4 September 2002
Macroevolutionary Progress Redefined: Can It Happen Without Gene Transfer? What'sNEW

• QI — The raw "quantity of information," simply the length of the string.
• LAC — The "least algorithmic complexity" of the string, equivalent to the length of the most efficiently encoded version of it, with any redundancies and long repeats compressed — analogous to the "zipped" version of a computer program or file.
• AM — The "amount of meaning" in the string, equivalent to the length of the LAC version after any meaningless portions have been removed.

Micro- and Macroevolution in Terms of Genetic Meaning

• Microevolution — Genetic changes that do not increase or decrease () the amount of meaning (AM) in the genome, with phenotypic effects that may range from critical (examples 1 & 2) to none at all (example 5).
• Macroevolution — Genetic changes that increase () or decrease () the amount of meaning (AM) in the genome, usually with major phenotypic effect. Macroevolutionary progress, naturally, requires an increases in AM, just as new computer capabilities require new programs.

	Examples of genetic changes	QI	LAC	AM
1	Mutations that cause amino acid substitutions in proteins such as viral coat proteins, temporarily evading the host’s immune system				M I C R O
2	Point mutations that activate or reversibly silence promoter or repressor subroutines
3	Gene or whole genome duplication only
4	Gene duplication followed by irreversible silent or optimizing mutations in one copy
4.1	Temporary loss of function by a repairable acquisition of a nonsense sequence
5	Physical loss from the genome of nonfunctional DNA such as introns
6	Mutation to nonsense of a formerly functional gene				M A C R O
7	Physical loss from the genome of a formerly functional gene
8	Acquisition of a resistance plasmid by a bacterium
9	Acquisition of mitochondria and plastids by cells
10	First acquisition of genetic programs for methanogenesis, photosynthesis, oxygen metabolism, nitrogen fixation, multicellularity, cell specialization, sexual reproduction, locomotion, digestive systems, circulatory systems, nervous systems, immune systems, woody stems, leaves, shells, gills, lungs, limbs, bones, teeth, scales, skin, hair, wings, eyes, ears, etc.

Discussion

For another example, related to item 4, in 1999, a team at University College London deduced a plausible way for trichromatic vision in the howler monkey to have evolved from dichromatic vision by gene duplication and random mutation (Dulai et al.). If their surmise is correct, one of the howler’s two opsin genes was duplicated, and a point mutation in one copy encoded a single amino acid substitution that altered the color sensitivity of the opsin protein. Subsequent deployment of this third protein made 3-color vision possible.

It may have happened that way. But if the genetic programs for gene duplication, and for random mutations at the targeted location ("directed mutation") are already present, then the actual genetic steps just described may be considered as the execution of existing programs. The amino acid substitution by itself is not different from that in item 1, and one protein coat or color sensitivity range has no more meaning than another. This evolutionary mechanism is still quite remarkable, but it has not been shown to be capable of producing the new programs for any of the steps listed in examples 8-10.

Examples 8-10 give examples of phenotypic changes resulting from genetic changes that increased AM, producing macroevolutionary progress as defined here (denoted by green "up" arrows in the AM column). The mechanism behind such a genetic change, in standard Darwinism, is generally believed to be mutation and recombination within an existing genome, as in example 4. But of course, mitochondria and plastids were likely acquired by symbiosis. Resistance plasmids, and apparently, a key component of the vertebrate immune system (Agrawal et al.) were acquired by gene transfer. Other examples of macroevolutionary progress are not supposed to require the acquisition of new programs by transfer, but transfer has not been ruled out as the source for any example. And closed-system experiments that would demonstrate macroevolutionary progress without transfer have not succeeded, neither in biology nor computer models.

Another theory, strong panspermia, accounts for macroevolutionary progress entirely by gene transfer in an open system. Its logic leads to the conclusion that highly evolved life has always existed. But the standard version of the big bang theory would preclude this version of panspermia, if the whole universe is a closed system that began without life. However, other versions of the big bang theory that do not preclude strong panspermia are consistent with the cosmological evidence. In any case, the lack of direct evidence for macroevolutionary progress in closed systems should not be ignored.

At this point, macroevolutionary progress in a closed system has not been demonstrated. Without experimental evidence, one can reasonably ask whether macroevolutionary progress in a closed system is possible. Or, in the terms just introduced, can the meaning in the geneome of a species increase without the benefit of gene transfer from outside the species?

What'sNEW

"Language: Disputed definitions" [

text], doi:10.1038/4551023a, p 1023-1028 v 455, Nature, 23 Oct 2008. Search for "Complexity", by M. Mitchell Waldrop.
20 Sep 2008: Woodstock of evolution?
19 Nov 2007: Ancient retroviruses spurred evolution of gene regulatory networks in humans and other primates.
Michael Hopkin, "Chimps lead evolutionary race" [text], doi:10.1038/446841a, p 841 v 446, Nature, online 16 Apr 2007. "It is possible that the genetic changes underlying brain size are very few." (Text and title ammended after first online publication.)
1 Dec 2006: Evolutionary Dynamics, by Martin Nowak, Belknap Press, 2006.
12 Nov 2006: The Making of the Fittest, by geneticist Sean B. Carroll, W. W. Norton, 2006.
14 Feb 2006: Researchers evolve a complex genetic trait in the laboratory?
28 Jan 2006: Important aspects of the history of life are replicable and predictable.
30 Sep 2005: The chimp genome has been sequenced. At least seventeen human genes contain exons missing in chimps.
26 Nov 2004: The evolution of a new fruitfly gene...
14 Apr 2004: "Can we ever hope to pin down the genetic changes that underlie the big steps in evolution?"
15 Jan 2004: Are normal microevolutionary processes sufficient to account for human origins?
2003, August 8: Gene transfer, wholesale?
Jack W. Szostak, "Functional information: Molecular messages" [text], doi:10.1038/423689a, p 689 v 423 Nature, 12 June 2003. "A new measure of information — functional information — is required...."
2003, April 7: Stephen Jay Gould's account of macroevolution, in a new Encyclopedia of Evolution....
2003, February 4: The latest results from a closed-system biological experiment.
A Reply from Aaron Kennedy prompts a discussion of issues related to this page, 26 Oct 2002.

References

Alka Agrawal, Quinn M. Eastman and David G. Schatz, "Transposition mediated by RAG1 and RAG2 and its implications for the evolution of the immune system," p 744-751 v 394, Nature, 20 August 1998.