Course Hero. "A Short History of Nearly Everything Study Guide." Course Hero. 18 Jan. 2018. Web. 20 Feb. 2018. <https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/>.
Course Hero. (2018, January 18). A Short History of Nearly Everything Study Guide. In Course Hero. Retrieved February 20, 2018, from https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/
(Course Hero, 2018)
Course Hero. "A Short History of Nearly Everything Study Guide." January 18, 2018. Accessed February 20, 2018. https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
Course Hero, "A Short History of Nearly Everything Study Guide," January 18, 2018, accessed February 20, 2018, https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
The chapter begins and ends with a discussion of axes, the first advanced tool, to examine human movement. It begins with the Acheulean axes created approximately a million and a half years ago in Europe, Africa, western and central Asia. They have not been found in the Far East, which puzzles scientists since Homo sapiens seemed to have reached there. In another puzzle paleoanthropologists realized in 1968 humans had been in Australia for as long as 60,000 years, but no one can explain how they managed to colonize an island so long ago. Bryson emphasizes as he did in the previous chapter the lack of a robust fossil record is a large reason why such problems exist.
The traditional theory explaining the migrations of Homo sapiens is there were two waves out of Africa. The first wave was composed of Homo erectus, which eventually evolved into Homo heidelbergensis and ultimately Homo neanderthalensis (Neandertals). In the second wave were the first Homo sapiens. However, there are researchers who say there was only one migration and only one hominid species that evolved continuously. In this theory, called multiregionalism, Homo erectus is a "transitional phase." Yet others argue that Homo sapiens may not have arisen from Africa at all, but rather from Asia. Part of the reason for this confusion is the fact "we know less about ourselves, curiously enough, than about almost any other line of hominids."
Increasingly, researchers have turned to ancient DNA, specifically mitochondrial DNA for answers. Discovered in 1964, mitochondrial DNA is passed on only through the mother and mutates rapidly, making it a good marker for tracking genetic histories. Using it, scientists found in 1997 the DNA of a Neandertal man was "unlike any DNA found on Earth now." Another study concluded modern Europeans are descended from "no more than a few hundred Africans." However, even the genetic evidence doesn't provide straightforward answers. Bryson quotes British scientist Rosalind Harding as saying there were likely "multiple migrations and dispersals in different parts of the world."
In this chapter Bryson returns to some recurring main ideas. First, major gaps exist in scientists' understanding of many processes. Paleontology is just one field where conflicting theories prevail, in part because of a scarcity of evidence. Second, genetic research promises new advances in many fields, paleontology included. He explains the shift from fossil evidence to genetic evidence to solve the mysteries of the advent of Homo sapiens.
However, despite new sources of evidence, the understanding of early hominid evolution has not been clarified. In many cases there appears to be a conflict between fossil-based evidence and genetic evidence. The most robust findings, though, are increasingly the result of genetic evidence. Ultimately, paleontologists need to find and study many more hominid fossils before science fully understands the history of the human species.