Biology

Cambrian Explosion: More Woes and Dodges

Image credit: Anomalocaris, Katrina Kenny & University of Adelaide/UNE Photos, via Flickr.

Eight years after Stephen Meyer’s book Darwin’s Doubtevolutionists are still failing to explain the Cambrian explosion. They struggle to explain new complexities or else try to change the subject.

Ctenophores Get Even More Complex

Comb jellies (ctenophores) are claimed by some evolutionists to be the first multicellular animals, emerging even before sponges! (See here for more.) But look at all the design features these small marine animals have: a nerve network, locomotion, digestion, and iridescent flashing lights in their eight “comb rows” of cilia. In 2018, Casey Luskin noted that over 1,200 homology groups (groups of genes that are similar and unique to a homologous group) would be required for the origin of the group that includes ctenophores. Now, the team that in 2019 brought to light one of the required genes for comb rows has doubled the complexity, and with it, multiplied the headaches for evolution.

In 2019, we described how Jokura et al.in Current Biology had identified a gene named CTEN064 that was “required to orient each cilium within the ‘compartmenting lamellae’ that hold the comb rows together.” Knockout experiments showed that without this gene, the comb jellies could not swim. Now, in a new follow- up study published in bioRxivJokura’s team announced the discovery of another required gene they call CTEN189. Without this gene, the cilia become disoriented, out of sync, and disconnected from the compartmenting lamellae (CL). Of particular interest, this protein acts at the opposite end of the CL — the distal end — as opposed to CTEN064 which localizes to the proximal end. This struck the researchers as a kind of “two-story building” arrangement:

Our findings demonstrate a two-story building of CP [comb plate]comprising the proximal CL, as the building foundation that rigidly fixes the ciliary orientation. The distal CL would reinforce the elastic connectionamong cilia to overcome the hydrodynamic drag of giant multiciliary plates. [Emphasis added.]

A Flailing Rowing Team

All two-story buildings humans have observed coming into existence were intelligently designed. How could blind evolution come up with a two-part arrangement, a foundation and a reinforcing structure, simultaneously? Without both, the cilia (even if they are assumed to have emerged) would be unable to coordinate their movements. They would be like members of a rowing team flailing in all directions. The comb plate is beginning to look like an irreducibly complex system, but the authors are not done with the designs they found. In their paper — titled, “’Two-story building’ of a ctenophore comb plate provides structural and functional integrity for motility of giant multicilia” — they mention that these “giant multicilia” comprise tens of thousands of cilia working together in functional harmony.

Tens of thousands of cilia are bundled in a CP via structures connecting adjacent cilia, called compartmenting lamella (CL), which are the basis for the structural iridescent color and the coordination of ciliary movement of the CP.

Consider too that all eight of the comb rows must be coordinated for the animal to swim in a purposeful direction, whether for locating food or escaping predators. That’s a lot of complexity to account for.

Quick, Change the Subject

When discussing the most embarrassing problem to Darwinism, it helps to join the dodgers. There are numerous ways to distract attention from Meyer’s challenge to explain the origin of the genetic information required to build 18 animal body plans appearing in the geological blink of an eye. Here’s a new trick: talk about how Cambrian fossils changed the Earth’s carbon cycle.

In a paper this month in Science Advances11 authors discuss “Perturbation of the deep-Earth carbon cycle in response to the Cambrian Explosion.”

Earth’s carbon cycle is strongly influenced by subduction of sedimentary material into the mantle. The composition of the sedimentary subduction flux has changed considerably over Earth’s history, but the impact of these changes on the mantle carbon cycle is unclear. Here, we show that the carbon isotopes of kimberlite magmas record a fundamental change in their deep-mantle source compositions during the Phanerozoic Eon…. These observations demonstrate that biogeochemical processes at Earth’s surface have a profound influence on the deep mantlerevealing an integral link between the deep and shallow carbon cycles.

What, pray tell, are these “biogeochemical processes” that occurred on the surface? Why, they were the sounds of hammers and saws building 18 new animal body plans (secondary productivity) out of microbes (primary productivity) on the surface. Anything to say about that?

It also provides a novel perspective on the evolution of the global carbon cycle and supports the emerging view that the extent of marine primary productivity has markedly changed through Earth’s history.

Cambrian Artwork

Over at New ScientistMichael Marshall draws the connection more closely. He starts with artwork of a Cambrian sea, with Anomalocaris on the prowl. “The Cambrian explosion 500 million years ago saw a huge variety of animals evolve — and also led to carbon being buried in the seabed and ultimately carried into the planet’s mantle.” The lead author of the paper seems to have wanted to distract attention from explaining the origin of the animal body plans to focus on a different subject.

When animal life exploded in the oceans more than 500 million years ago, it changed the face of the planet. Now it seems the effects of that burst of evolution reached thousands of kilometres into Earth’s heart.

“We can link a major event that is happening at the Earth’s surface with a fundamental change in the deep Earth,” says Andrea Giuliani at ETH Zurich in Switzerland….

Giuliani and his colleagues now say they have evidence This evolutionary blossoming had effects thousands of kilometres inside Earth.

Finally, a Touch of Doubt

Three weeks later in New ScientistMichael Marshall again gave the usual spiel about the “burst” of evolution, stretching the time as far as possible by conflating the “Cambrian period” with the “Cambrian explosion” that was a small fraction of the period (ten million years at most and more likely five million).

The Cambrian period, from 541 to 485 million years ago, saw a great flowering of animal lifedubbed the Cambrian explosion. A number of major animal groups originated at this time, including many that still exist today.

Marshall also repeats a common non-explanation for the explosion: the notion that a “changeable environment … might have driven rapid evolution,” as if rocks and tides have creative powers, or can act as driving instructors for simple organisms, teaching them how to go places on the highways of evolutionary progress.

This time Marshall doesn’t propose oxygen did it, or slime. Instead, he has evolution fly delta. He shares a new proposal that a river delta formed the Chengjiang fossil site, one of the richest Cambrian fossil beds in the world. This makes sense when you don’t think about it. A location prone to violent floods“may have helped drive the evolution of early animals.” A shifting environment “may have helped drive the rapid evolution in the Cambrian.” It “might have” driven rapid evolution. As we all learn, though, “might” does not make right.

To his credit, Marshall does quote a skeptic of this notion: Zhao Fangchen at the Nanjing Institute of Geology and Palaeontology in China.

Zhao is sceptical of this.“The sedimentary environment of the Chengjiang biota does not tell us much of an evolutionary story,” he says, because other Cambrian fossils show animals were also living in deeper regions.

This brief taste of logic is quickly forgotten by another dodge back to a discussion of what a certain animal’s common ancestor was. Well, it was nice while it lasted.

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