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/sci/ - Science & Math

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1983287 No.1983287 [Reply] [Original]

Question for Biology/Evolutionary peoples:

What is the evolutionary advantage to having each hemisphere of the brain control the opposite side of the body?

Like Right Hemisphere controls Left side of the body, and vise versa?

>> No.1983313

sage

>> No.1983331

bump!

>> No.1983333

For the millionth time, not everything is to do with evelution........

>> No.1983335

>>1983333

I wasn't saying it was, I was simply asking a question.

>> No.1983336

The same concept that causes us to use networking cables in twisted pairs instead of parallel wires.

>> No.1983337

So basically there isn't any sort of evolutionary reason for this happening?

>> No.1983338

>>1983337
I just told you the reason. It is because our nervous system is twisted in side our body. Why is it twisted? To suppress electromagnetic interference.

>> No.1983340

>>1983333
what other factors contribute to biology being the way it is?

>> No.1983343

>>1983340
The only factors that contribute to biology being the way it is, is survival and replication of the biological entity carrying that template.

>> No.1983349

because in the earliest life forms, before specialised brains, it made sense to have the sensory apparatus identifying food to activate the muscles on the side of the body that would allow it to eat i.e. feel something on the left, activate right sided muscles to approach.

The question isn't one of advantage but of one that has nor been outcompeted by alternative systems.

OTOH, what is the religious POV on this phenomenon? 'Because God wanted it to be like that' - funny how it's not mentioned in any religious texts (i.e. sources of all human knowledge)

>> No.1983389

>>1983338

Haha okay sorry bro, I wasn't understanding that at all!

>> No.1983414

>>1983338
yo can i get a source on that, thats kinda interesting

>> No.1983529

>>1983414
Not same person, but semi-related:
http://www.youtube.com/watch?v=njIRAKW5WHc#t=3m

>> No.1983726

>>1983340
Entropy.

There are some things in nature that haven't prevailed because they are optimal for certain tasks or because they have a function but simply because they don't cause problems.

That said, your question is very interesting.

>>1983336
>>1983338
Sounded reasonable for a moment, but I don't buy it. EMI shouldn't play a role in neuronal excitation and I don't believe it's the reason for inverting the whole system. Nerves run parallel over great distances, they just cross in the Medulla oblongata.

I think it's more complicated than that.

>> No.1983798

>>1983726
Read about electricity and magnetism then read about the heart and it will all make sense to you.

>> No.1983857

>>1983726
If our body didn't have an electromagnetic interference suppression paradigm even the smallest external interference would compromise the bio-electrical equilibrium out cells rely on. We are talking about electrical fields in the body as subtle as 20millvolt. It doesn't take a very powerful external EM field to disturb that. Heck the 80millivolt dipole field generated by cells in the heart would effect the less powerful EM field in certain parts of the brain. It took evolution 1 billion years of trial and error to discover this.

>> No.1983859
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1983859

>>1983726
Me again, I think I've found an interesting paper on the topic:

http://www.ncbi.nlm.nih.gov/pubmed/8748090

What it basically says is that it all boils down to the inversion of vision in the pupil.

The crossing of motor nerves in the medulla is a common feature of all vertebrates. Another shared feature is the eye. This kind of eye produces an inverted vision: What comes in from the right side is projected on the left side of your retina (See picture). Neurons are wired so that the information reaches the responsible areas in the brain as fast as possible.

Because of this it has been postulated, that by cross-wiring the motor neurons, the organism gains reaction speed: If you see a predator moving on your right side, the information is processed in the left side of the brain which can immediately coordinate a defensive reaction carried out by your right arm. I think this is a quite elegant and logical explanation.

>> No.1983943
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1983943

>>1983857
>>1983798
Okay, I have to admit I don't know much about EMI and how it is compensated for in the human nervous system. Certainly, like you describe it, there has to be some kind of mechanism. But are you certain that a single crossing of all motor nerves in the medulla is enough to do that? Is this theory one of yours or have you read about it somewhere, if so, where?

Also, can you dig out some papers or books on the topic? I'm in neuroscience but my knowledge about the EM fields the body creates and how they affect each other is pretty weak. I'd really like to know more. Thanks bro.

>> No.1984002

>>1983859
There shouldn't be any speed advantage using one side or another, because sensing and action are both performed by the same hemisphere. That is, seeing a threat on the right side and coordinating movement of the right side will both be done by the same hemisphere, whether it's the right or left...

The inversion of the image of the eye is the key. Vertebrates originally were deuterostomes, organisms that were essentially upside-down in body plan. It's likely that this inverted plan interfered with normal processes such as feeding and seeing things, so the head in effect twisted completely around to place the eyes back on top and the mouth and anus ventral. This design persisted because it's advantageous in marine worm-like animals to have the eyes pointing up and the mouth and anus pointing down.

>> No.1984012

/sci/, I have never had much faith for the scientific aspect of this board due to all the troll threads. But god damn it, I learned something today.

I sincerely hope for more threads like this for I found this topic fascinating.

Thank you /sci/ and never give up hope of ridding yourselves of the trolls.

>> No.1984062

>>1984002
>There shouldn't be any speed advantage using one side or another, because sensing and action are both performed by the same hemisphere
Yes, you are obviously right, what was I thinking?
Even though I believe your explanation, could you give me a source? I'd like to read some more about it.

>> No.1984106

>>1984062
Unfortunately I wasn't able to find anything online... I'm just regurgitating what I remember from a vertebrate anatomy course years back. Seems like any text on the subject may shed more light.

>> No.1984131

What is the evoluntionary advabtage of my left testicak hanging lower than my right?

>> No.1984136

>>1984106
No problem. Thanks for looking anyway.

>> No.1984138

>>1983287
Evolution is a series of mutations in population, not a series of acquired advantages.

Go suck lamarcks cock some more you uneducated faggot.