We Became Human by Mistake
A new theme in human evolution is making the rounds. According to the story, a mistake led to the human brain, and the rest is history.
Live Science headlined in bold print, “Did a Copying Mistake Build Man’s Brain?” (We assume this includes woman’s brain, but this could arouse controversy, depending on whether the mistake is deemed a good or bad thing). Not to be outdone, New Scientist titled their version in a less sexist way, “One gene helped human brains become complex.”
The provocative headline stems from “new research” from the Scripps Research Institute that identified a gene that appears to result from a gene duplication:
“There are approximately 30 genes that were selectively duplicated in humans,” study researcher Franck Polleux, of The Scripps Research Institute in La Jolla, Calif., said in a statement. “These are some of our most recent genomic innovations.“
An extra copy of a gene gives evolution something to work with: Like modeling clay, this gene isn’t essential like the original copy, so changes can be made to it without damaging the resulting organism.
By “selectively duplicated,” Polleux was clearly referring to natural selection, not selection by an intelligent designer wanting to make humans smarter. The gene, SRGAP2, appears to be involved in the efficient organization of the cerebral cortex.
When the researchers added the partially duplicated gene copy to the mouse genome (mice don’t normally have it) it seemed to speed the migration of brain cells during development, which makes brain organization more efficient.
The mice, however, were not observed to start writing music or philosophy.
Somehow, using evolutionary dating assumptions, the Scripps team was able to surmise that this gene got duplicated not once, but twice in human evolution: the first time 3.5 million years ago, when it duplicated completely, and again 2.5 million years ago, when only part of it got duplicated.
These cells that expressed the incomplete duplication of SRGAP2 also had more “spines” — knoblike extensions on the cell surface that connect with other brain cells, which make them look more like human brain cells.
Interestingly, the incomplete copy of the gene seems to have showed up just as the extinct hominin Australopithecus made room for the genus Homo, which led to modern humans. That’s also when the brains of our ancestors began to expand and when dramatic changes in cognitive abilities are likely to have emerged.
Sarah Reardon in New Scientist expanded the story to imagine different lineages of humans with different numbers of gene duplications of SRGAP2. “When it comes to brain development, slow and steady wins the race,” she began. “A single ancestral human gene that made two copies of itself may have helped the evolution of our large brains 2.5 million years ago, as our ancestors were diverging from australopithecines.”
Her final paragraph quoted team leader Evan Eichler proving that science can be fun:
What’s interesting about the duplication, Eichler says, is that it would have changed brain development immediately and dramatically. Human ancestors with two, three, or even more copies of SRGAP2 – and consequently stark differences in their cognitive abilities – could have been running around together at one point. “That’s fun to think about,” he says.
Live Science was even more dramatic about the scientific earthquake generated by this fun thought. Eichler said, “These episodic and large duplication events could have allowed for radical — potentially Earth-shattering — changes in brain development and brain function.”
Yet so little is understood about how the matter of the brain connects to the mind, the self, cognition and intelligence, as an essay by Sumit Paul-Choudhury explored on New Scientist. Along that line, perhaps another PhysOrg article would be appropriate in connection with the daring assertions above: “Has modern science become dysfunctional?”
OK; if this is a new law of nature, let’s count all the SRGAP2 genes in mammals and see how they correlate with cognitive function. Are you smarter because of knoblike spines on your brain cells? If so, IQ should be a direct reflection of your knobs, making some people Einsteins and others witless nobs who are spineless.
Here’s the question you should ask when reading stupid claims like this. How would they ever know? If evolution made a mistake and duplicated a gene, then our intelligence arrived by mistake. But evolution is what evolution does; i.e., this was not a mistake at all. Stuff happens.
Now, if an evolutionist wants to reach outside of evolution and engage in philosophy, to determine whether something was mistaken, or whether a mouse’s brain is less efficient than a human brain, then he (or she) is making reference to Truth, something that is outside of nature. Truth must be timeless, universal, necessary, and certain. It is not made of particles, and cannot evolve.
If, on the other hand, the scientist says that science is not about Truth, but about exploration, then the game is over. Science is not about finding the truth. It’s just something “fun to think about” (whatever thinking refers to in a primate brain with more or less knobs and spines). Maybe it’s the kind of fun a chimpanzee gets from scratching its butt. So if scratching your head or your butt is fun, have at it. Enjoy; both ends are equally cognitive.
Some may choose to believe they became human by mistake. The rest of us will go to church and, using all our mental faculties (mind, emotions and volition) the way they were intended, will praise the Creator who designed the human brain and soul for His pleasure, who implanted in human beings–the only rational physical creatures He made–a bit of His image: the ability to reason about things timeless, universal, necessary and certain.