From the headlines you might think that with the discovery of some new Chinese embryo fossils, the enigma of the Cambrian explosion has been solved. The announcement from Virginia Tech trumpets, "New evidence of ancient multicellular life sets evolutionary timeline back 60 million years."

A Virginia Tech geobiologist with collaborators from the Chinese Academy of Sciences have found evidence in the fossil record that complex multicellularity appeared in living things about 600 million years ago — nearly 60 million years before skeletal animals appeared during a huge growth spurt of new life on Earth known as the Cambrian Explosion. (Emphasis added.)

In keeping with the usual practice, media around the world reproduced the claims uncritically. Live Science turned their coverage into a photo gallery, stating in the captions, "The fossils may capture the transition from single-celled to multicellular life, perhaps as an early ancestor of today’s animals…" then, adding as an escape hatch, "or perhaps as an evolutionary dead-end."

The popular media make a big deal of "differentiating cells" found in the fossils. Shuhai Xiao, geobiologist at Virginia Tech, hedged his bets about the interpretation of the cells, but apparently did not discourage speculation that they represent the hoped-for transitional forms:

The discovery sheds light on how and when solo cells began to cooperate with other cells to make a single, cohesive life form. The complex multicellularity evident in the fossils is inconsistent with the simpler forms such as bacteria and single-celled life typically expected 600 million years ago.

While some hypotheses can now be discarded, several interpretations may still exist, including the multicellular fossils being transitional forms related to animals or multicellular algae. Xiao said future research will focus on a broader paleontological search to reconstruct the complete life cycle of the fossils.

The embryos were found in China’s Doushantuo formation, in strata dated at 600 million years old by the geologists. This is about 60 million years before the commonly accepted start of the Cambrian explosion. Is that enough time for 23 new phyla to explode onto the scene?

For sorting out the facts and what they mean, a look at the original publication is helpful. In fact, the paper in Nature is less audacious, accepting that other interpretations are possible, cautioning that more research is needed:

Guided by these new fossils, our search for the phylogenetic home of the Doushantuo ‘animal embryos’ should focus on complex multicellular eukaryotes. Complex multicellularity evolved independently in animals, ascomycetes, basidiomycetes, and multiple green, red, and brown algal clades. Among these groups, modern volvocine green algae and animal embryos provide partial but imperfect interpretive analogues. Future research should aim at a broader paleontological search to reconstruct the complete life cycle of these fossils and to explore other interpretive analogues of complex multicellular eukaryotes.

The embryos bear some outward resemblance to simple colonies like Volvox, spherical multicellular organisms that undergo sexual reproduction and have flagella on their outsides. The fossilized colonies were, as far as the discoverers could tell, unflagellated. Inside the spherical aggregates, nested groups of cells reminded the discoverers of Russian dolls; they called these "matryoshkas." They also found evidence for differentiation between germ cells and body cells. They believe that some cells underwent programmed cell death (apoptosis); this also occurs in Volvox, but that simple colonial organism is thought to have evolved much later in the Permian or Triassic. As we reported in June, apoptosis dates at least to corals at 550 million years ago, and has been virtually unchanged since.

The authors realize these spherical shells are a long way from Cambrian animals, whether "stem group" (first branching) or "crown group" (fully evolved) forms. They are clearly not anything like the Cambrian (crown-group) animals. At best, they could not falsify an interpretation that these embryo-like shells were, perhaps, maybe, at the beginning of the start of something big:

A life cycle including a matryoshka stage excludes a phylogenetic affinity with crown-group animals, where embryogenesis does not produce a matryoshka and germ — soma separation occurs ontogenetically later in sexual reproduction. However, the present evidence does not force the falsification of the stem-group animal interpretation. Crown-group animals and their closest living sister group, the choanoflagellates, are separated by important morphological gaps.

Realizing that all the crown-group traits could not be expected so early, they conclude that something is better than nothing: "it remains possible that the Doushantuo fossils could be stem-group animals that evolved an autapomorphic life cycle involving a matryoshka stage."

Notice they said "could be," not "are." As long as they are assuming that Cambrian animals evolved according to the Darwinist understanding, anything "could be" part of that story. Single cells "could be" the beginning stages of stem-group animals. Choanoflatellates "could be" a sister group. Ediacarans "could be" early experiments in multicellularity. Imagination sets no limits to such hypothetical thinking.

What’s new about these fossils? Nothing. Similar embryos were found in the 1990s by J. Y. Chen and Paul Chien in the same Doushantuo formation, and reported in the peer-reviewed literature (Xiao et al. cite that paper in their references). The story is recounted in both Stephen Meyer’s book Darwin’s Doubt and in the Illustra film Darwin’s Dilemma. The presence of embryos in the Precambrian didn’t solve the Cambrian explosion problem then, and it doesn’t now. In fact, they make the problem worse, because they show that the Precambrian strata were perfectly capable of preserving transitional forms, had they existed.

