Why did humans evolve such a big brain? As you all might know the brain is relatively the most energy-consuming organ in the body. It is therefore not cheap, resource wise, to have a bg brain. Therefore there must have been a real good reason why our brains have grown so big. If I remember correctly there was a 3x size increase from the earliest hominoids to us humans. There are many theories foating around. What do we think about this subject in sciforums. I shall mention some theories here shortyly. 1. radiator theory. A brain needs to be cool to perform well. The evolution of more veins for cooling allowed for a bigger brain. 2. Switch in diet. The brain consumes a lot of energy. Did we become carnivorous which allowed us to grow bigger brains? 3. Expertise. We needed more expertise to survive in a new environment (savanah). 4. Baldwin effect. A entirely cultural phenomenon (as picking up a rock and throwing it at something) led to increase in brain size. 5. Social effect. We became more social and we needed a bigger brain for these complex social interactions. We became more dependent on social interactions to survive in a new hostile environment. 6. Add your own.
6. Political effect: we need big brain to be political. 7. Sciforum effect: we need more brain to discuss here.Please Register or Log in to view the hidden image! 8. Environmental: we may need more brain to survive in pollued,unnatural envirinments.
I don't know how serious this last one was, but it seems to me that polution is a recent event, and hence the evolution of our brain occurred much earlier. Therefore I do not see how our brains could have evolved to deal with pollution.
How will a larger brain help cope with increased pollution? You would think that evolving a system for metabolizing toxins, or expelling them from the body more efficiently would be more likely.
Assume volume size of the brain equates to levels of intelligence, it could give you the ability to recognise the pollution as such, and devise ways to avoid it's killing you. mentally considered and logically avoided, you could find method to survive environemntal contamination in a single generation, much shorter time frame than physical evolution on it's own would allow.
In theory, I suppose it would help us avoid pollution. However, even with our large brains, pollution is a problem, and there is no way that we will be able to be free of those pollutants within a ingle generation. In fact, it may take several. This wouldn't really account for evolving a large brain in response to elevated pollution, since it doesn't really think ahead. However, I see what your saying, and was curious about Kumar's perspective.
10. According to the Aquatic Ape Theory (AAT) humans began to develop bigger brains, as they began living near water. This is due to a change in diet. When hominids were living in arboreal environments, their diet was low in two major fatty acids, Docosahexaenoic acid (DHA) and arachidonic acid (AA), which are important to development of the brain. DHA is required to construct neural membranes and the membranes of photoreceptor cells, and AA is an important part of blood vessel walls, which supply the brian with nutrients. Without these nutrients, growth of the brain is limited. Marine and aquatic environments are high in these fatty acids, and thus when humans moved into proximity of water sources, and started to consume marine invertebrates, it is believed they received more of these limited fatty acids, therefore allowing for expansion of the brain.
Hmmm, would this mean future human may be bigger than present human? See... big brain can control body better, so bigger brain, better control, supposedly. But bigger brain may lead to body mis-proportion, right? So, the bigger the brain, the bigger the body. Hit me. Not to mention that some pre-historic human seemed to be larger than present human.. Shoot me. Oh, and by the way, spurious, maybe you should have included 'brain size/body size' ratio instead of merely brain size.... elephant have bigger brains than human, yet they seem to be less intelligent..... maybe...
I assumed that it was obvious that our brains have gotten relatively bigger, but good that you point it out. Some people might misunderstand it. I also do not think our brains can get much bigger, since we have already seem to have hit the limit of the birth canal width of women. A baby with a bigger brain will not fit. An option would be an even bigger heterochronic effect. That are babies are born at a relatively early stage (they are basically born prematurely already compared to chimps for instance) and that there is an even longer period of growth outside the womb. But maybe we also already reached the limit for this phenomenon. Babies that are born prematurely have more health problems than normal babies after all. I don't see how a bigger brain could help polution. How can there be selection for bigger brain due to a polluted enviroment? Maybe there is even the opposite effect. Maybe big brains do worse in polluted enviroments because they might be more sensitive to the effects of pollution.
