The ground finch, Geospiza fortis, is a medium-sized bird that lives on the small island, Daphne Major. In 1977, after a drought caused the small seeds they normally ate to become scarce, the finches evolved larger beaks that allowed them to crack and eat the larger seeds.

In the 1980s, a new finch species, G. magnirostris appeared.

Fast forward to 2003-04 when another drought occurred. Like in 1977, the seeds the birds normally ate became scarce. Because the G. magnirostris had a larger, heavier beak, they had a much easier time eating the larger seeds that remained.

The G. fortis were forced to try to get by eating the smaller seeds. Those finches with smaller, more dextrous bills had the advantage and by the following year, the G. fortis had a significantly smaller beak - around 5% on average.

Since the major difference between this drought and the one in 1977 is the presence of a second species competing for seeds, the Grants conclude that G. fortis evolved a smaller beak in order to escape this competition.

This change to evade competition, known as character displacement, has been inferred many times when competitors are more different where they co-occur than where they live apart. This is the first time, though, that the entire process has been observed from start to finish.

Source: New Scientist (subscription)

When Paabo first announced the project, he drew a lot of skepticism since there were very few bits of mitochondrial DNA to work with. Things have taken a turn for the better since Paabo announced he found nuclear DNA in a 45,000 year old Croatian Neanderthal museum specimen and has been able to sequence a million base pairs of it.

The researchers� hope is to recover the entire sequence of the Neanderthal genome, but that will depend on which they can recover enough DNA. From sampling so far, no particular gaps in the sequence are apparent. �We are hitting all the chromosomes and getting good coverage,� Dr. Egholm said. If no single specimen yields a full sequence, the genome might be recovered by combining DNA from several individuals.

One of the most important results that researchers are hoping for is to discover, from a three-way comparison between chimp, human and Neanderthal DNA, which genes have made humans human. The chimp and human genomes differ at just 1 percent of the sites on their DNA. At 1 percent, Neanderthals resemble humans at 96 percent of the sites, to judge from the preliminary work, and chimps at 4 percent. Analysis of the DNA at the sites at which humans differ from the two other species will help understand the evolution of specifically human traits "and perhaps even aspects of cognitive function," Dr. Paabo said.

Both the New York Times and Discover Magazine mention the possibility of cloning a Neanderthal and possibly bringing the species back from extinction, but at this point, that sounds a bit far fetched. Yes, we've been able to clone a sheep and other animals, but it's been almost a matter of luck that these animals have survived through birth. Most don't. And given the ethical debate surrounding human cloning, I'd image that cloning a Neanderthal would receive the same backlash.

Source: Discover Magazine (Sept 2006), New York Times

Author:

I've always liked Michael Shermer's witty, skeptical approach to virtually everything in his Scientific American columns. Regardless of whether I agree with his conclusions, he always offers me a new perspective on various, obscure topics. So it was with great interest that I picked up his new book, Why Darwin Matters.

In the book, Shermer argues that science is under attack from Evangelical Christians, and it's about time that scientists stand up and debunk Intelligent Design for what it is - a way for Evangelicals to infuse religious teachings into secular education. If they don't, they risk allowing religious proponents to redefine "science" to support their claims.

According to the widespread myth, Darwin became an evolutionist at the Galapagos Islands in 1835 after discovering natural selection during his research there. But according to his diaries, Darwin wasn't convinced of evolution until two years later. It took him until 1844 to share his findings with his botanist friend, Joseph Hooker, where he wrote "I am almost convinced, (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable." In fact, Darwin spent 22 years struggling with the question of whether to publish his findings. After all, if species could evolve through natural selection, what place was there for God? In 1859, he finally published On the Origin of Species, and only because another researcher, Alfred Russel Wallace, independently came up with the theory of natural selection and was considering publishing it.

