Oooh! I have a giant spider living in my house. A couple weeks ago, I thought I saw something largish creep under the fridge in the middle of the night, but I wasn't sure that my eyes weren't playing tricks in the dark. Until a few minutes ago when I went to roll up the curtain of my bedroom window and saw the little critter hunched motionless right below the window where the floor meets the wall. It's very dark brown with a light fuzz of short hair all over. The body alone looks well over three centimeters, making it the largest live spider I've ever seen that wasn't under glass.

Now I finally have a pet to rival the turtles in Becca and Avraham's courtyard. I wonder if I should leave my window screens open to let in bugs for it to eat. I wonder what I should name it.

Woo hoo! Steve has arrived in Israel! I picked him up from the airport this morning, and we spent most of the day in Seth's apartment with me working and him catching up on his sleep. Now I'm gonna take him out for the full Jerusalem Shabbat experience. I don't think he knows what he's getting into.

This is going to be a very fun adventure. :)

Today in Gemara shiur, the text touched tangentially on the phenomenon of the ilonit, a woman whose congenital biology prevents her from ever experiencing puberty. Occurrences of this apparently had been observed a sufficient number of times for the Talmudic sages to have developed a method for definitively establishing whether or not a person was affected by this syndrome, in addition to deducing the legal implications of such a condition. Since I'd recently read Middlesex by Jeffrey Eugenides (excellent book, by the way), I suspected that this class of woman might share the same intersex condition as the protagonist of the novel, namely 5-alpha-reductase deficiency. I thought of this because the Tosafot commentary on the passage mentioned that this condition could be diagnosed with certainty at 20 years of age and that the presence certain masculine characteristics might hint at the condition even in childhood. Since I don't know the full details of how this determination is made, I couldn't make a truly educated guess about whether an ilonit is the same as a person with an 5-alpha-reductase deficiency, but I was curious anyway.

So to try to confirm or deny this speculation, I hit up Wikipedia to give myself a booster shot of knowlege about intersexuality. As I read, I became amazed at how complicated the issue is. I mean, I knew there was more than one type of hermaphroditism and more than one possible aetiology for most of those types. But when the article started rattling off nearly a dozen different chromosomal patterns that could potentially manifest an intersexual phenotype, I was a bowled over a bit.

However, the real shocker was learning about chimerism, where a single organism is composed of more than one population of genetically distinct cells. This can happen naturally if the embryos of fraternal twins fully fuse into a single embryo. In this case, the organism can be considered its own twin! Chimerism might be invisible to the naked eye, or could manifest as an anomaly as slight as each eye being a different color or as radical as a hermaphrodite with a full set of functioning organs of both the male and female varieties. A regular circus sideshow, folks.

The question that then arose in my mind was, "why doesn't the immune system of a chimera attack the cells of a different population?" In searching for an answer to this question, I found a really good article on chimerism which implies that nobody knows the answer yet. It certainly would be an incredible breakthrough in immunology if we could figure this out. It could mean organ transplants with no risk of rejection or even a cure for diseases where the immune system fails.

Nature simply never fails to fascinate...