The Brain’s Big Bang or The Great Leap Forward is a term used to describe something remarkable that appears to have occurred approximately 50,000 years ago. Suddenly overnight in evolutionary time a psychic explosion occurred bringing with it language, art, and spirituality. No longer were we little more than tool using apes. Suddenly we were adorning ourselves with beads, carving fetishes out of bone or ivory and painting breathtaking images in caves.
Just exactly what happened is obscured by time and a poor fossil record starting 500,000 years ago. But advances in modern genetics have made it possible to extract clues from what little fossils there are. One of these clues involves duplicate genes.
Duplicate genes are not unusual or rare. The mechanism that makes new copies of genes in human frequently makes duplicates and it is estimated that 5% of the human genome consists of these duplicates. Of particular interest are a set duplicates found by two groups of genetic scientists led by Evan Eichler and Franck Polleux. They identified 23 genes in humans that have not been duplicated in any other primate species including our closest relative chimpanzees.
Of these 23 genes one called SRGAP2 is particularly interesting because it plays a role in the development on neurons in the cerebral cortex. SRGAP2 was duplicated approximately 3.4 million years ago forming SRGAP2B. Then again 2.4 million years ago to form SRGAP2C, and then was duplicated a final time 1 mya to produce SRGAP2D. It’s not clear at this time if SRGAP2B and SRGAP2D are functional, but it’s interesting to note that the SRGAP2C appeared at the time our human ancestors first started using tools.
One would think that perhaps SRGAP2C performs a new function or augments the original SRGAP2 gene. It does neither but instead interferes with the original gene by slowing it down thus giving neurons time to produce more connections. This in effect allows the neurons to perform a more complex brain. When scientist introduced SRGAP2C into the brains of developing mice their neurons produced denser connections with other neurons. Planet of the apes comes to mind.
Aside from duplicate genes another gene of interest is the FOXP2 gene that some are calling the language gene. The FOXP2 gene is a “conservative gene” meaning it changes very little over time. For example, between about 70 million years ago and about 5.5 million years ago experienced one change and then again 200,000 to 50,000 years ago. Why is it note worthy? Research suggests that it appears to give humans the precise control of their lower jaw and vocal apparatus necessary for a complex language.
The human form of FOXP2 is present in every living human. This is remarkable because both parents must carry the gene for it to be expressed. To put it in perspective this would be like having every human in the world have blue eyes. In other words, it was heavily selected by evolution.
The discussion about genes could go on forever and the previous ones covered only touch on the ones receiving the most recent internet attention. For example, a study conducted by Gayà-Vidal M & Albà MM (2014) found about 200 genes in humans that have evolved faster than in primates. But the question remains. What drove The Brain’s Big Bang or The Great Leap Forward?
One theory that attempted to explain the accelerated evolution involves the supereruption of the Toba supervolcano around 69,000 and 77,000 years ago. The Toba catastrophe hypothesis postulates that the eruption caused a decade long volcanic winter. This with the lingering cool period that followed which some estimated lasted approximately 1,000 years caused a drastic decrease in the human population. Some estimate that there were as few as 3,000 mating pairs of humans on the entire Earth. This may explain the low level of genetic variation among present day humans. There are problems, though, it fails to explain the survival of Neanderthals, Denisovans, and Homo Floresiensis which all survived the eruption by 50,000 years or more, neither does it explain the accelerated evolution that preceded the event by some 3 million years.
Most scientists now consider the evolution of the human brain as a special event where numerous genes were heavily selected buy some poorly defined mechanism for increased intelligence. Bruce Lahn, an assistant professor of human genetics at the University of Chicago described it this way, “Simply put, evolution has been working very hard to produce us humans.”
The last theory to be covered is the Ancient Aliens fringe theory. The Ancient Aliens theory suggests that aliens figured heavily in human evolution and cultural devolvement. Allow me to state upfront that almost 100% of everything seen in the TV show Ancient Aliens and on books on the subject is just bull crap. With that said, the theory does have some merit though highly speculative.
The most creditable proponents of the Ancient Aliens theory are I.S. Shklovski and Carl Sagan. In their book 1966 book “Intelligent Life in the Universe” they speculate that the myths of the Sumerians may represent evidence of alien contact. The legend of the Oannes, an amphibious creature that taught the Sumerians laws, farming, language and mathematics, may represent such an alien contact. They also point out that the Sumerian language is strange in that it has no Cognates with any known language and is only understood because their successors the Akkadians compiled Sumerian-Akkadian dictionaries.
It should be repeated at this point that though Sagan may be given some credit the Ancient Alien Theory he always stated that the idea is highly speculative. He reiterated his position in his 1979 book Broca’s Brain and took to task Von Däniken and other writers for uncritical thinking. He did reaffirm his earlier position that ancient contact was possible but improbable.
Improbable as it may seem genetic engineering via viral vectors would explain much. For example how we can all share the same complex set of genes that make us humans. Remember earlier it was stated that everyone having the FOXP2 was like everyone having blue eyes. Another bit of evidence may be representative art, cave painting and carved fetishes. Representative art appears to have first occurred in Europe and not in Africa as expected and spread from there very much like a virus.
So was it as Bruce Lahn stated, “Simply put, evolution has been working very hard to produce us humans.” or did aliens, improbable as it sounds, tinker with our genes.