eBook
Related collections and offers
Overview
The astonishing new story of human origins
Was Darwin wrong when he traced our origins to Africa? The Real Planet of the Apes makes the explosive claim that it was in Europe, not Africa, where apes evolved the most important hallmarks of our human lineage—such as dexterous hands and larger brains. In this compelling and accessible book, David Begun, one of the world's leading paleoanthropologists, transports readers to an epoch in the remote past when the Earth was home to many migratory populations of ape species.
Drawing on the latest astonishing discoveries in the fossil record as well as his own experiences conducting field expeditions across Europe and Asia, Begun provides a sweeping evolutionary history of great apes and humans. He tells the story of how one of the earliest members of our evolutionary group—a new kind of primate called Proconsul—evolved from lemur-like monkeys in the primeval forests of Africa. Begun vividly describes how, over the next 10 million years, these hominoids expanded into Europe and Asia and evolved climbing and hanging adaptations, longer maturation times, and larger brains, setting the stage for the emergence of humans. As the climate deteriorated in Europe around 10 million years ago, these apes either died out or migrated south, reinvading the African continent and giving rise to the lineages of the gorilla, chimpanzee, and, ultimately, the human.
Presenting startling new insights about our fossil ape ancestors, The Real Planet of the Apes is a book that fundamentally alters our understanding of human origins.
Product Details
| ISBN-13: | 9781400874279 |
|---|---|
| Publisher: | Princeton University Press |
| Publication date: | 10/27/2015 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 264 |
| Sales rank: | 968,392 |
| File size: | 24 MB |
| Note: | This product may take a few minutes to download. |
About the Author
Read an Excerpt
The Real Planet of the Apes
A New Story of Human Origins
By David R. Begun
PRINCETON UNIVERSITY PRESS
Copyright © 2016 Princeton University PressAll rights reserved.
ISBN: 978-1-4008-7427-9
CHAPTER 1
THE EARLY YEARS
Imagine that you are standing in a desert in northern Egypt at a place called the Fayum and are suddenly transported back 33 million years in the past. You are now standing in a forest rich in biodiversity. It's daytime, and up in the trees a creature about the size of a gibbon is moving cautiously about, using its forward-facing eyes with stereoscopic vision to detect the ripest fruit, its dexterous hands to pick and peel it, and its excellent sense of smell to make sure not to stray into the territory of another one of its kind. This is Aegyptopithecus. It is one of the few animals you see in Fayum that seems familiar to you, a primate that looks like a cross between a lemur and a monkey (figure 1.1).
Because Africa is separated at this time from Eurasia by a vast body of water, the Tethys Sea, many of the creatures of the Fayum are unique to Africa, and, because many have not left descendants, they are unfamiliar to us today. On the ground there are large, weird-looking animals vaguely resembling rhinos, but with horns that are side by side instead of one behind the other. You see a variety of browsing animals that mimic rhinos, pigs, deer, and other browsers but are not related to living forms either. There is a diversity of carnivorous animals (creodonts) that also went extinct without leaving descendants. You do see some elephants, but you do not recognize them because they are the size of cows and have no tusks. Since we are near the coast, you see mangroves and swamps, with crocodiles, turtles, and a variety of water birds. Because they spend most of their time in the water you are unlikely to spot a dorudon, an ancient whale with arms and legs!
In the trees with Aegyptopithecus there are many other primates, including other catarrhines, more primitive anthropoids, and even tarsiers. There is also an array of insectivores, bats and shrewlike animals and rodents, the latter mostly ground dwelling. While the composition of the fauna at Fayum is unlike that of any modern forest, because most of the species are extinct, together they comprise an ecosystem much like the relatively dry forests of parts of equatorial Africa today.
Although Aegyptopithecus lived before the Old World monkeys and apes diverged from one another, some scientists think that the common ancestor of Old World monkeys and apes may have resembled Aegyptopithecus (see plate 4). We are blessed with a rich fossil record of Aegyptopithecus and other early catarrhines from the bountiful deposits of the Fayum depression in Egypt. Researchers first discovered fossil primates at Fayum at the beginning of the twentieth century, and researchers are still working there. For much of the last half of the twentieth century, a luminary in the field, Elwyn Simons, directed scientific research at the Fayum. Simons was the dissertation supervisor of many of the most accomplished researchers in paleoanthropology, and I am happy to know him. When we first met I learned that he had supported my application for a grant to have another look at the fossil apes of Europe.
