Freethought & Rationalism Archive

Al Fresco · 10-27-2003, 09:45 AM

Botanical Society of America's Statement on Evolution

Presents an informative synopsis of the evolution/creation controversy and an interesting discussion of the use of evolutionary principles to predict the origin of two wheat species and then to recreate them.

Dr.GH · 10-27-2003, 10:38 AM

Thanks for the link. A good thing to read.

Al Fresco · 10-27-2003, 10:57 AM

My pleasure. It is published in the latest "Skeptical Inquirer" as a Special Report.

beastmaster · 10-27-2003, 11:07 AM

Thanks, Al Fresco. The wheat story is a good example of how "new information can be created" naturally, how evolution has been confirmed in *both* the field and the laboratory, and how evolutionary theory yields practical results benefitting humankind (even if it were somehow, some day proved "false").

Quote:

For example, plant biologists have long been interested in the origins of crop plants. Wheat is an ancient crop of the Middle East. Three species exist both as wild and domesticated wheats, einkorn, emmer, and breadwheat. Archeological studies have demonstrated that einkorn is the most ancient and breadwheat appeared most recently. To plant biologists this suggested that somehow einkorn gave rise to emmer, and emmer gave rise to breadwheat (an hypothesis). Further evidence was obtained from chromosome numbers that showed einkorn with 14, emmer with 28, and breadwheat with 42. Further, the chromosomes in einkorn consisted of two sets of 7 chromosomes, designated AA. Emmer had 14 chromosomes similar in shape and size, but 14 more, so they were designated AABB. Breadwheat had chromosomes similar to emmer, but 14 more, so they were designated AABBCC. To plant biologists familiar with mechanisms of speciation, these data, the chromosome numbers and sets, suggested that the emmer and breadwheat species arose via hybridization and polyploidy (an hypothesis). The Middle Eastern flora was studied to find native grasses with a chromosome number of 14, and several goatgrasses were discovered that could be the predicted parents, the sources of the BB and CC chromosomes. To test these hypotheses, plant biologists crossed einkorn and emmer wheats with goatgrasses, which produced sterile hybrids. These were treated to produce a spontaneous doubling of the chromosome number, and as predicted, the correct crosses artificially produced both the emmer and breadwheat species. No one saw the evolution of these wheat species, but logical predictions about what happened were tested by recreating likely circumstances. Grasses are wind-pollinated, so cross-pollination between wild and cultivated grasses happens all the time. Frosts and other natural events are known to cause a doubling of chromosomes. And the hypothesized sequence of speciation matches their observed appearance in the archeological record. Farmers would notice and keep new wheats, and the chromosome doubling and hybrid vigor made both emmer and breadwheat larger, more vigorous wheats. Lastly, a genetic change in breadwheat from the wild goatgrass chromosomes allowed for the chaff to be removed from the grain without heating, so glutin was not denatured, and a sourdough (yeast infected) culture of the sticky breadwheat flour would inflate (rise) from the trapped carbon dioxide.

The actual work was done by many plant biologists over many years, little by little, gathering data and testing ideas, until these evolutionary events were understood as generally described above. The hypothesized speciation events were actually recreated, an accomplishment that allows plant biologists to breed new varieties of emmer and bread wheats. Using this speciation mechanism, plant biologists hybridized wheat and rye, producing a new, vigorous, high protein cereal grain, Triticale.

Al Fresco · 10-27-2003, 12:49 PM

Typical creationist response: "But they are still just different knds of wheat."

10-27-2003, 09:45 AM	#1
Al Fresco Regular Member Join Date: Mar 2003 Location: Sandpoint, ID Posts: 363	Statement on Evolution Botanical Society of America's Statement on Evolution Presents an informative synopsis of the evolution/creation controversy and an interesting discussion of the use of evolutionary principles to predict the origin of two wheat species and then to recreate them.

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10-27-2003, 10:38 AM	#2
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	Thanks for the link. A good thing to read.

10-27-2003, 10:57 AM	#3
Al Fresco Regular Member Join Date: Mar 2003 Location: Sandpoint, ID Posts: 363	My pleasure. It is published in the latest "Skeptical Inquirer" as a Special Report.

10-27-2003, 12:49 PM	#5
Al Fresco Regular Member Join Date: Mar 2003 Location: Sandpoint, ID Posts: 363	Typical creationist response: "But they are still just different knds of wheat."

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