So, there are monkeys in South America and in Africa. How did they get there? That’s essentially what Alan de Queiroz wants to answer in The Monkey’s Voyage: How Improbable Journeys Shaped the History of Life, albeit in a roundabout way.
If you’re a creationist, especially a young-Earth creationist, you don’t have to worry too much about this. The answer is “God did it!” (Or possibly, “God did it, praise Jesus!” if you are feeling particularly devout at the moment.)
Alas, I am not a creationist, so I have to look to science for an answer.
In school, I learned that the continents move. I know, right? But it’s a real phenomenon, called continental drift, and it’s powered by this even cooler phenomenon called plate tectonics. Unlike the way we learned it in school, though, the discoveries of drift and plate tectonics didn’t go smoothly. There were a lot of bumps in the road, as de Queiroz recounts.
But what about those monkeys? Well, the problem is that South America and Africa were last connected millions of years before the New World and Old World monkeys became separate species. What’s up with that? Did they pull a human-migration and come down through a Siberian land bridge? Why aren’t there any monkey fossils in Canada, then?
Because they floated on tree rafts.
I’ve said it before; I will say it again. Science is awesome. Science does not remove wonder from the equation; science amplifies the wonder. If there is anything more wonderous than the ponderous million-year movements of continents, it’s the image of intrepid animals, clinging to an impromptu raft of floating trees and soil as the currents carry them towards another continent or an oceanic island far offshore.
This is essentially the sentiment de Queiroz tries to convey with The Monkey’s Voyage. He certainly shows off his own passion for science and wonder for nature in his personal anecdotes about trips to New Zealand and throughout the United States. His narrative is complicated by the fact that, unlike, say, plate tectonics or global warming, this theory of biogeographic long-range dispersal through things like rafts, birds, etc., is not yet a consensus. There is still a strong contingent of scientists who believe that long-term dispersal plays no role in the distribution of species and support an all-out theory of vicariance—distribution via continental drift and more conventional, shorter-duration dispersal.
But this is a brand of exciting in itself. So many science books present scientific discoveries to readers as a fait accompli: “Look at this wonderful shiny theory! Look at all this evidence we have! All the other competing theories have bitten the dust!” And then there is much champagne-opening and sexy partytimes. (Except there is no sexy partytimes, because scientists do not get invited to those sorts of parties.) Instead, The Monkey’s Voyage involves some very cutting-edge, very much “of the moment” science. De Queiroz is obviously confident enough in disperalism to have written this book, but he diligently presents both disperalist and vicariance views, as well as the many and sundry perspectives within these camps. (I should mention that de Queiroz isn’t saying that dispersal or vicariance exclusively explains the distribution of species. Rather, he chronicles the changing opinion within the scientific community from primarily-vicariance to vicariance-and-dispersal.)
De Queiroz says that he hopes “to explain what this dramatic shift in thought tells us about both the nature of scientific discovery and the history of life on a grand scale”, and in this respect I think he succeeds admirably. I’ve read a lot of history of science books, and they often explain how scientific exploration and discovery has changed over the centuries (usually by using words like rigorous). They seldom paint a good picture of what it was like to do science in the twentieth century, however, by which time philosophies of science and the scientific process were well-entrenched, sometimes dogmatically. With occasional shout-outs to Popper and Kuhn, de Queiroz looks at how people’s attitudes towards scientific discovery have coloured their own approaches to this biogeographic discussion. He challenges the myth that science is a monolithic thing; at the same time, he shows how all scientists are still working within a common, loose framework and towards the same goal of knowledge validated by evidence.
Still, I hesitate to call The Monkey’s Voyage a popular science book. It gets far more technical than I would expect the average lay-person to want to follow. I consider myself a fairly literate person, in terms of science, and I found de Queiroz’s explanations hard to follow at times. It isn’t just the jargon—which he acknowledges as a potential obstacle and tries to minimize—but also a problem of organization. He chunks things like a scientist, anticipates counterarguments and carefully comes up with ways rebuttals, until the result is a little too convoluted. The actual eponymous monkey chapter is buried far towards the end of the book and quite short compared to the rest.
Don’t let this deter you from reading the book if the subject still interests you. Despite the higher barrier to entry, it remains fascinating and well-written. It’s about a subject that is contemporary and still developing within the scientific community, and I think that’s very exciting. De Queiroz encourages us to think about how life has evolved along with the changing face of the planet, and that’s a very intriguing idea. It’s definitely worth a book or two. If all you are after is a light, pop sci read, then The Monkey’s Voyage will not hold your attention. But if you really want some meaty biogeography for your weekend, then Alan de Queiroz has got you covered.