evolution
loom | February 7, 2005Growing up as I did in the northeast, I always assumed that the really weird life forms lived somewhere else--the Amazonian rain forest, maybe, or the deep sea. But we've got at least one truly bizarre creature we can boast about: the star-nosed mole. Its star is actually 22 fleshy tendrils that extend from its snout. For a long time, it wasn't entirely clear what the moles used the star for. The moles were so quick at finding food--larvae, worms, and other creatures that turn up in their tunnels--that some scientists suggested that the star could detect the electric fields of animals.
That…
loom | January 28, 2005Thanks to the many people who left comments on my recent post about some recent work on the intersection of stem cells and human evolution. I noticed that several people expressed variations on the same theme, one which deserves a response. To recap briefly: a great deal of research indicates that a couple million years ago, our hominid ancestors lost the ability to make one of the main sugars that coat mammal cells, called Neu5Gc. This ancient chapter in our history turns out to have a big effect on current research on embryonic stem cells. When human stem cells are raised on a substrate…
loom | January 27, 2005Recently I assisted the folks at Soundprint with an hour-long radio documentary about how humans are driving evolution in new directions. Here's the show, available on Real Player.
loom | January 23, 2005Last October, word leaked out that something might be seriously amiss with the embryonic stem cell lines approved by President Bush for federally funded research. Today, the full details were published on line in Nature Medicine. It's an important paper, and not only because it points out a grave problem with the current state of stem cell research. It also shows how scientists who do cutting-edge medical research are looking back at two million years of human evolution to make sense of their work. At a time when antievolutionists are trying hard to wedge creationist nonsense into science…
loom | January 18, 2005The Guardian has a long but disjointed report about the dispute over Homo floresiensis. Articles like these rarely give a very good picture of scientific disputes, since all parties involved only get a couple catchy quotes apiece. I've been particularly puzzled by Teuku Jacob, the elderly Indonesian paleoanthropologist who sparked the controversy by taking possession of the bones and locking them away from the Indonesian and Australian researchers who found them. So I was pleased when my brother, a linguistic anthropologist who does research in Indonesia, passed on this link to a translation…
mikethemadbiologist | January 17, 2005The NY Times had a good story on the Dover, PA evolution issue on Sunday. It seems to me that there are three classes of 'issues' people have with evolutionary biology:
Biblical literalism. Many can not accept that the Bible isn't the literal word of God. I think we can beat this one pretty easily: the contradiction between Genesis 1 & 2, the earth is round, the earth travels around the sun, etc. To do so, we not only have to demolish it with logic, but also with proud declarations: "I am not a literalist." Make literalism a bad thing (and I think it is). As one Dover resident said, "…
loom | January 10, 2005The more time I spend talking to biologists, the more they remind me of detectives. I have two stories in tomorrow's New York Times that make this connection particularly clear. In the first, E.O. Wilson attempts to solve the mystery of a plague of ants that devastated some of the earliest Spanish settlements in the New World. In the second, I look at another mystery--is there life on Saturn's moon Titan. The space probe Huygens will be falling into its hazy atmosphere on Friday to see what lurks under its cloak. I inteviewed University of Florida chemist Steven Benner who will be trying to…
loom | January 8, 2005Not long ago I had a remarkable experience: I got to visit the nursery for what might prove to be a new form of life. At Michigan State University, a group of computer scientists, biologists, and philosophers run the Digital Evolution Laboratory. There, they are developing software called Avida which allows them to create virtual worlds swarming with digital organisms. Avida's residents show a lot of the important features that scientists consider essential requirements for life. Their evolution is particularly impressive, because it parallels evolution in the wet world in all sorts of subtle…
loom | January 6, 2005When you consider a tapeworm or an Ebola virus, it is easy think of them as being evil to their very core. That's a mistake. It's true that at this point in their evolutionary history these species have become well adapted to living inside of other organisms (us), and using our resources to help them reproduce themselves even if we get sick in the process. But one of the big lessons of modern biology is that there are no essences in nature--only the ongoing interplay of natural selection and the conditions in which it works. If the conditions change, organisms may evolve into drastically…
stcynic | January 2, 2005Carl Zimmer has another stellar post on his blog, this one about the evolution of the immune system. It's a review of this article (PDF format) by Klein and Nikolaidis, entitled The descent of the antibody-based immune system by gradual evolution. This article points up a very important point that I was making in an exchange in the comments a few weeks ago, about nested heirarchies as a powerful line of evidence for evolution. All animals, living or dead, can be placed into groups based upon shared derived characteristics and those groups form tree-like heirarchies. Branch B splits off from…
