How did our ancestors survive? part – 4
In my previous post, I wrote about how our ancestors, the hunter-gatherers collected and processed food to survive. I understand that there are whole volumes written about the hunter-gatherers and even now there are some tribes who hunt and gather. So, what is more to know and what could be interesting to know. For me, the most important thing to ponder is not so much what we know but what we do not know.
The survival of our ancestors is explained by science based on very little evidence. Some of the evidence points to the increasing of the size of the brain which was caused by standing erect. Since the brain sizes did not increase right away, the benefits were not immediate. This is where the gap is. Why would nature continue on increasing the brain sizes without great benefit?
For example, let’s say the first benefit of increased brain size is the usage of tools. No other animal used tools as much as humans did. This is attributed to standing up and thus freeing up the hands. But, it took 3 to 4 million of years from bipedalism to using tools. All these years standing up had more disadvantages than advantages and so how did this help survival?
What were the disadvantages? According to Daniel Lieberman, pregnancy is one of the disadvantages as shown in the excerpt below.
One major drawback with being bipedal is coping with pregnancy. Pregnant mammals, four-legged or two-legged, have to carry a lot of extra weight not only from the fetus but also from the placenta and extra fluids. By full term, a pregnant human mother’s weight increases by as much as 7 kilograms (15 pounds). But unlike in quadrupedal mothers, this extra mass has a tendency to cause her to fall over because it shifts her center of gravity well in front of the hips and feet.
Lieberman, Daniel (2013-10-01). The Story of the Human Body: Evolution, Health, and Disease (Kindle Locations 780-781). Knopf Doubleday Publishing Group. Kindle Edition.
Another drawback is the slow pace of growth in human intellect. For example, for thousands of generations, the tools were same and did not improve much which means the intellect did not develop by leaps and bounds. Then there is the question of language, art and above all consciousness. It is generally understood that only humans are conscious of their own existence and no other animals have consciousness.
Intellect has been the key for human survival. There is no doubt about it but how this intellect developed is still an area where science can only guess because I am not so convinced that the answer lies in the skull sizes relative to the body sizes of animals and humans.
Weaker body than a chimp, bigger brain size that needed more energy and longer period (from birth to childhood) to develop and lesser speed than a four-legged animal. None of these characteristics seem to be meant for survival. I somehow cannot fully accept the simpler explanation of survival of the fittest. It somehow does not seem to apply for early humans.
Despite all those disadvantages, for millions of years our ancestors lived the life of hunter-gatherers before settling down and farming. What genetic makeup came into being for survival? Was it a hope that this genetic makeup was necessary so modern humans could reap the benefits? How can generations and generations of humans bear one disadvantage after another to genetically propagate a weaker body in the hope of developing a bigger brain that will later on provide major advantages?
I don’t know whether we will know for sure but it sure is fun to speculate which I will do in my next post on this topic.
Thanks for reading and have a great day!