loom | October 4, 2004Congratulations to Linda Buck and Richard Axel for winning the Nobel Prize for Medicine today. They won for their pioneering work on the 600 or so receptors that we use to smell. As is so often the case these days, the research that wins people the Nobel for Medicine also reveals a lot about our evolution. This February, for example, Buck published a paper in the Proceedings of the National Academy of Sciences, in which she and her colleagues charted the evolutionary history of human olfactory receptors.
As Buck explains, it appears that many olfactory receptor genes mutated beyond repair in…
loom | September 23, 2004Every now and then you come across a scientific hypothesis that is so elegant and powerful in its ability to explain that it just feels right. Yet that doesn't automatically make it right. Even when an elegant hypothesis gets support from experiments, it's not time to declare victory. This is especially true in biology, where causes and effects are all gloriously tangled up with one another. It can take a long time to undo the tangle, and hacking away at it, Gordian-style, won't help get to the answer any faster.
I was reminded of this while reading Andrew Brown's review of A Reason For…
loom | September 20, 2004I am sure that in 50 years, we are going to know a lot more about how the mind works. The fusion of psychology and genetics will tell us about how our personality is influenced by our genes, and they'll also show exactly how the environment plays a hand as well. The preliminary evidence is just too impressive to seriously doubt it. Likewise, I am sure that we will have a deeper understanding how our minds have evolved, pinpointing the changes in DNA over the past six million years have given us brains that work very differently than apes. Again, the first results can't help but inspire a lot…
loom | September 15, 2004The soft spot on a baby's head may be able to tell us when our ancestors first began to speak.
We have tremendously huge brains--six times bigger than the typical brain of a mammal our size. Obviously, that big size brings some fabulous benefits--consciousness, reasoning, and so on. But it has forced a drastic reorganization of the way we grow up. Most primates are born with a brain fairly close to its adult size. A macaque brain, for example, is 70% of adult size at birth. Apes, on the other hand, have bigger brains, and more of their brain growth takes place after birth. A chimpanzee is…
loom | September 13, 2004Evolution works on different scales. In a single day, HIV's genetic code changes as it adapts to our ever-adapting immune system. Over the course of decades, the virus can make a successful leap from one species to another (from chimpanzees to humans, for example). Over a few thousand years, humans have adapted to agriculture--an adult tolerance to the lactose in milk, for example. Over a couple million years, the brains of our hominid ancestors have nearly doubled. Sometimes scientists distinguish between these scales by calling small-scale change microevolution and large-scale change…
loom | September 2, 2004Today scientists took another step towards creating the sort of simple life forms that may have been the first inhabitants of Earth. I wrote a feature for the June issue of Discover about this group, led by Jack Szostak at Harvard Medical School. Szostak and his colleagues suspect that life started out not with DNA, RNA, and proteins, but just RNA. This primordial RNA not only carried life's genetic code, but also assembled new RNA molecules and did other biochemical jobs. Szostak and others have created conditions in their labs under which today's RNA can evolve into a form able to cary…
loom | September 1, 2004"A world without memory is a world of the present," Alan Lightman wrote in Einstein's Dreams. "The past exists only in books, in documents. In order to know himself, each person carries his own Book of Life, which is filled with the history of his life...Without his Book of Life, a person is a snapshot, a two-dimensional image, a ghost."
Most people would probably agree with Lightman. Most people think that our self -knowledge exists only through the memories we have amassed of our selves. Am I a kind person? Am I gloomy? To answer these sorts of questions, most people would think you have to…
loom | August 30, 2004While doing some research on human evolution, I stumbled across the web site for a wonderful meeting that was held in March at San Diego to celebrate the sequencing of the chimpanzee genome. You can watch the lectures here. By comparing the chimp genome to the human genome, scientists are discovering exactly how we evolved into the peculiar species that we are. If you find yourself in an argument with someone who claims that evolution has nothing to do with cutting edge science, plunk them down in front of these talks. Without evolution, genomics is gibberish.
(Note--Oliver Baker informs me…
loom | August 27, 2004Is Intelligent Design the same thing as creationism? The people who back Intelligent Design have spilled an awful lot of ink saying they're different. Even self-proclaimed creationists have tried to claim a difference. Somehow, both of these camps think that any confusion between the two is evidence of the lazy arrogance of evolutionists. In fact, the evidence points towards Intellgent Design being just a bit of clever repackaging to get creationist nonsense into the classroom. (See this useful article.)
