In the figure above, the red lines indicate moderns humans having a greater width from those particular sections of bone as compared to archaic humans. The opposite is true for the blue lines. This means that our faces (as you can tell if you've ever looked at a chimp) are considerably smaller than those of archaic humans while our brain cavity within the skull has increased greatly, by a factor greater than 10%. This was likely to make room for the greater brain size while still compensating for the fact that we must hold our head on our shoulders. If the skull remained the size that it was, it would be considerably heavier and demand a greater energy supply toward muscle development. Humans have since pushed more for brains than brawn and have such evolved away from such a complication. Another possibility is that, as brain size increased, the face was naturally condensed into a more concentrated area in order to better fit our ever-expanding frontal lobes, though further testing must be done to prove. All in all, the reasons for any one change in evolution can often be unclear, but our peculiar skull seems to be the result of our most expensive organ to run; our brains.
Citation:
Lieberman, Daniel E., et al. “The Evolution and Development of Cranial Form in Homo Sapiens.” PNAS, National Academy of Sciences, 5 Feb. 2002, www.pnas.org/content/99/3/1134.full.
I find it very interesting that our skull shape has changed this drastically, in what I would consider a short time in terms of evolution. As with most evolution concepts, this change only happened because the 'fittest' survived. I also wonder how much of this change can be attributed to the Big Brain hypothesis, which states that we evolved big brains to reproduce and survive in complex social situations.
ReplyDelete- Rund Tawfiq (3)
Thank you for replying! Personally from what I've learned in evolutionary biology and analytical psychiatrists, it seems that we evolved the bigger brain first and then came to define it through social behavior. I guess what I'm saying is that the brain was molded by complex hierarchies after the fact, as our populations grew more intricate.
Delete-Colby Ells (1)
That's very interesting! Thanks for sharing. Do you know what the time span is from the archaic human's skull and the modern humans? Do you think there would be differences across different human species? Also, do you think humans' skulls are still evolving and changing? What are your thoughts?
ReplyDelete- Angelina Weng (3)
A great read. Since having a bigger brain seems to endow greater survival odds would it be possible that our brains now are shrinking since they are used less compared to people before? What I mean is that with all the modern technology today and people not memorizing as much or applying skills would the brain shrink over time to compensate or stay the same?
ReplyDelete-Trung Le (2)
This article really caught my attention because even though I knew that modern humans' faces are smaller & less longer than our ancestors, I didn't even put two and two together to realize that the shift had to happen in order to house our bigger, cognitive-filled brain. I wonder what will happen over time- will we continue to expand our brain capacity and potential, therefore evolving larger heads and smaller faces? Will we revert back to longer faces due to technological advances and less "pressure" on our own brains? Also, does a bigger head housing a bigger brain make you smarter than a neighbor who has a smaller head? Only the future will tell!
ReplyDelete-Kamilla Leao (2)
Thank you for replying! A smaller head would not lead to less inteligence - unless of course some defect was involved. The reason for this is that the brain is generally proportional to the body that uses it, and as such a smaller brain is needed to move a smaller body and this does not affect the 'thinking' parts of the brain in the slightest. Otherwise really small people would only be as smart as monkeys!
Delete-Colby Ells (1)
This is so cool! I didn't think about the reason why our skulls are bigger. Makes sense!
ReplyDelete-- Hannah Kullberg (2)
Very interesting to think about how the human body has evolved over time. In my sophomore year I took an evolution course that opened my eyes just how much the human body has changed over time.
ReplyDeleteThis was definitely an interesting read! It makes me wonder how much evolution could occur over several more generations and if humans would look even more different than they do now.
ReplyDelete-Sunaina Sharma (3)