Masters of the Planet: The Search for Our Human Origins, by Ian Tattersal, Palgrave Macmillan, 2012, $26.00
The Social Conquest of Earth, by Edward O. Wilson, W. W. Norton, 2012, $27.95
Scholars who teach and write about "Big History" (such as David Christian, in Maps of Time or Fred Spier, in Big History and the Future of Humanity) incorporate scientific discoveries made during the twentieth century to demolish the young earth claims that Christians have made, based upon primitive calculations derived from genealogies found in the Bible. Rather than "give heed to fables and endless genealogies" (1 Timothy, 1:4) only to conclude that the world is no more than 5,000 to 10,000 years old, historians like Professors Christian and Spier use scientific evidence provided by geologists, archaeologists, paleontologists and astronomers who have demonstrated that the universe is some 13.7 billion years old and the earth is 4.5 billion years old.
For example, during the 1920s astronomer Edwin Hubble used the Mount Wilson telescope and redshift spectroscopic readings, to demonstrate that the most distant galaxies are moving away from our Milky Way galaxy at faster speeds (now thought to be approximately 90 percent of the speed of light) than the speeds at which most closer galaxies are distancing themselves. He also "showed that by measuring the rate of expansion, scientists should be able to estimate how long the universe has been expanding."
Moreover, "if the universe is expanding, then it must have been much smaller in the past than it is now." Doing the math working backwards, you get the probability of an infinitely small universe that got its start from a "big bang," now thought to have occurred some 13.7 billion years ago. [Maps of Time, pp. 29-31]
Of course, that's not to suggest that scientists have an answer to the question of what caused "nothing" to explode into something the size of a galaxy within a fraction of a second. Lee Smolin has speculated that our universe might have originated from a black hole in another universe, but that begs the question of the origin of the universe with the black hole. In reality, cosmologists are no more capable of explaining how nothing resulted in the big bang than monotheists are, when asked: "How was God created?" Scientists cannot even rule out the possibility that "time and space may have been created at the same time as matter and energy." [Ibid, p.23]
Nevertheless, "beginning a tiny fraction of a second after the big bang, modern science can offer a rigorous and coherent story, based upon abundant evidence" [Ibid]. Scientists theorize that the big bang created hydrogen and helium atoms as well as the four fundamental forces, including gravity, which govern our universe. Further, they theorize that gravity subjected unevenly distributed clouds of hydrogen and helium to immense compression and, thus, immense heat until hydrogen atoms fused into helium. The resultant hydrogen explosions caused the formation of stars.
In support of their theory, they offer the following demonstrable facts: (1) the existence of omnipresent cosmic background radiation, (2) stars overwhelmingly composed of hydrogen and helium which (3) convert hydrogen into helium as stars age and die.
Long before our star -- the sun -- and our solar system were formed some 4.5 billion years ago, supernovae prepared the groundwork for both planet formation and life on earth by creating and blasting into deep space all of the chemicals found on our periodic table.
But, as is the case when attempting to explain how "nothing" exploded into something, scientists remain equally unable to explain how "chemical evolution" emerged into life on earth. They do not even agree on a basic definition of life.
Professor Spier defines "life" as, "A regime that contains a hereditary program for defining and directing molecular mechanisms that actively extract matter and energy from the environment, with the aid of which matter and energy is converted into building blocks for its own maintenance and, if possible, reproduction." [Big History and the Future of Humanity, p. 77]
Notwithstanding their inability to explain how life emerged, Professor Christian, Professor Spier, and Ian Tattersall (curator emeritus in the Division of Anthropology of the American Museum of Natural History, whose book is under review here) accept the conventional wisdom that life emerged on earth some 3.5 billion years ago. As Mr. Tattersall puts it, "all life forms are ultimately linked at the genomic level to a single common ancestor that lived more than 3.5 billion years ago." [p. xvi] Supporting their assertion are fossils of cyanobacteria (i.e., blue-green algae), which demonstrate that stromatolites existed as far as back as 3 billion years ago.
According to Marc Kirschner and John Gerhart (writing in The Plausibility of Life: Resolving Darwin's Dilemma), evidence from fossils demonstrate that "representative animals of all but one of the 30 major modern phyla were present" as far back as 543 million years ago. [pp. 57-58]
Primates, argues Mr. Tattersall, emerged only 60 million years ago, soon after the extinction of dinosaurs. Chimpanzees and humans split from gorillas some 9 million years ago and humans split from chimpanzees some 5 to 7 million years ago. "But whatever the exact times of the divergence, this all means that if the common ancestor of the knuckle-walking chimpanzees and gorilla also walked that way, then so must the chimpanzee-human ancestor." [Masters of the Planet, p. 13].
The first hominids (bipeds) appeared in Africa, probably some 7 to 6 million years ago. The genus Australopithecus emerged some 4.2 million years ago and appears to have been transitional, adapting from life in trees to life on land. Fossil evidence shows that Australopithecines were equipped with arms to swing from trees, but legs to walk long distances. They were using stone tools as far back as two million years ago. [p. 73]
Although Tattersall believes that the genus Homo evolved from one of the many species of Australopithecines, he acknowledges that "it is really hard to pinpoint where among these diverse creatures the origin of our genus lay." [p. 85] Nevertheless, the fossil record demonstrates the existence of many species within the genus Homo, beginning and evolving since two million years ago: Homo habilus, Homo egraster, Homo georgicus, Homo mauritanicus, Homo erectus, Homo floresiensis, Homo heidelbergensis, Homo neanderthalensis and Homo sapiens.