Review: Neuroanthropology Chapter 4, "Evolution and the Brain"

1/29/2019

by Leah Fontaine

In chapter four, Greg Downey and Daniel H. Lende discuss the human brain and the many theories that talk about how and why humans have evolved differently than other primates. It begins by discussing the correlation between brain and body size in many animals and how humans have a disproportionately large brain compared to the body. While other mammals have developed better systems for eating and reproduction, human's brain size has caused potential problems in both highly necessary features of survival. The disproportionate aspects of our brain doesn't stop at its total size however, and can be seen even in the size of the different parts of our brain especially the neocortex. The chapter goes on to discuss how the connections in the brain create many of the differences we see both physically and that create some of our abilities culturally. Changes in environment can greatly affect the connections that developing brains make and with humans developing so much outside of the womb there are many differences between people. Humans are a very social species which has helped develop the distinctive way that our brains work. Children are dependent on others to take care of them and this long time of dependency gives humans the chance to teach offspring more and provides opportunities for more diversity. Our ability to pass down our knowledge allows us to build on it. This along with our ability to empathize and work with each other has shaped how our brain has developed.

With my background mostly centering around culture and religion, this chapter makes me think more about childrearing and the way that has a lasting impact on all humans. I'm interested in what ways environment and culture can create and change different connections in the brain and how drastic these differences can be especially when looking at those who have experienced trauma or abuse.

11 Comments

Janae Hunter

1/29/2019 06:48:08 pm

I thought the most interesting part of this chapter was where the authors were talking about the homologs in other primate brains. I never knew that primates had such similar brains to humans. I wish the authors would have talked more about the 'chimera' procedure conducted by Deacon. That was an interesting procedure that I think could have added to the conversation.

Janae Hunter

2/27/2019 09:22:13 am

After going back over the chapter, it still stands that the author introduced a lot of great topics but never flushed them out. I wish they would have expanded upon the topics more, but one thing that stood out to me when was when they were talking about how absolute brain size doesn't determine social complexity and intelligence, because if so whales would be one of the smartest creatures on the planet. This was one of my favorite chapters to read.

Madi Moore

1/29/2019 09:24:26 pm

Before I even finished reading the last paragraph of your blog post, I was also immediately thinking about those who have experienced trauma/abuse and how environmental changes affect those victims. I think another interesting point that the authors of chapter 4 highlighted included directing our attention to why brain evolution happened, and not focusing so much on how we are talking about it. As much as we have progressed, I still feel like a lot of times science might in a way "stall" because of discrepancies in semantics and the like.

Madi Moore

2/26/2019 08:19:10 pm

I still can appreciate the fact that the chapter 4 authors stressed the point of asking the question "why brain evolution happened" and not dwell on the way that people talk about brain evolution. I think asking "why brain evolution happened" is so important when considering people who have experienced trauma and abuse. Synthesizing information from (Falk 2014), could one use the comparative approach when discussing why brain evolution happened by comparing people who have experienced abuse and people who have not experienced abuse? How would one go about establishing causal relationships here?

Brian Rivera

1/30/2019 09:07:49 am

This chapter introduced a lot of ideas very briefly. Like other people in the comments, I wanted to explore many of these ideas in more depth. We talked about the balance between depth and brevity given that book chapters are introducing multiple fields of study in a couple of pages. However, I am not sure I left this chapter better equipped to tackle questions in Neruoantrhopology. I am particularly interested in finding a way to ground what we mean by "changes" or "connections" in the brain since these can happen both in small to large temporal and spatial scales. It seems we can find ways that evolutionary pressures modified the brain but how can we distinguish this from the changes due to developmental plasticity and how should we understand the difference between these two forces.

Daniel Quillen

1/30/2019 09:44:07 am

What's interesting to me is what specifically requires such a long development in the brain. Which structures and functions evolved to require such a long period of child rearing. These functions could tell us key things about what it means to be human and what, if anything, truly separates us from other species.

Brian Rivera

1/30/2019 09:52:00 am

A question that emerged from reading this chapter is how exactly does niche construction become a evolutionary process? We have talked about the modification of the environment by social primates to the point that they might modify evolutionary forces (like predators behavior). However, this doesn't fully explain whose genes get to transfer. If niche construction results in longer lives and better chances of reproductions for everyone what forces come to dominate or select amongst the individuals? I feel this is necessary question because the opposite would mean that all members have an equal chance of reproduction. Do the advantages of niche construction then give way to sexual selection?

Kaitlyn May

1/30/2019 09:59:28 am

As someone in the field of Educational Psychology and Neuroscience, the section on child rearing stood out to me as well. I also wished that it had been discussed in more depth. I think that child rearing pairs nicely with Brian's question about how niche construction becomes an evolutionary process. Research shows that we tend to parent our children how are parents parented us. We also seek out partners who are more like us. Often, the home environment, or niche, is a key part of this parenting practice. Of course, this is merely one example of how niche construction can act as an evolutionary process, but it is the first that came to mind when reading through the comments.

Moe Prince

2/27/2019 08:27:43 am

Human brains aren't developed evenly throughout. There are certain areas which are more highly developed that others. Brain matter is an expensive thing to produce which requires higher quality food. This is especially important since the human gut it underdeveloped. Brains are grown not hard-wired. The areas you use grow while the ones you don't disappear.

Brian Rivera

2/27/2019 02:14:36 pm

The section on social intelligence was particularly interesting to revisit. This is because there were suggestions both in the book chapter and in Falks paper about human visual acuity being developed to recognized mouth movements. This suggest that the social environment of the ancestors of humans was a driving evolutionary force, a point we have visited multiple times (discussions about high stressors being other humans, and niche construction). I think this “runaway social selection” is important because it shifts the emphasis of evolutionary human-specific behaviors from overall primate evolution to a more recent time period. So it might be that the evolutionary forces that influenced the brain of modern humans begins with this “cognitive arms race” where humans become “their own principal hostile force of nature”.

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10/14/2021 02:41:31 am

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