Compared with most apes, Aegyptopithecus was small. Based on fossil evidence, scientists think it weighed about 6 kilograms (about 16 lb.). It had a large face with a prominent snout that had to be large in order to house well-developed organs, thus providing Aegyptopithecus with an excellent sense of smell, a feature it shares with living prosimians. In contrast, apes have a much flatter profile. Most prosimians mark their territories with oily secretions from scent glands and have a better-developed sense of smell than most monkeys and apes, which do not mark territories with smelly secretions. In this way, prosimians are more like many other animals that rely on scent, whereas apes have shifted the dominant sense from the nose to the eyes. We also see this reflected in the brain of Aegyptopithecus, which had comparatively large lobes in its brain devoted to processing smell. The brain of Aegyptopithecus was small and, when scaled relative to body mass, was closer to modern prosimians than to most monkeys and apes. Of course, 33 million years ago, the brains of the ancestors of living prosimians had not reached their current size, so for their time period, Aegyptopithecus was probably fairly brainy. In many ways Aegyptopithecus was an intermediate form between prosimians and anthropoids, even though Aegyptopithecus was not only an anthropoid but also a catarrhine.
Remember when I said above that the first members of a group will be hard to discern from their closest relatives because most of the characteristics that allow us to classify animals in a particular group had not yet evolved? This is the case with Aegyptopithecus. Luckily for us, however, the teeth give Aegyptopithecus away. Like all catarrhines, including us, Aegyptopithecus had a dental formula of 2:1:2:3. Let me explain. We have 32 teeth in our mouths, if they all come in normally (many modern humans have impacted or even missing last molars, or wisdom teeth). Each of our jaws — the upper jaw, or maxilla, and the lower jaw, or mandible — has 16 teeth, 8 on each side of each jaw. Eight times four is 32. These 8 teeth are used to identify the dental formula. In humans, they consist of two incisors, one canine, two premolars and three molars. New World monkeys, for example, have three premolars instead of two, as do most prosimians. So Aegyptopithecus shares with catarrhines the 2:1:2:3 dental formula.
In addition to the number of teeth in its mouth, Aegyptopithecus shares something else with most other catarrhines: the form of its teeth, particularly the molars. Aegyptopithecus has hominoid-shaped molars. In fact, it and other close relatives from the Fayum are sometimes referred to as dental apes. The upper molars have four cusps with three arranged in a triangle (trigon) and the fourth at the back inner corner of the tooth. The lower teeth are arranged in a distinctive pattern of five cusps, with a Y-shaped groove separating them (figure 1.2). We will run into this so-called Y-5 cusp pattern again later in this book, but not among Old World monkeys, which have their own specialized dental morphology.
For many years Aegyptopithecus was interpreted as a fossil ape precisely because of its molar anatomy. Its broad, flat molars and Y-5 dental pattern were considered to be shared uniquely with apes. We now know that this molar morphology was shared by the ancestors of Old World monkeys as well, but, as I mentioned, the monkeys have moved on. In a very real sense, they are more evolved than we are, at least in molar morphology.
In the Old World monkeys, tooth shape kept evolving as their teeth became ever more specialized for processing leaves and other fibrous foods. We call their teeth bilophodont, that is, a tooth (dont) with two (bi) cusps or bumps on the tooth connected by a ridge (lophs). Among anthropoids, only Old World monkeys have bilophodont molars, which they use like scissors to slice through vegetation. They are bilophodont in both their upper and lower molars, which therefore look similar to each other, unlike the easily distinguished upper and lower molars of Aegyptopithecus and the apes.
The oldest known Old World monkey fossils (Prohylobates and Victoriapithecus) have bilophodont molars but with traces of the crests that are found in the teeth of hominoids and Aegyptopithecus. While we cannot say with certainty what additional attributes Prohylobates and Victoriapithecus had to aid in their leaf-eating habits, living Old World monkeys have specializations in their cheeks and stomachs to help them get enough nourishment from their mostly leaf-based diets.