loom | December 31, 2004Evolutionary biologists face a challenge that's a lot like a challenge of studying ancient human history: to retrieve vanished connections. The people who live in remote Polynesia presumably didn't sprout from the island soil like trees--they must have come from somewhere. Tracing their connection to ancestors elsewhere hasn't been easy, in part because the islands are surrounded by hundreds of miles of open ocean. It hasn't been impossible though: studies on their culture, language, and DNA all suggest that the Polynesians originally embarked from southeast Asia. We may never be able to…
stcynic | December 28, 2004Dean Esmay never replied to my post explaining why ID should not be taught in science classrooms, but in checking back at his blog for a response I'm beginning to think that the real problem is that he just doesn't understand evolution well at all. For instance, notice this post, where he says:Scientists thing they have found a way that mutation can drive rapid evolutionary change. That flies in the face of most evolutionary theory, which tends to hold that mutation is not the primary way by which creatures evolve. But from studying dogs, they think they may have identified how it might work…
loom | December 27, 2004Size matters. At least that's the result of some recent research on long-term evolutionary trends that I'll be reporting in tomorrow's New York Times. Here are the first few paragraphs...
Bigger is better, the saying goes, and in the case of evolution, the saying is apparently right.
The notion that natural selection can create long-term trends toward large size first emerged about a century ago, but it fell out of favor in recent decades. Now researchers have taken a fresh look at the question with new methods, and some argue that these trends are real.
Biologists have recently found that in…
loom | December 16, 2004Intelligence is no different than feathers or tentacles or petals. It's a biological trait with both costs and benefits. It costs energy (the calories we use to build and run our brains) which we could otherwise use to keep our bodies warm, to build extra muscle, to ward off diseases. It's also possible for the genes that enhance one trait, such as intelligence, to interfere with another one, or even cause diseases. Over the course of evolutionary time, a trait can vanish from a population if its cost is too high.
On the other hand, intelligence may offer some evolutionary benefits, by…
loom | December 10, 2004Imagine you're a columnist. You decide to write something about how the National Park Service is allowing a creationist book to be sold in their Grand Canyon stores, over the protests of its own geologists, who point out that NPS has a mandate to promote sound science. Hawking a book that claims that the Grand Canyon was carved by Noah's Flood a few thousand years ago is the polar opposite of this mandate. So what do you write? Well, if you're Republican consultant Jay Bryant, and you're writing for the conservative web site Town Hall, you declare that this as a clear-cut case of Darwinist…
loom | December 10, 2004The Australian media are doing a fantastic job of keeping up with the developments with Homo floresiensis. Here's the first three-dimensional reconstruction I've seen of the little hominid, made by an Australian archaeologist. It's published on the Australian Broadcasting Corporation's web site. I'm sure that as more bones emerge, the image will improve, but this is still a wonderful first look.
loom | December 9, 2004Homo floresiensis update: The Economist weighs in on the "borrowing" of the fossils. They mention that when the bones were removed, they were simply stuffed in a leather bag. This is not exactly the sort of procedure you see in protocols for avoiding contamination of ancient DNA. In the Australian, the discoverers of "Florence" vow to return to the fossil site, and this time they'll put their discoveries in a really good safe. Wise move.
loom | December 6, 2004In tomorrow's New York Times, I have an article about how to reconstruct a genome that's been gone for 80 million years. The genome in question belongs to the common ancestor of humans and many other mammals (fancy name: Boreoeutheria). In a paper in this month's Genome Research, scientists compared the same chunk of DNA in 19 species of mammals. (The chunk is 1.1 million base pairs long and includes ten genes and a lot of junk.) The researchers could work their way backwards to the ancestral genetic chunk, and then showed they could be 98.5% certain of the accuracy of the reconstruction.…
loom | November 30, 2004I have a short piece in today's New York Times about how male swallows are evolving longer tails, which female swallows find sexy. Here's the original paper in press at The Journal of Evolutionary Biology. Measuring the effects of natural selection is tough work, the details of which are impossible to squeeze into a brief news article. Scientists have to document a change in a population of animals--the length of feathers, for example--but then they have to determine that the change is a product of genetic change. We are much taller than people 200 years ago, but it's clear that most, if not…