virus: Fwd: What Is Lamarck's Signature?

Wade T. Smith (morbius@channel1.com)
Fri, 18 Jun 1999 00:34:49 -0400

Very interesting, and highly understandable for the layman- memetic neo-lamarckian processes would seem to be 'level 3' processes, where mutation is a willed behavior.


http://www.biomednet.com/hmsbeagle/56/viewpts/op_ed

What Is Lamarck's Signature?

by Edward J. Steele and Robert V. Blanden (Posted June 11, 1999 Issue 56)

Abstract

Historically, scientists have viewed with skepticism the effects on inheritance of use and disuse. Antibody genes, however, may contain evidence for a Lamarckian-type transfer of genetic information from the soma to the germline.

In science, people depend much of the time upon "signatures" to interpret events they cannot directly see. For example, the identification of subatomic particles in cyclotron atom-smashing machines depends on the tracks the particles leave in cloud chambers. Similarly, no one doubts that the craters on the moon's surface are the impact sites of large cosmic bolides, such as asteroids, although nobody ever witnesses the impacts.

We now have clear evidence for what we call "Lamarck's signature" written into the DNA sequences of genes, telltale signs of soma-to-germline transfers of genetic information that have profound implications for the evolution of living organisms. The evidence comprises data and analyses from our research on the genes of the immune system of higher vertebrates, which produces disease-fighting antibodies. It has been published both in the scientific literature and in a recent book for the general reader, Lamarck's Signature: How Retrogenes are Changing Darwin's Natural Selection Paradigm.

Before describing this evidence, it is worth briefly reviewing the history of ideas about the evolution of living organisms. In 1809, long before the publication of Charles Darwin's Origin of Species in 1859, the French biologist Jean Baptiste de Lamarck first articulated the idea that species transform themselves "one into the other." He assumed that acquired characteristics developed in parents by use or disuse of specific body parts could be inherited by the offspring. Modern neo-Darwinists reject this idea outright.

Charles Darwin's fundamental contribution to evolutionary theory was the concept of "natural selection": parent organisms possessing the best characteristics for survival in their environment would produce the greatest proportion of offspring in the next generation. Darwin imagined that new species would arise over evolutionary time through this mechanism. This revolutionary idea had a dramatic effect on the intellectual and spiritual life of the time because it contradicted the religious view that God had created all species in one week a few thousand years ago.

But Darwin also borrowed, and modified from Lamarck, the concept of the inheritance of acquired characteristics. Lamarckian arguments of "use or disuse" appear in many places in Origin of Species, arising from Darwin's observations of the exquisite variations and adaptations of plants and animals under domestication. To quote Darwin:

With animals the increased use or disuse of parts has had a marked influence . . . in the domestic duck . . . the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild-duck; and this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parents.

And:

The great and inherited development of the udders in cows and goats in countries where they are habitually milked, in comparison with these organs in other countries, is probably another instance of the effects of use.

Darwin proposed that during the development of an acquired adaptation, the cells of the target organ (somatic cells) would be excited to emit genetic material in a form he called "gemmules" or "pangenes," which were discharged into the bloodstream and, in the course of their circulation around the body, would enter sperm and eggs (germ cells) and be transmitted to the next generation. Darwin called this idea of use-inheritance "pangenesis." This seminal contribution is, however, most often expunged from history by neo-Darwinists. Why has this apparently innocuous proposition, which Darwin embraced so completely, been so violently controversial?

First, in 1885, three years after Darwin's death, the German biologist August Weismann, responding to Darwin's theory of pangenesis and Lamarck's ideas, proposed a theoretical barrier between somatic cells and germ cells. "Weismann's barrier" was assumed to prevent germ cells from receiving any genetic changes from body cells. Weismann tested his theory by chopping off the tails of rats shortly after birth and then breeding the animals. They never produced tailless offspring. Critics have pointed out, however, that such experiments did not test Lamarck's idea. A chopped tail is a modification that is not produced by the rat. Lamarck believed that only modifications produced by the response of organisms to their environment would be inherited. Of course any reasonable individual might have considered the fact that the Jewish custom of circumcising young boys had never resulted in a baby boy born without a foreskin.

