Below is an HHMI BioInteractive short film on the epic voyages of Darwin and Wallace that led each to independently discover the natural origin of species and to formulate the theory of evolution by natural selection.
Many textbooks are smothered with Charles Darwin as being the “father” of natural selection, rarely mentioning Alfred Wallace at all. In scientific circles, both men are credited with arriving at natural selection theory independently.
It is important to note that their theories were not entirely identical. Darwin’s theory is more focused on individual struggle while Wallace’s tends to concern itself with populations and groups. Wallace possessed more combined field time than Darwin, and in my opinion, Wallace explored more smaller isolated lands than Darwin which led to the Wallace Line – an imaginary boundary line separating ecozones that explains the differentiation of species among groups.
There is a richer backstory to both Darwin and Wallace, but to end this blog post, be comforted in knowing that they remained friends, despite minor disagreements. For example, Darwin believed that animal breeding could demonstrate natural selection, but Wallace always disagreed, arguing that such demonstrations are examples of artificial selection rather than natural selection (Wallace was correct). The short film below highlights how both men arrived at their theories.
Millions of years ago, the first eyes calmly yawned at the sun’s light that massaged the earth. These primitive eyes did very little but detect light that helped organisms to establish day/night cycles and allowed them to coordinate behavior. Throughout time, eyes became more complex as organisms evolved more complex bodies and behaviors. This led to a gradual series of fine-tuned focusing muscles, better optics, and morphological changes that provide a survival advantage to animals in detecting prey – or predator.
Below are some resources and videos regarding the evolution of the eyes.
This video, “Eyes,” is part of the “Evolve” History Channel 11-part series that looks at the evolutionary origins of a particular trait. “Eyes” is the evolutionary story of how the eye was molded into the exquisite complicated organ we see today.
Here’s a TED-Ed animated story on “The Evolution of the Human Eye” by Joshua Harvey.
“To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I confess, absurd in the highest degree…The difficulty of believing that a perfect and complex eye could be formed by natural selection , though insuperable by our imagination, should not be considered subversive of the theory.” –Charles Darwin