Paleontologists think that Aegyptopithecus, like nearly all monkeys and all apes, was active during the day, or diurnal. We conclude this because Aegyptopithecus has eye sockets similar in size to those of living diurnal monkeys with skulls of roughly the same size. Nocturnal primates always have large eyes, in order to capture more of the available light at night. Aegyptopithecus is also sexually dimorphic in the size and shape of its canines, which means, simply, that the canines of males and females look different. Males have elongated blade like canine teeth, whereas females have shorter, conical canines. This is typical of anthropoids that live in social groups in which males compete for rank and mates. Aegyptopithecus had relatively stocky arms and legs compared with most monkeys, and powerful hands and feet for grasping. It was probably a relatively cautious climber, unlike most monkeys living today, which move with great speed and agility in the trees. Aegyptopithecus is the best approximation we currently have of the animal from which Old World Monkeys and apes evolved.
Aegyptopithecus was a not-quite-ape. But what did the first true ape look like? We lack fossils that represent the earliest populations of Old World monkeys and apes. Again, this is not surprising and should not be taken as an indication that the fossil record is so inadequate that we should give up trying to interpret it. It is incomplete, to be sure. In fact, the fossil record can be described as consisting of a few words per chapter of a book thousands of chapters in length. Try putting together the whole story from that! You will never succeed, but you will learn a great deal by looking at the fossils that we do have.
For example, although we have many fossils from the skull, teeth, and limbs of Aegyptopithecus, we do not know from the fossil evidence whether or not it had a tail. I think it probably did. All Old World monkeys have tails, even if in some cases you can't see them under the fur. All apes lack tails. Given that Aegyptopithecus lived before the apes and Old World monkeys evolved and that it gives us a good idea of what the common ancestor of Old World monkeys and apes looked like, if Aegyptopithecus did not have a tail, then monkeys would have had to re-evolve one. No one I know thinks that this is even remotely likely. So, despite the ape-looking teeth of Aegyptopithecus, we know that more change had to come before we can say we are dealing with true hominoids. Aegyptopithecus was, broadly speaking, a common ancestor of Old World monkeys and apes, but not the last common ancestor. There is a gap in the fossil evidence between Aegyptopithecus and the populations that diverged into the first members of the Old World monkey and ape clades. Recently though, a new taxon has been discovered that partly fills this gap and comes from what seems at first to be an unlikely place.
Saadanius is a fossil about 28 million years old, occupying the time gap between Aegyptopithecus and the first potential apes that I will discuss below. It is from Saudi Arabia, which may seem odd, but in fact at the time Saudi Arabia was part of mainland eastern North Africa, and its ecology was similar to that at Fayum. The Saadanius site is actually about halfway between the Fayum to the north and the first potential fossil-apes sites in Kenya and Tanzania. Saadanius is larger than Aegyptopithecus, as are the oldest hominoids, but is otherwise quite similar in many anatomical details to Aegyptopithecus, with one important exception. At the base of the skull in all modern and most fossil catarrhines, there is a tube, the ectotympanic tube, running from the outer to the middle ear. All hominoids and cercopithecoids, living and extinct, have this bony tube on the bottoms of their skulls. Aegyptopithecus does not, which is another indication that Aegyptopithecus is more primitive than the last common ancestor of living catarrhines. On the other hand, Saadanius has the tube; so, it is more evolved and closer to the last common ancestor of apes and Old World monkeys, because it shares a feature not found in Aegyptopithecus or any non-catarrhine primate. Since Saadanius is only 28 million years old, it is probably younger than the split between cercopithecoids and hominoids, which is dated by the molecular clock to be at least 30 million years ago. It was mostly likely a survivor, a relic, of a lineage that existed earlier. Even so, it gives us a lot of help in getting closer to that elusive last common ancestor. By about 26 million years ago, we start to pick up evidence of another catarrhine, one that we might just be able to call an ape.
KAMOYAPITHECUS: THE FIRST APE?
The oldest fossil that represents an ape is probably a piece of an upper jaw representing the genus Kamoyapithecus, which is named in honor of the legendary Kenyan fossil hunter, Kamoya Kimeu. Kamoyapithecus is known from the site of Lothidok (or Losodok), in northern Kenya, and dates to about 26 million years ago, which falls in the geological epoch known as the Oligocene ("epoch" is the formal term for the main subdivisions of periods; the Oligocene and the Miocene, which comes right after the Oligocene, are epochs in the Tertiary period) Aegyptopithecus is also from the Oligocene but is older, at about 31 to 33 million years. Lothidok, like Fayum, was a forest full of archaic African mammals, since the sea barrier to faunal exchange with Eurasia was still in place. It was probably ecologically similar to Fayum, a bit on the dry side compared with many modern tropical forests, and somewhat drier than the forests in which our next characters in this story, Proconsul and Ekembo, lived.
