The Origin of Biological Information
The sequence of nucleotides in genetic molecules affects their structure and function. Origin-of-life research therefore includes the question of how useful sequence-dependent information first emerged and became heritable.
The Investigative Question
How did prebiotic polymers acquire sequences capable of useful functions, replication, and eventually cumulative evolution?
What We Observe
RNA and DNA are not important merely because they are long molecules. The order of their nucleotide units matters.
Different sequences can fold differently, interact with different molecules, and ultimately produce different biological effects.
Scientific Background
In existing life, genetic information is inherited and altered by mutation, recombination, and selection.
Before Darwinian evolution could operate efficiently, however, some system of sufficiently reliable heredity had to exist.
Why It Matters
The origin of biological information connects chemistry with evolution. Once sequence differences can be copied and can influence reproductive success, natural selection can begin accumulating useful variations.
What Is Known
Random and chemically biased polymer sequences can be produced experimentally. Laboratory selection demonstrates that populations of nucleic-acid sequences can evolve functional properties when replication, variation, and selection are supplied.
What Is Proposed
Origin-of-life models propose that relatively simple replicators first generated heritable sequence variation and that chemical or Darwinian selection subsequently enriched sequences with useful properties.
What Remains Uncertain
The threshold between ordinary chemical selection and open-ended Darwinian evolution is not known historically. Neither is the nature of the first hereditary polymer or the amount of information required by the earliest evolvable system.
Key Numbers
Genetic information is encoded in the sequence of nucleotide units. Darwinian evolution requires heritable variation that affects reproductive success.
Design Relevance
Biological information is central to Intelligent Design arguments because living systems depend upon sequences that perform specific functions.
The scientific question concerns how functional and heritable sequences could emerge during the transition from prebiotic chemistry to evolving biological systems. Origin-of-life research investigates chemical selection, replication, variation, and other processes that might contribute to that transition.
Intelligent Design advocates such as Stephen Meyer make a further inference. They argue that because intelligent agents are known to produce functionally specified information, intelligent causation provides a better explanation for the origin of biological information than unguided chemical processes alone.
That conclusion is an Intelligent Design interpretation of the evidence. The underlying scientific problem — explaining the origin of functional, heritable biological information — remains an important part of origin-of-life research regardless of which explanation is ultimately preferred.
Assessment
Once a replicating hereditary system exists, mutation and selection provide a demonstrated mechanism for accumulating functional information. Explaining the emergence of a sufficiently capable hereditary system is part of the origin-of-life problem itself.