Leaky proto-cells in the sea, Mulkidjanian and his colleagues note, would have much higher exposure to sodium than potassium, even near hydrothermal vents on the ocean floor, making it difficult to maintain any imbalance between the two. But that does not mean that the cells necessarily arose in a potassium-rich environment. In fact, geothermal areas in the modern world are usually highly acidic and thus deadly. "It could still be that cells evolved the ability to generate and maintain a high [potassium-to-sodium] ratio in their cytoplasm for functional reasons," Szostak notes. "The basic question is whether the observed high K–Na ratio reflects the historical environment in which life originated or underwent early evolution, or instead reflects some underlying chemical necessity, such as better functioning of certain cellular components."

Furthermore, life started on an Earth that may not have had continent-size landmasses but rather a series of archipelagos formed by volcanoes, much like the islands of Japan today. As a result, the water cycling through these areas may have been very different, notes marine chemist Jeffrey Bada of the Scripps Institution of Oceanography at the University of California, San Diego.

And then there is the fact of evolution itself. Cellular life has changed the makeup of its internal fluid—the cytosol—countless times over the eons, and modern-day life-forms exhibit a wide variety of compositions. "Is it not at least equally likely that they have modified their cytosolic compositions to accommodate their cytosolic functioning once they had control over this process, which all modern cells do?" asks geochemist Jim Cleaves of the Carnegie Institution of Washington. "Any modern environment which matches this composition would then be purely coincidental." In fact, Cleaves argues it may be impossible to tell what early life—or even the first universal common ancestor of life—was like, given all the intervening evolution. It's akin to trying to "infer an abacus from a modern PC," he notes. "You might be able to infer a TRS-80, but then it all gets a bit hazy and there might be no vestigial remains of the intervening stages of biological evolution."

But life has preserved some things down through more than three billion years of evolution: for example, the shielding of enzymes and other internal cellular workings from oxygen to allow them to operate. Of course, the early Earth's atmosphere lacked oxygen, instead it was rich in other gases, such as hydrogen sulfide. "This is the same smell that you can find on a trip to Yellowstone National Park, where [hydrogen sulfide] seeps from the mud pots, geysers and other underground exit sites," Mulkidjanian notes. The first cells evolved in such a place and "their progeny carried the affinity for such an environment from mother cell to daughter cell through the past three billion years."

6 Comments

1. 1. thekenyanpaul 07:02 AM 2/16/12

   What crap! There are thousands of geothermal vents worldwide, have they found any of these thin-membraned leaky bacteria yet? This is pseudo-science in overdrive! No evidence at all but wild speculation like the ancient philosophers...

   Reply | Report Abuse | Link to this

2. 2. Bill Crofut 11:53 AM 2/16/12

   Re: "The argument matches a perhaps prescient suggestion from Charles Darwin in an 1871 letter: "But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts, light, heat, electricity, etcetera present that a protein compound was chemically formed, ready to undergo still more complex changes."
   
   The quote seems to have been truncated:
   
   It is often said that all the conditions for the first production of a living organism are now present, which could ever have been present.— But if (& oh what a big if) we could conceive in some warm little pond with all sorts of ammonia & phosphoric salts,—light, heat, electricity &c present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present day such matter wd be instantly devoured, or absorbed, which would not have been the case before living creatures were formed. [Letter to J. D. Hooker, 1 Feb [1871]
   
   http://www.darwinproject.ac.uk/editors-blog/2012/02/15/darwins-warm-little-pond/
   
   At least one attempted experiment would seem to have been less than successful:
   
   http://www.ucsc.edu/news_events/press_releases/text.asp?pid=837
   
   Re: "Of course, the early Earth's atmosphere lacked oxygen, instead it was rich in other gases, such as hydrogen sulfide."
   
   This claim has met with some opposition:
   
   "Geological evidence often presented in favor of an early anoxic atmosphere is both contentious and ambiguous. The features that should be present in the geological record had there been such an atmosphere seem to be missing....Ever since the work of Oparin…and the success of the experiments conducted by Miller...the dogma has arisen that Earth’s early atmosphere was anoxic, probably highly reducing...Conjecture and speculation, based on a knowledge of the chemistry of living matter, gave to them the composition of their starting materials, and it would have been surprising if they had not achieved the results they did."
   [Harry Clemmey and Nick Badham. 1982. Oxygen in the Precambrian Atmosphere: An Evaluation of the geological Evidence. GEOLOGY, March, p. 141]

   Reply | Report Abuse | Link to this

3. 3. elderlybloke 02:42 PM 2/16/12

   According to what I have learned about the history of Oxygen, it was the work of Cyanobacteria ,slowly building it up over a billion or so years and leaving the former anoxic loving life with only a few homes(like Hot Springs).

   Reply | Report Abuse | Link to this

4. 4. Bill Crofut 10:16 AM 2/18/12

   Geologists Clemmy and Badham would seem to be indicating the presence of oxygen in the
   
   atmosphere of the Earth from the beginning (i.e., not biologically manufactured).

   Reply | Report Abuse | Link to this

5. 5. poihths in reply to thekenyanpaul 09:53 PM 2/22/12

   Fundamental misunderstanding is rarely a sound basis for comment. The whole point is that the early leaky critters kept on developing and became the non-leaky critters we find today. In other words, they managed to change a little bit during the last blink-of-an-eye three billion years.

   Reply | Report Abuse | Link to this

6. 6. charwiz in reply to thekenyanpaul 06:08 PM 2/26/12

   
   Although hydrothermal vents are what we would consider a harsh environment, they are teeming (abundant) with life. As long as the vents remain active, which is usually one to two years, animals thrive there. In fact, more than 300 species live around the vents and are unique to this type of environment. These creatures, including tubeworms, fish, crabs, shrimp, clams, anemones and chemosynthetic bacteria, have learned to survive the complete darkness, the extremely hot vent water and the tremendous water pressure.
   
   charwiz
   charwiz2005@yahoo.com
   
   
   
   
   
   
   
   
   http://www.onr.navy.mil/focus/ocean/habitats/vents2.htm

   Reply | Report Abuse | Link to this