Cambrian Explosion: a whole nervous system (Introduction)

by David Turell , Wednesday, March 02, 2016, 16:09 (3188 days ago) @ dhw


> dhw: For those of us who believe in common descent, ALL ‘types' appeared at some time, and were later modified but are (at least theoretically) traceable to the original. The very fact that some nervous systems are dorsal and some are ventral seems to me to provide evidence that different cell communities in different organisms come up with different solutions to the same problems, depending on their own structure at the time of the innovation....-Denton's point was the original body plan in all organisms had the nerve cord ventral and heart, vessels and gut dorsal and with the appearance of vertebrates everything suddenly reversed with no evidence for gradual changes, all controlled by the same genes. Not Darwinian at all. Same functional organs, different positions. A completely different body plan, seemingly by saltation. I view it as advanced pre-planning for upright posture. He made no comment, but used it as anti-Darwin evidence.