Scientists show how bigger brains could help us see better

June 25, 2014, University of Bath
Brain diagram. Credit:

(Medical Xpress)—Bigger brain areas could have evolved to help us perceive more, and more accurately, according to a new study published by scientists at the University of Bath.

It has become increasingly common to hear reports that big brains are not necessary, or even an evolutionary fluke. However, a new article from psychologists at Bath found that increases in the size of brain areas, such as the , are an essential element of evolution.

As part of the study, the researchers found that an increase in the size of the visual part of the brain in different primate species, including humans, apes, and monkeys, is associated with enhanced visual processing.

It is controversial whether overall brain size can predict intelligence. However the size of specialised areas within the brain is associated with specific changes in behaviour such as reducing the susceptibility to visual illusions and increasing the or fine details that can be seen.

First author, Dr Alexandra de Sousa of the University's Department of Psychology explained: "Primates with a bigger visual cortex have better visual resolution, the precision of vision, and reduced strength. In essence, the bigger the brain area, the better the visual processing ability.

"The size of brain areas predicts not only the number of neurons (brain cells) in that area, but also the likelihood of connections between neurons. These connections allow for increasingly complex computations to be made that allow for more accurate, and more difficult, visual perception."

Co-author, Dr Michael Proulx, Senior Lecturer (Associate Professor) in Psychology at Bath added: "This paper is a novel attempt to bring together the micro and macro anatomy of the brain with behavior. We link visual abilities, the size of brain areas, and the number of neurons that make up those to provide a framework that ties brain structure and function together.

"The theory of brain size that we discuss can be tested in the future with more behavioral tests of other species, gathering more comparative neuroanatomical data, and by testing other senses and multisensory perception, too. We might be able to even predict how well extinct species could sense the world based on fossil data."

For the study, Dr Alexandra de Sousa, an expert in brain evolution, provided measurements from her and other's neuroanatomical research. Dr Michael Proulx, an expert in perception, found psychological studies of visual illusions and visual acuity in the same species or general of animals.

The paper 'What can volumes reveal about human brain evolution? A framework for bridging behavioral, histometric and volumetric perspectives' is published in Frontiers in Neuroanatomy this Wednesday 25 June - an online, open access journal.

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1 / 5 (2) Jun 25, 2014
Re: "...can be tested in the future with more behavioral tests of other species, gathering more comparative neuroanatomical data, and by testing other senses and multisensory perception..."

In every other species, the epigenetic landscape is linked to the physical landscape of DNA in organized genomes via the effects of olfactory/pheromonal input.

"Socioaffective neuroscience and psychology may progress more quickly by keeping these apparent facts in mind: Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans (Keller et al., 2007; Kohl, 2007; Villarreal, 2009; Vosshall, Wong, & Axel, 2000)." -- http://www.ncbi.n...3960071/

This article appears to be another attempt to make "snake-centric evolution" fit into the context of ecological variation that leads to ecological adaptations.
5 / 5 (2) Jun 25, 2014
It is highly likely that evolution of vision progressively included more and more features of the environment. The earliest eye spots could only detect light and dark, later eyes could detect movement, the visual system in frogs can detect moving flies but not stationary ones and so on.

Colour vision evolved at least twice with fish having up to 11 different colour receptors that use a different system to the later evolved mammalian colour vision having up to 3 or 4 colour receptors.

Human visual system ignores infra red, ultra violent and polarisation of light and contrives depth from a range of depth cues including stereo vision (for up to around 1.5 meters), motion-in-depth, focal change with depth and geometric cues. Colour as perceived is also a contrivance of the visual system based on colour cues including wavelength, relative position of coloured object among other objects and ambient lighting conditions.
not rated yet Jun 25, 2014
It is highly likely that none of the visual information subjectively experienced is raw visual data but is, rather, contrivances based on several sources of information. For instance context and expectation can change what is reported, visual illusions are relatively easy to produce, motion appears smooth despite eye saccades and we do not see the out of focus and colourless peripheral vision as being out of focus and colourless. The blind spot in our eyes is filled in and people going blind often continue to see familiar objects even when this is physically impossible for them.
not rated yet Jun 25, 2014
For contrast to the focus on vision in this article, see 'Inferring Gene Family Histories in Yeast Identifies Lineage Specific Expansions"

"The creation of new genetic content in the form of new genes is a key component of genome evolution." Creation of new cell types is nutrient-dependent but must be balanced by the metabolism of nutrients to species-specific pheromones that control the physiology of reproduction.

