THE USM SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian date: 2458631.5
"My brain has no heart. My heart has no brain. That's why when I speak my mind, I seem heartless and when I do what's in my heart, I seem thoughtless."
-I don't know who wrote this, but if you do, please let me know.
THE DAILY ASTRONOMER
Tuesday, May 28, 2019
The Stars That Made Us Walk Upright
Awhile ago (a week, geologically), our food-foraging forebearers developed the ability to walk upright, as opposed to meandering about the swamps and savannas with backs arched over and arms swung low. This evolutionary development proved quite beneficial for them as erect postures rendered their movements swifter and enabled them to develop finer motor skills in the fingers that had previously dangled low to the ground. Such dexterity and efficiency came in handy when pursuing prey, eluding predators and, eventually, constructing rudimentary tools. Of course the absence of an erect spine didn't prove to be as much of an impediment for our simian grandparents who tended to swing gracefully between low hanging tree branches. For this reason, some evolutionary biologists have surmised that migrating out of forests and into grasslands might have prompted our posture transformation.
How, you might be wondering, could this evolutionary blasphemy possibly pertain to the stars? Are we suggesting that the forebearers were so enraptured by the night sky they moved out onto the grasslands so as to get a better look at it?! Well, no, actually. However, a recent theory suggests around 3 -5 million years ago (around the time of the Australopithecus) a series of relatively nearby supernova explosions casts copious quantities of cosmic rays onto Earth. This charged particle onslaught was thought to have been so powerful that it allowed many of these rays to penetrate below the magnetic field and into the planet's lower atmosphere. The introduction of these electron-exciting rays ionized the air to such an extent that lightning strikes became far more frequent than they had been. The increase in lightning discharges increased the incidence of forest fires around the region inhabited by members of the Australopithecus genus.
Forests were -and are- constantly catching fire through natural processes. In fact, periodic fires serve to revitalize forests. However, if these fires are more frequent than usual, forests won't have the time to recover. Constant fires would have depleted, rather than sustained the forests. It is possible that the widespread destruction of these sylvan tracts would have prompted our ancestors to relocate to the grasslands which would have exerted the evolutionary pressure on them to eventually walk erect. Or, so goes the theory...
-Highly massive stars explode through the galaxy approximately once every 400 - 800 years. On occasion, a cluster of these supernova explosions might have occurred close by a few million years ago. Researchers think this might be the case because of the disproportionately high abundance of the isotope of Iron-60 in the ocean crusts: an isotope known to be a by product of Type II supernova detonations.
-The explosions ionize the atmosphere, causing a sharp increase in lightning strikes.
-The lightning strike increase relates to a commensurate increase in forest fires, causing our forebearers to retreat to less forested regions where they would develop erect postures.
Theories aren't ever really correct. They can be widely accepted until some evidence is discovered to contradict some of the theory's tenets.
Did a clustering of exploding stars accelerate human evolution?
We will never knew with satisfying certainty. It is certainly plausible to suggest that we're sitting here in front of a computer screen for 8 - 12 hours a day because our ancestors eventually walked upright due to widespread forest fires induced to some extent by supernova explosions ionizing our air.
What is certain is that everything in the cosmos is interconnected, sometimes closely, at other times remotely. Many of these connections are so intricate that we've only started to understand some of them. Others await discovery. Life, being it so grinding and annoying, will, at least, never be boring.