Skeptic Magazine shows no skepticism towards the Miller-Urey experiment, instead claiming the experiment simulated the early earth’s atmosphere.
Recently I went to a local bookstore and found myself perusing the latest issue of Skeptic Magazine, “A Perspective on the Nature and Origin of Life.” The cover story was on the origin of life, and written by chemical engineer Paul F. Deisler Jr. (Vol. 16, No. 2). While the article admits that “[c]urrent scientific detection technology and exploration have not yet found traces within the transition period to show how non-life became life,” it nonetheless puffs the weak evidence for the origin of life. In particular, it promotes the Miller-Urey experiment without any mention of the fact that there are severe questions about whether the gasses it used were present on the early Earth. Instead, the article states:
The pioneering Miller-Urey Experiment created amino acids–the building blocks of life–in an environment that simulated atmospheric conditions on the early Earth.
It further notes that the experiment used “water, methane, ammonia, and hydrogen.”
The problem, of course, is that our best knowledge of the earth’s early atmosphere shows that it contained insignificant levels of methane and ammonia and insufficient amounts of hydrogen to produce amino acids.
Stanley Miller had not in fact “simulated atmospheric conditions on the early Earth.” And this has been known for quite a long time. Origin of life theorist David Deamer states:
This optimistic picture began to change in the late 1970s, when it became increasingly clear that the early atmosphere was probably volcanic in origin and composition, composed largely of carbon dioxide and nitrogen rather than the mixture of reducing gases assumed by the Miller-Urey model. Carbon dioxide does not support the rich array of synthetic pathways leading to possible monomers …
(D.W. Deamer, “The First Living Systems: a Bioenergetic Perspective,” Microbiology and Molecular Biology Reviews, Vol. 61: 239 (1997).
As I discuss here, there’s very good reason to understand why an atmosphere on Earth of volcanic origin would not contain methane or ammonia. A 2010 paper in Cold Spring Harbor Perspectives in Biology states that the chemical properties of the Earth’s mantle have not changed over time, and thus if volcanoes don’t produce appreciable amounts methane and ammonia today (which they don’t), then they also wouldn’t back then:
Geochemical evidence in Earth’s oldest igneous rocks indicates that the redox state of the Earth’s mantle has not changed over the past 3.8 Gyr (Delano 2001; Canil 2002).
(Kevin Zahnle, Laura Schaefer, and Bruce Fegley, “Earth’s Earliest Atmospheres,” Cold Spring Harbor Perspectives in Biology (2010).)
The papers cited in the quote above confirm this point. For example, Canil’s 2002 paper in Earth and Planetary Science Letters found that vanadium redox states in peridotite-bearing mantle xenoliths and Archean cratons imply that Earth’s mantle was just as oxidized in the Archean as it is today. The paper concludes:
Abiotic synthesis of molecules and hydrocarbons that can lead to life in early Archean mantle-derived volcanic gases requires they contain significant H2 and CO, but such reduced components are not supported by results of this and many other studies, which imply a scenario of Archean mantle redox not unlike that of today. Life may have found its origins in other environments or by other mechanisms.
(Dante Canil, “Vanadian in peridotites, mantle redox and tectonic environments: Archean to present,” Earth and Planetary Science Letters, Vol. 195:75-90 (2002) (internal citation removed).)
The situation is summed by authorities Kasting and Catling as follows: “For the 4 billion years for which a geological record exists, no evidence for a pronounced change in mantle redox state exists.” (James F. Kasting and David Catling, “Evolution of a Habitable Planet,” Annual Review of Astronomy and Astrophysics, Vol. 41:429-463 (2003).)
Deisler’s article in Skeptic Magazine is anything but skeptical when it comes to the Miller-Urey experiment, as offered zero discussion whatsoever about significant criticisms of the experiment. Instead, the article described the experiment as if there were no problems at all, and claimed it supports “the conclusion that the building block molecules, including nucleotides, were present on the early Earth.”
Skeptic is promoting this misinformation and skewed information about the Miller-Urey experiment to students, ignoring the scientific views of highly credible scientists who are in fact skeptical of the validity of the experiment.
A comic-book-style section at the end of the magazine titled “Junior Skeptic” says, “First rule of skeptical investigations? Turn on the lights!” Too bad these so-called skeptics don’t practice what they preach!