Fast forward to the modern era and the scientific community is virtually united in agreement that evolution happened. The same cannot be said for the cultural landscape. According to a 2005 Pew Research poll, 42% of Americans hold creationist views that "living things have existed in their present form since the beginning of time" compared to 48% who believe that humans "evolved over time." 64% are ok with teaching creationism in classrooms, while more than half of those individuals think evolution should be replaced by creationism in biology classrooms.

Even President Bush was quoted as saying that Intellectual Design (ID) should be taught in schools. The media frenzy was so potent that Bush's science advisor was compelled to clarify the President's words in a New York Times article. In it, he explained that the President meant that while ID might be discussed a part of the "social context" in science classes, it was not to be considered "science" and that "evolution is the cornerstone of modern biology." As a former creationist turned evolutionist, Shermer sets out to explain the hype surrounding the creation v. evolution debate and clarify the positions and motivations of both sides.

Shermer opens his book with the definitions of a scientific theory, the historical context in which Darwin introduced his theory, and the main tenants of the theory of evolution. He also introduces the foundations of the Intelligent Design philosophy - theologian William Paley's famous watchmaker argument. The 1802 philosophy posited that if you found a watch on the ground, you'd know that it must have a maker because of its complexity. Similarly, because the world is complex, it must have had a designer - God. Both Paley and Darwin sought to explain the world around them, but while Paley took a top down, religious approach, Darwin started from the bottom with natural selection. The religious community latched on to Paley's arguments. After much debate, the scientific community went with Darwin.

Evolutionary theory has developed considerably since Darwin's time. Shermer provides numerous examples of how scientists know evolution happened and how they test their hypotheses. He then tackles the question of why people don't accept evolution, pulling from a speech William Jennings Bryan was set to make, but never did, during the Scopes Trial of 1925 - that evolution implies that there is no God, that it leads to atheism and a life without morality or meaning. In fact, most people don't care about the basic tenets of evolution or the evidence supporting it. They're more upset with the notion that accepting evolution would somehow degrade our humanity and leave us Godless and immoral.

In probably the most comprehensive section of the book, Shermer sets his sights on the fallacies of logic in their Intelligent Design argument and argues against them one by one. If you've ever wanted to read an eloquently written challenge to ID, pick up this book. Shermer leaves no stone unturned when addressing common ID issues such as the plausibility of a supernatural creator, the burden of proof, that disproving evolution doesn't prove creationism (as they'd like you to believe), that one more fossil is needed to fill a particular gap as proof of evolution. He also refutes what he considers to be the 10 most cogent arguments with evolutionary science.

Next, Sherman tackles creationism and Intelligent Design in the courtroom. He discusses the 1987 Louisiana case that asked for balanced time for creationism and evolution and the 2005 Dover case that wanted a disclaimer for Intelligent Design added to the science curriculum. He then shows that the real agenda of Intelligent Design is to convince people that Darwinism is atheistic, thus shifting the debate from creationism v. evolution to God vs. no God. In other words, the ID community wants to convince you that if they can disprove evolution, that automatically means creationism (or ID) is correct.

Like Shermer's Scientific American columns, this book was a joy to read. In this book, Shermer tries to do three things: explain why evolution is considered science and intelligent design is not, defend science from those people who want to change its very definition to suit their religious needs, and show how you can still believe in God and accept evolution.

While, unfortunately, believers in Intelligent Design and creationism probably won't bother to pick up this book, it offers a compelling and thorough argument for evolution to anyone sitting on the fence or wanting to learn more about evolution.

"There may have been times when one early hominid species evolved into another one without branching off into multiple species," White says. His view contrasts with that of researchers who suspect that hominids branched into many species over the past 6 million to 7 million years.

To prove that Au. anamensis branched from an earlier, as-yet-unknown population would require evidence that the Australopithecus species lived at the same time as Ar. ramidus, the Berkeley scientist notes. No such evidence exists.

