RSSCategory: Evolution

Huge find of ancient whale fossils in the desert

November 14, 2011 | By | Reply More
Huge find of ancient whale fossils in the desert

In a desert in northern Chile, scientists are busy digging out dozens of fossils of the ancestors of modern whales, many of them complete skeletons. The fossils are up to seven million years old. This will add to an impressive collection of whale and pre-whale fossils already in the scientific record. And see here.

Share

Read More

Your great great grandparents were sponges, and their great grandparents were fungi

October 26, 2011 | By | 6 Replies More
Your great great grandparents were sponges, and their great grandparents were fungi

About 10 years ago, I had the opportunity to view a set of videos called “The Shape of Life.” It was an amazing journey because it suggested that the earliest animal ancestor of human beings was the sponge. I watched this video several times, because I had trouble wrapping my mind around this finding. It was an excellent set of videos that I still highly recommend.

The mind-boggling conclusion that we are descendants of sponges was reinforced in my mind back in November, 2004, when I read a fascinating article about our ancestors in discover magazine, pulling out the article: “This Is Your Ancestor.” It is a story of an evolutionary microbiologist named Mitchell Sogin, who wanted to know the animal from which all other animals came. He extrapolated backwards from today’s oldest known species: jellyfish, sea anemones, sponges, mollusks and starfish.  When he grouped each of these organisms according to their first appearance on Earth, the most likely candidate appeared to be the sponge. As the Discover article points out, sponges don’t look much like animals, though they are truly animals, not plants, and there are 9,000 species of sponges on the planet.

Sponges are multicellular, but the cells don’t add up to much: no tissues, muscles, organs, nerves, or brain. But this simplicity can be deceptive. Some sponges come armed with glasslike skeletal spikes, microscopic and as beautiful as snowflakes. . . . Sponges are the earliest, most primitive multicelled animal, Sogin says. Some scientists believe the ability to grow different cell types started animals on the evolutionary road to becoming humans. With just a few kinds of cells, only loosely connected, the sponge manages to produce a variety of as symmetrical shapes, from cups and fans to tubes and piecrust shapes. Sponges survive handsomely on their own and can even shelter other sea creatures… Sponges are also the earliest sexual re-producers; most are hermaphroditic, producing both eggs and sperm which they release into the water.… Sponges don’t just sit still-many actually move… One sponge moves 4 millimeters a day.


Sogin used an innovative ribosomal RNA analysis and he worked at it for more than 20 years. His conclusions are stunning:

The sponge was indeed at the base of animal lineage, and just above it were the cnidarians, such as jellyfish, anemones and corals. They, like the sponge, have a saclike body form. They developed tentacles and an opening like a mouth at one end. But there were other forms of life lower down the line of descent that scientists might not have expected. Suddenly, they made sense. One of the sponges cell types is the distinctively shaped choanocyte, a cell equipped with a tiny long filament, called a flagellum, surrounded by a collar studded with even tinier hairs called microvilli. Thousands of these flagella beat constantly at the water and move it past the sponges feeding cells. As it happens, Sogin found that the sponges’ immediate evolutionary predecessors are the choanoflagellates, which represent what life would have looked like just before animals in the form of sponges emerged. Scientists had long suspected that the choanoflagellates could have been the nearest things to animals without actually being animals.

The Discover article then points out that the only thing older than the choanoflagellates in the same line of organisms are the fungi.  Sogin has determined that “fungi and plants are very different from each other, and fungi are actually more closely related to animals. [W]e share a common, unique evolutionary history with fungi.” The same article points out that this common evolutionary heritage of fungi and animals explains “why fungal infections are so difficult to treat–they’re more like us than we thought. They are similar targets.” Therefore, the next time you see a sponge, show some respect, since sponges are the first multicellular animals, and “all the other animals emerged from this imple architecture and are built upon this platform.” What animal would be find a bit upstream from sponges? Worms, another of our ancestors. Worms are “the first creatures with bilateral symmetry.” The worm, along with fungi and sponges, organisms highly deserving of your respect because they are in your line of ancestry.