These new embryos are also less complex than the Ediacaran colonies that Meyer discusses in Chapter 4 of Darwin’s Doubt. The Ediacaran period began 635 million years ago (see Meyer, Fig. 1.6). Meyer’s date for the sponge embryos and the first Ediacaran fauna is 570 million years ago, although there seems to be some disagreement among paleontologists about when they first appeared. But even if one were to assume these new embryos precede the previous embryos by 30 million years, can anyone really believe that no new innovations occurred in more time than the entire Cambrian explosion?

The level of innovation in these new embryos is actually far less than what is already known about the Ediacaran fauna. Meyer points out that the Ediacaran represents a "mini-explosion" of its own (pp. 86-88), with new life forms appearing suddenly with no known precursors. Later, they went extinct, apparently bearing no relationship with the Cambrian animals that exploded onto the scene some 13 million years after they disappeared. Since the Ediacaran creatures are much more complex than the embryos, one should focus on their innovations as having possible evolutionary significance. But, as Meyer shows, the Ediacarans lack the complex body plans of the Cambrian animals. And even if one were to accept the Ediacarans (or the embryos) as stepping stones, "the total time encompassed by the Ediacaran and Cambrian radiations still remains exceedingly brief relative to the expectations and requirements of a modern neo-Darwinian view of the history of life" (p. 87).

New Anomalocaridid from China

Another complex Cambrian animal, related to the famous apex predator Anomalocaris, has been found in early Cambrian strata in China. Reported in Nature, it has been named Lyrarapax unuispinus (harp-shaped thorny-clawed predator). What’s interesting about this fossil is not its phylogenetic affinities, but its exquisite preservation. Look at the details in this fossil:

Here we describe Lyrarapax unguispinus, a new anomalocaridid from the early Cambrian Chengjiang biota, southwest China, nearly complete specimens of which preserve traces of muscles, digestive tract and brain. The traces of brain provide the first direct evidence for the segmental composition of the anomalocaridid head and its appendicular organization. Carbon-rich areas in the head resolve paired pre-protocerebral ganglia at the origin of paired frontal appendages. The ganglia connect to areas indicative of a bilateral pre-oral brain that receives projections from the eyestalk neuropils and compound retina.

You can see the dark carbon traces in the photographs. The fossils are so detailed that the scientists were able to trace the connections of neurons from the brain to the appendages.

Notice, too, that this animal already had muscles, a digestive system, a brain and associated nervous system, grasping claws, and compound eyes. With its tail fan and lateral flaps, it was apparently a good swimmer and hunter. This is in the early Cambrian. Whether it should be classified with the arthropods or onycophorans is beside the point. Look at the fossil and think: how do you get all those complex organs and systems from a spherical colony of cells? Darwin is still in a dilemma.

Operating System Explosion

After marveling at this fossil, we can weight the merits of an analogy presented in a news release from UC San Diego. Some of veteran evolutionist Russell Doolittle’s successors and students came up with an interesting formulation:

The evolution of worms, insects, vertebrates and other "bilateral" animals — those with distinct left and right sides — from less complex creatures like jellyfish and sea anemones with "radial" symmetry may have been facilitated by the emergence of a completely new "operating system" for controlling genetic instructions in the cell.

That’s right: now they give us an operating system explosion to account for the Cambrian explosion. Things are exploding all over in the Darwin literature.

They found a protein in bilaterian animals, TRF2, that is not present in radial animals, which only had one "operating system" called TBP. "While their hypothesis initially seemed far-fetched" (how does an operating system "emerge" without design?), that miracle led to more miracles — apps!

"In our current model, there was originally only a single TBP-based operating system, and then the emergence of the new TRF2-based operating system led to new gene networks (‘apps’) that facilitated the emergence of bilateria," said Kadonaga [a biology prof at UCSC]. "These new gene networks included those that are involved in the development of the body plan and the mesoderm. We postulate that the new TRF2-based networks provided the extra diversity of regulatory function that led to the evolution of more complex organisms — specifically the bilateria, which constitute about 99 percent of living animals."

And that’s where muscles, digestive systems, nervous systems and limbs came from. That a reputable university would race to the bottom for this kind of explanation of the Cambrian explosion should be taken as a sign of desperation.

Meyer dealt extensively with gene networks in his book and in a new Epilogue published in the paperback edition, so we need only link to it. Suffice to say that in our uniform experience, the emergence of operating systems and apps are always due to intelligence.

Image credit: Fossil of a 600 million-year-old multicellular organism/Virginia Tech News.