What is the evolutionist explanation for the "Cambrian Explosion"?

Question

This seems to me to be a stumbling block for the theory, something that I've not heard a good explanation for in scientific terms. What is the "official" evolutionist explanation for it? Just curious, not trying to bash here.

Thanks.

Well, Leviathan, you certainly win the "smug ***" award of the day, if nothing else...

Answer 1

The "Cambrian Explosion" is a period when a vast array of segmented creatures, trilobites in particular, appeared and new forms and combinations of features arose rapidly. The most likely explanation is that the homeobox genes evolved at this point in time. The homeobox genes control what appears in each segment -- eyes, wings, legs, antennas, and so on. This master switch enabled rapid changes in form and structure count.

Answer 2

Walcott has put forth a lot of research on this subject and he suggests that there was not so much an explosion of diversification at this time, as there was a lapse (or lipalian period) right before that has not been recorded geologically in fossil specimens. There was evolution before the cambrian period but at a very small yet increasing scale, which ramped up during the lipalian age but was not recorded in sulfuric isotopes and thus makes the cambrian period appear to arise from nowhere.

Answer 3

I am not familiar with what you have heard, but it is indeed no "stumbling block"...

Though some (mostly non-scientists) claim that the Cambrian explosion (@540 mya) produced many complex life forms too quickly for the theory of evolution they omit the fact that it occured over a span of tens of millions of years (or so), and that multicellular life is known from almost 650 mya (Vendian, or Ediacaran, Period).

Within this rather long time frame exist many transitional fossils, as well as primitive forms of extant groups (all within the predictability of evolutionary theory).

The expansive diversification of this period can be explained by (among other things) new niches for animals to occupy; the basic animal "blueprint" evolving/finalizing (hox genes); and an expanding environment more conducive to "complex" species (atmospheric oxygen increased)

Answer 4

you're good - his argument is depending thoroughly on hypothesis (note his use of the be conscious "in all likelihood") - not often a "truth". Secondly, the fossil record shows few flatworms because they're smooth-bodied creatures that do not extremely fossilize. Thirdly, from a creationist attitude, ALL animals got here upon contained in the fossil record did not "deposit their fossils" over a lengthy era of time, yet quite they were all buried at about a similar time, in the course of the Flood. merely about all fossils are found in sedimentary rock - rock that change into sediment - FLOOD sediment. Flatworms are got here upon on the bottom ("Cambrian") because they were already residing on the bottom even as the flood buried them contained in the sediment. "Cambrian" and all the different "age" names are literally not a lengthy time period in any respect, yet quite burial positions. The animals are got here upon contained in the order they were buried, not the order in which they "developed". EDIT: @ SpaceWasp - <> The sediment got here from the topsoil of the pre-Flood global. keep in thoughts there have been no oceans earlier the Flood. many of the Floodwater remains obtainable today, contained in the oceans. something is locked up in glaciers and floor water. What we locate contained in the fossil record is thoroughly in step with burial by flood. The animals that stay on the bottom (alongside with shellfish) are already residing there even as they get buried; then fish, then amphibians and better/speedier marine mammals and reptiles, then slower land animals, then speedier/smarter/larger land animals, and ultimately, people, apes and birds might want to be the merely good to be killed, because people can ascertain out a thanks to stay afloat till the merely good minute, apes can climb to the optimal treetops, and birds can fly round till they run out of gas. In those style of cases, their bodies might want to opt for the flow and decay and customarily not be buried and preserved as fossils, and that is precisely what we see. Their fossils are very uncommon.

Answer 5

There's no such thing as an evolutionist.

There's people who worship a sky-fairy and attribute everything it and people who don't and prefer logic and reason and empirical data and evidence.

Go read a book on evolution and you'll see that for yourself. You could read Gould's book called 'wonderful life' about the Burgess Shale or a book from one of the actual palaeontologists involved - 'the crucible of creation' by simon conway morris.