For more about sponges, see my 2006 post titled “My Life as a Sponge.” For a quick ride down the evolutionary highway, visit this post.

Share

Read More

Darwin’s strange inversions

October 2, 2011 | By | Reply More
Darwin’s strange inversions

In this humor-laden short TED talk, philosopher Daniel Dennett discusses things that seem to be intrinsically sweet, sexy, cute or funny. Actually, there is NOTHING that intrinsically has any of these qualities. These qualities don’t exist out in the world. Rather, you need to look inside our brains to determine any of these qualities. We are wired to have these reactions when we encounter certain stimuli. There is nothing sweet, for example, in a molecule of glucose.

Share

Read More

Prominent scientists take strong stand against the teaching of creationism in science courses

September 19, 2011 | By | Reply More
Prominent scientists take strong stand against the teaching of creationism in science courses

Here is the statement signed by David Attenborough, Richard Dawkins, Robin Dunbar and numerous other scientists who oppose the teaching of creationism and intelligent design in U.K. schools:

Creationism and ‘intelligent design’ are not scientific theories, but they are portrayed as scientific theories by some religious fundamentalists who attempt to have their views promoted in publicly-funded schools. There should be enforceable statutory guidance that they may not be presented as scientific theories in any publicly-funded school of whatever type.

Share

Read More

Walking backwards 400 million years

September 5, 2011 | By | Reply More
Walking backwards 400 million years

Please allow me to tell you about today’s trip to Missouri’s Cuivre River State Park, about 1 1/2 hour drive from St. Louis. My family and our friends had lunch in the picnic area before setting out on a short hike on a half-dry creek bed. To the right you’ll see a typical portion of this walk (clicking on these images will give you bigger higher-res versions). No, we didn’t see any bears or snakes, but it was a beautiful day (high temperature about 70, after a summer filled with 100 degree days) and we saw quite a few small spectacular things.How about this blue moth, for example? I looked up this article and it really seems to be a moth and not a butterfly.

[More . . . ]

Share

Read More

Explaining the punctuation of equilibrium

August 16, 2011 | By | 1 Reply More
Explaining the punctuation of equilibrium

The April, 2010 edition of Discover Magazine profiles biologist Lynne Margulis, famous for her well accepted suggestion that eukaryotic bacteria did not evolve in linear fashion, solely as as a result of natural selection. Rather,

mitochondria and plastids–vital structures within animal and plant cells–evolved from bacteria hundreds of millions of years ago, after bacterial cells started to collect and interactive communities and live symbiotically with one another. The resulting mergers yielded the compound cells known as eukaryotes, which in turn gave rise to all the rest-the protoctists, fungi, plants and animals, including humans.

There was a shocking idea at the time (1967), but, as described in this article by Dick Teresi, the more recent ideas of Margulis are even more controversial. The Discover Magazine article documents her arguments that symbiosis is “the central force behind the evolution of new species.” This position runs counter to the holding of modern conventional scientific wisdom, that new species arise through “gradual accumulation of random mutations, which are either favored or weeded out by natural selection.” Margulis holds that random mutation and natural selection play a minor role and that the big leaps in the evolutionary record “result from mergers between different kinds of organisms, what she calls symbiogenesis.”

The Discover article takes the form of an interview, in which the dominant theme is that “natural selection eliminates and maybe maintains, but it doesn’t create.” Margulis argues that the laws of genetics “show stasis, not change.” She was prompted by the fact that there is no record of major fossil change until 542 million years ago, yet all of a sudden we see the Cambrian explosion. Stephen Jay Gould coined this phrase, “punctuated equilibrium,” “to describe a discontinuity in the appearance of new species.” According to Margulis, her explanation of symbiogenesis explains these discontinuities and should thus be considered the primary mechanism for evolution.

Margulis carefully distinguishes her approach from arguments based on “intelligent design.” She holds that those who advocate for “intelligent design” have nothing meaningful to offer to the scientific conversation.

