What Darwin Never Knew
How did the discovery of DNA prove that Darwin’s theory of evolution was correct and how does it change the way we view evolution today and into the future?
Michael Nackman of the University of Arizona studied how some of the Pincate Desert’s pocket rock mice evolved to blend in with volcanic rock. A mutation in the mouse’s DNA changed its fur colour from light to dark. Now, rock pocket mice exist with light or dark fur.
Sean Caroll studied why one fruit fly species has spots on its wings, but another does not when the two species both have the spot-coding gene. One DNA portion differed in the spotted fly. Injecting this DNA portion into the non-spotted fly resulted in spotted wings. These DNA portions are called switches, and they activate and deactivate genes.
David Kingsley and Dolph Schluter studied why the ocean stickleback has spikes on its belly, but the lake stickleback does not. A mutation in the lake stickleback’s DNA broke the switch that activates the spike-coding gene. The gene that codes for the stickleback’s spikes also codes for hind legs in other animals.
Arkhat Abzhanov and Cliff Tabin studied how the Galapagos finches have different beaks by looking at the birds’ embryos. The birds had the same beak-coding genes, but they differed by how much and when the switch activated the gene.
Neil Shubin of the University of Chicago studied how fish evolved to walk on land. He found a fossil of a flat-headed fish with leg-like fins. They had the same bone structure as the limbs of all other four-legged animals. In the paddlefish, a relative of the fossil Tiktaalik, the same genes code for fins as they code for limbs in humans. A few mutations changed the ancient fish’s fins to limbs.
Through the study of DNA, scientists have discovered that mutations in the genome cause evolutionary change. Switches in an organism’s DNA activate and deactivate hox genes that code for physical features. Mutations can affect these switches, therefore affecting the organism’s physical features. This proves that Charles Darwin’s theory of evolution was correct. We can now discover how almost any organism differs from another, and how it evolved and came to be.
• What Darwin Never Knew notes & transcript
Bacillus anthracis and Escherichia coli are members of the Eubacteria Kingdom because they have prokaryotic cells, are unicellular, and their cells have a cell wall of peptidoglycan.
Halobacterium salinarium and Sulfolobus acidocaldarius are members of the Archaebacteria Kingdom because they have prokaryotic cells, are unicellular, and their cells have a cell wall containing uncommon lipids.
The Aegagropila linnaei and the Undaria pinnatifida are members of the Protista Kingdom because they have eukaryotic cells, and their cell wall is cellulose.
The Hericium erinaceus and the Hydnellum peckii are members of the Fungi Kingdom because they have eukaryotic cells, are multicellular, are heterotrophs, and their cell walls are chitin.
The Hydnora africana and the Rafflesia arnoldii are members of the Plantae Kingdom because they have eukaryotic cells, are multicellular, are autotrophs, and their cell walls are cellulose.
The Hydropotes inermis and the Nasikabatrachus sahyadrensis are members of the Animalia Kingdom because they have eukaryotic cells, are multicellular, are heterotrophs, and have no cell wall.