Standing Novation
We human beings are in an elite class. We’re in the proud and privileged group of organisms that can walk on two legs. The bipeds. I mean think about it. There’s us, kangaroos, birds (although they don’t really count, since it isn’t how they usually get about), beyond that I’m struggling. But why? Why, when the majority of the mammalian world are scrambling around on four limbs, do we attempt this two-legged balancing act. Well, surprisingly enough, the answer seems to come from a deep dark corner of our galactic neighbourhood, with the cataclysmic explosions of a handful of stars around 7 million years ago.
When we talk about the Earth and its life-nurturing qualities, we often think of it as a sort of single parent; solely harbouring the burden of care for its needy biological offspring. This isolated view is convenient, and it gives the Earth an amount of credit that perhaps it is due. But it is somewhat neglectful of literally everything else in the Universe. For example, our species’ evolution from ape to slightly-less ape. Despite what some would have you believe, Homo sapiens didn’t get here just by being “really smart and stuff”, we got lucky and our winning lottery ticket came in the form of cosmic rays bursting out of the dramatic death throes of nearby stars.
Cosmic rays are just the clumpy innards of atoms (atomic nuclei) moving very fast, just below the speed of light, in fact. How they are accelerated to such head-spinning speeds has long been a source of debate, but it is now widely accepted that they are launched from stars in the violent eruption of a supernova. Now this is all fine, but how did this stellar debris initiate our ancestors to go from downward dog to mountain pose? The answer is way cooler than you might expect, it’s lightning!
As cosmic rays race into the upper atmosphere they shatter atoms in the air with their bludgeoning energy, triggering a cascade of particles that stream down through the layers of gas. This in turn electrically charges the air which then discharges into the ground in the form of lightning. Lightning, being all hot and loud, spells trouble for forest regions like that of humanities flourishing cradle in Africa, around 3 million years ago.
As I mentioned earlier, the period a million years either side of 7 million years BC was a rather boisterous era for our dear Milky Way galaxy. Stars we’re seemingly popping off left, right and centre; causing cosmic rays to rain down on the Earth like actual rain on a British wedding. The increase in cosmic rays had lightning storms putting on more regular performances, which sparked fires that ravaged the canopies and the tree life, giving way to vast grasslands. Our ancestors had to adapt, no longer could they clamber with foot and hand in step, the tall grass of the Savannah demands a lofty view for hunting and spotting predators.
It’s so subtle, isn’t it? It’s energetic fragments as small as small can be. And yet it changed the course of human history. Normally when we think of existential threats from space, we think of a city-sized rock hurtling towards us, presenting a danger so potent that only Bruce Willis has a chance of saving of us by punching the sucker towards Mars. We forget that we are just one tiny little mote of blue in a vast torrent of energy and matter; exploding, colliding and evolving through the thrash of lightning.