The Atavism

Friday, July 13, 2007

Arachnophilia

I like spiders. I mean I really like spiders. So, even though my recent field trip to the Cook Islands was all about the landsnails, and I collected hundreds of them, I wasn't going to miss the opportunity to explore a whole new spider fauna. It would actually have been impossible to avoid sipders in the cooks, blazing a trail through the bush means you find yourself reflexively expelling air and scrapping an unseen web of you every couple of minutes. The web spinning spiders behind these snares are only the tip of the arachnid iceberg though, so today I’m going share some pictures of a spider that takes a completely different approach to getting fed.
A. whitneei, side on
That’s Athamas whitmeei, a widespread pacific jumping spider. Quite often my search for arboreal snails on the leaves of shrubs on Rarotonga’s mountains would also turn up these guys with their wonderful orange spots (which are worn only by the males). The one in the photo was actually stalking around our motel unit while I was taking photos of snails so I guess they’re quite happy to adapt to different environments.
Look into my eyes…
Unlike their passive, web-spinning cousins jumping spiders need to go out and hunt their food. As a result they have very good vision. The two large, forward-looking eyes can resolve and image onto their retina which appears to be have four different classes of ‘cones’ (one more than our red, green and blue tuned cells) which may allow them to see a much greater range of colours than ourselves. Even sharp-eyed hunters can fall prey to other hunters. For mammals and birds choosing where to place your eyes is something of a trade off. Forward facing eyes like Athamas’ help you zero in on your target but limit your ability to see around you. Hence sheep with eyes on the side of their head and wolves with forward looking ones. Athamas as no such trade-off to make, having eight eyes in your body plan leaves a couple spare to point backwards!
Look into my eyes…
Posted by David Winter 2:23 PM | comments(1)| Permalink |

Tuesday, July 10, 2007

Academic Brinksmanship

Now I understand it. Professor Jim Flynn's modest proposal did always seem more like publicity gathering than a real suggestion. I think now I see that it was actually academic brinksmanship; introducing an idea so unpalatable that anything else will seem downright reasonable. An Alliance member coming out and saying helping young woman choose whether to have children or not might be nice would gather about zero column inches, raisng the spectre of a modern eugenics programme gets you on TV to put the sensible approach forward as an alternative to the extreme suggestion that got you there in the first place. That's all I wanted to say.
Posted by David Winter 4:28 PM | comments(0)| Permalink |

Monday, July 9, 2007

What Judgement would step from this to this?

Last week I was here

Today I am here

I am back from a wildly successful field trip with the long downhill slide of measuring, dissecting and stealing DNA from the corpses of the samples I collected over the last month. I am utterly unable to briefly sum up the experience and whenever I am asked to I acquire a glazed expression and breathlessly inform people that “you can get on a plane and go to sleep and when you woke up you’re in a whole other country where the climate is completely different and the forests are made of different trees and everyone rides scooters and uses triangular money.” You can expect some ‘travel blogging’ of about that quality here over the next few weeks coupled with some hopefully more interesting pictures of the Cook Islands and a few of the bugs and critters that call those islands home. And there might be some science too if you really want.

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Posted by David Winter 12:54 PM | comments(0)| Permalink |

Nature and Nurture

Not for nothing, but I thought it might be a good time to share a little lesson from quantitative genetics. You here people talk about genes for thinks a lot, the “gene for blue eyes”, the “gay gene”, “the warrior gene” or even “the god gene”. In fact, most genes are not nearly as deterministic as all that. Interesting traits like personality, height and even intelligence result from the complex interplay of the genes you inherit from your parents and the environement those genes are expressed against. Sometimes this leads people into a false dichotomy, imagining that there is in some way a debate between how much nature and nurture contribute to some trait or other (the big three it seems are homosexuality, criminality and intelligence). The interplay between genes (which impart make the environment against which they are expressed) and environment is far too complex to allow the relative importance of either to split. In fact, the degree to which a given trait is genetically programmed is dependant on the environment against which the genes are expressed. Lets take a crude example that equates to the way most people imagine genes and environment interact to give a trait (to be topical well use ‘intelligence’ which readers can define for themselves): On the bottom axis we have some measure of how well an environment fosters intelligence (I guess good education systems, books at home and parents that value intelligence) and the vertical axis there is some metric of intelligence (lets say something like ‘g’ or IQ) The red line tells us how intelligent someone will be in each environment if they have the ‘genius’ gene and the blue line the same for the ‘dullard’ gene (did I mention this was a gross simplification). In this case putting a little extra effort into education (the environment score) helps the dullards out just a bit more than it does the geniuses. The end result is the same though; no matter how permissive the environment we would still say that intellect is controlled by these two genes. Now, imagine that everyone experiences an environment that fits with about 18 in our made up intelligence-fostering axis. This is very different! In this new environment the dullard and genius genes have no effect on the intelligence of their holders. Without changing anything except the environment the genes are expressed against a trait has moved from being completely genetically determined to having nothing to do with genes! How are we to rate the relative importance of nature and nurture if genes contribute to the environment and the environment determines how genetically determined a trait is. Seems to me like a good question to think about if you want to add to 8 generations of fear of a coming genetic meltdown or declare homosexuality to be ‘in the genes’ or ‘not’.
Posted by David Winter 12:43 PM | comments(2)| Permalink |