Last night’s episode of the science series Cosmos: A Spacetime Odyssey ventured into the fractious debate over the nature of life on earth, with the host clearly defending evolution. Neil deGrasse Tyson explained evolution and offered a critique of intelligent design in the latest episode of the science show.
The theory of evolution remains one of the most important theories in all of science, as well as being a source of great controversy. Scientists and liberal religious thinkers overwhelmingly accept evolutionary theory, while certain religious groups and individuals are opposed to the idea of life evolving through natural processes over billions of years.
The pilot episode of this reboot of the classic Cosmos series hosted by Carl Sagan touched on evolutionary theory, but this latest episode jumped right into the debate with remarks on common descent, artificial selection, the tree of life and the evolution of the eye. Neil deGrasse Tyson hosts the new series that debuted earlier this month.
Dogs are an example of how artificial selection works. Dogs, Tyson explained, evolved from wolves that were relatively tame by nature – self-selection based on “tameness” rather than on toughness. From that long-ago starting point, humans bred wolves to have a variety of desirable qualities.
The episode describes the Tree of Life, a bushy representation of how species have diverged again and again over time. A trunk represents the common ancestry of all life on Earth. There is no need to appeal to an intelligent designer, Tyson said.
Creationists sometimes question the validity of the Tree of Life, and by extension of common ancestry. A response published Monday by the Discovery Institute, a research and education organization focusing on intelligent design, criticized the version presented as Cosmos for not being as accurate as the show claimed. The criticism was based on the Institute’s claim that morphology and genetics produce two very different Trees.
The latest episode of Cosmos addresses the role of DNA in evolution. Tyson narrates an animation showing how DNA splits and replicates when cells divide. Sometimes there is a minor issue with this process, and a mutation happens. The mutation may do nothing or it may produce a small change. A bear might end up with white fur instead of brown. This difference could help the bear survive better in a snowy landscape.
Tyson also addresses the evolution of the eye, another source of debate with advocates of creationism. Creationists tend to argue that the human eye could not have evolved by natural processes. This is an example of an argument from irreducible complexity, the eye and all of its critical parts could not have evolved together by blind chance. Tyson critiques intelligence design as unnecessary when evolution explains the eye quite well.
The final reference to evolution on Earth came in the form of Carl Sagan’s animation showing four billion years of evolutionary history, from single-celled organisms to humans, in 40 seconds.
The Discovery Institute’s response, penned by staffer Casey Luskin and posted to the site Evolution News and Views, draws heavily on criticisms of the power of evolutionary explanations to account for changes from one species to another.
A large part of Luskin’s statement addressed Neil deGrasse Tyson’s use of artificial selection as an example of how evolution works. According to the Discovery Institute, artificial selection can’t produce change beyond a certain point, so that dogs will always remain dogs. The ability of mutations driven by natural selection to produce new species is one of the fundamental elements of evolutionary biology.
Luskin attacks the show’s main points with lengthy quotes from biologists and some added commentary. The response attacks the show point-by-point. Tyson draws criticism for not pointing out the flaws in evolutionary biologists’ Tree of Life. Luskin’s response ends by arguing that the evidence for a purposeful intelligent designer is compelling.
When Neil deGrasse Tyson spent an episode of Cosmos explaining evolution, and added in a critique of intelligent design the response revealed a real threat perceived by proponents of creationism.
By Chester Davis