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he continued, and it soon became clear that there were an extensive variety of organisms difficult to classify, such as those found in the Cambrian-era Burgess Shale. But there are a number of Cambrian fossil beds, such as in China, where important phyla such as Chordata evolved. “In the Cambrian, some claim that there were as many as a hundred phyla, but the evidence does not support this. We now believe that morphological diversity did not explode as much as Gould originally suggested, although the explosion in evolutionary experimentation was real. By the time we get to the Cambrian, as at the Burgess Shale, the systems are very complex, such as trilobite eyes. Evolution was experimenting with many wondrous varieties, such as all the armor on the heads of trilobites.”

What Is the Origin of Complex Life?

Intelligent Design theorists argue that evolutionary theory cannot account for the increase in organismal complexity. That is, how can we explain the increase of information in something like the genome in a world filled with entropy and the decay of information? This problem is addressed by Peter Gogarten, a professor of molecular and cell biology at the University of Connecticut, who demonstrates how often prokaryote organisms (simple cells like bacteria) experience horizontal gene transfer between organisms. They swap genes! “Over long periods of time gene transfer makes organisms existing in the same environment more similar to one another. This is most clearly seen in the case of organisms that live in environments that are otherwise inhabited by distant relatives only.” Thus, Gogarten concluded, “the boundaries between prokaryotic species are fuzzy. Therefore the principles of population genetics need to be broadened so that they can be applied to higher taxonomic categories.”

If organisms can swap genes, they can also acquire genes and thereby increase the information complexity of their genomes. If Lynn Margulis is right, this is in fact how simple prokaryote cells evolved into complex eukaryote cells (of which we are made), through symbiogenesis, which she described succinctly as “the inheritance of acquired genomes” and more formally in its relationship to symbiosis as “the long-term physical association between members of different types (species).” The problem with making evolution primarily about genetics (neo-Darwinism), Margulis concluded, is that “[r]andom changes in DNA alone do not lead to speciation. Symbiogenesis—the appearance of new behaviors, tissues, organs, organ systems, physiologies, or species as a result of symbiont interaction—is the major source of evolutionary novelty in eukaryotes: animals, plants, and fungi.”

Creationists and Intelligent Design theorists also like to claim that the theory of evolution is a faith-based religion to which scientists must swear allegiance in order to obtain research grant money. They should have heard Margulis bellowing from the dais that neo-Darwinism is dead. Echoing Darwin, she said, “It was like confessing a murder when I discovered I was not a neo-Darwinist.” But, she quickly added, “I am definitely a Darwinist. I think we are missing important information about the origins of variation. I differ from the neo-Darwinian bullies on this point.” Neo-Darwinists tend to focus on plants and animals, Margulis complained. “We live on a bacterial planet,” and evolutionary theory must be able to account for the evolution of the cell, “the fundamental unit of life,” and all that a cell contains: “A minimal cell has DNA, mRNA, tRNA, rRNA, amino acylating enzymes, polymereses, sources of energy and electrons, lipoprotein membranes, and ion channels, all contained within a cell wall, and is an autopoietic [self-regulating feedback] system.” The theory of symbiogenesis does just that, although there are scientists who remain skeptical.

How Many Branches Are There

on the Human Evolutionary Tree?

Creationists’ demand for just one transitional fossil is most notably made when it comes to human evolution, for which they claim there are none. They should