BY DR. JOSE PALU-AY DACUDAO
(Part 5)
HOMO erectus lived from almost two million to around 30,000 years ago (a point in time when Homo sapiens had developed the intelligence and sapience to draw cave paintings).
Homo habilis lived more than 2.3 to 1.6 million years ago.
Peculiarly, Australopithecus survived the extinction of Homo habilis its ancestor, and first occurred in the fossil record about 4.2 million years ago, and died out about 1.4 million years ago.
I would guess that most people nowadays would regard whacking these members of our genus Homo as murder (and perhaps Australopithecus as well). Yet they had brains that were smaller than dolphins which we kill all the time.
How about intentionally slaying a future descendant of our species that has a larger brain then ours?
Obviously, it hasn’t come to that point yet. But it might, as will be explained below.
Curiously enough, during most of our species’ history, brains bigger than the skull’s capacity of about 1350 cc could not have occurred. Our brains are about the same as anatomically modern humans that lived an estimated three hundred thousand years ago. Any larger and you get a cephalopelvic disproportion.
What happens? The baby and probably the mother dies. You might be able to save the mother by gruesomely chopping up the baby and getting its pieces out. (This is a bit personal because my head got stuck in my mother’s birth canal for four hours before her obstetrician did a Caesarian Section for cephalopelvic disproportion. I would have died stillborn if it were not for the CS.)
For more than three hundred thousand years, the human pelvis prevented us from evolving larger brains. You might ask why?
It’s because when ancient Homo species began to walk on two legs, the pelvis had to narrow as the trochanters of the femurs grew closer, a requisite for being bipedal. Thus large-headed babies died (probably along with most of their moms) because their mothers couldn’t push them out of the birth canal.
In fact, the birth of a baby is most difficult in female humans of all mammals. (Not a problem with big-headed dolphin infants since their legless mothers can grow wide pelvises.)
It was only recently when the Caesarian section (named after famous Roman leader Julius Caesar who was allegedly delivered this way) was invented that babies with heads wider than the birth canal could survive. (Caveat: CS is done for various reasons, such as placenta previa, etc. And such babies may have normal heads smaller than the normal pelvic canal. We are only interested in CS that has to be done because of cephalopelvic disproportion. Because CPD could be due to the infants’ skulls, and therefore brains, are larger than usual.)
Thus, it seems that humanity at present is now free to evolve bigger brains (as long as a doctor with the proper instruments is around to do a Caesarian section). There must be people alive today with bigger brains than any before the CS was invented, else they would be dead at birth.
We are now living at a time wherein our brains are the largest.
There doesn’t seem to be a study yet of a correlation between intelligence and delivery by CS indicated by cephalopelvic disproportion (CPD). Get a list of certified geniuses. See if there is a higher rate of CS because of cephalopelvic disproportion among them compared to the general population.
Another way: Collect the students in a large school. Identify all that were delivered because of cephalopelvic disproportion by CS. See if they are topnotchers. And so on.
Another interesting study would be determining if women that were born of CS indicated by cephalopelvic disproportion also tend to give birth by CS indicated by CPD.
If true, it implies that the trait of narrow pelvises, or more optimistically bigger brains, are being passed on to the next generation. This has to be investigated further. I certainly would love to, but in my setting, grants for such endeavors just aren’t available.
If the trait of bigger brains is being passed on to the next generation, then sci fi stories of large-headed hyper-intelligent humans in the future are probably good predictors.
So, there is cause for optimism for the future of humanity. If our species survives for another hundred thousand years, we may yet see bigger brains in our consequently brighter descendants./PN
