Sunday, 28 September 2008

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.

Sunday, 7 September 2008

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.


Vasopressin Receptors And Hand Baggings

This paper on the genetics of human pair bonding came out last week. The idea that genes affect behaviour is not a new one, but the extent of their influence is argued over. Usually it is evangelicals, whose world view is dependant on the absurd notion of free will and its implications for “sin”, that make loud denial noises at the thought that our choice making may not be absolutely free. Another problem they have is that if our genes affect our behaviour and personality, then the mind becomes all the more physical and ideas of a supernatural consciousness become even less likely. From studies on flies, sexual orientation can be absolutely altered by disrupting the fruitless gene, so the precedence is there.

This recent study, which is quite timely after a hand bagging incident at work because of someone having an affair, shed some light the genetics of human pair bonding. It has been known for some time that the brain “hormone” arginine vasopressin (AVP) has an association with pair bonding in Voles. There are 3 species of closely related voles; montane voles (Microtus montanus), meadow voles (Microtus pennsylvanicus), and prairie voles (Microtus ochrogaster). The first 2 are non monogamous, whereas the prairie voles are monogamous. It was found that one of the proteins that recognizes the AVP; the vasopressin 1a receptor (V1aR) was responsible for the difference. Not surprisingly, drugs that affect the activity of this gene inhibited pair bonding in prairie voles. Furthermore, it was found that it was the promoter (control region) of the gene that determined the type of social bonding behaviour that developed, and a rather elegant study that swapped the promoter between species found that non monogamous voles could be made more like the monogamous species. The difference in promoters is an extra 428 base pairs. It is thought that this might alter the amount of V1aR in the relevant brain areas (ventral forebrain). Indeed, increasing the amount of V1aR in the ventral forebrains of non monogamous meadow voles turned them monogamous.

So, what about humans? Well, it turns out that the V1aR promoters comes in several different forms. One of these forms called the 334 allele has shown a strong correlation with marital harmony in studies of twins. There was no effect with women, but in partnerships where the man carried two copies of the 334 allele, 34% of marriages experienced a serious crisis/ threat of divorce in the last year. This figure fell to 15% in men with no copies of this allele. Interestingly, men with two copies were twice as likely to cohabit rather than marry when compared to men with no copies of the allele.
Other studies have also corroborated this by showing that 334 affects RNA (and by extension protein) levels in the hippocampus of post mortem subjects. Studies in healthy volunteers have also demonstrated an association between 334 and activation of the amygdala, a part of the brain already known to be involved in pair bonding.

It would be unlikely that only one gene affects this behaviour, and not surprisingly the dopamine system has also been implicated, so our pair bonding behaviour is probably the result of the interaction of several genes.
Anyone interested in the nature nurture debate may be interested in Matt Ridley’s talk here.

Thursday, 4 September 2008

Black Hole Forms Stars At Galactic Centre

This Video (taken using the Hubble Space Telescope) shows the orbits of stars around the super massive black hole at the centre of our galaxy. It is thought that the black hole itself may be responsible for the formation of these stars.

The original article appears here.

Tuesday, 2 September 2008

Large Hadron Collider

Bit unusual for me to branch into physics, but it has come to my attention that the turning on of the large hadron collider may be delayed due to a Law suit. It has been filed because of fears that it may cause a black hole that could destroy the earth. So, while we are waiting on the edge of our seats for it to start producing data, here is a little song to keep us amused.

Stephen Hawking's voice in this reminds me of the time a couple of us tried to compose a message from him (with a ZX spectrum) to leave on a friends answer phone - crazy days :-)
Crazy question for lee: could a black hole be transported in a rocket?