Funmurphys: the Blog

Scientists and engineers love equations. Not only do they make the modern world possible, they can be a lot of fun at parties. At least the kind scientists and engineers throw. And we (I’m just a country engineer) all love a good back of the envelope calculation, which is how one turns a WAG (Wild Assed Guess) into a SWAG (Scientific Wild Assed Guess). So I have to applaud Prof Andrew Watson for this Cosmic SWAG of a calculation:

Is there anybody out there? Probably not, according to a scientist from the University of East Anglia. A mathematical model produced by Prof Andrew Watson suggests that the odds of finding new life on other Earth-like planets are low, given the time it has taken for beings such as humans to evolve and the remaining life span of Earth.Structurally complex and intelligent life evolved late on Earth and it has already been suggested that this process might be governed by a small number of very difficult evolutionary steps.

Prof Watson, from the School of Environmental Sciences, takes this idea further by looking at the probability of each of these critical steps occurring in relation to the life span of Earth, giving an improved mathematical model for the evolution of intelligent life.

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His model, published in the journal Astrobiology, suggests an upper limit for the probability of each step occurring is 10 per cent or less, so the chances of intelligent life emerging is low – less than 0.01 per cent over four billion years.

I bet that makes him a big hit at all the parties, especially with thePanspermia-ists, who were a pretty lively bunch to begin with.

Or we’ve all got rhythm in our bones, even if it was discovered in our teeth.

Dr. Timothy Bromage discovered a pattern to growth rings in human teeth, and then in our bones as well. Then he discovered them in other organisms, including that lab favorite, the rat:

The newly discovered rhythm, like the circadian rhythm, originates in the hypothalamus, a region of the brain that functions as the main control center for the autonomic nervous system. But unlike the circadian rhythm, this clock varies from one organism to another, operating on shorter time intervals for small mammals, and longer ones for larger animals. For example, rats have a one-day interval, chimpanzees six, and humans eight.

The article links short intervals to small size and short life:

Reporting his findings today in the “Late-breaking News” session during the 37th Annual Meeting of the American Association for Dental Research, Bromage said, “The same biological rhythm that controls incremental tooth and bone growth also affects bone and body size and many metabolic processes, including heart and respiration rates. In fact, the rhythm affects an organism’s overall pace of life, and its life span. So, a rat that grows teeth and bone in one-eighth the time of a human also lives faster and dies younger.”

Humans have by far the most variation in these long-term incremental growth rhythms, with some humans clocking as few as five days, and others as many as ten. Correspondingly, humans have the most variability in body size among mammals.

I assume you have the exact same question I do – namely, do human also have the most variability in life span among mamals as well? Should I be happy that my son, who just turned 14, still has some baby teeth left? Maybe people who live fast and die young are just metabolically programmed that way. Will life insurance companies request a tooth so they can set their rates appropriately? Maybe you should look a gift horse in the mouth.