The modern scientific method of finding out truths about the world, the universe, originated 500 to 600 years ago in Europe. It has produced the estimates of the time of origin of major events of natural history of interest to this class as listed on the handout.

Timeline handout:

The origin of life on Earth was approximately 3.6 billion years ago. The first life forms or species were single celled and cloned to reproduce. Cloning means an organism makes a copy of itself to produce the next generation. The origin of sexually reproducing species was approximately 1.2 billion years ago. Reproduction is necessary to perpetuate species because individual organisms are mortal.

Dinosaurs’ origin approximately 240 million years ago and extinction 65 million years ago is an example of Darwin’s principle of NATURAL SELECTION against. There were other mass extinctions prior to the dinosaur mass ( many different species) extinction.

The dinosaur extinction was probably due to a comet or meteor striking and exploding like many , many nuclear bombs on the earth ; and throwing so much debris up into the atmosphere that it blocked much of the sun’s light for many, many years; and thereby killing much plant life that was the food of the dinosaurs.

Mammals ( we are mammals) lived simultaneously with dinosaurs. They were small , furry animals relative to dinosaurs, and the reduced amount of plant food was enough for their smaller bodies to survive the loss of plant life. Thus, mammals were SELECTED FOR in the Darwinian sense. Mammals were fit relative to dinosaurs; survival of the fit species.

Charles Darwin’s law or theory of evolution has two main parts. Most people who know of Darwin’s law are familiar with his idea of 1) NATURAL SELECTION. However, Darwin also found that 2) ALL LIFE IS RELATED TO ALL OTHER LIFE THROUGH COMMON ANCESTRAL SPECIES. This is the principle of PHYLOGENY as represented by a “THE TREE OF LIFE” diagram.

The Tree of Life represents COMMON ANCESTORAL relations between different species at nodes of branching on the Tree diagram ( see handout of Primate Order section of Tree of Life).The Tree of Life diagram implies a timeline from bottom to top. Thereby it represents EVOLUTION by NATURAL SELECTION of new traits and retention of some old traits. The primate order is an order of the mammal class. ( all primates are mammals ; not all mammals are primates; increasingly inclusive categories as we go down on the Tree of Life).

Three characteristic traits of mammals are ,1) mammary glands to feed the young, 2) warmblood ,3) bodily fur. Primates retain these traits; and primates evolved stereoscopic vision as an adaptation to living in trees. This is not to be confused with the Tree of Life metaphor ; primates actually did live in trees. Stereoscopic vision, by way of eyes in front of the head forming a parallel lines of sight , gives sharper vision at a distance. Thereby, primates didn’t fall out of the trees to death , and could catch insects more exactly.

It was Darwin’s claim that all life is related through common ancestral species INCLUDING HUMANS (!) that was controversial (not so much natural selection), because it conflicted with the Christian doctrine of human origin by God’s creation in the Garden of Eden.

The idea that humans had evolved out of an earlier ancestor AT ALL was controversial. Darwin specifically hypothesized that the living species with the closest back in time or fewest generations back to a common ancestor with humans are chimpanzees; and that humans originated in Africa. Subsequently, scientists explored parts of Africa looking for fossil remains evidence of a so-called MISSING LINK species. The idea is links in a chain as representing a line of species , one link descending from the previous links. The “missing link” would connect humans to our common ancestor on the Tree of Life with chimps.

A fossil with characteristics constituting a link between a human “link” and a chimp “link” was discovered by Raymond Dart in Southern Africa ; and subsequently by many others . This proved Darwin’s claim true.

Dart found a fossil with a chimp sized brain BUT BI-PEDAL, OR HABITUALLY WALKING ON TWO FEET INSTEAD OF FOUR (quadrapedal). The phylogenetic-Tree of Life classification term for habitually bi-pedal primates is HOMININ.

... Last class I mentioned the LaMarckian _false_ evolutionary hypothesis concerning how the giraffe species evolved long necks out of short necks. This has been termed INHERITANCE OF ACQUIRED CHARACTERISTICS. It is wrong in that a giraffe stretching its neck to reach food higher up would _not_ pass on to its offspring the characteristic or trait of a longer neck. If a longer neck were acquired during a parent’s lifetime it would not be inherited by their offspring. _However_, with CULTURE and LANGUAGE, we humans do have a LaMarckian -LIKE ability to pass on cultural “traits “ to offspring. Cultural inventions, “acquired” or invented during the lifetime of parents and grandparents can be inherited by children and grand-children through language and culture