The finding is interesting because Au. anamensis is early hominid species that evolved into Australopithecus afarensis, made famous by the discovery of Lucy. (Named because Beatles song 'Lucy in the Sky with Diamonds' was playing when they found her skeleton.)

Since Ar. ramidus and Au. anamensis lived in the same place and negotiated comparable habitats, it's plausible that the earlier hominid evolved directly into the later one, remarks anthropologist Alan C. Walker of Pennsylvania State University in University Park, a member of the team that found Au. anamensis fossils in Kenya.

From 4.2 million to 1.2 million years ago, Australopithecus evolved increasingly larger jaws and teeth from one species to the next with minimal or no evolutionary branching, Walker proposes.

Anatomical comparisons of earlier Au. anamensis and Au. afarensis finds, conducted by anthropologist Donald C. Johanson of Arizona State University in Tempe and his colleagues, also indicate that the older species evolved directly into Lucy's kind. Their study will appear in the Journal of Human Evolution.

Source: Science News

One of the biggest questions raised against the theory was how the human mind could have evolved from a more primitive animal brain. Humans make complex decisions, are driven by emotions, impose social and moral constructs, and participate in religious activities. Surely, there was a distinction between the human mind and the animal mind. In addition, since at least the Greeks, philosophers had been arguing for a mind/body dualism, meaning the two were fundamentally other and separate.

Darwin was the first to argue that the human brain wasn't so different from the animal brain and that the mind/body distinction was an illusion.

Today, scientists are still trying to explain what the mind is and how it works. A recent article in Scientific American Mind by Professor Eric Kandel of Columbia University describes this new science of mind. (subscription required)

First, mind and brain are inseparable. The brain is a complex biological organ of great computational capability that constructs our sensory experiences, regulates our thoughts and emotions, and controls our actions. The brain is responsible not only for relatively simple motor behaviors such as running and eating, but also for the complex acts that we consider quintessentially human, such as thinking, speaking and creating works of art. Looked at from this perspective, mind is a set of operations carried out by the brain, much as walking is a set of operations carried out by the legs, except dramatically more complex.

Second, each mental function in the brain - from the simplest reflex to the most creative acts in language, music and art - is carried out by specialized neural circuits in different regions of the brain. This is why it is preferable to use the term 'biology of mind' to refer to the set of mental operations carried out by these specialized neural circuits rather than 'biology of the mind' which connoted a place and implies a single brain location that carries out all mental operations.

Third, all of these circuits are made up of the same elementary signaling units, the nerve cells. Fourth, the neural circuits use specific molecules to generate signals within and between nerve cells. Finally, these specific signaling molecules have been conserved - retained, as it were - through millions of years of evolution.

]]> http://www.sciencereport.net/2006/04/14/darwin-human-evolution-and-the-science-of-mind/feed/ http://www.sciencereport.net/2006/04/08/fishapod-fossil-discovered/ http://www.sciencereport.net/2006/04/08/fishapod-fossil-discovered/#comments Sun, 09 Apr 2006 01:24:48 +0000 Krista http://72.249.45.163/~science/2006/04/08/fishapod-fossil-discovered/ One of the most extraordinary transitional fossils has been found - a 383 million year old ‘Fishapod.’ Transitional fossils are the remains of two different kinds of organisms mixed together. This one is called Tiktaalik (pronounced tic-TAH-lick) and means ‘large shallow water fish.’

Fossils of the recently discovered creature are approximately 9ft long and were dub out of rock formations on Ellesmere Island in the Canadian Arctic. It’s been dubbed ‘fishapod’ because it has the scales, teeth and gills of a fish but also a neck, bones in its pectoral fins that look like a primitive wrist and fingers, a big rib cage, which suggests the creature had lungs.

The discovery adds to the growing number of transitional fossils that evolution advocates cite as proof. In particular, it’s a great example of the fish-tetrapod transition.

For coverage, see Time, Nature, and the NY Times.

Source: Boing Boing