Chapter 32

You are allowed teach that here

Lecture by Jerry Coyne, part of the series of E. O. Wilson lectures. His recent book is Why Evolution is True.

Comment from audience member: Why talk about this here? "Surely everyone here believes in evolution." This was clearly not true, as one noted during the question period. Surprising questions about the basic concepts of evolution showed a serious lack of understanding in the audience.

Evolution is still not a widely accepted idea, at least not in this country. Fewer than 30% of people surveyed in the U.S. say that they agree with it, which ranks us 31 out of 32 industrialized countries surveyed. Even worse: the idea that higher organisms (e.g., us) evolved from earlier species is accepted by only 16% of the people. [Yikes!]

Is evolution true? Stephen Jay Gould said, There is so much evidence that it would be perverse to deny it.

What is "evolution" as scientists understand it? First, what's a theory? A set of propositions to explain the world. Evolutionary theory includes at least these ideas:

  • Evolution: Life changes over time.
  • Gradualism: Changes in life forms are gradual.
  • Speciation: Forms of life grow into separate branches, which we observe as species.
  • Common ancestry: The branches derive from common ancestors.
  • Natural selection: The process driving adaptation of populations is natural selection acting on naturally occurring variation.
  • Non-selective processes: Other factors can produce change in populations, but not adaptation.

Here's how he defines "Darwinism" in his book: "Life on earth evolved gradually beginning with one primitive species -- perhaps a self-replicating molecule -- that lived more than 3.5 billion years ago; it then branched out over time throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection."

The fossil record is not perfect. It is not always possible to find the single direct ancestor of a modern form, nor all the transitional forms from some distant ancestor.

Vestigial features in current species make sense only in light of evolution. Vestigial feature = a feature of a species that was an adaptation in its ancestors, but has either lost its usefulness completely, or has been coopted for new uses. (Coyne uses the term "retrodictions" sometimes.) Examples:

  • Hind limb buds in dolphin embryo at 24 days;
  • Hair on human fetus at six months;
  • Vestigial hind legs in whales;
  • Wings of flightless birds;
  • Vestigial non-functioning genes: yolk proteins, vitamin C, olfactory genes in humans.

Lots of examples of bad design, solutions Gerry-rigged from something else that appeared in the ancestor, e.g., prostate gland.

Real-time evolution is seen, e.g., in the beak of the finch in Galapagos. A time of severe drought, small seeds were all gone. The beak average size across the population grew 10% in a single year.


  • 63% of people in the U.S. say that they believe in angels.
  • 70% say they believe in hell.
  • Religion was as useful, comforting, in oppressed societies where there was high inequality. (And, yes, that inequality is growing again right now.)
  • Why do some people hate evolution as an idea?
    • Humans are not special.
    • All life is the same.
    • We have no special purpose.
  • If a fact contravenes an article of faith, 64% of people in the U.S. will reject the fact.

And, as a footnote, he thinks that E. O. Wilson is wrong on group selection. Sterile worker bees help the queen make many copies of their genes. [I heard the assertion but didn't understand the argument.]