Finished reading 'Nature via Nurture' by Matt Ridley (2003), a non-fiction work on (surprise!) the nature-nurture debate. Easy to read, well researched, extremely thorough. Highly recommended.

One bit of interesting research. It's been long known that in men that the index finger is shorter than the ring finger, while in women the two are usually equal. Apparently, the difference in length in a man is proportionate to the amount of prenatal testosterone that the fetus produced. So now I can go look at people's fingers in court today and figure out whether they have more testosterone than me.

Another factoid that surprised me: average human brain size has DECREASED by more than 15% since the last ice age. The author of 'Nature via Nurture' suggests that this might be similiar to the difference in brain size between a wolf and a dog. I personally have something of a large head (I wear baseball caps on the last notch and they are a bit tight), so perhaps I'm harder to domesticate.

They've also statistically linked a tendancy towards violent behavior to a gene found on the X-chromosome. The mutated form of the mono-amine oxidase A gene results in lowered production of the enzyme of the same name and a higher tendancy towards anti-social behavior. It's a recessive gene, which means that women would have to have two copies of the mutated form, while men would only need one because of the lack of corresponding copy on the Y chromosome. Of course, this discovery raises all sorts of privacy and other issues.

Finally, check this experiment on fruit flies and memory:

In 2001, Josh Dubnau working with Tim Tully did an exquisite experiment on a fruit fly....First he made a temperature-sensitive mutation in a particular fly gene, called shibire, the gene for a motor protein called dynamin. This means that at 30 C the fly is paralyzed, but at 20 C it recovers completely. Next Dubnau engineered a fly in which this mutant gene is active only in the output from one part of the fly's brain, called the mushroom body, which is essential for learning to associate smells with shocks. This fly is not paralyzed at 30 C, but it can not retrieve memories. When such a fly is trained, while hot, to pair a smell with danger, then asked, when cool, to retrieve the memory, it performs well. In the opposite circumstances, when the fly is asked to perform the memory while cool and retrieve the memory while hot, it cannot.

Conclusion: the acquisition of memory is distinct from the retrieval; different genes are needed in different parts of the brain. The output from the mushroom body is necessary for retrieval but not for acquisition of memory, and the switching on of a gene is necessary for that output.

Pretty amazing stuff they can do these days.