TTC Video What Darwin Didn’t Know: The Modern Science of Evolution

TTC Video – What Darwin Didn’t Know: The Modern Science of Evolution
Lecturer: Scott Solomon, PhD

Writing the final pages of his masterpiece The Origin of Species, Charles Darwin looked ahead to the work yet to be done on his groundbreaking theory of evolution by natural selection. “In the distant future,” he predicted, “I see open fields for far more important researches.”

The discovery of the rules of heredity;
The identification of DNA as the carrier of genetic information;
Fossil discoveries that fill major evolutionary gaps and offer new insights;
The ability to read the genetic code of any organism; and
The power to manipulate genetic material.

The Theory of Evolution Takes Off

• Natural selection in real time: Darwin believed that evolution always advances with extreme slowness. But biologists in the field have documented wild species-from Galapagos finches to flies infesting fruit-that acquire useful adaptations with stunning speed, sometimes in only a few generations.

• Universal genetic code: Darwin introduced the “Tree of Life” and the possibility that all of life evolved from a common ancestor, a view that was largely rejected in his own time. But biologists have demonstrated that every known type of life-from bacteria to human beings-uses the same DNA code inherited from a single ancestor.

The Road to Humans

Darwin did not deal with the evolution of humans in The Origin of Species, saving that controversial topic for The Descent of Man, which he published in 1871. Together with his colleague Thomas Henry Huxley, Darwin argued that humans share a common ancestor with the great apes, based on the many similar anatomical features we share with them. In What Darwin Didn’t Know, you learn that the evidence for this connection has grown impressively since Darwin’s day. For example, recent DNA analyses show that our closest living relatives are chimpanzees. Next closest are gorillas and then orangutans. While the last common ancestor of all four lived around 10 million years ago, we shared a common ancestor with chimpanzees until as recently as 5 to 7 million years ago. You also explore the following intriguing findings and conjectures about human evolution:

• Neanderthals and Denisovans: Two extinct branches of the human family tree are the celebrated Neanderthals and a recently discovered species or sub-species called the Denisovans. Both interbred with humans at some point, and a small percentage of their DNA has spread widely through modern human populations.

• The future of Homo sapiens: Is human evolution over thanks to modern medicine? Some biologists think so, but major evolutionary changes may be in our future as we exploit our ability to edit the human genome. Furthermore, any humans who leave the planet will face strong evolutionary pressures in extraterrestrial environments.

Evolution Is Inevitable

Professor Solomon points out that Darwin didn’t just suggest that species can evolve. One of the most important messages from the modern science of evolution is that evolution is a necessary feature of life. As long as life includes heredity and reproduction, all living things will evolve. Even a species that appears to have stayed the same for millions of years will turn out to have undergone many small changes, just to keep up with a changing environment. In short, evolution isn’t just possible. It’s inevitable.

In the final paragraph of The Origin of Species, Darwin slyly compared his discovery of evolution by natural selection to the revolution wrought by Isaac Newton with his law of universal gravitation. “There is grandeur in this view of life,” Darwin wrote about his theory, “.that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

Just as Newton had no idea about Einstein, Hawking, or his many other successors, so Darwin was in the dark about the brilliant scientists who would build on his work, creating the biological golden age that we are living through today-a story told masterfully by Professor Solomon in this thrilling course.

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