The Time Before History: 5 Million Years of Human Impact - Colin Tudge I wasn't impressed with the writing in the first Tudge book I read, Trees. The subject matter turned out to be fascinating; I learned a great deal about trees, their impact on the environment, and their importance to the biosphere but the booked dragged on and on.

This was not the case with The Time Before History, a terribly interesting look at human evolution and how it's impacted our environment and how it might impact it in the future.

The first half of the book sets the stage, discussing how the environment works, how it changes over time, and the role of animals in regulating it. Tudge makes one of the best defenses of evolutionary biology that I've ever read, and there's a wealth of interesting information that I had not known before. Vid.: I never knew that the upthrust of the Himalayas leached carbon dioxide from the atmosphere, causing a cooling effect (an "icebox world") that forced the early hominids out of the deep jungle and into more open forest lands.

Tudge also makes the most understandable case for the transition from hunting/gathering to farming that I've ever seen. Essentially, it was a combination of three factors: (1) He argues that humans had been opportunistic cultivators for as much as 20 millennia before the Agricultural Revolution c. 10,000 BC; (2) the mass of land under cultivation reached a critical point where it was interfering with traditional hunting lands; and (3) there was a climate shift that further reduced the availability of prey and made humans more dependent on crops. These factors tipped the balance permanently toward agriculture and was the key to (as the Pentagon might say) Man's "full spectrum dominance" of his environment. From an individual point of view, farming 'sucks' -- it's hard physical labor and subject to the fickle whims of uncaring Nature and (if that weren't bad enough) it ushered in an era of physical disability (diseases, malnutrition, etc.) and social stratification (all the ills of urban civilization we've been trying to cope with since Sumer, at least). From an evolutionary point of view, however, it gave our species the definitive edge over all others and it gave farmers (as a group) the edge over hunters, pushing them to the periphery.

The last chapter of the book takes a look at where Man is headed in the next 500-1,000 years and a million. Here I think Tudge is a bit optimistic. He sees population topping out around 10-12 billion and then slowing falling back toward 5-6 billion over the next 5 centuries or so, and that in the long term, humanity and Earth will reach an equilibrium: We're going to lose a lot more biomass before things settle out but we'll survive it.

To get there, though, he argues that we need to cultivate an "economy of reverence" rather than an "economy of exploitation." Exploitative economies have succeeded in the past because there's been vast scope for waste -- before the modern era, localities often exhausted their resources but overall there was scope for expansion and experimentation. Today, the situation is far different and exploitation is a recipe for disaster -- there's no more room to waste. Of coures, we've seen a move toward economies of reverence in the last few years but I'm afraid it's the usual human reaction of "too little, too late" and our future is going to look a lot more like Soylent Green than Star Trek.