Er bod llawer o'r ymennydd yn parhau i fod yn ddirgelwch, rydym yn gwybod llawer mwy am y peth nag y mae pobl yn sylweddoli. Fodd bynnag, some of the claims made about it are just plain weird
On July 31st 2016, this blog will have been in existence for four years exactly. A huge thanks to everyone who’s made the effort to read it in that time (an alarming number of you). Normally there’d be a post on the day to mark the occasion, but this year the 31st is a) a Sunday, a b) my birthday, so even if I could be bothered to work that day, it’s unlikely anyone would want to read it.
Fodd bynnag, today also marks the ridiculously-unlikely-but-here-we-are American release of my book. How did it get to this point?
I’ve been a “professional” science writer now for four years, and I’ve been involved in neuroscience, in one guise or another, since 2000, the year I started my undergraduate degree. In that time, I’ve heard/encountered some seriously bizarre claims about how the brain works. Oftentimes it was me not understanding what was being said, or misinterpreting a paper, or just my own lack of competence. Weithiau, it was just a media exaggeration.
Fodd bynnag, there have been occasions when a claim made about the brain thwarts all my efforts to find published evidence or even a rational basis for it, leaving me scratching my head and wondering “where the hell did THAT come from?” Here are some of my favourites.
The brain has a one terabyte information capacity
Yn y gorffennol, one terabyte of storage capacity would have seemed incredibly impressive. Ond Moore’s law has put paid to that. My home desktop PC presently has 1.5 TB of storage space, and that’s over seven years old. Could my own clunky desktop be, in terms of information capacity, smarter than me?
Mae'n debyg. Some estimates put the capacity of the human brain as low as 1TB. A lifetimes worth of memories wouldn’t fill a modern-day hard drive? That seems far-fetched, at least at an intuitive level.
The truth is far more uncertain. Some estimates put the brain’s capacity as high as several petabytes, thousands of times higher than the original surprising estimate. And there are many estimates that range between these two extremes, and beyond.
Much of this confusion lies in the uncertainty regarding exactly sut information is stored in the brain, and also in the often misleading notion that “the brain is like a computer”. In many ways it isn’t, and trying to explain it in terms of one can confuse matters. Still, it’s weird to think we might soon have smartphones more intelligent than us.
There are more connections in the brain than there are atoms in the universe
This weird claim has popped up often. Wrth gwrs, it’s nonsense. Every connection (synapse) in the human brain is made of millions of atoms, so this statement is effectively saying “there are more atoms in the brain than there are in the universe”. Unless every brain exists in its own separate pocket universe and nobody has noticed, this is a ludicrous claim.
The most obvious source of this is the movie Amelie. In fairness, the quote in that film is that there are more possible connections in a brain than atoms in the universe. This is more understandable; with tens of billions of neurons offering trillions of possible combinations, we start seeing more substantial numbers.
Nid yw'n golygu anything though. It’s clearly meant to convey the incredible complexity of the brain, but you could apply the same logic to a decent sized bag of rice. “There are more possible arrangements of rice in a 10kg bag than there are atoms in the universe”. Profound? Arguably. Helpful? Not really.
We only use 10% of our brains
This is a classic bit of nonsense that seemingly won’t go away. The implication is often that we only use 10% of our brains, so there’s 90% just waiting to be activated, potentially giving us superpowers.
A lovely idea, but not true. The brain is an intensely hungry organ, using around 20% of our body’s energy just to function normally. Having an organ using copious energy doing mostly nothing is an evolutionary dead end, if nothing else. If we only used 10%, natural selection means we’d only cael bod 10%. Maybe we are indeed the end result of a primate with much larger brains they didn’t use? Pity those poor fools and their basketball-sized-skulls.
Mae yna, Fodd bynnag,, a hint of truth to the claim. While we do use all of our brains, we don’t use all of it at once. The way the energy supply of the brain is arranged, our bodies can’t supply enough to increase activity in all of the brain simultaneously, so only a small fraction of it can be “activated” at once.
You know that old joke about why men struggle to think? The one that ends with “only enough blood to run one at a time?” It’s like that, only scientific.
Babies full of cannabis
Here’s an interesting one. The brain and nervous system uses endocannabinoid transmitters and receptors, the same receptors cannabis works on to produce its signature effects. These are believed to fulfil various roles, from memory to metabolism, but their overall purpose is still debated.
One theory, that I came across in a presentation in my student days, is that we’re flooded with natural cannabis when we’re born. Think about it: you’re a very small, still-forming human and in a very messy and intense sequence of events your universe has just gone from a warm wet sack to a sterile hospital room. That should prove intensely traumatic. But not if you’re “stoned”. Think about it some more: you’re unnaturally relaxed, and inexplicably hungry. Very useful traits in a newborn.
This may have stemmed from the claim that breast milk is full of cannabinoids, but I’ve not been able to track down any reliable studies supporting this notion. Shame, it’s quite an intriguing idea.
Men stare at breasts because…
Heterosexual men like staring at breasts. I’m confident that this isn’t a far-fetched statement. But why? Women’s breasts, outside of breastfeeding, don’t really “do” anything; they’re just “there”. Human women have prominent breasts all their adult lives, rather than just during child rearing like most mammals. You’d think men would just get used to them eventually, but apparently that doesn’t happen.
This suggests that there’s some evolved trait in the brain that makes men permanently fascinated by breasts. Are they a sign of health? A subconscious implication of fertility, to ensure passage of the genes? neu, as one theory I read argues: is it because visible breasts resemble your mother’s buttocks?
That’s correct. One argument is that, for a tree climbing primate, the site of your mother’s buttocks in front of you suggests both safety and successful climbing, so is a reassuring sight. felly, a preference for keeping your mother’s buttocks in view would be a useful survival trait, one exploited in the evolution of human females with the production of prominent breasts.
I can’t remember where I first encountered this theory, but it sounds like a Freudian fever-dream.
The UK version is still available from Guardian Bookshop for £7.99
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