Brains got larger and more complex
Trillions upon trillions of ongoing chemical events enabled life forms to plan ahead, imagine, and visualize. Every few hundred thousand years or so, enormous meteors slammed into the earth causing mass extinctions that decimated species and huge populations. In one of Earth’s great cataclysms, the Permian Extinction 245 million years ago, 95% of all animal and sea life disappeared. Ice Ages came and went. New beginnings brought adaptations, divergent evolutions, and different types of species.
One hominid species that emerged, Homo sapiens, came equipped with an adaptive awareness, altruistism within the tribe, aggression, and a cunning competitiveness, too. Homo sapiens migrated out of Africa north about 60,000 years ago, spreading throughout Europe and the Middle East. As Homo sapiens moved into Europe, a neighborhood that our Homo neanderthalensis ( Denisovian, too) cousins had called home for three hundred thousand years, our ancestors replaced their Neanderthal counterparts. By 23,000 years ago, H. neanderthalensis had become extinct. Possibly, as in Cortez’s conquest of Mexico, our ancestors had carried a new disease with great virulence to the Neanderthals. From what little we know from the fossil record, it’s speculation. Perhaps Neanderthal extinction was due to “natural selection,” H. neanderthalensis being heavy-browed, tougher folk, more powerful, better adapted for the cold and successive ice ages; while we appear (at least to ourselves) more svelte, lithesome, and intelligent. But H.sapiens, with a brain that was 20% smaller than Neanderthals and DNA that was nearly identical must have had a slight molecular advantage, a mechanism that allowed for rapid adaptation, generation to generation. By using more of the histone proteins wrapped within his DNA, perhaps man had learned to better utilize a greater percentage of his 46 chromosomes – to imprint learned experiences and pass that information on to his offspring. With more DNA being accessed by more histone proteins modifications each generation had just a few more tools for survival. Each generation learned a bit more, and imprinted that learning within their eggs and sperm. Each H. sapiens child that came into the world was a slightly new edition, with a slightly revised set of what Lamarck termed “acquired characteristics.”
Where H. neanderthalensis had stayed essentially unchanged over 300,000 years, Homo sapiens had “complexified” more of its histone proteins to imprint more of the instinctual behaviors and physiological responses that were most important to compete and survive, and slightly adapted from generation to generation. Only within the last decade has interdisciplinary science discovered this molecular mechanism to “self-evolve” as the science of Epigenetics. With what were probably less sophisticated epigenetic mechanisms, H. neanderthalensis followed a Hominid family tradition and became extinct. The sole survivors of the Hominid line, Homo sapiens, have flourished.
Like the first cells, we excelled at controlling territory and the resources in it but more importantly, we learned how to learn, listen to our instincts, and pass them on. Having just migrated from the plains of Africa, we were naturally fierce fighters with better weapons than the less competitive Neanderthals. Looking down at our planet from orbiting spacecraft, man has changed faster in the last 30,000 years than did the Neanderthals in their 300,000. On the molecular level, man must have evolved a wider range of histone protein modifications, or imprinting techniques, and better epigenetic markers that utilized greater percentages of our DNA.
The capabilities of the human brain represent not a culmination, but an adaptation, one of an infinite number of progressions toward order and conquest. With a vast array of instincts we inherit learned ancestral experiences, we reproduce, protect our families, find solutions, teach others, and create the future. To accomplish all this as a species man has instinctively, ruthlessly, and naturally controlled territory, utilized resources, eliminated the competition, and developed a brain that evolves itself.
Still Portrait of a Neuron
Not until 1894 and with the aid of a microscope, however, was the human mind able to contemplate, see, and then accurately draw the cellular organization of its own brain. Over many decades of painstaking microscopy, the Spanish neuroanatomist, Ramon y Cajal, compiled the first portraits of brain cells, their intricate arborizations and layered organization.
Cajal explained what he saw – the brain as a finite multitude of individual cells called “neurons ” that remained in one place, hard-wired for adult life, and gradually died off. His “Still Portrait of a Neuron” remained still. As The Neuronal Theory this concept remained hard-wired as well, as the prevailing central dogma of neuroscience for nearly 100 years