Another Strike Against the Panspermia Hypothesis

The Earth's oldest ice has been thawed, and its drippings contained fragments of very, very old DNA. Scientists recently brought this DNA back to life.

As he describes in a recent PNAS paper, microbiologist Kay Bidle and colleagues at Rutgers discovered DNA pieces in thawed chunks of Antarctic ice that ranged in age from 100,000 to eight million years old.

When they tried to make the bacteria "viable" again—that is, when they tried to get it to grow and reproduce in lab cultures—the researchers found that the older samples were much more fragmented than the newer ones. From these samples, they calculated a "DNA half-life:" The length of DNA fragments in the ice breaks in half about every 1.1 million years.

They attributed the DNA breakdown to its long-term exposure to cosmic radiation, which digs another nail into astrobiology's Panspermia Hypothesis. The idea, which dates back to the writings of the 5th Century Greek philosopher Anaxagoras, is that the "seeds of life" are found throughout the universe. In 1973, the co-discoverer of DNA Francis Crick proposed a "directed panspermia" theory: An advanced alien civilization, perhaps facing its imminent demise, intentionally spread small grains of DNA in random directions through the universe, some of which landed on Earth.

Panspermia, though an immensely popular idea in science fiction, has been widely criticized in the astrobiology field, mostly because the specific combination of carbon, nitrogen, and oxygen necessary for life isn't found widely in the universe.

Moreover, stellar winds and cosmic rays make space is a harsh environment for poor little traveling microbes. Biddle's latest research seems to support this latter point. As he recently told Nature News: "If you take the speed of a comet and take the distance it would need to travel it would take longer than eight million years to do that. In a comet the DNA would be completely deteriorated."

(For more astrobiology goodness, check out my Master's thesis about the hunt for life on Mars.)

Happy For You

A couple of days ago, I caught an old episode of the Ellen show when Beyonce Knowles was the guest. It was Beyonce's 25th birthday, and Ellen surprised her by bringing out her childhood dance teacher. When Beyonce saw her teacher—for the first time in years—she was overcome with emotion. She covered her mouth with the back of her hand, and started crying.

And to my surprise, so did I.

Could our brains have a built-in capacity for experiencing "altruistic pleasure"—that is, feeling good about other people feeling good? Last month, NYT columnist John Tierney wrote about new research done by neuroscientists at the University of Oregon, in which they scanned the brains of 19 female subjects while they made decisions, via a computer, about donating real money to charity. As Tierney explains:

Sure enough, when the typical student chose to donate to the food bank, she was rewarded with that warm glow: increased activity in the same ancient areas of the brain — the caudate, nucleus accumbens and insula — that respond when you eat a sweet dessert or receive money. But these pleasure centers were also activated, albeit not as much, when she was forced to pay a tax to the food bank.

Now the philosophical question (which Tierney explores in a related blog entry) is, Does activation of a neurological pleasure center mean that people are: Truly Altruistic (because we have this innate wiring system that makes us feel good about helping people); or, Truly Selfish (because we're not actually behaving in order to help others, but just to make ourselves feel good)?

Ouch, makes my head hurt even thinking about. But the distinction, though subtle, is important. Viewed through the "lens"—I hate that phrase, but whatever—of evolutionary biology, I don't see how we can be anything but Truly Selfish.

At the end of the blog post, Tierney asks his readers: "...what do you think is your chief motivation in making charitable donations? Do you give because it makes you feel good, or because you (in accordance with Kant’s ideal of praiseworthy altruism) are painfully carrying out your duty?"

Forty-nine people commmented...Some goodies:

Trite:
Does it really matter why a person does something kind or compassionate for another person, for an animal, or for the environment? The point is that if every single human being would perform an act of kindness, this world would be a better place. —Bobbi

Pretentious:
A world in which positive relational networks enable one’s own pleasure to be generated from facillitating another’s sounds pretty ethically desirable to me. —Chris

Dismissive:
What this debates lacks is the admission that nothing is ever simple in human culture. —Mitch

Either Chauvinistic or Insightful, can't decide which:
all the participants were female—motherly love is as altruistic as it gets —David

Does Size Matter? It's all relative.

When I was about 12, my piano teacher extolled my long fingers: thumb to pinky, when stretched, could span 10 keys. But she was the exception. My sister calls them “alien fingers,” and it’s generally an awkward moment when a date first discovers his hands are smaller than mine.

Finger length is determined by the precise mix of hormones a developing fetus is exposed to. Men, who were exposed to more testosterone in the womb than women, generally have ring fingers that are longer than their index fingers. Women, exposed to more oestrogen, generally have longer index fingers. (The differences, of course, are but a couple of millimeters.)

A new study from the British Journal of Psychology found that this ratio of finger lengths may also indicate how well a child scores on math and verbal SAT tests.

After comparing the index and ring-finger lengths of 75 7-year-olds, psychologists from the University of Bath found the children whose ring fingers were longer than their index fingers--mostly boys--did better on math tests than verbal tests.

This makes sense, the researchers say, since previous research has shown that exposure to testosterone in the womb promotes growth in brain areas associated with math and spatial reasoning. It's not yet clear whether oestrogen exposure promotes growth of verbal areas of the brain.

...which means that apparently my hands are unusual in yet another way: unlike most girls, my ring fingers are longer than my index fingers. And indeed, my math standardized test scores were higher than my English scores. But what I really wanna know is: How'd I get all that extra testosterone? (And shouldn't I be, like, more competitive? Or at least less timid?)