My grandfather lived a long life, well into his eighties. In his later years, he was caught in the grip of full-blown Parkinson’s dementia, and doctors suspected Alzheimer’s disease. He didn’t recognize people he had known all his life. He generally couldn’t hold a conversation, not even a snippet of one. Toward the end, he simply was not the same Grandpa Bill that I had known as a child. Those more recent memories are perhaps the most vivid, but I try to treasure the older memories as more representative of whom I refer to when I talk about Grandpa Bill.
The funeral was hard, just as it had been for Grandma Deanie (a quick descent following stroke) and just as it would be later for Grandma Etta (Alzheimer’s again). I had to face the reality that I would never see these people again, that all I had left were the memories.
My mom, Bill’s daughter, is an ardent Christian and strongly convinced she will see her dad again in Heaven. Being convinced of that fact doesn’t make everything better for her – she took it all so hard – but it means that she can wait for a time when she’ll be with him again, for eternity, along with all the other relatives who’ve died or will die. I can tell it’s a comforting thought to her, as it is to most everyone who believes in a Heaven.
In the famous song ‘Imagine’, John Lennon asked us to imagine there’s no Heaven – it’s easy if you try, he said. What’s long been more difficulty for me is imagining that there is a Heaven.
How would it work, I wonder? Which Grandpa Bill is in Heaven? The most recent version, with dementia and sadness and confusion? Surely not, if Heaven is the wonderful place it’s supposed to be. So perhaps an earlier instantiation of him? But if a younger Bill is in Heaven, then we’re deprived of the memories and personal development (for better or worse) that happened in all those intervening years. We’re faced with the opposite problem: again it doesn’t feel like the Grandpa Bill I remember from childhood, if he’s just a young man who hasn’t had a fraction of the life experience that older fellow had.
You have ten times as many bacterial cells as human ones in your body, and that leaves out viruses and fungi. Are those non-human creatures in your body part of you?
It’s easy to think of them as ‘not you’, as little Others along for the ride on your body. They are parasites and symbiotes that feed off of us, help us digest food, might even protect us from infections – but they’re not part of me, right?
Enter Toxoplasma gondii, a protozoan parasite that infects all sorts of mammals but really loves getting into cats (the only place it can reproduce). In fact, its talent is finding its way from other mammals into cats. How does it do this?
By altering the behavior of intermediate non-cat hosts. If a mouse is infected, it starts hanging out in open areas. An infected rat actually seeks out cat urine, rather than running from it. Then, presumably, the mice and rats get eaten by hungry cats. In other words, T. gondii changes the behavior of its hosts in order to maximize the chance of finding its way inside a cat.
Of course, T. gondii doesn’t just find itself inside rats and mice on its way to cats. Often it gets into humans, through exposure to pet cats or from eating uncooked meat (a report in the UK discovered that up to 38% of stored meat was infected). Some infected people develop flu-like symptoms, but most people develop no symptoms and the infection remains latent and apparently inactive. For a long time, it was assumed that latent infection in humans had no real effect on the host.
Godel, Escher, Bach by Douglas Hofstadter has long been one of my favorite books. That book tackles what it means to be conscious and how consciousness or meaning could arise out of unconsious and meaningless elements (i.e. physical particles bouncing off of each other). It was witty and fun and enlightening, drawing from the math and logic of Kurt Godel, the impossible artwork of M.C. Escher, the many-leveled fugues of J.S. Bach, as well as Zen, Lewis Carroll, meta-fiction, puzzles and more. I love Godel, Escher, Bach.
For that reason, I was tentative in 2007 when Hofstadter released I Am a Strange Loop, a thinner book than the earlier tome, and of narrower scope (but still tackling a broad and deep subject!). How could it possibly live up to Hofstadter’s original, Pulitzer Prize-winning work? Thus, I put off reading the new book for a while.
Having finished it recently, I admit I did feel a little let-down. Partly due to repetition (rehashing arguments and analogies made in GEB), and partly due to some slips into weak argumentation against straw man opponents. Once in a while, I found myself shaking my head where he could have tightened up his philosophical discourse and made his case stronger than he did.
