Merry Christmas and Aliens Among Us

Okay, we have a quiz today: What is shown in today’s picture? Hints to follow below, beginning with a story in today’s Los Angeles Times. See:,0,7347052.story

Since the mid 1800’s, when Mendeleyev and Meyer independently developed the first Periodic Table of the Elements, scientists have realized that certain elements have similarities. Mendeleyev and Meyer put these into the Groups or Families that form the vertical columns of the Periodic Table. Elements in a column of the Table possess similar traits. Beginning with the far right column of the table, we have the Noble Gases. These do not tend to engage in any chemical reactions with other elements. Just to the left of this column we have Fluorine, Chlorine, Bromine, and Iodine: the Halogens. The latter three are all used for disinfection, as just one example of their shared characteristics. And similar stories could be told for each of the columns of the Table.

Biomolecules on Earth are formed almost entirely from just six of the 100+ Elements: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur. My old professor at Loyola Marymount characterized Life as PSNOCH — using the symbols for these six Elements.

In today’s LA Times article, scientists hypothesized that arsenic could substitute for Phosphorus in biomolecules. Yeah, that Arsenic — the supposedly toxic element. They went to one of the most “alien” places on Earth, Mono Lake, to see how microorganisms have adapted to a low-Phosphorus/high Arsenic environment. They found that some of the microorganisms had substituted Arsenic atoms for Phosphorus atoms in some of their biomolecules as a means of adapting to this hostile environment.

This research is coming under scrutiny, largely because the research team — partially funded by your tax dollars, through NASA — has made the interesting leap of faith that this is clear evidence of life on other planets. This is much closer to science fiction than real science. But the best science fiction is rooted in science fact, and that is the case here. It makes sense from a chemistry standpoint that Arsenic — an Element just below Phosphorus on the Periodic Table — could substitute for Phosphorus in a biomolecule.

Which brings us to today’s quiz. Pictured is an alien life form from a science fiction television show of a few decades ago. This life form had a similar Element substitution to that of today’s Times’ article. In this case, Carbon was replaced by the Element below it on the Periodic Table: Silicon. Again, this is consistent with modern principles of the science of chemistry — but the TV show (1) didn’t pretend to be real science, and (2) didn’t abscond with your tax dollars in search for aliens among us.

If you have an answer, you can either comment to this post, or send me an e-mail at

I’ll be celebrating Christmas with family over the next few days, so don’t expect to hear from me until next week sometime. Merry Christmas to all!

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