Skip to comments.Evolution moves more quickly than scientists thought
Posted on 11/19/2006 1:00:27 PM PST by DaveLoneRanger
ST. LOUIS - Evolution happens. But it can also stop and turn on a dime.
A new study of lizards in the Bahamas shows that the natural selection pressures that drive evolution can flip-flop faster than previously thought - even in months.
"Darwin was right about so many things," said Jonathan Losos, a former Washington University biologist who led the study. "In this case he was wrong. He thought that evolution must occur slowly and gradually."
The lizards and their changing leg lengths are yet another case of evolution occurring in real time. From finches that evolve longer beaks in a few years to bacteria that adapt to strange feeding regimens in days, evolution, as a science, has leapt out of musty museums and into the field.
Scientists say that, from a political perspective, the cases offer a vivid reminder of the continuous process that some people imagine proceeding only in fossilized fits and starts: First monkey, then man.
But for the scientists themselves, the cases show that evolutionary biology has, well, evolved into a predictive, experimental science like any other.
Losos had the perfect Petri dishes: 12 tiny islands in the Bahamas with small populations of insect-eating Anolis sagrei, six-inch long lizards that normally live on the ground but can adapt to life in trees.
On six of the islands, Losos introduced a predator, a large curly-tailed lizard that can gobble up the lizards. He theorized that at first, the fastest prey would survive as they ran for the trees. Natural selection would reward long legs. Then, as the little lizards adapted to life in trees, nimble twig maneuvers and shorter legs would be rewarded.
At the start of the experiment, the scientists, using dental floss nooses on the ends of 10-foot poles, caught all lizards and carefully measured their hind-limbs. After the first six months, their predictions held up. The average leg length of survivors was 2 percent longer than those that were killed. After a year, leg length was 3 percent shorter. The changes were small in absolute terms but statistically very large, said R. Brian Langerhans, a graduate student with Losos.
The study appeared Friday in the journal Science. Losos did the research while at Washington University, but left for Harvard University in June.
The lizard study echoes one of the classic cases of evolution-in-action: Darwin's finches on the Galapagos Islands. For more than 30 years, Princeton University biologists Peter and Rosemary Grant have measured changes in the finches' beaks. After extended droughts, small seeds became more scarce. In a few years, the finches evolved longer beaks to crack the larger, tough seeds that remained. Then as more plentiful times returned, the bird beaks got smaller again.
At Michigan State University, Richard Lenski is studying evolution in test tubes. For almost 20 years, he has reared 12 colonies of E. coli. They have divided more than 30,000 times - which, in terms of human generations, is longer than Homo sapiens has been around. Lenski has challenged the bacteria with strange feeding patterns - feeding them sugars, then starving them.
The colonies all adapted, quickly. But they used different genetic tricks to get there. Their DNA is now remarkably different: an example of parallel evolution.
It's difficult to know how an organism will adapt, and also how subtle environmental changes will kick evolution off in a striking new direction, said Ken Petron, a University of Cincinnati ecologist who worked with the Grants on their finches.
For example, on one trip to the Galapagos during a time of seed scarcity, the Grants expected to find the trend toward larger beaks. But a new, larger finch had colonized the island and was eating the larger seeds, Petron said. It was no longer an advantage for the smaller finches to grow larger beaks.
"It's very difficult to predict the outcome of evolution before it happens," he said.
But if biologists can get better at predicting evolution, it could have applications for areas in which humans are altering the environment and causing evolutionary pressures themselves, Langerhans said. Stanford University ecologist Stephen Palumbi has estimated a $50 billion "evolution bill" associated with the antibiotic and pesticide resistance that bacteria, weeds and insects have evolved in medicine and agriculture.
Had the experiment continued, Losos expected the lizard legs to get even shorter with successive generations. But two hurricanes in quick succession submerged the little islands. "All the living lizards were washed away. Bummer," Losos said.
Some eggs survived, however, and hatchling populations are growing. Losos plans to start the experiment over.
Moreover, such unexpectedly rapid change supports a young-earth creationist perspective. It shows that these minor changes do not take thousands or millions of years to occur. And this is further evidence against neodarwinian evolution. If this "microevolution" takes place quicker than it was thought, that means that the macroevolutionary changes would be more readily observable now, yet they are not.
See more coverage for this story on Creation-Evolution Headlines.
Get ready for the Typing Dogs.
Mainly the birds and the provisioning of the Beagle. His book has been nominated as the most likely travelogue to put even the most pedantic philosopher of all time--Heideggger--to sleep in ten minutes or less.
How does the evolution described in this article exclude evolution from a chimp to a human? Also, "zero to sixty" is not an apt analogy - humans and chimps share 99% of their DNA. They are biologically indistinguishable except for a few (critically important) differences.
Common ancestors, not chimp to human.
You obviously don't realize that the age of the earth is not calculated based on the evolutionary timeframes but rather based on geological evidence.
Fine, I'll say it...
Evolution is genetic change within a population. Period. Nothing more, nothing less and nothing else.
This study is yet another study that confirms that evolution is a biological fact because it demonstrates genetic change within a population.
This study cannot be used as a measure of the age of the earth. You may as well use ice cream to measure the age of the ice that made it possible.
The age of the earth is an entirely different issue. Period. Its either very old or very young, and the answer to that question depends in no way whatsoever on the study of biology.
Flame throwers on...
It hasn't evolved the staff at the Kansas City Star yet.
Is this evolution or natural selection? Basically, long-legged lizards survived and passd on their traits. A good example of natural selection. I think animal breeders rely on the tendency to pass on traits all the time. That's how we wind up with so many different breeds of dogs. But they're still dogs and these lizards are still lizards. Am I missing something?
Oh boy, here we go again. I guess the scientists needed a new reason to obtain additional funding so now they make up new crap to continue their "scientific" work. Nice, really nice. It's not like there's a book (Bible) that tells us how the Earth, humans, plants and animals really got here (Genesis 1:1 - 2:25).
"Evolution moves more quickly than scientists thought"
They don't know the half of it! :-)
In short, it is not evolution at all, but adaptability that was designed into the lizards from the beginning. The evolutionism camp is clearly grasping at straws, now that the revelation of the genetic code has demolished their hopes.
Me think that Ducks Unlimited evolved from the Boy Scouts.
You're right. Jewish scholars from 2,500 years ago knew much more about how the earth evolved than modern scientists. Let's listen to them.
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