A little clarity has emerged over at the new Sarkar Lab Weblog. They've created a "…
loom | August 26, 2004If you took a census of life on Earth, you'd probably find that the majority of life forms looked like this. It's a virus known as a bacteriophage, which lives exclusively in bacteria. There are about 10 million phages in every milliliter of coastal sea water. All told, scientists put the total number of bacteriophages at a million trillion trillion (10 to the 30th power). Bacteriophages not only make up the majority of life forms, but they are believed to have existed just about since life itself began. Since then, they have been evolving along with their hosts, and even making much of their…
loom | August 25, 2004Spiteful bacteria. Two words you probably haven't heard together. Then again, you probably haven't heard of altruistic bacteria either, but both sorts of microbes are out there--and in many cases in you.
Bacteria lead marvelously complicated social lives. As a group of University of Edinburgh biologists reported today in Nature, a nasty bug called Pseudomonas aeruginosa, which causes lung infections, dedicates a lot of energy to helping its fellow P. aeruginosa. The microbes need iron, which is hard for them to find in a usable form in our bodies. To overcome the shortage, P. aeruginosa can…
loom | August 23, 2004Marriage, we're told by the president and a lot of other people, can only be between one man and one woman. Anything else would go against thousands of years of tradition and nature itself. If the president's DNA could talk, I think it might disagree.
In the 1980s, geneticists began to study variations in human DNA to learn about the origin of our species. They paid particular attention to the genes carried by mitochondria, fuel-producing factories of the cell. Each mitochondrion carries its own small set of genes, a peculiarity that has its origins over two billion years ago, when our single…
loom | August 22, 2004After a couple months of merciless story deadlines, hard disk crashes, and strange viruses that you only find out about once you have kids, the Loom is creaking back to life. Expect several postings this week. For now, let me direct you to a review I wrote a couple weeks ago for The New York Times Book Review about Devil in the Mountain, a book about the Andes. The author, an Oxford geologist, dissects these mountains like a surgeon cutting open a living person. It reminded me of the times I've driven around with geologists; all of the landscape that blurs past most of us is a vast palimpsest…
loom | July 8, 2004Chris Mooney has just blogged on a depressing new report that came out today that documents how the Bush administration puts politics before science.
loom | July 7, 2004Could test tube babies be revealing some of the hidden workings of evolution? It's a definite possibility, judging from some recent reports about the balance of males and females.
For several decades, evolutionary biologists have been trying to figure out the forces that set this balance. It appears that they come down to a tug of war between competing interests. Imagine a species in which a freakish mutation makes the females gives birth to lots and lots of daughters. If you're a male, suddenly your chances of reproducing look very good--certainly better than all those females. Now imagine…
loom | July 5, 2004Recently I've been trying to imagine a world without leaves. It's not easy to do at this time of year, when the trees around my house turn my windows into green walls. But a paper published on-line today at the Proceedings of the National Academy of Science inspires some effort. A team of English scientists offer a look back at Earth some 400 million years ago, at a time before leaves had evolved. Plants had been growing on dry land for at least 75 million years, but they were little more than mosses and liverworts growing on damp ground, along with some primitive vascular plants with stems a…
loom | July 2, 2004In 1970, the natural history illustrator Rudolph Zallinger painted a picture of human evolution called "The March of Progress" in which a parade of hominids walked along from left to right, evolving from knuckle-walking ape to tall, spear-carrying Cro-Magnon. The picture is etched in our collective consciousness, making it possible for cartoonists to draw pictures like the one here safe in the knowledge that we'll all get the joke. I had actually wanted to show Zallinger's own picture, but, like others before me, I failed to find it on the web. I was inspired to hunt down the picture by the…
loom | June 30, 2004Our brains are huge, particularly if you take into consideration the relative size of our bodies. Generally, the proportion of brain to body is pretty tight among mammals. But the human brain is seven times bigger than what you'd predict from the size of our body. Six million years ago, hominid brains were about a third the size they are today, comparable to a chimp's. So what accounts for the big boom? It would be flattering ourselves to say that the cause was something we are proud of--our ability to talk, or our gifts with tools. Certainly, our brains show signs of being adapted for these…
loom | June 21, 2004We like to think of boundaries as being clear-cut borders, but at least in the biological world they generally turn out to be fuzzy zones of change. The line between land and sea is my own favorite example. Last summer my wife and I would sometimes take our oldest daughter Charlotte to the beach. At the time she was a year old and refused to put her toe in the water. This summer she heads straight in, but only about up to her knees. She runs back out and goes back in, repeating the circuit a few dozen times. Next year, I still expect to see her chin above the water line. In her own tadpoling…