Alan de Queiroz

I have to confess I was pleasantly surprised with this book. Judging only by the title, I read it thinking I was about to learn more about the evolution of our genus, and thus enhance my understanding or our own evolution. By reading it, I was taken into a completely different journey, one that took me to the heart of the complexities of life’s dispersion, challenging my many assumptions on the subject. And this makes the book interesting in two ways.

First, if you, like me, are unaware of biogeography as a scientific endeavor, this book will not only show you the history of the discipline, but also map its controversies, its main characters, and the current state of the art as far the author goes.

The second may be implicit, and not immediately obvious, but it relates to the way we tend to think about evolution and the development of life in general on our planet. Maybe it’s something unavoidable and that it relates to the way we humans tend to think in generic terms. We tend to prefer neat explanations, preferably simple and narratively compelling. However, that’s not how things happen or have happened to life. Deep is the deep history of time, and life, having been around such a long, long time throughout that history, makes what seems impossible at some point not only possible, but factual. Elaborate way to say that life, in all its complexities and long history, has managed to find innumerable ways to keep on going, to keep on striving, notwithstanding the many geological pressures it had to cope with.

So this book had the merit of making me rethink a lot of things I thought I understood, and many of my presuppositions about how life has spread about and occupied the whole of earth. If you, like me, have any interest in these topics, maybe you’ll find it as interesting as I did.… (altro)

Biogeography is the science of where various life-forms are found and, more importantly for this book, why. Given that an animal species, say, evolves in some particular place, how come that the same, or closely related, species may often be found in regions of similar climate but separated by seas, mountains, and other barriers that the animal does not ordinarily cross?

Apart from deliberate or accidental transport by humans - very important during the last few millennia but essentially irrelevant for the bulk of biological history - there are basically two types of explanations: long-distance dispersal and vicariance. The former is the chance successful dispersal across an "impassable" barrier, such as a storm blowing a bird across a sea too wide for it to fly across ordinarily. The latter means that an originally continuous range was broken into disjunct parts by some sort of environmental change: a sea opened, a land bridge sank, a warmer climate drove an originally lowland species up into mountain refugia.

Few would deny that both kinds of thing happen, but there has been strong disagreements about their relative importance. Darwin was much exercised by the possibility of plant seeds being carried across oceans by birds and similar kinds of long-distance dispersal. Around 1900 many biogeographers, convinced that such dispersal is very rare, felt justified in assuming former landbridges crisscrossing the oceans solely on the grounds of animal distributions. Around the middle of the 20th century an "extremist" school of vicariance biogeography, sometimes called panbiogeography, arose that, inspired by the then-new revelations of plate tectonics, held that the splitting and joining of continents was the overwhelmingly most important factor in determining distributions. This school was highly influential for a while but is now in retreat in the face of mounting genetic evidence for recent (geologically speaking) dispersals.

The book combines this intellectual history with an layman-friendly introduction to biogeography in general. It's a good read, but one might be slightly wary about the fact that de Queiroz is very much part of the dispersal-is-more-important-than-vicariance camp, and so no neutral chronicler. The title refers to the fact that New World monkeys by all appearances must have made it across the South Atlantic from their African point of origin, presumably on a natural raft.… (altro)

How is it that similar species can be found as far away as Africa and South America? This question has been raging at least since Charles Darwin. Until then, the generally accepted answer was God. Darwin, on the other hand, believed that it was caused by dispersal – seeds and insects carried on birds’ feet or on floating debris or even icebergs in the ocean – and experimented with radish seeds and sticks to prove his theory. That theory was fine for small insects and plants over short distances but what about longer distances and bigger animals like, say, monkeys. It would take a miracle for a monkey to survive the trip from Africa to South America and scientists rarely believe in miracles.

Then in the 1960s, the theory of tectonic plates and continental drift was proven, leading to a more scientific solution – vicariance which is when a georgraphical area breaks into separate parts creating a barrier between members of species so that the disparate members then evolve differently (*phew* I hope I got that right). When Gondwana, the supercontinent in the southern hemisphere, broke apart, monkeys and other species of plants and animals were left to follow different evolutionary paths on opposite sides of the world. This made more sense than Darwin and his ‘damned, benighted dispersalism’ and so dispersalism was tossed on the trash heap of scientific history never to be considered by rational scientists again.

Well, no, not never because, within a couple of decades, new scientific discoveries were making the theory of vicariance less tenable. According to the vicariance argument, Africa and South America split 100 million years ago but molecular-clock studies show that African and South American monkeys didn’t split until just 30 – 50 million years ago. Plus, monkeys didn’t appear in South America until 26 million years ago according to author Alan de Querioz, “as if out of thin air”.

So what is the explanation? Well, as it turns out, de Querioz makes a pretty compelling argument that perhaps scientific miracles, or at least near-miracles, do happen. According to him, the answer is “land rafts’, which periodically break off from continents and drift over very long distances. When the first monkeys arrived in the new World some 40 million years ago, the Atlantic was only 900 miles wide. With strong winds and currents, the trip could have taken as little as a week.

The Monkey’s Voyage is a fascinating attempt to explain not only the evolution of species but the evolution of scientific thought. Along with the science, de Querioz peppers the book with some often funny anecdotes about the men behind the science. His writing style is open, intelligent, honest (he admits when the evidence doesn’t match the theory) and, at times humourous, making the science easily accessible and, dare I say, fun.

Disclaimer: I am not a scientist so don’t go by anything I have written. Read the book, instead, because, in simple layman’s terms (ie. Mine) it’s one heck of an interesting read.… (altro)