Why I want to write a book on Xenobiology.

Its because there are idiots like the author of this article, who think they know something about the subject.

At first I was thinking I would write a long diatribe here describing in great detail all that the man is not aware of, but I realized that discussion of convergent evolution would fill an entire chapter of the book. So, I'm just going to make some bullet points:

Convergent evolution can happen, but its a far muddier issue than many think because:

• Evolution conserves DNA. Sometimes 'convergence' is just reexpression.
• Whenever you have a diverse group of anything, you can find subgroups that more closely resemble each other than they do the other members. This proves nothing.
• As was so strongly pointed out recently, the ability to evolve has evolved! This has implications on what body plans are easy to generate given the control structures that have evolved. If you assume different control structures (and they are essentially random) then different body plans are easier to evolve towards.
• Related to the last point is that the evolution of evolutionary strategies means that the historic evolutionary path of an organism matters in deciding what is easy or hard for it to adapt to. In a similar way, if you take a dozen engineers with widely varying backgrounds and ask them to design an object that meets certain constraints, they will invent wildly varying objects. Give the same task to a dozen engineers with very similar backgrounds, and they will produce much more similar objects. This is one of the main reasons that biodiversity turns out to be so important for ecosystem adaptability.
• The range of environments on Earth are constrained, not only by the fact that it is here, and not somewhere else, but because life modifies its environment. The result is a world more benign and friendly (for some values of 'benign' and 'friendly') than it would be if it were lifeless. It also means living conditions are clustered around a set-point chosen during a random walk. Some convergence under these conditions is expected. Change the set-point though, and the convergences happen else where in the design space. On other planets, they WILL have the set-points elsewhere.

Good Night thought.

I was just heading off to bed when I was struck by a thought I hadn't had before, at least, not in this form.

We all know that it took the cavemen a LONG time to get to the point of having spears, animal hides and whatnot. The archaeological record is not terribly well fleshed out for our earliest ancestors, but it looks like it was somewhere around a million years ago that Homo Sapiens Sapiens first appeared. Our first records of tool use are something like 50,000 years old. (I'm sure all the actual details on this are different now than the last time I studied this. I'm gonna have to read me some more books -- but I digress).

The point is that we know that creatures with brains essentially identical to ours spent upwards of 500,000 years before it occured to them to bang the rocks together.

The conclusion that most folks come to is "Boy, were we dumb!"

Maybe the right conclusion though, is that those first few steps are far, far, harder than we've ever imagined them to be.

Try this excercise, as its what caused me to have the idea for this post:

Imagine an intelligent species that has evolved in a very different environment than we did. Maybe they're aquatic. Maybe they live submerged in mud. Maybe they have only one manipulatory limb, and its in the middle of their backs, because it only evolved to help them scratch their butts. Imagine that the gravity, weather, atmosphere, biochemistry, are all radically different from here. Maybe the air is opaque. Maybe the atmospheric pressure is crushing and the gravity is intense, and manganese is the main element from which body supports are constructed.

Now, ask yourself, what's the first step on the road to interstellar flight? What could they do, given a brain as good as ours, and that environment? Stones might be rare and crumbly, fires may not stay lit. Make sure that NONE of the solutions you already know from history are viable. Now, invent a new one, and the next, and the next. Figure out how they get to where we are.

I've been working on this excercise for a week now, and all I can say is, the man that first figured out that you could use one rock to sharpen another was a FRICKEN GENIUS!

Awake!

I am the awake! I've had a coffee and shall have more soon. I've done the ablutions, and scraped off at least 3/4 of the slime, and I've found some pants and beat them on a rock until they bend again. It looks like I just need to have a quick breakfast and I'm all ready for denizsarikaya's garden party.