Tuesday, March 25, 2014

Neil deGrasse Tyson's Cosmos On Evolution

This past Sunday in India the second episode of Neil deGrasse Tyson's Cosmos was broadcast on National Geographic. The title was "What Molecules Can Do" and it was all about the evolution of life on earth. I quite enjoyed it. .. Just a couple of quibbles.

Dog evolution was showcased as an example of artificial selection which then Dr. Tyson used to argue for the efficacy of natural selection. It was depicted in cartoon form and the dog cartoons though showed quite a modern looking dog barking and scaring a wolf away from a campsite. This was meant to show the very early relationship  between dogs and humans. Early dogs wouldn't have looked as depicted in that frame. Its hard to point to modern dog breeds and find an analogue for the earliest dogs because they have changed so much and so late in their history. Still, a more smaller version of a wolf with a stubbier face would have been a best representative of early dogs, and not the hairier house pet looking one.

Later in the show Dr. Tyson wanting to emphasize that evolution is true says that the the "theory of evolution is a fact". That is a little confusing.  Evolution is a fact. Life has changed over the past 4 billion years and the theory of evolution is a theory that attempts to explain how it happened. There are many theories of evolution. Some like Lamarck's theory rely on organisms responding to environmental stimuli and the inheritance of acquired characters to explain change. Creationists in their garb of Intelligent Design have faith in an unknown intelligence guiding natural processes. Modern evolutionary theory that adds on to Darwin's and Wallace's insights is the most successful one.


  1. "Modern evolutionary theory that adds on to Darwin's and Wallace's insights is the most successful one". Can you really say it's the 'most successful' one when the others you mentioned don't even show up to the ballpark of the scientific method?

  2. Anon- fair point.. I guess "only scientific and successful one" would be a better way to put it.. :)

  3. I am still curious as to the mechanism and speed with which evolution by natural selection itself happened, like was it "punctuated equilibrium" or was it a slow and steady (continous) mode of evolution, or was it a combination of the two, or some altogether third process. Not many programs discuss this unforturtunately.. Thanks, Mohan

  4. natural selection along with random genetic drift are mechanisms of evolution while punctuated equilibrium refers to the tempo or pace of morphological change seen in the fossil record and its significance. as was originally proposed by Eldridge and Gould it said that morphological change is concentrated in short bursts during cladogenesis i.e. when a new species buds off from an ancestral species. This change in morphology can be driven via natural selection or drift. Gould later retracted somewhat from this position and suggested that change could occur at any time during the life of a species but it is only when a population gets reproductively isolated that any directional change gets fixed or becomes permanent enough to show up in the fossil record. then there are examples of lineages changing in a slow and steady fashion to.. so can't generalize.. nature has examples of both..