2017-07-11 Cui Yaming Intellectual
► The ancestors of the Heidelberg people are thought to have left Africa 1.8 million-800,000 years ago. Credit: Richard Gray
Written by | Cui Yaming
Editor-in-charge | Chen Xiaoxue
"Intellectuals" WeChat public account: the-intellectual
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Whether you're interested in human evolution or not, you've probably seen a "diagram of human evolution." On this picture, silhouettes of various half-human, half-ape animals are drawn, starting with chimpanzees, lined up, and slowly straightening up from left to right until the human on the far right is completely straight. If you're not a biology major, your first and deepest impression of human evolution may come from this vivid illustration. And you must have seen more than one, because it has been adapted and parodyed by various adaptations and spoofs since its birth, and some painted apes that stood up easily, and finally became procedural apes;
Used during the Cold War as a warning of a nuclear crisis;
Some say that humans are getting fatter;
There's also a Simpsons version.
One painting was spoofed to such an unbelievable degree that I am afraid that I would not be able to find a second one except for the mysterious Mona Lisa. This illustrates how popular this picture is. How succinctly it explains the process of human evolution. As soon as the painting was born, it was enthusiastically sought after by popular culture, and over the decades, countless people adapted and spoofed it, and it has become a benchmark in modern culture. Even the nitpicking Xie Ear wore the painting on his body. However, many anthropologists and evolutionists have a lot of opinions about this painting, believing that this map that helped many people understand human evolution has also deeply misled the melon-eating masses who know nothing about biology.
Trace the source
What's wrong with this diagram? Let's first look at what the original version of the painting looks like.
The painting originally came from a popular science book. It was born in 1965 as an illustration by the American natural history painter Rudolph F. Zallinger for the "Early Humanity" volume of Time-Life series. The original image was titled "March of Progress."
The original painting is a long picture of a total of 15 walking silhouettes of human ancestors. But because the drawing is so long, if it is reluctantly reduced as an illustration and printed on a page, the reader may not be able to see the details of the painting, living up to this excellent painting. In this way, the publisher can only print it on a folded page longer than four pages, and it needs to be fully expanded to see the full picture. However, if you don't unfold it, you can only see the third to fifth, and the last three portraits, for a total of six silhouettes. The various spoof versions that are now popular are adapted from this simplified version.
The number was fewer, and the central idea did not change: they all faced the right side, lined up one after the other, standing straighter from left to right than the other, and seemed to march together to the right.
The author of this book is the late paleoanthrophropology titan, american anthropologist Francis Clark Howell. clark howell）。 Since the author is so good, the illustrations will naturally not be bad. That's right, the 15 silhouettes on this map are all real scientific discoveries, including almost all the "human fossil" species found at that time.
►From left to right: Upper Ape, Protoconsur Ape, Forest Ape, Mountain Ape, Rama Ape, Australopithecus Australopithecus, Australopithecus, Australopithecus, Australopithecus, Homo erectus, Early Homo sapiens, Thoreau, Rhodesian, Neanderthal, Crosian, Modern Man.
Now it seems that some of these fossil species do not belong to humans, but are a side branch of human evolution. But still, what a perfect chain of evolution, from ape to man, interlocked. What went wrong?
Evolution is not a chain of interlocking chains
As we all know, this is a map depicting the evolutionary process of human beings. For an ordinary person who has no special knowledge of paleoanthropology, the leftmost picture is an ape, and the far right side of the painting is our modern man. This leads us to instinctively believe that human evolution began with apes, went through one evolutionary stage after another, and eventually became modern humans.
But evolution is not like this, like a chain, a chain of links. It's more like a branch on a tree, constantly diverging. Even if we only cut the small branches of human evolution from the big tree of evolution, there are branches and forks on it, and each small branch represents a branch of human evolution, but only the longest branch represents the evolutionary process of modern man.
On this map, the author put all the known fossils up and let them stand in a row and walk in unison. It's like you've been ordered by your mother to sort out a family tree, which should have looked like this:
And you've put it all together like this:
Grandpa - Grandpa - Uncle - Second Uncle - Uncle - Dad - Big Cousin - Lobby Brother - Second Cousin - Me
We don't have to think about it, the family tree should be divergent, and only one of them is your immediate family; rather than pulling all the family members in and arranging them in a straight line according to age. The reason is simple, your parents are your dad and mom, not your second cousin, even though he's older than you. Your eldest cousin, eldest cousin, and second cousin are all family members, but not your immediate family.