See: Nutrient-dependent/pheromone-controlled adaptive evolution: a model. http://www.ncbi.n...24693353

It accurately represents how ecological variation results in ecological adaptations via nutrient uptake and pheromone-controlled reproduction. The adaptations are manifested in the morphological and behavioral phenotypes of all individuals in all species, and they vary with epigenetic effects of nutrient stress and social stress.
1 / 5 (1) Jun 25, 2014
Eye regression in blind cave fish exemplifies an ecological adaptation, which means that the evolution of vision is also not likely to be due to mutations and natural selection.

If there was experimental evidence that suggested how vision "evolved," evolutionary theorists would probably be referencing published works that detailed that evidence, instead of telling us how likely it is that vision "evolved" and then regressed in blind cave fish due to ecological variations in the availability of nutrients.
"What is needed then—for the evolutionary case as well—is a broader and more systematic study, to discover whether or the extent to which complexity-by-subtraction occurs
1 / 5 (1) Jun 25, 2014
"...recent reports link substitution of the amino acid alanine for the amino acid valine (Grossman et al., 2013) to nutrient-dependent pheromone-controlled adaptive evolution. The alanine substitution for valine does not appear to be under any selection pressure in mice. The cause-and-effect relationship was established in mice by comparing the effects of the alanine, which is under selection pressure in humans, via its substitution for valine in mice (Kamberov et al., 2013).

These two reports (Grossman et al., 2013; Kamberov et al., 2013) tell a new short story of adaptive evolution. The story begins with what was probably a nutrient-dependent variant allele that arose in central China approximately 30,000 years ago. The effect of the allele is adaptive and it is manifested in the context of an effect on sweat, skin, hair, and teeth. In other mammals, like the mouse, the effect on sweat, skin, hair, and teeth is due to an epigenetic effect of nutrients..." = ecoLOGICAL adaptation
5 / 5 (2) Jun 25, 2014
If eye regression were a response to particular nutrients, you should be able to tell us which nutrients result in it and it should be repeatable in experimental populations even in lighted conditions.
1 / 5 (1) Jun 26, 2014
If eye regression were not a response to a nutrient-poor environment manifested in reversal of what evolutionary theorists think is mutation-initiated natural selection, they would have no trouble explaining cause and effect across species via conserved molecular mechanisms, and would not need to invent theories and stories about eye regression to accompany their ridiculous stories.

Try this: Stop attesting to the pseudoscientific nonsense you were taught to believe in and address the evidence I've been citing about the conserved molecular mechanisms of biologically based cause and effect that are manifested as the result of amino acid substitutions in the mouse to human model.
5 / 5 (2) Jun 27, 2014
You so matter-of-factly state the regression was due to nutrients rather than the eliminated selective pressure to maintain them due to the lack of light without a citation. Is their diet really nutrient poor?

How convenient it is that their diet would (somehow, as you "detail" no molecular mechanisms in your work) eliminate their vision and their pigmentation, two things under obvious visual selective pressure? This is the same conundrum you encounter trying to explain any other coloration/abiotic environment interaction. How very convenient that the polar bears' ancestors' diets turned them white when they live in snow and ice.
5 / 5 (1) Jun 27, 2014
Case in point: Eyes regressed in fish that live in caves. But JVK thinks light has nothing to do with it. No sir! It's because the water has poorer nutrients.

Never mind the same river water then exits these caves, in the light where fish have great vision!

What's next, humans developed fast legs, not because the fastest survived more often, but because of their diet?


Plus, your hypothesis is trivially testable with field work. Find niches with some of the many equivalents of Darwin's finches, then catalog and analyse what they eat.

But oh wait, this has been standard practice for naturalists for 2 centuries! You could use nothing more than statistical analysis to publish a proof, complete with at least some nutrient characterisation. But instead of doing that, you whinge!
5 / 5 (2) Jun 27, 2014
His claims completely defy causality. Let's not forget what he said about Lenski's experiment.

One of Lenski's populations (out of something like 12?) acquired a mutation that allowed the expression of citrate metabolism genes under aerobic conditions. Kohl claims the presence of the citrate in the media CAUSED the mutation, but that can't be the case when none of the other identical populations acquired it. There isn't a causal link if only 1 out of 12 had the response when all were subject to the same conditions.

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