Yet another feathered dinosaur has been discovered in China – this one is a relative of T. rex and is the largest creature with feathers, extant or extinct, to have been discovered. Yutyrannus lived about 125 million years ago and is an early cousin of the T. rex.

This is one of my favorite paleontological stories – in fact, it’s one of my favorite science stories because it demonstrates one of the ways in which evolution is testable. When Darwin first proposed his theory the fossil record was very scant. Further, the number of species currently alive is a very small portion of the number of species to have ever lived (scientists are fond of saying that most species to have ever lived are extinct).

This means that when we look at living things in order to infer the relationships among them, different plants and animals might appear to cluster in separate groups. Actually a thorough survey of living things shows a pattern of nestled categories that are blurry at the edges (I’m looking at you, platypus) and nicely reflects a branching pattern of common descent. But still, there do appear to be distinct groups. This appearance, however, is an artifact of the incompleteness of the sample of all living things represented by those species that are still alive.

Continue Reading »

The Tennessee bill that requires science teachers to teach the “strengths and weaknesses” of “controversial” topics has sparked public discussion on evolution and creationism once again. This means that we will cycle through the same series of arguments that have already been worked through, but that is the nature of the popularization of any topic, such as science. Inevitably in these discussions some people, wanting to be accommodating to all sides, ask some version of the famous question, “Can’t we all just get along?”

This view touches our democratic and individualistic sensibilities and our sense of fairness. Further, the political process is often one of compromise. Creationists are happy to exploit these facts, and claim that they just want what’s fair, they want “equal time,” they want to “teach the controversy,” and they just don’t think evolution should get any special treatment. They use these strategies because they resonate with the American culture. Also it’s easy to portray egg-headed intellectual scientists as ivory tower elitists. This all may be effective politics, but it is bad science and bad for education.

A recent editorial in the Tennessean plays the “compatible” card – here it is in its entirety:

Science has proved the universe began with a collision of two specks moving in an oversize void a very long time ago, evolving into what we have today.

How did they get together? Where did they come from? That is where God came in.

What I don’t understand is, why argue over evolution and creation when both theories are true?

Continue Reading »

A century and a half ago scientists knew very little about how life works, at least compared to what we know today. They knew little about the organelles that make up each living cells, the biochemical pathways involved in living processes, and knew absolutely nothing about genetics (which didn’t even exist yet as a discipline). It was in this context of relative ignorance that Charles Darwin proposed his particular theory of evolution and presented his argument for common descent and natural selection. The notion of evolution and common descent predates Darwin – scientists before him noticed a pattern in the sequence of fossils appearing in successive geological layers. Life seemed to be changing over geological time, with species in younger layers seeming to be derived from species in older layers.

Darwin added to that that basic observation his extensive personal observations of nature – that there is actually a great deal of variation within species, and that many species on the Galapagos seem to be derived from related species on the mainland, but changed to adapt to various niches on the islands. Still, evolution through natural selection was a remarkable hypothesis, but little more than a hypothesis. It is perhaps a good thing that there was so much left to discover about basic biology when evolution was proposed, for that created the opportunity to test this crazy theory.

Continue Reading »

You have probably heard of the crocoduck – the impossible chimera that exists only in the pseudoscientific imagination of Kirk Cameron and Ray Comfort. There is also the duckcroc, which is a real creature – an extinct crocodilian with a duck-like snout.

Well now, meet crocochicken. This creature does not yet exist, but only because the scientists who are tinkering with its genetic program are not allowed to let it hatch. Arkhat Abzhanov is an evolutionary biologist at Harvard University. He is engaged in a research program, the goal of which is to reverse some of the evolutionary changes that resulted in birds evolving form theropod dinosaurs. In essence, he want to reverse the evolutionary clock and produce a chicken with more reptilian features.

The particular feature he is working on is the duck’s bill. He is coaxing it down a different developmental path so that it ends up looking more like a crocodiles snout – hence the name “crocochicken.”

There is another researcher also doing similar research. Hans Laarson of McGill University and colleagues are also trying to reverse chicken DNA to develop along more primitive path – he is working at the other end, trying to get chickens to grow a dinosaur-like tail. His creation has been dubbed “dinochicken,” which is a much better term as chickens actually evolved from dinosaurs and not crocodilians.

Continue Reading »

I received the following question in my inbox this morning, and thought it would be a great topic for my blog today:

The dinosaurs were wiped out, along with much of the species of the Earth at some point. The few species that managed to survive eventually evolved and branched until something made it all the way to the modern human.

My question is – if humans were wiped off of the earth, would whatever primitive animal or insect that survives after our demise have no other choice than to evolve into something more intelligent than we are today? Or, is our human intellect the result of a very specific evolutionary path.

It makes sense to me that acquiring intelligence, at some point in the long, long process of evolution, would be one of the very few ways to get a leg up on your competition. The clever roaches live, ensure survival, pass along those smart genes. The next generation has an even higher bar, so only the most clever of those roaches survives, and so on.

