Rumination on Human Evolution

Jevin

Chameleon Enthusiast
So first off, background on me is I'm a 4th year university student majoring in Archaeology and Geology. This morning in my African Archaeology class, the last few slides were about tool use and which hominin specimens they are associated with. It introduced something new to me and discovered more recently referred to as pre-mode 1 tools, a possible lithic industry that predated the Olduwan tool industry, or mode 1, but pre-mode 1 currently isn't accepted as stone tools by the archaeological community because of where the artifacts were obtained and the lack of anymore hominin remains nearby.

For some reason this got me thinking about how in Archaeology, it is generally taught that as hominin brain size increased, so did tool complexity and intelligence. My inquiring mind then thought of how crows are known to be very intelligent and use items to help solve a problem. This immediately got me thinking that how Archaeology views intelligence and how it applies to human evolution wrong. Interestingly enough is upon going through textbooks from previous courses, I found that they do admit brain structure has a part to play in intelligence, but it is mainly brain size that matters in human evolution. Such is the case of Homo floresiensis, aka the hobbit, was a species of human that stood little over a metre tall and had a brain much smaller than any other human species from that era, yet it used tools and fire.

This lead me to come up with splitting what intelligence means in the field of archaeology, which I have come to interpret in it's most basic form, is the ability to solve a problem without prior knowledge. This also inherently leads to having to make a distinction between human and animal, to which I currently describe as advanced intelligence, or the ability to solve a problem with or without aid of prior knowledge. This of course requires the ability to recall information, which is again, not unique to humans. As a result this would redefine how Archaeology looks at what it means to be human and how we evolved, from a focus on what separates hominins from other animals to what defines humans as a species.

Essentially what I think this would do is remove the main thing preventing us from establishing when humans, as a genus, emerged from primates, which is currently the very definition of what is human in an archaeological sense. And learning from how Archaeology has evolved, this seems to me like the next logical step to advance the field of Archaeology, because it removes the human perspective in a way, it forces us to look at our evolution like any other animal, rather than getting hung up on defining traits of humanity, essentially making it more scientific.

Going back to tools and early hominins, this would redefine how we came to make tools, from relying on assumed intelligence, to cognitive abilities as a whole. I have basically started to ponder if the emergence of tools was a result of memory, more so than intelligence.

Here's why I think this, it's because it doesn't require much intelligence to hit two rocks together and break chunks off of one of the rocks. But to be able to break them in a way that you get a similar product every time requires the ability to recall and process information, the ability to learn. There's also the consideration of why would hominins start to use tools in the first place, considering that most hominins before us still had larger incisors and stone tools are not found consistently with hominin remains. This has been explained usually by the fact that early stone tools were considered to be one use items typically, and this is very similar to tool use in living primates. I suspect early homonins discovered that a simple angled edge was useful by accident.

As I continued to ponder, I looked up scale images of different primate brains and noticed an interesting correlation, which was that despite the size increases between species, is that the relative size of the memory portion of the brain scaled equally as brain size increased, while the frontal lobe scaled up. Having taken a few courses on the primates, I know that it is common for larger primates to use tools, and while this does correspond with brain size and the size of frontal lobe, it corresponds more closely with tools becoming more complex and refined with the increase of brain size. However, this is also reflected in homonins, as the stone tools got more complex and refined as brain size increased.

This got me thinking that initially, tools emerged more so from the memory portion of the brain, rather than the frontal lobe. The refinement of the tools seen through the archaeological history is more impacted by the increase in the size of the frontal lobe and increase in brain size. This would explain why Homo floresiensis was capable of using the fire and tools, as it had a small brain, but it was very structured and unlike primates, had a larger frontal lobe.

Flipside of this is Homo Neanderthalis, which had a larger brain, body, better eyesight and was better able to retain heat in colder environments than modern day humans. Why is it that a human species that would have been superior by current Archaeological criteria just disappear. Granted that all of us have DNA from Homo Neanderthalis, it has been established that they interbred with modern humans, but the reason they went extinct isn't exactly known, but there is the possibility that although they had a larger brain, it may have been less structured.

As far as I know, there hasn't been any study on the evolution of the actual size, structure and shape of the brain in homonins or a study of the same done on pre-hominin primates. I think it would be interesting to actually have a study done on this and see the findings. I'd be interested in seeing if in pre-hominin primates, that the area of the brain responsible for memory started to grow first, and then the frontal lobe and overall brain started to grow once hominins started to use tools. This would most likely redefine what was human and also when the genus of Homo emerged.

I'm actually interested enough in this that I'm not considering seeing if I could research it as a senior thesis or something, thoughts?
 

Jevin

Chameleon Enthusiast
And to any who read that enormous post, congratulations on not getting bored and taking the time to read it.
 

JacksJill

Chameleon Enthusiast
Have you read about the brain structures in crows that gives their smaller brain the ability to create and use tools? I found it fascinating. I would imagine without a living sample the brain analysis would be difficult at best. I'm sure you know more about the possibilities that I do.
 

Albert C

New Member
This is pretty technical, but it is now recognized that bird brains are much more like human brains than we used to think-- a large proportion of their brains are homologous to our cerebral cortex. To some extent, this applies to reptiles as well (remember all that mythology about "the reptilian brain"?).

Just to second your observation about tool use in crows, it is remarkably sophisticated. New Caledonian crows construct and save tools. They may also copy tools. Here's one report (see also the ones listed below it), and there are more: https://phys.org/news/2018-10-caledonian-crows-tools-multiple.html

I don't think anyone has a satisfactory definition of intelligence either for animals or humans.

Good luck with your senior thesis!
 

Albert C

New Member
Have you read about the brain structures in crows that gives their smaller brain the ability to create and use tools? I found it fascinating. I would imagine without a living sample the brain analysis would be difficult at best. I'm sure you know more about the possibilities that I do.
Yeah, there's tons of research attempting to measure the relative size of different brain structures in early hominids. https://www.indiana.edu/~brainevo/publications/schoenemann-hominid-brain-evol-2013.pdf
 
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