Here are some recent scientific discoveries to think about.

1. Many people have a rather naïve understanding of falsification and science. Supposedly, you are only allowed to come up with a rigorous hypothesis that makes distinct predictions, and if those predictions fail, you are supposed to toss out the basis of the hypothesis. But consider this recent study:

"Transactional Skew" (TS) theory proposes that such cooperation is possible through "shared reproduction," making it worthwhile to help close relatives because some of the same genes are getting passed along. Thus, the degree of shared reproduction should vary across groups by the degree to which they are related.

However, in a study across four species of paper wasps "“ long considered one of the best examples supporting this theory "“ the researchers found that not only was there cooperation and shared reproduction between sisters but also between distantly related or unrelated wasps.

Okay. The degree of shared reproduction should vary across groups by the degree to which they are related. But when a species, long considered one of the best examples supporting this theory, was studied in detail, this prediction failed. Has TS theory been falsified, such that scientists will now abandon it?

2. Here's another interesting example of a trait appearing long before it was really exploited by the descendents of the organism:

Salamanders and the tuatara, a lizard-like animal that has lived on Earth for 225 million years, were the first vertebrates to walk and run on land, according to a recent study by Ohio University researchers.

After studying the creatures at the Toledo Zoo, Stephen Reilly, associate professor of biological sciences, and doctoral student Eric McElroy determined that they use both forms of locomotion, which are energy-saving mechanisms generally believed to be important only in fast-running animals such as mammals and birds.
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The difference is not obvious in these critters, which tend to move with a slow, lumbering gait. That's led scientists to believe that the primitive animals could only walk.

But force data used to study the movement of these creatures' center of mass showed otherwise. In walking, the center of mass vaults up and over the limbs with each step. In running, the center of mass dips with each step, and tendons and joints in the legs act as biological springs. Mammals such as humans, dogs and horses can use both mechanisms to conserve up to 50 percent of their energy needed to walk and run.

When studying salamanders and tuataras, the researchers spotted the telltale vault and dip of center of mass movements in different strides "“ confirmation that the creatures mechanically walk and run. Because they are the oldest living examples of four-legged animals, the new findings suggest that both energy saving mechanisms appeared when the first vertebrates moved onto land, Reilly explained. In comparison to previous research on other vertebrates, this also suggests that all terrestrial vertebrates "“ except for turtles, which are limited by their shell "“ can walk and run.

The researchers also showed, however, that walking and running in tuataras occur at the same speed and use about the same amounts of energy. Reilly believes that this could be a pre-adaptation in these primitive animals that have not evolved the need for speed, unlike other animals.

They came out of the ocean with the built-in ability to run.

3. Human evolution gets more and more interesting. Comparing the human and chimp genome shows us that humans are effectively reformatted chimps:

"When we looked at gene expression, we found fairly small changes in 65 million years of the macaque, orangutan, and chimpanzee evolution," said study author Yoav Gilad, Ph.D., assistant professor of human genetics at the University of Chicago, "followed by rapid change, along the five million years of the human lineage, that was concentrated on these specific groups of genes. This rapid evolution in transcription factors occurred only in humans."

All of this is neat, but it merely points to the really interesting question -

"The big question," he said, "is why are humans so different? What sort of changes in the environment or lifestyle would drive such a rapid shift in the expression of genes — in this case in the liver — in humans and in no other primate?"

The answer?

Part of the answer, he suspects, is rapid alterations in diet, probably related to the acquisition of fire and the emerging preference for cooked food. "No other animal relies on cooked food," he said. "Perhaps something in the cooking process altered the biochemical requirements for maximal access to nutrients as well as the need to process the natural toxins found in plant and animal foods."

That could very well be part of the answer. But that just leads to the even more interesting question "“ Why is it that only humans acquired the use of fire?

4. It's official. I now have an excuse if I misbehave on this blog:

Through three related experiments funded by the American Psychological Foundation, researchers from the University of Toronto and New York University (NYU) found that the psychological pressures experienced by people who belong to racially or socially stigmatized groups interfere with their ability to exhibit self-control when entering a threatening environment or after being made aware of their stigmatized status.

I've been aware of my stigmatized status for some time. No more holding back.

This entry was posted on Thursday, March 9th, 2006 at 11:47 am and is filed under Evolution, Front-loading, Humor, Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site. The trackback link is: http://telicthoughts.com/science-pickings/trackback/