An important part of exploring human evolution is building its own family tree for humanity. Needless to say, like a normal family tree, it should be a tree-like, divergent family tree, not a straight line. Regardless of the original intention of the painting "March of Progress", this practice of putting all the seven aunts and eight aunts found in the painting and letting them stand in line and walk in unison gives the impression that the human family tree is such a straight line.
In fact, evolution should be represented by a tree, not a line, and it took scientists a long time to realize. Initially, at Darwin's prompting, it was believed that humans evolved from modern apes, and hoped to find a "missing link" between humans and apes. In this way, every time people find a fossil that seems to be somewhere between ape and human forms, they declare that they have found this "missing link".
Later, as more and more fossils were discovered, it seemed that there was not only one ring missing between man and ape, but many rings. Therefore, people take it for granted that these fossils are arranged in chronological order. But this still does not solve the problem, because many of these fossils, which live very close to the time, have very different shapes. In this way, people gradually realized that human evolution was much more complex than initially thought, and may contain many different branches, like a tree, rather than a line.
Later, we found a large number of human fossils, but until now, we have not been able to fully determine which fossils represent the taxon belongs to the modern human branch. Different scholars have their own explanations, and this problem can only be solved by discovering more fossils.
Why haven't chimpanzees become humans yet?
In addition to the question of whether the "evolutionary line" or the "evolutionary tree", the painting has a less obvious problem. All the ancient humans in the painting are walking towards the modern man on the far right, which seems to imply that everyone is evolving in the direction of modern man. Is this really the case? Is the ultimate goal of these ancient humans to evolve into modern humans?
This is a very misconceptional question. Don't you wonder why today's chimpanzees haven't become humans yet? When will they become human? The reason why people ask such questions is because they do not understand the direction of evolution.
If you want to answer the question of whether evolution is directional, many people will say that evolution certainly has a direction, and the direction of evolution is from low to high, from simple to complex. Believe it or not, in the process of evolution, single-celled organisms have become multicellular organisms, and people are smarter than chimpanzees, is this not a process from low to high, from simple to complex?
Don't worry, let's start at the beginning. To understand the direction of evolution, it is necessary to look at what the forces that drive evolution are, and whether this force has directionality. What is the driving force behind evolution? In On the Origin of Species, Darwin details the reasons why species change, which is to adapt to the environment. In other words, the driving force of evolution is natural selection, and the purpose of evolution is to adapt to the environment.
Therefore, evolution does have a direction, and this direction is the direction of adapting to the environment. If a species is able to survive successfully through natural selection, it adapts to the environment, and we can say that it has evolved. However, species do not have to become more complex and advanced to adapt to the environment. Although single-celled bacteria have a very simple structure and are very low in the evolutionary tree, it does not affect their survival well, and their ability to survive well in their own environment shows that they do not need to evolve. Evolution doesn't work all the time, it only happens when the environment changes.
Any animal that exists in the world today is the product of evolution that has undergone a long period of adaptive evolution and can live freely in its own environment. Therefore, the reason why chimpanzees have not become humans now is because humans are not chimpanzees at all. The ancestors of mankind were indeed an ape, but not a chimpanzee or any living primate, but an ape that no longer existed. Chimpanzees also adapted to jungle life in the process of long-term adaptive evolution and became what they are now. Chimpanzees evolved in such a way that they didn't need to evolve into humans at all. Evolving into humans was another branch of apes closely related to chimpanzees.
In fact, the painting "The March of Evolution" was originally just an illustration, and the annotations to this picture in the book are explained very clearly, and its original intention does not imply the linear evolution of human beings, nor does it imply that human evolution has a certain directionality. The popularity of this painting in modern culture is definitely unexpected by the author. The epidemic made it completely detached from its original scientific nature, and eventually spread a misunderstanding of human evolution.
In this way, this phenomenal illustration is originally a perfect collision of art, culture and science, but it is also problematic because of scientific rigor. Sometimes I really have to admit that making science popular is really not an easy task.
About the Author:
Cui Yaming, born in 1986, a native of Chengdu, Sichuan, has a doctorate in paleoanthropology.
Edition Editor: Scarlett 丨
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