Leslie Orgel's Reality Check

Leslie Orgel is a pioneer in Origin of Life research. In 2008, a colleague published a manuscript by Leslie entitled, "The Implausibility of Metabolic Cycles on the Prebiotic Earth". It is a useful reality check on Kaufmann's autocatalytic sets idea.

In summary, Leslie is not a fan. He sums up his paper with this:

[S]olutions offered by supporters of geneticist or metabolist scenarios that are dependent on “if pigs could fly” hypothetical chemistry are unlikely to help.

The bottom line for any theoretical system involving autocatalytic cycles is that they can't have chemically unrealistic assumptions. The paper also has a good discussion on actual autocatalytic cycles in biology such as the reverse citric acid cycle and the formose reaction.

Overall, an important paper for me to keep in mind.

Nomenclature of Sets

I want to understand what's already been done on autocatalytic sets in relation to the Origin of Life. Wim Hordijk and Mike Steel seem to be the leaders in this area so I want to read their 2004 paper on the subject.

Unfortunately, they use Set Theory Nomenclature heavily in the paper (see example at right) and so I need to learn that first. Fortunately, I found this nice primer from Clemson University.

Symbol summary:

• members of a set are put in curly brackets: S = {1,2,3,4}
• x ∈ S means x is a member of set S (∉ means x is not in S)
• ∅ is the empty set
• |S| means the number of elements in the set
• S ⊂ T means S is a subset of T
• S ∩ T means the intersection of sets S and T
• S ∪ T means the union of sets S and T 
• S \ T means the elements in S that are not also in T (difference operator)
• If a reference set is defined as all possible elements, U, then S' is the complement of S and means all elements in U but not in S