Tuesday, November 28, 2006

Elephants, Humpbacks, and Humans

In my previous post, I suggested that a number of other species demonstrate many similar traits as humans, suggesting near human intelligence. These traits include the ability to use language, create tools, and interact in complex social hierarchies. Recently, elephants were added to the list of creatures thought to be able to recognize their reflections as an image of themselves, rather than another animal. Self-consciousness suggests an ability to have mental concepts, including an idea of a self. This has also been observed in chimpanzees, bonobos and orangutans, and humans (by two years of age).

Another recent discovery notes similar types of brain cells in humpback whales and humans, of a sort that may relate to intelligence. These types of cells are not found in dolphins, but are found in other primates.

One of the reasons many reject evolution is that they don't want to accept that humans are not special. These people like the idea, promoted by certain religions, that humans were a special creation of God, and that everything in the universe is essentially an elaborate stage. God's attention is focused on us and us alone. This notion has also gone farther, with certain ethnic and cultural groups believing that God does not even favor all humans equally, but gave special information to one tribe of people and no one else. This kind of elitism is betrayed for what it is, pride, when we objectively look at the world. There are many cultures, many religions, and there is beauty and worth in each of these religions, even if none is completely right about everything. Likewise, there are other creatures that differ from us by very little.

It is likely that humans could only achieve our current situation because, in addition to our intelligence, we walked upright, had hands that could make tools, and vocal cords that could make a great variety of sounds. And, as noted in other posts, it is very unlikely that we are the only planet in the universe with intelligent life.
The following very short article relates to the development of planets around stars, about which I made a post some time ago. I'll quote the whole article, which appeared on globeandmail.com.

Planets really made from dust
Globe and Mail Update
Monday, October 09, 2006

Floating discs of debris do indeed turn into planets, and now the world finally has evidence to prove it.
Scientists analyzing data from the Hubble Space Telescope have at last confirmed the long-held belief put forward by philosopher Emmanuel Kant more than 200 years ago.
Until now, astronomers have detected more than 200 extra-solar planets and have seen many debris disks around young stars, but they have yet to observe a planet and a debris disk around the same star.

Again, this does not relate directly to biological evolution, but it shows that the universe incorporates evolution even in its non-biological history. This is a different meaning of evolution from the evolution referred to in natural selection. This is the more general notion that relates to things which change progressively over time and don't change back.

The idea that planets can form from space dust has been around for a while, as the article notes. Over time, more and more evidence has been produced and this process continues. Now we can safely assert that there are hundreds of billions of hundreds of billions of stars in the universe, and many, if not most, of these have planets around them.

The number I gave above is not just hyperbole of the sort associated with Carl Sagan. The accepted round number for stars in our galaxy is 100 billion. And an all sky survey that counted galaxies reached a similar number of galaxies in the universe. Some of these are smaller than the Milky Way but many are much larger. So a hundred billion hundred billion is accurate, to a few orders of magnitude.

We cannot yet determine if any of these other planets has life of any sort, let alone complex, possibly intelligent, organisms. But if we accept that the universe is a well-ordered place, with the same laws operating here as anywhere else, we can only conclude that there should be a great number of planets with life. Considering the number of animals on earth which have similar intelligence and social lives as humans (apes, dolphins, whales, and elephants), I think it very unlikely that we are the only species in the universe contemplating these same questions.

Sunday, November 26, 2006

A recent search for articles and papers providing evidence for evolution turned up a wide variety of examples.

Evolution of typhoid bacteria
This is fairly technical and I'm not qualified to sumarize it or elaborate on the evidence, but the opening summary reads as follows:

In a study published in the latest issue of Science (24 November, 2006), an international consortium from the Max-Planck Society, Wellcome Trust Institutes in Britain and Vietnam, and the Institut Pasteur in France have elucidated the
evolutionary history of Salmonella Typhi. Typhi is the cause of typhoid fever, a disease that sickens 21 million people and kills 200,000 worldwide every year. The results indicate that asymptomatic carriers played an essential role in the evolution and global transmission of Typhi.

Clearly, these biologists have no difficulty understanding this disease in terms of evolution, and we are fortunate for this, as they are working to keep us one step ahead of diseases that clearly demonstrate a propensity to evolve. This is a growing problem in hospitals, since strains of bacteria are evolving that are not killed by standard antibiotics.

This article opens, "Virginia scientists are finding pockets of oysters in the Chesapeake Bay that have adapted to genetically resist the deadly diseases that threaten the broader population. 'We have what appears to be an evolution of disease-resistant oysters,' said Ryan Carnegie, an assistant research scientist at the Virginia Institute of Marine Science." This shows the other side of the "arms race" between bacteria and the organisms they infect. Some have even suggested that this to some extent accounts for continuing evolution rather than a steady-state situation in which all organisms have evolved to some peak level of survival ability.
Wheat's lost gene helps nutrition

Domesticated varieties of wheat have a gene that normally is not turned on. That is, the gene is present, but another gene is needed to turn it on, so that it acts on the development of the plant. By figuring out a way to turn this gene on, scientists have increased the nutritional quality and decreased the time to reach maturity. For those worried about eating genetically modified foods, the scientists have found a way to turn the gene on by cross-breeding domestic and wild strains of wheat. This may help improve the nutrition for people all over the world. These kinds of advances can never be provided by "intelligent design" theory. How would you predict something like this if you had no way to fathom the designs created by this intelligent designer?