[More . . . ]

Share

Read More

And now there’s Error Management Theory

May 20, 2011 | By | 2 Replies More
And now there’s Error Management Theory

Why do people so readily believe in Gods?  Dominic D.P. Johnson presents “Error Management Theory” (the name plays off Terror Management Theory).  This is an excerpt from the abstract Johnson’s book, The Error of God: Error Management Theory, Religion, and the Evolution of Cooperation:

“Error Management Theory” is derived from signaling theory, suggests that if the costs of false positive and false negative decision-making errors have been asymmetric over human evolutionary history, then natural selection would favor a bias towards the least costly error over time (in order to avoid whichever was the worse error). So, for example, we have a bias to sometimes think that sticks are snakes (which is harmless), but never that snakes are sticks (which may be deadly). Applied to religious beliefs and behaviors, I derive the hypothesis from EMT that humans may gain a fitness advantage from a bias in which they tend to assume that their every move (and thought) is being watched, judged, and potentially punished by supernatural agents. Although such a belief would be costly because it constrains freedom of action and self-interested behaviors, it may nevertheless be favored by natural selection if it helps to avoid an error that is even worse: committing selfish actions or violations of social norms when there is a high probability of real-world detection and punishment by victims or other group members. Simply put, supernatural beliefs may have been an effective mindguard against excessively selfish behaviour – behavior that became especially risky and costly as our social world became increasingly transparent due to the evolution of language and theory of mind. If belief in God is an error, it may at least be an adaptive one.

I spotted this abstract while exploring a website titled Evolution of Religion. Here’s the aim of the project, of which Dominic Johnson is a part:

Religious believers incur significant costs in terms of time, energy and resources that could be spent elsewhere. Religion therefore poses a major puzzle for disciplines that explain behavior on the basis of individual costs and benefits—in particular economics and evolutionary biology. To many scholars, religious beliefs and behaviors appear so bizarre and so costly that they fall outside rational explanation, leading instead to explanations based on psychosis, cognitive accidents, or cultural parasites. The aim of our project is to conduct a scientific examination of exactly the opposite hypothesis—that religious beliefs and behavior confer adaptive advantages to individual believers, and were therefore favored by natural selection over human evolutionary history. In other words, religion may have evolved.

For further reading on the evolution of religion, the website offers this reading list.

Share

Read More

On dealing with the lack of hell

May 14, 2011 | By | 21 Replies More
On dealing with the lack of hell

I sometimes listen to AM religious talk radio because I’m amazed at the sorts of the things I hear. Today, while listening into local St. Louis 24/7 “TruthTalk” Christian radio station KJ SL in my car, I heard a bit of contentious discussion between a radio host and a caller. I believe that the host of the radio show was Bob Dutko. Dutko has long held the position that “Jesus really is the only way and He really did rise from the dead, physically and historically.”

When I first tuned in, the caller was talking, saying something much like this: I believe that the spirit of God resides in every person, and that people can live good and meaningful lives without belonging to any church. I believe that God will reward them based upon the good things that they do, and based upon how they treat others, regardless of whether or not they follow any religion. Good-hearted people who do not believe in Jesus or follow a religion will not go to hell.

The host told the caller that his “new age” religious outlook was hopelessly naïve, and that he needed to read the Bible, whereupon he would see that there is only one way to avoid hell is by accepting Jesus Christ as Savior.

[More . . . ]

Share

Read More

Creating Doubt in Science

April 12, 2011 | By | 9 Replies More
Creating Doubt in Science

There is currently a strong suite of Discovery Institute bills running through state legislatures to allow “alternative theories” to be taught in science classes. See list here: Antievolution Legislation Scorecard. There is not a direct link back to the Discovery Institute, but it is their wording, seen before and passed in places like Texas and Louisiana and Tennessee.

From a legal standpoint, the bills look harmless, closely resembling intellectual freedom policies. But the point is clearly to sow confusion about the difference between science and just making things up, especially in regard to evolution and climate science.

Hemant Mehta suggests that it would only be fair to show this video in churches where the churches put their books into science classes.

Share

Read More