Brains are awesome. Zombies eat them. Cannibals eat them. Hot-spring dwelling amoebas eat them. Aliens in sci-fi eat them. Also, brains are good for information storage and stuff. It is important to have brains. But would extraterrestrials have brains (that they haven’t sucked out of humans)? In Agent to the Stars, a book by John Scalzi, the extraterrestrials are basically big blobs of goo. They have no brains. They presumably store information, perform bodily functions such as metabolism and waste removal, and engage in movement in all cells. That would be awesome for us. There would be no kidney failure, no brain tumors, no broken bones, no disease! Why then aren’t we big blobs of goo? Wouldn’t big blobs of goo be simpler to evolve than all of our specialized cells? I mean we have a different organ for every bodily function, and each of those organs is made up of a complex structure of cells. Wouldn’t it be simpler to just have one cell that does everything?
The truth is there are cells that do everything. They are called bacteria (and also amoebas, protists, archaeans,etc.). In an evolutionary sense, bacteria and other single-celled organisms are quite succesful. They are in every environment on earth, including boiling battery acid, glaciers, highly saline environments, and even in our guts. They can form colonies, cooperate with other organisms and reproduce in fantastic ways. However, these cells, that do everything, do nothing well. This is not to say that single-celled organisms are slackers. It just means they are not adapted for passing on signals, protecting other cells, or storing information. They are adapted to reproduce, and exchange nutrients and waste with their environment. That is the problem. They require so much energy to perform these basic functions that they have none to spare for extraneous information storage. Intelligence (loosely defined as non-DNA information storage,and exchanging signals to facilitate movement and reaction to an environment) requires specialized cells that are not involved in consumption of nutrients or reproduction. Our glial cells provide protection, nutrients and insulation to neurons. Neurons have very little to do but pass signals on and store information but they do it well. Therefore, I predict that any intelligent extra-terrestrial species will have specialized brain cells.
Note: I absolutely love Agent to the Stars and John Scalzi’s books in general! I recognize that he must be more creative, more intelligent and a better writer than I and I do not wish to denigrate his many accomplishments. This post is intended to set forth an argument and a prediction about differentiated tissues. If you disagree with my argument, please feel free to comment (politely!) about my wrongheaded-ness.
A quick google search on “Water as the Basis of Life” will come up with all sorts of unsubstantiated claims and calls to action to stop polluting. I want to answer the question “WHY is water the basis of life as we know it?” (Please note: This is not a complete answer and I welcome additions in the comment section!)
The chemical structure of water is H2O meaning that for every Oxygen atom there are two Hydrogen atoms. Because of the electron structure of these atoms, both hydrogen atoms sort of get pushed to one side of the molecule (see picture). The angle between the two hydrogen atoms is 104.45 degrees. Unlike many other compounds, this somewhat awkward angle means that water doesn’t stack neatly in solid form. This is why water is less dense as a solid than it is as a liquid. The great majority of people will say, “So?” The real point to make here is that if ice sank, an entire body of water could freeze in the course of a winter and the lower layers of that body of water would never melt. The great mixing pot of our planet (the ocean), which threw together self-replicating molecules and vesicles to create the first cells, would never have existed at all if ice sank.
Water is one of many compounds that form Van der Waals bonds. Van der Waals bonds are weak electrostatic attractions between molecules. It takes a relatively large amount of energy to heat water until the Van der Waals bonds break, so heat gain/loss happens relatively slowly. This (and an atmosphere) is what keeps our planet at relatively stable temperatures, so that life has a relatively stable temperature platform to operate from.
The final point I’d like to make about water has to do with recent research into astrobiology. Scientists have discovered that common (non-water) compounds in comet-ice, when subjected to high rates of radiation, form Polycyclic Aromatic Hydrocarbons. These PAH’s are very similar to DNA/RNA and life on earth probably evolved because these compounds were present in the comets that bombarded earth early in her history. This is a really cool discovery all by itself, but it also supports my idea that life is water oriented, even life on other planets. Additionally, this means that life on other planets will have a genetic information storage mechanism similar (but probably not identical) to our DNA.
I have presented a couple of the many characteristics of water which make water a likely starting point for life on other planets. I welcome further additions/opposing hypotheses in the comment section so long as they are polite and relevant. Tune in next time I post for an explanation of why I think the aliens will be multi-cellular with differentiated tissues!