signifies the intentions of both parties and wrasse are even allowed into the mouths of large predators, where they are unharmed. Sabre tooth blennies on the other hand do a similar display but instead of cleaning the other fish, they take a chunk out of it. This is a problem for YECs.

However, I want to use an example that Darwin used (more against the idea that god was a loving creator). He cites the Ichneumonoidea – a group of parasitoid wasps that lay their eggs in the living bodies of their insect hosts (usually caterpillars).

Darwin writes:

“I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of Caterpillars, or that a cat should play with mice.”


There are several special adaptations that are needed:

A suitable host must be located.

The host must become infected – hence the long ovipositor. Some species (eg Ephialtes manifestator) can locate their host through wood and drill to them . Other species also paralyse their hosts, so the toxin is yet another adaptation. Many species also parasitize dangerous spiders so avoiding becoming dinner is another adaptation.

The larvae must evade the hosts’ immune system.

The larvae must keep the host alive and fresh for as long as possible to ensure fresh meat.

In the example below, involving the Blue butterfly as a host, we see several adaptations. These include locating the host and distinguishing it from ant larvae (bear in mind that the ants can’t even do that) and avoiding being attacked by the ants. This latter applies to both infected pupae and adult wasps.

So, the fundamentalist is left with a problem. How did these specific adaptations arise if animals were intended to be vegetarian? They either have to claim god made them that way (lacking any evidence) or claim that some evolution occurred – although that would have to be incredibly fast for a vegetarian wasp to become a wood drilling, ant avoiding spider paralysing, immune system evading parasite.

Of course, the problems for YECs don’t stop there. They believe in the flood. There were only of two of every non clean kind on the ark. That means no ant colony to feed the blue butterfly larvae for the Ichneumon to eradicate. Mind you, the ants would have been killed by lancet flukes (Dicrocoelium lanceolatum). That’s if Anty the ant eater didn’t get them first.

Pretty Picture

This shows the ventral nerve cord(green) and muscles (red) of a freshwater leech. The blue "circles" around the chord are the nuclei of nerve cells associated with the chord (one node per body segment). Branches of the chord can be seen going into the body segments. More nice photos can be seen here.

Parasite Adaptation 1: The Trypanosome

Parasites justifiably get a bad rap. At best, they are gross things that burst out of the bodies of other organisms alien style. At worst, they can cause severe human disesase. One species (Ascaris lumbricoides) infects a quarter of people on the planet. This however is a relatively benign parasite compared to those of the malaria parasites – which infect up to 200 million new people a year, and may kill up to 3 million people a year. It is therefore understandable that we should feel uncomfortable about them. However, if we can think dispassionately about them, and consider them as organisms, they are really quite remarkable and have evolved some amazing solutions to survive in a hostile environment. In fact, parasitism may be the most popular lifestyle there is as most species have several parasites, and even parasites have parasites of their own.

All organisms live in an environment that presents challenges that have to be overcome – be it a lack of water, light, oxygen or predators. Parasites though live in an environment that is actively trying to kill them. Animals (and plants) have evolved elaborate immune systems that try and kill invading organisms, and in return, parasites have evolved counter measures. Some species, such as Leishmania sp. effectivly live in baths of digestive enzymes, bleach and toxic radicals called phagolysosomes. Others can also immunosuppress their hosts. An example of this would be the hook worms (Ankylostoma sp). As an aside, these are actually being tested to treat allergies. Some species (Leishmania again) can make the host produce an entirely inappropriate immune response that actually antaganises the type of response that would kill the parasite. Some species (Schistosoma sp) even cover themselves in host molecules to disguise themselves.

One group called the Trypanosoma brucei complex have a rather interesting way of evading the immune system. These are transmitted by tsetse flies and cause a wasting disease called ngana in cattle. In humans, two subspecies (T. brucei rhodesiense and T. brucei gambiensie) cause sleeping sickness. Normally, an infected individual will show peaks and troughs in the number of parasites in their blood. See Figure 1.

Figure1

This is due to the immune system clearing the parasites from the blood and new variant parasites arising that have different properties. The surface of trypanosomes is almost completely covered by a molecule called the Variant Surface Glycoprotein (Figure 2). This coat also forms a barrier that prevents the immune system seeing or reaching important membrane proteins. This is important, because if the immune system could see and reach an essential parasite surface molecule, that does not vary, that could be the end of the infection.

Up to 10% of the Trypanosome genome may be devoted to different VSG genes. The proteins they encode invoke a strong antibody response and as this response develops, it kills the trypanosomes that express that particular VSG type. Some individual trypanosomes will suddenly change the VSG molecule they express at the surface. The result is that the immune system can no longer recognise them and has to generate antibodies to the new VSG. This process repeats itself and keeps the parasite about a week ahead of the immune system. This will continue until the host dies or receives chemotherapy. The energy costs involved in producing large amounts of antibody also affects the host and results in a reduced capacity to produce more antibodies. This means that the infection ultimately gets worse.

Now the god bit. Fundies who believe in a literal garden of Eden and talking snake claim there was no death and suffering before the fall, therefore no trypanosomes (and Tyrannosaurs ate plants!) One particular one that some readers will be familiar with wrote this sick piece on the boxing day tsunami in which he wrote “He [Darwin] makes one big mistake – he assumes that the world as it is now is the world as God created it. But that is not the case. When you read Genesis One notice the repeated refrain, ‘And God say that it was good’. God did not create the world to have natural disasters, cancer and death. Something came into the world which has upset the natural order of things and polluted the whole environment. That is why, as Paul tells us in Romans 8, the whole creation ‘groans as in the pangs of childbirth’. We are faced with two choices – either the world is as it is because that is the way things are, or things are the way things are because sin came in and corrupted a good and perfect creation.”

Apparently we are to blame, and Robertson later writes “What is the explanation and solution for all this? How can we explain and more importantly cope with this bent universe and our perverse human natures?”"

This is just total bollocks (no apologies for terminology, a spade is a spade) and contradicted by fossil tumours, fossil deformities, fossils with bites, fossils with their last meal of a conspecific inside them, evidence of volcanism and earth quakes and mass extinctions all considerably pre-dating the existence of man to name but a few. It really is pathetic that people hold this view.

Despite the total absurdity of the claim, there are also internal inconsistencies in the fundie argument – although it is also applicable to the loving god argument in general. The point is that supposedly only god creates and he does so with a purpose. Now, if there was no suffering or disease, then why invent an immune system? If he is loving, then why create a trypanosome that has “built in” methods of specifically overcoming an immune system? This leaves you with the problem of loving God designing something that could have no purpose because there was no disease, then creating something to overcome this non purpose and cause suffering. It’s too mental for words.