Lamarck's concept was next tested by the Austrian biologist Paul Kammerer through a famous experiment on the midwife toad, Alytes obstetricians. Unlike most toads, which mate in water, Alytes mates on dry land. Male toads of water-mating species grasp the females around the waist, maintaining the embrace for days until spawning. To maintain this grip on slippery females, the males develop horny-spined nuptial pads on their palms and fingers. Alytes do not have or need these pads because the female's skin is dry and rough. Kammerer reported that when Alytes toads were induced to mate in water over several generations they developed nuptial pads as an acquired hereditary trait. Critics claimed the results were fraudulent. Although unproven, these charges drove Kammerer to suicide.

The third historical figure to cause an adverse reaction to Lamarckian thought was the Russian plant breeder T.D. Lysenko, a staunch Lamarckian who was appointed by Stalin to improve Russian agriculture. From the 1930s to the 1950s, Lysenko applied questionable procedures to demonstrate crop yield improvement using a seed treatment and germination process called "vernalization" that completely alienated Western scientists and helped turn them against Lamarck's ideas as well. Lysenko also ruthlessly pursued his scientific opponents, who were executed or sent to the gulag by Stalin, reinforcing the negative associations of "Lysenkoism" and hence Lamarck's ideas.

Now, however, consider the evidence from modern molecular biology. Antibody genes have a unique property: their DNA sequence rearranges from the original "germline configuration" to a "somatic configuration." This rearrangement occurs only in lymphocytes (a type of white blood cell) and is essential for the production of antibodies by a subset of these cells, termed B cells.

In B cells responding to infection, rearranged antibody genes undergo rapid mutation. Those mutant B cells making the most effective antibody are then selected. Analysis of antibody genes from germ cells of a variety of species (humans, mice, chickens, sharks, and toads) reveals certain features that could only arise after somatic rearrangement of the DNA, mutation, and selection of B cells. These features are incompatible with neo-Darwinism, which argues that evolution occurs only via random mutation in germ cells, followed by natural selection acting on the whole living organism that carries the mutation. They are, however, compatible with a neo-Lamarckian process of feedback to germ cells of mutated and selected genes from somatic cells (in this case, B cells). All the molecular mechanisms needed for such feedback are completely documented in the scientific literature.

There is also evidence, though not as extensive, of such feedback for genes other than antibody genes. Thus "Lamarck's signature" is written into germline genes (the equivalent of the moon craters). Direct proof will require an experiment to show the soma-to-germline impact. Such an experiment can be designed and is technically feasible. The key question now is the frequency of soma-to-germline feedback, which will determine whether it is possible to detect such an impact in real time.

Edward J. (Ted) Steele is a professor of biological sciences at the University of Wollongong, Wollongong, New South Wales, Australia.

Robert V. Blanden is a professor of immunology and cell biology at the John Curtin School of Medical Research, Australian National University, Canberra.

Lamarck's Signature: How Retrogenes Are Changing Darwin's Natural Selection Paradigm - the hypothesis reviewed by Gert Korthof. From Was Darwin Wrong?, Korthof's extensive reviews of books critiquing evolution.

Lamarck and His Theory of Evolution - an outline by Thomas E. Hart of Lamarck's scientific work and theories in the context of his time. From the Brown University project The Victorian Web.

Stalin as Lysenko's Editor: Reshaping Political Discourse in Soviet Science - an article by Kirill Rossianov on the relationship between Stalin and Lysenko and the rejection of neo-Darwinism in the Soviet Union.

Rethinking Darwin - interviews with Robert Blanden and Edward Steele. Transcript and RealAudio from the Australian Broadcasting Corporation.

Cut Off Their Tails - a review of Lamarck's Signature from New Scientist.

Jean-Baptiste Lamarck (1744-1829) - a brief biography. From the Museum of Paleontology at the University of California at Berkeley.

1999 BioMedNet Ltd. All rights reserved.