Claim CB035.1:

Free oxygen is fatal to abiogenesis scenarios such as those that Stanley Miller experimented with. Evidence indicates that the early earth had significant oxygen.

Source:

Response:

1. There is a variety of evidence that the early atmosphere did not have significant oxygen (Turner 1981).
   
   
   • Banded iron formations are layers of hematite (Fe₂O₃) and other iron oxides deposited in the ocean 2.5 to 1.8 billion years ago. The conventional interpretation is that oxygen was introduced into the atmosphere for the first time in significant quantities beginning about 2.5 billion years ago when photosynthesis evolved. This caused the free iron dissolved in the ocean water to oxidize and precipitate. Thus, the banded iron formations mark the transition from an early earth with little free oxygen and much dissolved iron in water to present conditions with lots of free oxygen and little dissolved iron.
   • In rocks older than the banded iron formations, uranite and pyrite exist as detrital grains, or sedimentary grains that were rolling around in stream beds and beaches. These minerals are not stable for long periods in the present high-oxygen conditions.
   • "Red beds," which are terrestrial sediments with lots of iron oxides, need an oxygen atmosphere to form. They are not found in rocks older than about 2.3 billion years, but they become increasingly common afterward.
   • Sulfur isotope signatures of ancient sediments show that oxidative weathering was very low 2.4 billion years ago (Farquhar et al. 2000).
   
   The dominant scientific view is that the early atmosphere had 0.1 percent oxygen or less (Copley 2001).
   
   
2. Free oxygen in the atmosphere today is mainly the result of photosynthesis. Before photosynthetic plants and bacteria appeared, we would expect little oxygen in the atmosphere for lack of a source. The oldest fossils (over a billion years older than the transition to an oxygen atmosphere) were bacteria; we do not find fossils of fish, clams, or other organisms that need oxygen in the oldest sediments.

Links:

Tamzek, Nic. 2002. Icon of obfuscation. http://www.talkorigins.org/faqs/wells/iconob.html#Miller-Urey

References:

Further Reading:

Wiechert, Uwe H. 2002. Earth's early atmosphere. Science 298: 2341-2342.

---

---