If evolution started in Africa, then how come.....
Darwinians constantly tell us that evolution started in stable places like the deep ocean and Africa, where seasons don't matter much. Random mutation and natural selection take a long time, so the conditions had to be suitable and stable for a long time.

Here's a surprising observation of brain change with seasons. Apparently the phenomenon is well-known in some circles, but it's not part of 'scientific literacy', and I've never heard of it before.

While the consequences of such neural plasticity have been studied at the synaptic level, minute changes in neuronal and synaptic activity over short time-scales, the impact of longer-term behavioral variations on neural structure and activity is largely unknown. Notable exceptions are songbirds that display seasonal variation in song repertoire and correlated anatomical changes in song nuclei. Although seasonal brain plasticity has mostly been studied in birds, mammalian brains, including humans, also display such effects. Some of the most drastic yet largely unexplored seasonal changes in brain structure have been observed in small mammals, like shrews and weasels.

We investigate long-term seasonal changes in the mammalian brain, known as Dehnel’s effect, where animals exhibit plasticity in body and brain sizes to counter metabolic demands in winter. We find large seasonal variation in cellular architecture and neuronal activity in the smallest terrestrial mammal, the Etruscan shrew, Suncus etruscus. Their brain, and specifically their neocortex, shrinks in winter. Shrews are tactile hunters, and information from whiskers first reaches the somatosensory cortex layer 4, which exhibits a reduced width (−28%) in winter. Layer 4 width (+29%) and neuron number (+42%) increase the following summer.

The quantity of change is especially surprising. Part of the brain shrinks by about 1/3 in winter, loses about half of its neurons, then regrows in summer! We're accustomed to thinking of brains as fully formed after adulthood. This notion has long been disproved in terms of overall age, and it's clearly incorrect in terms of seasons as well.

If we started in equatorial places where seasons don't exist, how were we able to migrate quickly out to temperate and arctic regions? There was no motivation to evolve this complex brain-switching mechanism in constant-temperature tropical areas where fruits and nuts are available at any time of year. It would have been an "inefficient energy-waster" there. If we didn't already have it when we moved into wintry places, we would have been "inefficient" there. Can't have it both ways.

There's a tempting analogy to human activity patterns in organized villages and civilizations. In spring we plant new crops and breed new livestock and build new houses. In winter we hunker down and consume what we harvested and stored in the fall. Plant and consume crops, plant and consume neurons.

Our seasonal activities, supposedly "learned" in fairly recent times, parallel how the brain handles seasons. Maybe these activities weren't learned or "socially constructed" after all. The same brain changes happen in birds and shrews, who clearly didn't "socially construct" farms and villages and civilization.

Later thought: Actually this is consistent. We already know that daily activity patterns, involving changes in brain function, are innate. We know that monthly (moonly) activities, involving changes in brain function, are innate. Why not seasons? And taking it to the next step, what about long-term patterns of civilizations? Empires, revolutions, genocides, Golden Ages, collapses, all seem to follow a firmly determined pattern. Each civilization believes that it's "making political decisions" to create or avoid those eras, but they happen to everyone anyway.

Labels: Grand Blueprint

  ¶ 12:43 PM