Archive for September, 2009

Are mass extinctions inevitable?

September 24, 2009

It is well known from the fossil record that there have been a large number of extinction events of various magnitudes.  Some famous examples include the Cretaceous-Tertiary extinction that killed off the dinosaurs 65 million years ago and the Great Dying 250 million years ago where almost everything died.  It has been postulated that mass extinctions occur every ~30 or ~60 million years.  Most explanations for these events are exogenous – some external astrophysical or geological cataclysm like an asteroid slamming into the Yucatan 65 million years ago or large scale volcanic eruptions.  However, as I watch the news every night, I’m beginning to wonder if life itself is unstable and prone to wild fluctuations.  We are currently in the midst of a mass extinction and it is being caused by us.  However, we are not separate from the ecosystem so in effect, the system is causing it’s own extinction.

I listen to a number of podcasts of science radio shows (e.g. CBC’s Quirks and Quarks, ABC’s The Science Show, BBC’s The Naked Scientists, …) on my long drive home from work each day.  Each week I hear stories and interviews of scientists finding that climate change is worse than they predicted and we’re nearing a point of no return.  (Acidification of the oceans is what scares me the most.)  However, in all of these shows there is always an optimistic undertone that implores us do something about this, under the assumption that we have a choice in what we do.   It is at this point that I can’t help but to smirk because we really don’t have a choice. We’re just a big dynamical (probably stochastic) system that is plunging along.  We may have the capability to experience and witness what is happening (a mystery of which I actually have the privilege to think about for a living) but we don’t have control per se as I wrote about recently.

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Seeing red

September 18, 2009

This week’s Nature has a fascinating article where gene therapy was used to reverse colour blindness in monkeys.  The remarkable thing is that the monkeys were red-green colour blind from birth because they lacked a long wavelength (L-opsin) gene.   A virus containing the human L-opsin gene was injected into the monkey’s eyes.  The virus inserted the gene into some of the medium wavelength cones.  It took about 20 weeks for the inserted gene to be expressed robustly. The amazing thing is that almost immediately after robust expression the treated monkeys were able to discern the frequencies that were missing before in behavioural tests.  In essence, they could now see the colour red when they couldn’t before.

The rapidity in which the behavioural effect occured implies that the neural plasticity required to adopt a new colour was minor.  It could be possible that the neural mechanisms for the missing colours already exists since only the males of the species are colour blind (the females are not) and could thus be tapped into immediately.  However, the gene was inserted randomly into the cones and developmentally it takes a few months before babies can distinguish colours so it is not obvious at all as to how the circuits could be idle for so long and suddenly be activated.

I think understanding how a new colour can suddenly pop into existence may be the avenue to investigate the neural basis of qualia.  The researchers of the study are conducting human trials now on patients that have retinal degeneration.  If it works, then it is only a matter of time before they try it on healthy humans with colour blindness.  We can then ask them what they actually experience when they see red for the first time.

Energy efficiency and boiling water

September 11, 2009

I’ve noticed that my last few posts have been veering towards the metaphysical so I thought today I would talk about some kitchen science, literally. The question is what is the most efficient way to boil water.  Should one turn the heat on the stove to the maximum or is there some mid-level that should be used?  I didn’t know what the answer was so I tried to calculate it.  The answer turned out to be more subtle than I anticipated.

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Reframing the evolution debate

September 4, 2009

I firmly believe that given the way our brains work, some arguments can never be resolved. This includes political and economic issues (e.g. efficient markets) and also the debate between evolution and creationism.  I think many scientists feel that the way to fight creationists is to challenge them at every level and try to win the debate using reason and overwhelming evidence.  If that doesn’t work then creationists should be shut down by legal and other means because they might take over and send us back to the Dark Ages. Unfortunately, if a creationist has a prior with zero support over the possibility that the earth is 4.5 billion years old then no amount of evidence can ever change their opinion.  That is why I think the Richard Dawkins strategy of equating science with atheism may not be a winning one.  I think there is a different approach that may even get creationists interested in modern biology and science as a way for them to get closer to God.

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