Hypothetical Life Thought Process
I just thought I would say a few words regarding the process I use when thinking about alien life. I am certainly no biological or zoological expert but I have more than the average ammount of knowledge about evolution and the various life forms that we share this planet with. I use this information to project what has happened here, to what may have happened elsewhere.
There is a very important distinction, which needs to be made when categorising life: universals and parochials. I believe these terms originated from Dr. Jack Cohen, one of the most influential and successful proponents of xenobiology.
Simply put, a universal is a structure, device, behaviour or process which is so useful and achievable that it crops up again and again in nature. Examples include flight, sight, fur and parasitism. These are things we see over and over again in the animal kingdom, evolved completely independantly in numerous, unrelated species. Often, a given environment will force organisms to evolve similar strategies. The flight and feeding behaviour of a hummingbird is superficially very similar to that of some moths; completely unrelated species evolving along similar lines to exploit similar niches.
On the other hand, parochials are accidents, simply random structures which, for seemingly no reason have become entrenched in all descendents. There is no real evolutionary pressure to explain them and given a rerun of evolution, would be unlikely to come up again. For example, vertebrates have the usual five-digit plan. Even in animals where this is less obvious, like horses or whales, their evolutionary past reveals that they did once have the same five-digit plan as their distant fishy ancestors that once crawled laboriously out of the oceans. Why five digits? Why not four or six? Actually, all those hundreds of millions of years ago, there were numerous species of fish with varying numbers of digits. It is just that the tetrapods were the ones to survive and populate the land. Mostly parochials are no better than nusances, but ones so deep in the structure of the animals that it is now impossible to evolve away from. The fact that our foodways and airways cross, often leading to choking, has no evolutionary advantage and is simply the way things are by accident.
Why this is important when thinking about alien life, is that we should expect to see universals anywhere we find life, and we will be surprised when we find new parochials. If there really are lifeforms on other planets, and if they have evolved in similar environments to those found on earth, then we will find eyes, we will find parasites and we will find wings. It may sometimes be hard for us to recognise them for what they are but we can be sure they are there. What we will not find on other planets are races of creatures who look exactly like caucasian humans except for their pointed ears or ridged noses, speaking perfect American English.
If I ever see life from another planet in my lifetime (highly improbable), I will be just as interested in the similarites they have to life on earth, as I am in the differences which set them apart.
There is a very important distinction, which needs to be made when categorising life: universals and parochials. I believe these terms originated from Dr. Jack Cohen, one of the most influential and successful proponents of xenobiology.
Simply put, a universal is a structure, device, behaviour or process which is so useful and achievable that it crops up again and again in nature. Examples include flight, sight, fur and parasitism. These are things we see over and over again in the animal kingdom, evolved completely independantly in numerous, unrelated species. Often, a given environment will force organisms to evolve similar strategies. The flight and feeding behaviour of a hummingbird is superficially very similar to that of some moths; completely unrelated species evolving along similar lines to exploit similar niches.
On the other hand, parochials are accidents, simply random structures which, for seemingly no reason have become entrenched in all descendents. There is no real evolutionary pressure to explain them and given a rerun of evolution, would be unlikely to come up again. For example, vertebrates have the usual five-digit plan. Even in animals where this is less obvious, like horses or whales, their evolutionary past reveals that they did once have the same five-digit plan as their distant fishy ancestors that once crawled laboriously out of the oceans. Why five digits? Why not four or six? Actually, all those hundreds of millions of years ago, there were numerous species of fish with varying numbers of digits. It is just that the tetrapods were the ones to survive and populate the land. Mostly parochials are no better than nusances, but ones so deep in the structure of the animals that it is now impossible to evolve away from. The fact that our foodways and airways cross, often leading to choking, has no evolutionary advantage and is simply the way things are by accident.
Why this is important when thinking about alien life, is that we should expect to see universals anywhere we find life, and we will be surprised when we find new parochials. If there really are lifeforms on other planets, and if they have evolved in similar environments to those found on earth, then we will find eyes, we will find parasites and we will find wings. It may sometimes be hard for us to recognise them for what they are but we can be sure they are there. What we will not find on other planets are races of creatures who look exactly like caucasian humans except for their pointed ears or ridged noses, speaking perfect American English.
If I ever see life from another planet in my lifetime (highly improbable), I will be just as interested in the similarites they have to life on earth, as I am in the differences which set them apart.
posted by Daley Paley at 12:03 AM
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