Biological information systems, like any others, struggle constantly with randomness. Our bodies are precision instruments to measure very many things at the same time – light, vibrations, gas pressures, concentrations of salts and hormones, to mention a few. Any of these measurements can be thought of as a sample. Now, randomness can cause the sample to lie quite far off from the actual measure. A possible solution is to resample the sample! This is not intuitive, and I will explain it below. Perhaps this is the reason why many signalling pathways in biology have so many links in the chain from receiver to effector!
The Central Limit Theorem states that if you draw a sample from a population and calculate the mean of the sample, and then repeat it several times, the means will form a normal distribution around the true mean of the original population. This means that even if the original population has a wild distribution, repeated samples of the population come closer and closer to the true mean.
Take a look at this example to see what it means:
Here, the original distribution is on the top left – highly irregular. But if we take samples of two numbers at a time from this distribution and plot their means, we end up with the distribution on the top right – already a great step towards normality! With three and four in the sample, we get the bottom left and bottom right, respectively.
Nearly all cell surface receptors signal through a pathway of messenger molecules. Not just one, but a whole cascade. The traditional explanation for this phenomenon is that the signal can be easily amplified in this way. But perhaps the real driver is the stability of the readout that can be gained. There are similar organisational features in other places too, for example in the transmission of visual information from the retina. The signals pass through a few serially arranged neurons on their way to the visual cortex. Perhaps this is what prevents our field of view from flickering? (The rods are exquititely sensitive and can detect a single photon.)
Perhaps I should write this up and submit it to the journal of Medical Hypotheses? (This is one of the few scientific journals that require no proof whatsoever, and as a result the journal contains everything from well-supported testable hypotheses to completely far-out ideas, such as the benefits of masturbation against nasal congestion.)
What do you think?🙂