Category Science

Drunken Walks 2: Neutral Drift Boogaloo

In our last episode, our heroes saw that just by taking lots of steps in random directions, you could wind up arbitrarily far from where you started. This time, we’ll take a look at what it means for population genetics and evolution.

As we’ve all learned, evolution is “allele frequency change in a population over generations”. And the way we all visualize this, I think, is to think of a population in which one member has a slight advantage over the others, such as sharper teeth, better resistance to poison, slightly more efficient camouflage, etc. As generations pass, a greater and greater percentage of the population has this advantageous trait, until eventually it’s the norm. Either that, or detrimental traits get removed from the gene pool.

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Rant O’ the Day

Kung Fu Monkey explains why George Bush’s endorsement of Intelligent Design is a crock, and why it matters. A lot.

Includes the best characterisation of ID ever:

Intelligent Design, or as it’s more commonly known: “Creationism Trying to Look Serious By, Say, Squinting — Like Denise Richards Playing the Nuclear Weapons Expert In That Bond Movie“.

I’m jealous. I wish I had that kind of flamage-fu.

Drunken Walks (But Not the Pubcrawl Variety)

Imagine a drunk standing in the middle of a field. Every time he tries to walk a step, he winds up staggering in a random direction: north, south, east, or west. How long will it take him to get to the edge of the field?

We can look at it intuitively, and say that he’s as likely to stagger north as south, as likely to go east as west. So after 100 steps, he will most likely have made 25 steps north and 25 steps south, which cancel out; and 25 steps east and 25 west, which also cancel out. So he’ll just keep staggering around his spot in the middle of the field until he sobers up.
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Google vs. Creationism

One of the claims made by young-earth creationists (YECs) is that the Grand Canyon was formed when the waters of Noah’s flood subsided; a whole lot of water drained off and carved a channel in the rock.

Geologists have known for a long time that this idea is ridiculous. For regular folks like me, though, Google Maps can help illustrate why it’s nonsense. Read More