New synaptic molecular evolution theory

Human intelligence has little or nothing to do with brain size – scientists have known this for awhile. Having a bigger brain will not necessarily make you more intelligent than another person. A relatively recent report by the Daily Mail Newspaper discussed a study that compared human brains to the brains of other species. The research and its findings were very interesting.

Researchers found that mammals have a higher percentage of proteins in the synapses – brain regions of interconnected nerves. They also discovered that of the 600 proteins found within the synapses of mammalian brains, about half of those synapses are found in invertebrates. Only one-quarter were found in single-celled organisms – which are a species without nerves.

The Daily Mail Newspaper quoted one lead researcher who stated, “This work leads to a new and simple model for understanding the origins and diversity of brains and behavior in all species. We are one step closer to understanding the logic behind the complexity of human brains.”

This highly-complex brain study contributes knowledge about the differences in a highly-important group of brain proteins between species. This study did not produce a comparison between the relative contributions of differences in these proteins. Nor did the study fully determine the relation of brain size to intelligence in humans or any other species. Because of the inconclusiveness, it is virtually impossible to draw any conclusions about their importance. Our brains are highly-complex organs and many external and internal factors determine differences in behavior and learning in all types of species.

What were the results of this study?

Researchers discovered genes which encoded proteins similar to the mouse postsynaptic proteins in all of the species – even yeast! There were obvious differences in the numbers of types of the proteins between the yeast, vertebrates and invertebrates. Basically, as organisms became more complex, they were found to contain a wider variety of postsynaptic proteins. In yeast, a species without nerves, these proteins were utilized in a wide-variety of jobs including: decision making, breaking down proteins, moving substances around the cell, and responding to the environment.

When comparing the mice proteins with the fruit fly proteins, the mice showed a much more complex range of postsynaptic proteins. Also, different regions of the mice’s brain displayed different combinations and levels of proteins. This eludes to the fact that they may actually be responsible for some of the different functions in these areas of the brain… Pretty confusing stuff, but it makes sense.

What were researchers able to learn from these results?

Researchers in this study believe that basic proteins that make up synapses have evolved over time to become more complex. This evolution of proteins has created differences in cognitive abilities between different species and to the adaptation of different regions of the brain for different functions.

Basically, this study has contributed to knowledge about the differences in certain groups of brain-proteins between different groups of species. The brain is an extremely complex organ and there are many differences between different species which create differences in cognitive abilities and behavior. Humans have a significantly more complex set of synapse proteins than other species. This allows us to have cognitive differences in behavior, thinking, memory, etc.

Why was this study done?

They hoped to determine how the synapses have evolved and why different types of species behave in more complex ways. Researchers also make it a point to note that all existing discussions of how the brain and behavior evolved failed to take into account the possibility of “synaptic molecular evolution.” Researchers worked by looking at differences between synapses in different species. Species ranged from: single-celled species to humans.

To take into account “synaptic molecular evolution,” scientists looked at proteins that were located in a certain part of the synapse – called the postsynaptic region. For starters, scientists took sequences of certain genes which contained the blueprints for 651 proteins found in the postsynaptic regions of mice. They then used computers to match similar sequences in the genetic coding of 19 different species.

The species included: simple species that did not have nervous systems like yeast (a single-celled organism), and a range of organisms with nervous systems such as: invertebrates (i.e. insects or worms), non-mammalian vertebrates (i.e. fish), and mammalian vertebrates (rats, chimpanzees, and human beings).

The researchers looked into the function of these proteins in yeast. Next, they determined which proteins were found in the postsynaptic regions of fruit flies. They then compared the fruit flies postsynaptic regions with that of mice. Eventually, they were able to look into mice’s brains and discover where these different proteins were found.

In my opinion, this study can get a little bit confusing. There is still a lot of material that was left unexplained that is still being researched. Based on this study, scientists will have a solid foundation developed for researching new molecular evolution theories. This is one of the latest “evolution of brain power” theories that has surfaced, so I figured that I’d share it with the blog. I will keep you all updated if I discover a new one!

Where did the story come from?

Dr. Richard Emes and colleagues from Keele University, Edinburgh University, the Wellcome Trust Sanger Institute, and the Okinawa Institute of Science and Technology did the research. Their research study was funded by Wellcome Trust, the Medical Research Council, Edinburgh University, GlaxoSmithKline, the e-Science Institute, and the European Molecular Biology Organisation. The study was published in the Nature Neuroscience medical journal.