Let me be clear, I am an evangelical Christian. My view is definitely not in line with the "young earth special creation" theology that is a most vocal viewpoint, but not the most widespread one. Most Christians, if they think about it at all, accept some form of evolution and assume God intervened somehow, to create the human spirit. So let me just say that I understand evolutionary science very well, and I accept natural selection as the best biological explanation for all the life on Earth. Whether life, and humans in particular, arose biologically is really up to God, and He has so far declined to express a public opinion.
Accepting for the nonce a biological origin for human life, we must learn a better way to understand the process. I have read a few times from various authors that evolution does not proceed in a straight line from less advanced to more advanced, but that the "tree of life" is rather like a branching bush, and the fossils and archaeological material we are able to gather give us a glimpse here and there about our biological and social history.
In Masters of the Planet: The Search for Our Human Origins, Ian Tattersall probably discusses every one of the species so far known that either led to the origin of humans, or were related species that our ancestors would have occasionally encountered. It is becoming clear from the fossil record that there were usually several species of hominin in existence at any one time. The fact that many of us can now get a genetic test to determine how many of our genes are actually Neanderthal or even Denisovan, attests that there was indeed contact between early human and human-related creatures. For a Euro-American such as myself, the Neanderthal contribution is about 3%.
A major, major theme of Dr. Tattersall's is that in our behavior, and particularly the complex language skills that underlie our symbolic mode of thinking, we differ dramatically from other apes and from the related and ancestor species for which sufficient anthropological information can be discerned. We literally cannot imagine a non-symbolic inner life. I was speaking to my French professor many years ago, about the "breakthrough" experienced by French students when they first dream in French. At some point she asked, "Don't you ever dream without words?" I said I didn't think that is possible. At least, it never happens for me; some parts of a dream may be "observation", but if another person is present in the dream, there is always speech. Even the more, I told her, I have an inner dialog running at all times, and frequently, when I close my eyes, I can hear it.
The chapters of the book follow a rough time sequence, outlining hominin development from "bipedal apes" through more and more modern body types, plus a number of variations. There were always a few various, related species present simultaneously. For example, just under two million years ago, when the "Turkana boy" lived, that youngster represented a gracile (slender) body style very similar to ours, though his bones were thicker-walled indicating great strength. Another species present around that time was a more robust hominid: Homo ergaster, if that name still applies. This name, by the way, is being used for a kind of grab-bag of fossils that almost surely represent several species. There are also fossils that overlap this era that are termed "hyper-robust". So the Turkana boy was kind of like a basketball player, with others which lived at the same time that would be more at home among the Philadelphia Eagles (and might be able to carry two of them down the field!), plus some of more middling robustness…truck driver types?
The success of the species that led to us, and related species, was by no means assured. There had to be a compelling reason for upright stance, for example, because the grasslands that began to develop a few million years ago were dangerous places. Social organization must have been the key attribute that allowed a weak, hairless biped, that couldn't yet run the way we can, to traverse open country and not be eaten posthaste.
The last four chapters cover in detail the transition from "archaic human" to "anatomically modern" humans, and finally to "behaviorally modern" people. The last step is the hardest. Homo sapiens of the Cro-Magnon variety had a big brain, but so did their Neanderthal cousins and perhaps another 2-3 species. But starting about 80,000 years ago, and culminating some 60,000 years ago, that brain began to work a lot differently. Cultural artifacts show the difference. The first decorated objects are 75,000-77,000 years old. Paintings in caves as old as 41,000 years have been found. Furthermore, when African humans entered Eurasia, probably along the north edge of the Sinai peninsula, they soon spread to all corners of the earth, including areas the Neanderthals apparently considered too cold for them, and into Australia, which no other hominids seem to have entered.
Dr. Tattersall discusses how and whether this change was something waiting to happen because of other characteristics that had developed, called exaptations by evolutionary scientists. It is hard to imagine that the sudden symbolic flourishing arose by a series of closely spaced special mutations. Brain functions that arose for other reasons must have facilitated the development of language.
We don't yet know very much about it. How much more we might learn, it is hard to say. On one hand, we are "naked apes" (per the 1967 book by Desmond Morris). On the other, we have a symbolic inner life that no other creature has been shown to have, and we have ultra-complex social organizations that are different not just in size but in kind from anything found elsewhere among other animals.
The last chapter focuses on speech, using the opening phrase from the Gospel of John, "In the beginning was the word." It really is words that make us what we are. Cute Geico commercials aside, Neanderthals and all other hominids didn't speak as we do. None of their cultural artifacts show evidence of the kind of symbolic thought that we take for granted. They were clever and capable, and functioned quite well for tens of thousands of years, and their extinction is still a bit mysterious (no, our ancestors probably didn't eat them; more likely, they ate everything else and left nothing for them).
Lest we fall prey to hubris, just because we can think symbolically, doesn't mean that we all are great thinkers. People are lazy, and most folks prefer to avoid thinking too much. Not everyone reports a continuous inner voice. There is a reason that many jobs such as factory assembly line work are called "mindless": It isn't hard to learn the task, and in very little time a person is doing it over and over without noticing much of anything along the way. The fact that so many such tasks are now being performed by industrial robots shows how mindless they are. No robot has yet achieved the smarts of the average cockroach.
I'll wind this up. The book is fascinating, it conveys a ton of information, and it sets a foundation for anyone reading it to evaluate future discoveries by hominid paleontologists. It is a must, even if you happen to believe in "young earth special creation." It is never wrong to learn the stories the rocks tell.
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