Abiogenisis and Evolution

I’m reading the tail of a very long comment thread at Pharyngula, and I come across one of my pet peeves. A creationist claims that evolutionary theory can’t explain the origin of life, and someone claims in response that evolution doesn’t have anything to do with that, it’s a separate problem called “abiogenesis.”

Uh, well, half right. Certainly, the theory of evolution doesn’t depend on a theory of abiogenesis: however life first arose, once it came about natural selection started working on it, driving evolution. Abiogenesis was also certainly an evolutionary (by natural selection) process, and we should expect any theory of abiogenesis to look like a smooth, evolutionary transition from non-life to life, without a dramatic boundary between inanimate chemicals and primitive organisms. So the creationist isn’t exactly wrong to conflate the two theories, if he’s making a theological point or something; but what we already know about evolution doesn’t depend on how life started in the first place.

Because once there is some sort of life going on, it’d take something like a god culling the fittest out of the gene pool to keep natural selection from taking it’s course.

Real War

I get annoyed every time I hear about how tragic it is that 4000+ US soldiers have been killed* in Iraq. Of course, every death is tragic to someone, but people die all the time. In particular, about 90 people aged 15-24 of every 100k die each year in the US, without even going to war. Since there are about 170kUS soldiers in Iraq, a soldier is about 5x more likely to die in Iraq than if s/he had stayed home. Still, the odds of dying at home would have been pretty darn small, so a year in Iraq actually only reduces your life expectancy by about 90 days** (out of 76 years baseline life expectancy). Smoking, for example, cuts about 11 minutes per cigarette: 90 days of life expectancy would be 1 per day for 35 years–or 10 per day for 3.5 years. 60,000 dead and 300k wounded in 10 years in Vietnam. It’s been a fairly safe war for US soldiers.

Each year, about 43,000 people in the US die in car accidents. In the past 8 years, some 4000 people in the US have died by acts of international terrorism. So far, the Iraq war is costing us about $2 trillion.

Estimates of Iraqi deaths due to the war vary wildly, from a little over 100k to over 1M, out of a total population of 28M.

*According to Wikipedia, there are about 30,000 more wounded in combat and about another 30,000 wounded, diseased, or other impairments outside of combat.

**Very rough estimate. Life expectancy = <L> = P(surviving a year in Iraq) x (76 years) + P(dying in a given year in Iraq) x (current age of about 20 years) = (.9953)(76) + (.0047)(20). Soldiers will be healthier on average than the general population, so would probably have been more likely to survive/longer life expectancy if they’d stayed home. Also, it doesn’t account for reduction in life expectancy due to non-lethal injuries, the chance of which might reduce <L> by an even rougher 3 years more. And not all soldiers are there to fight, so the actual reduction in <L> will depend on mission.

Basics of DPS

Roughly, a video game warrior’s threat can be described by it’s ability to output damage (dps) and it’s ability take damage (total hitpoints, adjusted for armor and resistances, depending on the game and situation). Let’s parse dps:

The simplest measure of dps is average damage per attack times number of attacks opportunities per unit time. In a first person shooter, that might be

dps = (rate of fire) x (damage per shot)

In a Dungeons & Dragons game, like Neverwinter Nights 2, a fighter could expect something like

average damage per attack = d = (max damage) + (min damage)2 + (str bonus) + (other modifiers)

damage per round = d x (number of attacks per round)

= d x {1 + int([BAB-1]/5)}

= d x {1 + int([level-1]/5)}

In MMOs I’ve played, including WoW, Star Wars Galaxies*, Pirates of the Burning Sea, and maybe EVE Online,

dps = (average attack damage)/(attack speed)

because for some odd reason, attack “speed” in those games is actually the time between attacks, or the attack period, instead of the rate of attack, like “speed” would mean in the rest of the world.

These numbers can be useful for comparing small tweaks among similar characters, but they aren’t realistic approximations of the actual dps you’d see while you’re playing a game. First, of course, you have to actually hit your target, and these formulas don’t account for accuracy**. Then, some games award extra dps for critical hits or head shots. There are also area effect attacks, situational bonuses (like sneak attacks and backstabs), debuffing attacks that do less damage but tilt the battle in other ways, etc. Which is good, because if video games could be distilled to such simple equations, they wouldn’t be any fun.

*mathematically, this was the most muddled and egregiously unbalanced game I’ve ever seen. SOE has changed the rules drastically since I played, hopefully for the better.

**formulas accounting for accuracy will get pretty monstrous, of course

Damage Per Second

Damage per time is a measure of how lethal a player or non-player character is in video game combat. Damage is measured in “hit points,” “health,” or whatever the game you’re playing calls it. Time is measured in seconds (appropriate for a first person shooter or real-time strategy), or turns (for old-school role playing games, for example), etc.

This blog is about the math behind video game rules, especially combat. Often, they’ll abstract descriptions that won’t help anyone play any particular game any better, but you might think about them if you’re designing games. Sometimes, I’ll discuss tactics and strategies useful in particular video games.

I’ll also blog about whatever I’m thinking about, so if I’ll wander way off the theme.