For my July 2009 diary, go here.

Diary - August 2009

John Baez

August 1, 2009

This impressive photograph taken by Sophie Gerrard shows acid pollution in the streets of Mandoli, India, the result of processing scrap electronic equipment.

August 8, 2009

Here are the most romantic Paris street names I know:

August 27, 2009

Yay! The dean said my leave application will be approved! I'm going to Singapore!

My wife Lisa is taking a 1-year leave of absence from U.C. Riverside to visit the Department of Philosophy at the National University of Singapore, usually known as NUS. I'll be visiting the Centre for Quantum Technologies, or CQT. This is a research institute on the campus of NUS, but not strictly part of the university. We'll be going from July 2010 to the end of June 2011.

I visited the CQT back in March of 2008, as described here in my diary and also week262 of This Week's Finds. That's when I got the first informal offer of a visiting position there. It's been a bit complicated working out the details. But now it's coming true!

August 28, 2009

Today I put another paper on the arXiv: Higher-dimensional algebra VII: groupoidification, written with my students Alex Hoffnung and Christopher Walker. I've been finishing lots of papers in the last year — projects that have been hanging over my head like swords of Damocles. It feels like a lot of writing. Let me see how many pages: Hmm, that's 460 pages! And I plan to finish one more by next week. This will be the last of them, for a while: That'll bring the total up to 475. No wonder I'm tired!

Of course many of these took years to write, but they're all coming out now, and it takes an extra burst of energy to finish each one. It's exciting to work on lots of different subjects, but changing gears takes work. So, I'm pretty exhausted, but happy.

August 30, 2009

There's a nice article on the domestication of wolves in the magazine American Scientist: Back on September 28, 2007, I wrote a diary entry on the domestication of wolves — or in other words, dogs, because they're really the same species as far as their ability to interbreed is concerned. So, think of this as a continuation of that.

Nobody is sure when people first started making friends with wolves, or how long the domestication process took. But Russian biologists did an interesting experiment that sheds some light on this. They kept a colony of silver foxes and bred them to be less scared of people, and less aggressive.

After just 10 generations, 18% of the foxes sought human contact and showed little fear! And after about 30 generations, a true "domesticated fox" had developed. At the end, the Russians had 700 domesticated foxes — but they ran out of money when the USSR collapsed, and had to sell 600 of them as pets. At last report, "Most of the project expenses are covered by selling the foxes as pets, but the project remains in a difficult situation, looking for new sources of revenue from outside funding".

Anyway: domestication can happen quickly under laboratory conditions, but that only sets a lower bound on how long it took for wolves to become dogs.

Shipman's article summarizes our rather sketchy state of knowledge:

Another way of estimating the time at which domestic dogs originated is to consider their genetic differences from wolves. One prominent group of researchers, including Robert Wayne, along with Carles Vilà of the Uppsala University in Sweden and their collaborators, initially estimated in 1997 that dogs diverged from gray wolves 100,000 to 135,000 years ago. After more study, they revised their divergence date to between 40,000 and 100,000 years ago. Another group, led by Peter Savolainen of the Royal Institute of Technology in Sweden, favored the Chinese wolf, a subspecies of the gray wolf, as the probable ancestor and estimated in 2002 that it was domesticated between 15,000 and 40,000 years ago.

How do these genetic estimates stack up against the fossil record? Until 2009, the oldest known remains of domestic dogs were two adult skulls dated to between 13,000 and 17,000 years ago, from Eliseevichi, a region in Russia. Both had the relatively broad, short snout typical of dogs, and both were large, heavy animals, nearly the size of great Danes.

Then a team led by Mietje Germonpré of the Royal Belgian Institute of Natural Sciences reported a stunning new finding in the February 2009 issue of Journal of Archaeological Science: a nearly complete fossil dog skull dated to 31,680 ± 250 years ago.

The article then describes Germonpré's research in more detail: studies of canine skulls from various Paleolithic sites in Europe, studies of mitochondrial DNA in ancient canine bones, and best of all, how this work led to the realization that a fossilized dog from Goyet Cave in Belgium was about 31,680 years old! This is about the time of the earliest cave paintings in Europe. For example, the Chauvet Cave in France has paintings about 32,900 ± 490 years old, and also the footprints of a human child, along with dog footprints that seem to be following her!

Carbon dating of charcoal from "a torch the child carried" — but how do they know that? — says it's about 26,000 years old.

What this article really makes me want to learn about are the various European cultures of the Upper Paleolithic. I'd never paid them much attention, but when you think that these are epochs of human culture that lasted longer than "civilization as we know it", you realize they must be worth understanding! This is when many of the truly great inventions and discoveries were made: art, language, basic tools...

So, just to get myself started, let me list a few cultures centered around France, going backwards in time:

All these cultures count as Upper Paleolithic. The Upper Paleolithic started in Africa around 50,000 BC as Homo sapiens began to use more sophisticated stone tools; this may have coincided with the rise of language. The Upper Paleolithic reached Europe about 46,000 BC, and shortly thereafter the Neanderthals there went extinct.

For my September 2009 diary, go here.

Language is largely made to show off, gossip, confuse people, delude them, charm them, seduce them, scare them, exploit them, etc. And, as a side effect, convey information. Just a side effect, you fools. - Nassim Taleb

© 2009 John Baez