Why do I think that Kamoyapithecus is an ape? It has teeth that, although larger, resemble those of Aegyptopithecus. There are subtle differences in the degree of development of certain attributes of the molars that potentially indicate an evolutionary change between Aegyptopithecus and Kamoyapithecus. In addition, the canines of Kamoyapithecus are massive, unlike the more slender male canines of Aegyptopithecus and more like those of Ekembo (see below). However, given the differences in size between the two, it is hard to say if the dental differences are just size related or are evolutionarily significant. The anatomy of the teeth suggests that Kamoyapithecus had an apelike diet consisting mainly of fruits, but then so did Aegyptopithecus. Frankly, if it had been found alongside Aegyptopithecus, it would probably be considered to be a larger version of the same animal.
There is so little to work with of Kamoyapithecus, which is known only from a few pieces of the upper jaw and some isolated upper teeth. In 2013 we caught a bit of a break with the publication of a new ape fossil from Tanzania. This creature, called Rukwapithecus, is about the same age as Kamoyapithecus. But as luck would have it, Rukwapithecus is known only from a lower jaw, so the two cannot be compared directly. However, on the basis of that jaw, Rukwapithecus is much smaller than Kamoyapithecus and looks distinctly more primitive. While Nancy Stevens (who very kindly showed me a beautiful cast recently) and colleagues think that Rukwapithecus is an early hominoid, I think it more closely resembles Pliopithecus, an ancient offshoot of the catarrhines (I will discuss Pliopithecus a bit later on). Either way, it is amazing to have a fossil like this in Tanzania, and it tells us that we should be prepared for any possibility in paleontology.
Kamoyapithecus and Rukwapithecus are known from the right time period and in the right place, East Africa near the end of the Oligocene, to be viable representatives of the ancestors of later apes. It would be nice to have some limb bones, to see if there are differences in the direction of later apes, and more bits of the skull, to see how they compare with Aegyptopithecus and Saadanius, but for these we will have to wait for future discoveries. But in sediments that are just a few million years younger, researchers have found fossils with a more definitive ape look.
ENTER PROCONSUL AND EKEMBO
Proconsul is an excellent example of an intermediate taxon between the more primitive monkey-like primates and more modern apes. A great diversity of fossil apes flourished between about 20 and 17 million years ago, and one of them, although we do not know exactly which one, is probably more closely related to living apes than the others are. Together they represent the ancestors of all living apes, including humans (table 1.1).
(Continues...)
Excerpted from The Real Planet of the Apes by David R. Begun. Copyright © 2016 Princeton University Press. Excerpted by permission of PRINCETON UNIVERSITY PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
PREFACE viiINTRODUCTION 1
CHAPTER 1 THE EARLY YEARS 27
CHAPTER 2 OUT OF AFRICA: AFROPITHECUS AND FRIENDS 62
CHAPTER 3 OUT IN THE WORLD: EARLY APES SPREAD IN EUROPE 73
CHAPTER 4 HOME AGAIN: THE NEW AFRO-EUROPEAN APES 97
CHAPTER 5 THE BIG EAST-WEST DIVIDE 118
CHAPTER 6 EAST SIDE STORY: OUR COUSINS SIVAPITHECUS AND THE ORANGUTANS 123
CHAPTER 7 WEST SIDE STORY: THE AFRICAN APES OF EUROPE 147
CHAPTER 8 THE DESCENDANTS OF DRYOPITHECUS 162
CHAPTER 9 BACK TO AFRICA AGAIN 187
POSTSCRIPT 227
ACKNOWLEDGMENTS 231
NOTES 233
REFERENCES 237
INDEX 239
What People are Saying About This
[The Real Planet of the Apes] is enthralling, making accessible an absolutely critical period of human evolution and the scientific debates surrounding the interpretation of its evidence.
—Steven Mithen, New York Review of Books
Compelling.
—Darren Naish, ScientificAmerican.com
Begun adopts a refreshingly broad approach by exploring the evolution of the apes as a whole. . . . There is much to like in this enjoyable book.
—Simon Underdown, Times Higher Education
Backed by 30 years of field work and research, Begun’s theory is worth a look.
—William Hageman, Chicago Tribune
An engaging, superbly written account of the evolutionary history of apes.
—Choice