New Gene Map Reveals Surprising Differences

This article reports on a new way of comparing gene maps that picks up on subtle differences from individual to individual in something called 'copy number variants' or CNPs. This may be a revolutionary development because it may enable scientists to identify genetic causes of certain diseases. This says to me that the genetic reproduction process is very complex and so there can be lots of variation before something becomes significant enough to cause an evolutionary change.

Evolution can happen quickly, study finds

I'll quote the first few paragraphs, since they say better than I many important points about evolution and how new research is confirming the theory, rather than challenging it.

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.

The article goes on to describe science at work, testing hypotheses, improving theories. Scientists measured leg length of a lizard on various islands in the Bahamas. Then they introduced a predator and used evolution to predict how the lizards' legs would change in response. They thought the legs would grow longer initially, since the longer legs would allow the normally ground-dwelling lizards better chances to survive by running up trees. Once the population had lived in the trees a while, however, they expected leg length to decrease again, as it provides a better way to get around in the trees. They found the predicted changes.

For another example of how scientists are testing and verifying evolution, see the next article.

Robot Tadpole Sex Sheds Light on Vertebrate Evolution

Quoting the first few paragraphs:

The distant forebears of humans and other vertebrates were much squashier than their descendants. They possessed flexible rods known as notochords that served as primitive backbones, but no vertebrae. Scientists think vertebrae evolved to
help our ancient predecessors swim more powerfully by stiffening the body so attached muscles could generate more force.

"The fossil record shows vertebrae evolved independently at least four separate times. That shows they must really be functionally important," said vertebrate physiologist John Long at Vassar College in Poughkeepsie, N.Y.

To test this idea, Long and his colleagues built robot fish with backbones of varying strength to simulate extinct animals. They then "mated" the best swimmers to see how generations of "offspring" evolved to swim better.

Here again, a test of the idea of evolution, with no guarantee that the results would confirm the hypothesis. This is a physical version of something that is often done on computers, creating "genetic algorithms." It demonstrated that the hypothesis was confirmed. The faster swimmers, when "mated," (that is when "computer simulations that modeled the genetic mixing that occurs during sex to produce the next generation" were used to generate new designs for the swimmers), produced a structure that does stiffen the region down the center where the spinal cord would be in primative organisms.

But they also found that the hypothesized evolution only accounted for 40% of the improved swimming speed. Evolution found other ways which the scientists had not thought of to improve the "design" of the model. They plan to introduce a robot predator to test how well visual sensing device similar to something in fish can improve through evolution.

Monday, November 06, 2006

Evolution of Complex Organs

One of the most common attacks on evolution is to assert that complex organs such as the eye could not evolve since they only work when all parts are present. National Geographic, obviously intent on showing that this claim is false, has published an article in the November 2006 issue detailing the wealth of evidence for how such organs evolve. For the Internet version of the article, see http://www7.nationalgeographic.com/ngm/0611/feature4/.

The jist of the article is that marvels such as the eye, the arm, feathers, and flowers are, in fact, built up from primative beginnings through minute changes that over millions of years add up to the organ in question. Furthermore, the same genes are used in different organisms to develop different forms of an organ or limb. For example, "Insects and humans use the same genes to tell cells in their embryos to turn into photoreceptors. And both kinds of photorecptors snag light with molecules known as opsins" [p. 126]. This is as would be expected if eyes of insects and humans evolved from some very early common ancestor which evolved a simple way to detect light. Later elements like the lens of a more advanced eye evolved out of a transparent protein called crystallins, which existed well before the eye used them to build a lense.

This puts the lie to another accusation made against evolution, that only microevolution has been demonstrated (slight changes within a given species, such as foxes with different colored fur in the arctic and the temperate zones), not macroevolution (the evolution of new species). Small changes, over a long enough time, can lead to major differences in the way a set of genes shapes the organism. It is not a quirk of some intelligent designer that all mammals have virtually the exact same skeleton, even though the bones are often put to very different uses: whale "hands" are fin for swimming, bat "hands" form wings, and human hands can create complex tools. The same goes for feathers, which evolved from scales, serving various uses during the intermediate period between scales and flight feathers.

Despite all this evidence, the same false accusations are made over and over and over again by proponants of creationism and intelligent design. Yet they claim it is the scientists who are dishonest, giving the public a false sense of certainty regarding evolution. [For one example, see: http://www.discovery.org/scripts/viewDB/filesDB-download.php?id=118 .]

Saturday, November 04, 2006

Evolution of the Human Brain


The above link is to an article describing a discovery relating to how the human brain differs from the brains of other mammals and may shed light on how our brains have evolved to allow more complex thought. To quote the article: "Cell adhesion controls many aspects of brain development including growth and structure, and enables neurons to connect with other neurons and supportive proteins. Differences in the molecular connections of human neurons compared to the neurons of chimps, mice and other animals, could help explain why the human brain is capable of far more complex cognitive functions."

This discovery is related to DNA sequences that determine when genes are switched on or off. The effect of DNA is not just to determine the genes and hence the morphology of the organism. The same genes can generate different features in an organism depending on when it is allowed to work and when it is prevented from working. This could explain why humans and chimpanzees share 98 percent of the same genome, yet the end result is quite different. This provides a new avenue for evolution, one that does not change the genes but when they turn on and off. For more on this idea, see the next article.