Category Archives: origin of life

Nick Lane Lecture

Enjoy this lecture, as it echoes many of the points i have made on this blog:

Comparing 50 Years

When it comes to the topic of abiogenesis, I am neither a denier nor a cheerleader.  That is, I don’t deny the earth spawned life and argue it is so improbable that it did not occur. I don’t think we know enough to make such negative claims.  But neither do I buy into the notion that abiogenesis research has been making great progress over the years and solutions are right around the corner.  I’ve heard that unfulfilled promise for too long now not be to be jaded.  Personally, I think scientists are about as baffled about the origin as life as they were in 1953.  What does this all mean?  I don’t know.

Nevertheless, periodically you will come across cheerleaders who will hold up this study or that study as something that is supposed to be ground-breaking or as something that demonstrates the progress that is being made.  My response is not to criticize, but to withhold judgment and wait to see if anything comes out of this study or that study.  So I’ve been doing a lot of waiting.  Anyway, if you don’t have the expertise to judge such claims, simply step back and survey the big picture.  Go back to 1953 and again contrast a known field of scientific success (akin to using a positive control) with abiogenesis research over the years.

Since both dramatic findings were laid in the lap of the scientific community at the same time, it would be instructive to compare their respective track records of success.

An easy way to compare them is to take advantage of the fact that 2003 was the 50th anniversary of both papers, as human beings love to celebrate milestones.

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1953 and Beyond

Stanley Miller published his original paper that isolated amino acids from an electrical discharge in one of the most widely read scientific journals called Science. It was published on May 15, 1953.  What is most uncanny about this date is that another famous scientific paper was published just three weeks earlier in the other most widely read journal in the scientific community, Nature. This was Watson and Crick’s revolutionary paper that first outlined the double helix model of DNA.  Since both dramatic findings were laid in the lap of the scientific community at the same time, it would be instructive to compare their respective track records of success.

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When did life first appear?

The Earth’s rock record begins around 3.8 billion years ago with a period that is known as the Archaean.  The Archean can be split into different eras, where the early Archaean extends from 3.8 to 3.6 billion years ago, the Paleoarchaean extends from 3.6 to 3.2 billion years ago, the Mesoarchaean extends from 3.2 to 2.8 billion years ago, and the Neoarchaean extends from 2.8 to 2.5 billion years ago.  At this point, a new period known as the Proterzoic begins and it will extend all the way until about 550 million years ago, the time of the Precambrian.

I have long assumed that life appeared on this planet approximately 3.5 billion years ago.  But lately, the evidence for such ancient life seems to be evaporating.  The crown jewel among the ancient microbial fossils has been the filamentous cyanobacteria from 3.5-billion-old Australian chert that were first described by William Schopf from UCLA.  Yet in 2002, Martin Brasier and colleagues made a strong case that those fossils are not remnants of living things, but represent the activity of ancient and exotic geochemical processes [1].  And a recent study has just confirmed these are not fossils (HT to Joe):

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Darwin’s warm pond idea fails test

Life on Earth was unlikely to have emerged from volcanic springs or hydrothermal vents, according to a leading US researcher.

Experiments carried out in volcanic pools suggest they do not provide the right conditions to spawn life.

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More Thoughts on the Decline Effect

Jonah Lehrer has some more thoughts on the Decline Effect:

The first letter, like many of the e-mails, tweets, and comments I’ve received directly, argues that the decline effect is ultimately a minor worry, since “in the long run, science prevails over human bias.”

Lehrer then quotes Feynman who discusses the famous 1909 oil-drop experiment and explains why it took so long for scientists to zero on the correct measure for the charge of the electron:

Why didn’t they discover that the new number was higher right away? It’s a thing that scientists are ashamed of—this history—because it’s apparent that people did things like this: When they got a number that was too high above Millikan’s, they thought something must be wrong—and they would look for and find a reason why something might be wrong. When they got a number closer to Millikan’s value they didn’t look so hard.

As Lehrer notes, this is yet another example of the “selective reporting in science.”  But Feynmann was trying to make another point:

he warned the Caltech undergrads to be rigorous scientists, because their lack of rigor would be quickly exposed by the scientific process. “Other experimenters will repeat your experiment and find out whether you were wrong or right,” Feynman said. “Nature’s phenomena will agree or they’ll disagree with your theory.”
But Lehrer is quick to puncture the obvious naivety associated with this claim:

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Shadow Life Sensationalism

You have probably heard this story by now:

But now researchers have discovered a bacterium that appears to have replaced that life-enabling phosphorus with its toxic cousin arsenic, raising new and provocative questions about the origins and nature of life.

News of the discovery caused a scientific commotion this week, including calls to NASA from the White House asking whether a second line of earthly life has been found.

Whether or not the bacteria actually replace phosphorus with arsenic is something that will eventually be sorted out.  But for now, we can be confident that no “second line of earthly life has been found.”

“This is different from anything we’ve seen before,” said Mary Voytek, senior scientist for NASA’s program in astrobiology, the arm of the agency involved specifically in the search for life beyond Earth and for how life began here.

“These bugs haven’t just replaced one useful element with another; they have the arsenic in the basic building blocks of their makeup,” she said. “We don’t know if the arsenic replaced phosphorus or if it was there from the very beginning – in which case it would strongly suggest the existence of a shadow biosphere.”

Yes, we do know it wasn’t there from the beginning.  How?

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