Do you remember where you were when you first saw the closed-circuit TV footage of the 7/7 London bombings in 2005?
Hopefully not, else you may be imagining things — no such footage exists. But if you claimed to remember it, you would be in good company. Around 40% of British college students said they remembered such a video, when filling out questionnaires a mere three months after the bombings. It seems as if people had invented a memory to fill in or coalesce the details of an event they had seen or heard described later.
Psychology professor Elizabeth Loftus has studied false memories like these for a while. For example, one study she worked on showed participants a Disneyland ad with Bugs Bunny in it. Almost a third of people who had been to Disneyland at some point in their life falsely reported that they had met Bugs Bunny and shook his hand there — falsely because Bugs Bunny is a Warner Brothers character. The false memory was much less likely in people who were shown the same Disneyland ad without Bugs Bunny in it.
Normally our bodies receive sensory input through eyes, ears, skin and other systems, and those inputs synch up in consistent ways, such that our brain can put it together into a coherent picture of the 3D world around and including us. My visual input is basically just a sterooscopic movie, but because it matches so well with tactile and other input (you feel the toe-pain of a rock right when you see that familiar foot object hit it), we interpret those images as us being inside a 3D world. Really we construct the world around us — and we presume our construction is veridical because it consistently predicts the matching up of sensory events (occasional illusions notwithstanding).
This makes perfect sense if, as we assume, we are bodies inhabiting a 3D world — bodies including brain systems that integrate sensory input from different feedback devices (including inner feedback from proprioception and the like). But if this is the case, then we should theoretically be able to disrupt or alter the brain processes that synch up our various sensory experiences, such that our consistent, 3D view of the world from our own body’s perspective is thrown out of whack. But what would happen, in that case?
We’re all familiar with claims of out-of-body experience such as, say, looking down on your own body from above. That is to say, some people report visual input that seems to locate itself in a spatial location within the 3D world that is not the same as usual. In fact, they may see an image of their own body, much like what we see in a mirror; except in the case of a mirror the various sensory modalities still match up. When seeing yourself in a mirror, the proprioceptive and muscular feedback of lifting your arms corresponds to visual feedback of the arms moving up in the mirror image, as well as peripherally seeing the arms come up as normal. In an out-of-body experience, however, the body could move (or not) in a way that doesn’t correspond to the changes in sensory (usually visual) input to the experiencer.
“So what is this mind of ours: what are these atoms with consciousness? Last week’s potatoes! They now can remember what was going on in my mind a year ago — a mind which has long ago been replaced. To note that the thing I call my individuality is only a pattern or dance, that is what it means when one discovers how long it takes for the atoms of my brain to be replaced by other atoms. The atoms come into my brain, dance a dance, and then go out — there are always new atoms, but always doing the same dance, remembering what the dance was yesterday.”
–Richard Feynman (The Value of Science)
Back in 1953, researchers at the Smithsonian Institution concluded from radio isotope tracings of chemicals entering and leaving the body that we replace around 98% of our bodies’ atoms every year or so.
Most of us are familiar with the cells in our body being replaced (the new daughter cells being made up largely of new food we take in). Skin cells slough off constantly and yet we retain skin. Hair is lopped off and new hair comes out. The stomach lining is replaced in a matter of days, the liver in weeks. An 18% yearly calcium replacement in the adult body replaces most of our bones in a few years. Neurons essentially stay for life (though adult neurogenesis sometimes replaces these).
But even those cells that are not replaced through duplication — even those holdout cells like neurons — have shifting make-up on the level of particles. New atoms flow in to replace old ones.
Now, we need not concern ourselves with whether or not every single atom actually gets replaced, or on what timeframe. We can at least be confident that a very large and significant amount of material in our bodies — even in our brains — was not there previously and won’t be there for very long. As Feynman put it, our bodies and brains are last week’s potatoes.
Obviously, this suggests that the individual atoms in our brains aren’t like packets of information holding memories or personality. Rather, the structure is what is important to cognition: whatever materials can instantiate that structure so as to carry out the computations and lead to the proper outputs are sufficient.