It's been one of those days when I've had a lot of ideas. Some days I get nothing all day, and some days every single thing I see or read or hear produces a huge firework of new ideas. As an example, I was reading the Economist on the tube home tonight. It was running a survey of evolution, and one of the articles had this quote:

"[Genetic scientists] showed that head lice and body lice diverged 75,000 years ago. Since body lice live in clothing, and most other species of mammal support only one species of louse, the inference is that body lice evolved at the same time as clothes. That is an interesting coincidence, and some think it doubly interesting in that it coincides with the eruption of Toba [a massive volcano that severely disrupted the earth's environment for a number of years]."

This makes me think: so, the world suddenly had a nuclear winter that caused cold (but not fatally cold) temperatures in Africa, where all humans lived at that point, and wrecked crops. I'm not speculating on the preceding; it was mentioned earlier in the article. This would have (a) forced the invention of clothing, because it was cold, and (b) forced a lot of migration. So a lot of humans would have been forced out of this pleasant lush land where there was lots of food, almost a garden paradise, into lots of other places where the going was tougher, by very sudden climate change, almost like an act of God. Being forced out of a garden by God sounds familiar. But the real clincher: before they were forced out of the garden, everybody was naked.

The same article later on produced more. Like this one:

"The brains of modern people are only about 6% larger than those of their immediate African predecessors. Perhaps more surprisingly, they are smaller than those of Neanderthals."

The article had been talking about the two main theories of what happened to the Neanderthals: were they out-competed, or did they interbreed with Homo Sapiens. The consensus is that either way, they clearly weren't as good as Homo Sapiens. But their brains were bigger. So maybe they were smart and peaceful, but they were destroyed by an influx of vicious little Homo Sapiens? The loud and dumb triumphing over the wise Neanderthals, too intelligent to contemplate genocide... it would make a good story, anyway.

Then there was this:

"[T]he size of a primate's brain, adjusted for the size of its body, is directly related to the size of the group it lives in. (Subsequent work has shown same relationship holds true for other social mammals, such as wolves and their kin.) Humans, with the biggest brain/body ratio of all, tend to live in groups of about 150."

The idea of the Ideal Village size is one I've come across before, and it fascinates me. Is there something deep in our psyche that craves social groupings of about 150 people that we don't get in big cities? Could there be some kind of business opportunity in creating a website called The Village, where you formed close-knit villages -- like social networks, but limited in size to exactly 150 people? So if you wanted to invite a new person into the group, you'd have to kick a different person out. Maybe on the basis of how well everyone else in the group knew them, a process that would self-select towards progressively better-connected groups. What would be the advantages of such close-knit groupings online? Networking? Support? Babysitting? Job advice? People to live with? Would physical proximity to people in your Ideal Village be encouraged, or is it irrelevant?

Then I got off the tube and started walking home, and saw this headline:

MIRACLE DIET HALTS AGING

What if a miracle diet really did halt aging? As in: today, right now, we discovered a diet that would halt aging, but only if that diet was all you ever ate. You'd remain perfectly healthy, never get any older, but that's all you could eat -- I dunno, a mixture of olive oil and almonds, or something. Would you occasionally sacrifice a little aging in order to eat a steak? Would you keep eating other stuff until some perfect age, or would you stick at your current age? Or would people start treating aging as more of a personal choice -- people would stick at 18 for a few years, then get bored and move on to 30, then eventually deliberately hit middle age? What if getting older was your fault, and not unavoidable?

Back home, some email, the first part of this blog entry, then some more reading, finishing off this already very inspiring article (if I were this writer, I would have found it monumentally difficult to stay on topic):

"Natural selection causes evolutionary changes that give people the means to exploit their new, more complex circumstances [civilization]. That makes the cultural environment still more complicated. And so on. Dr. Deacon believes this process has driven the capacity for abstract thought that accounts for much of what is referred to as intelligence. He sees it building up gradually in early hominids, and then taking off spectacularly in Homo Sapiens."

So complexity of cultural environment exploded exponentially. We can see that happening. But what will happen? Will it continue to rise, producing this amazingly complex society we can't envisage? Since I can't envisage it, I won't bother trying. But what about the other possibility: will cultural complexity at some point reach a limit, when we can no longer handle the complexity of daily life with our current brain? Some people would claim that's already happened.

Has all of that got you thinking?

I love one of these days.