Assume the only surviving species is a left undisturbed by the universe, and is coerced by its environment to compete and adapt until the end of time. Would intelligence be unavoidable?

This is a great question. Is the evolution of intelligence inevitable given the clear survival advantages of being smarter. This question is relevant to the Drake equation – on planets with life, how often will a technological intelligence arise?

Continue Reading »

Archaeopteryx lithographic is one of my favorite fossils. The Berlin specimen is practically a work of art. It is also a classic example of a transitional species, with a compelling blend of avian and dinosaur features. As much as it’s possible for a single fossil to be so, Archaeopteryx is a smoking gun of the evolution of birds from theropod dinosaurs.

It is also a much maligned fossil. Creationists have attacked it in every way imaginable, calling it a fraud, and ironically at times saying it’s just a dinosaur, and at others saying it’s just a bird.

But perhaps the most common misconception about the fossil, and about transitional fossils in general, is that their value as evidence for an evolutionary connection is dependent on their being a literal ancestor of the descendant group (in this case, birds). In other words, Archaeopteryx’s value as a transitional fossil is dependent on it being on the direct line that led to birds. This, however, is almost certainly not the case, and is also mostly irrelevant.

Continue Reading »

I have always had a fascination with paleontology – the reconstruction of extinct species and landscapes. I still enjoy documentaries that do a good job of transporting me to another world in the Earth’s past.

One disappointing aspect of such reconstructions, however, is that we have very little idea what many extinct creatures really looked like. You can only tell so much from fossilized bones. Occasionally we get skin impressions as well. But artists have largely guessed when it comes to color. We can make educated guesses, from looking at extant species and basic principles such as camouflage, but this has significant limitations. Could we ever infer the coloration of a tiger from it’s fossils? Probably not.

In addition, there are many specialized soft-tissue features, sometimes even defining features of animals, that do not fossilize – a camel’s hump, for example, or an elephant’s trunk. What dramatic features of dinosaurs or ancient mammals have we simply no clue about from their fossils?

Continue Reading »

Remember Michael Egnor – the creationist neurosurgeon who made a second career out of embarrassing himself with nonsensical blog posts over at the DiscoTute’s blog, Evolution News and Views? His crowning achievement on this score, in my opinion, was his argument that if evolution were true brain cancer should result in improvements in the brain.

I haven’t heard from Egnor in a while, but now I learn that he has his own blog, called “Egnorance.” The name is a nice touch on his part – some bloggers have been using the term “egnorance” to refer to Egnor’s particular brand of nonsense. It is sometimes successful to take a term meant to be derisive and adopt it as your own in order to turn it around. At the least it can take the wind out of the sails of your critics. Unfortunately, the content of the blog is a bad as ever.

This came to my attention because Egnor wrote a blog post responding to my recent post about Michele Bachmann’s creationist stance. Egnor (true to his style) thought he could get a blog post out of my use of the term “creationist” by projecting his own intellectual dishonesty. Egnor does provide an excellent example of the apologist form – exploiting any vagueness in meaning to create confusion and the appearance of sinister intent on the part of those with whom he disagrees.

Continue Reading »

The Republican primary season is already starting, and we are in for another round of candidates saying embarrassing things about science. To be fair (this is not a political blog so I want to make sure I don’t come off as partisan) bad science is not limited to the Republican party. But there are some issues where they definitely take the lead – and evolution/creationism is one. In some states creationism is on the Republican party platform. Last election cycle 4 of 10 Republican primary candidates endorsed creationism over evolution when asked directly in a debate.

This cycle we have Michele Bachmann, congresswoman from Minnesota, who is already on record as supporting creationism. In 2006 she stated:

“there is a controversy among scientists about whether evolution is a fact… hundreds and hundreds of scientists, many of them holding Nobel prizes, believe in intelligent design.”

Now, following a speech to Republicans in New Orleans, she said to reporters:

“I support intelligent design. What I support is putting all science on the table and then letting students decide. I don’t think it’s a good idea for government to come down on one side of scientific issue or another, when there is reasonable doubt on both sides.”

Continue Reading »

Following the branching bush of human evolution is getting increasingly difficult. When I studied human evolution in college, things were much simpler. There were a few Australopithecus species followed by a few Homo species, leading to modern humans. It was recognized at the time that these fossil species probably did not represent a nice clean straight line to Homo sapiens, but it seems the family tree has become much bushier than was imagined at the time.

Here is a recent representation of the hominin family tree. We have added more species of Australopithecus and Homo, plus new genuses of Kenyanthropus and Paranthropus (not even including older genuses that predate Australopithecus).

Now researchers have announced the discovery of yet another species of early hominin, about 2 million years old – likely a late species of Australopithecus named A. sediba. They discovered four individuals – two adults, a child and an infant, who likely fell into a “death trap”  in a cave in what is now Malapa, South Africa.

Continue Reading »