The viewer’s eye begins at the lower left of the image. A small figure—somewhat grotesque, hunched, and covered in hair—moves to the right, its fists touching the ground.  It resembles a human in form, yet it is a distorted, primitive human. Something about its proportions seems wrong: unnatural. In many versions this first figure is a simple monkey; in others it’s a chimpanzee, a gorilla, or an unspecified ape. It is the beginning. The march has started.

To its right stands a creature slightly larger, more upright, and less hairy. It is still recognisably ape-like, but it implies progress.Next comes another figure striding with determination—more upright, more human—followed by another, and then another. Each stage in the march appears more developed, more human than the last. Step by step, the head becomes larger, as if to house a bigger, more developed brain; the back straightens; the skin becomes smoother. Farther right, a square human chin is already visible, and tools appear—stone axes, spears. We have advanced. At the far right, leading the procession, strides a resolute figure, taller than all the rest: a sturdy, handsome adult human male. This is the thinking human, Homo sapiens—the crowning glory of the march of evolution, the march of progress.

This image is the most famous visual shorthand for the theory of evolution. Over the years, it has spawned hundreds of versions, along with thousands of parodies and adaptations. Its simple graphic logic captures the eye—and the imagination—telling an intuitive story of the past 25 million years of human development.It is so iconic that it is hard to think about evolution without it. It can feel as though it has always been with us.  A superb – and remarkably effective  – image, except for one minor problem:

Evolution simply does not work this way.


Evolution simply does not work this way. A version of the March of Progress with Darwin at the front. | Shira Holland via DALL·E

An Image is Born

In 1859, Charles Darwin published his groundbreaking book On the Origin of Species, which laid the foundations for modern evolutionary theory. At the core of this theory was the idea that nature is not fixed, but constantly changing. The species we see around us today were not always here, and they will not remain forever. They change and evolve, and may even split into new species. This process is guided by the principle of natural selection—a mechanism in which individuals best adapted to their environment are more likely to survive and produce fertile offspring, thereby passing their traits on to future generations.

Twelve years later, in The Descent of Man, Darwin extended the theory to humans, arguing that we, like all living creatures, evolved from earlier species. Contrary to popular belief, he did not claim that humans descended from monkeys; rather, he argued that humans and modern apes share a common ancestor, from which both the ape lineages and the human lineage diverged. He also predicted – correctly – that fossil remains of additional human species would one day be found, helping to bridge the gap between that ape-like ancestor and modern humans.

Indeed, as early as 1857, Homo neanderthalensis (Neanderthals) was first classified, based on bones discovered in a quarry in Germany’s Neander Valley. Most subsequent human species (hominins) were identified during systematic searches for “missing links” in human evolution. In 1891, the Dutch anatomist Eugène Dubois discovered the first remains of Homo erectus (“upright man”); in the first half of the twentieth century, early remains of Australopithecus africanus were found; and in 1964, Louis Leakey and Mary Leakey added Homo habilis (“handy man”) to a list that would only continue to grow.


At the core of the theory was the idea that nature is not fixed but constantly changing. On the Origin of Species | Shutterstock, An Van Assche

As information about early human species accumulated, scientific inquiry into early human evolution expanded: When and where did each species live? What abilities did it possess? What distinguishes one hominin from another, and what do they share? Is a given species one of our direct ancestors, or a lost side branch on the evolutionary tree—a dead end? And what relationships existed among different human species living side by side?

One popular book documenting this growing body of knowledge was Early Man by Francis Clark Howell, published in 1965 as part of Time-Life Books’ 25-volume Life Nature Library series. It was later issued in an abridged edition for younger readers as part of the Life Young Readers Library, and was distributed in many countries. 

Given the series’ educational aims, the books were filled with accessible visuals meant to bring dry facts to life. In Early Man, illustrator Rudolph Zallinger was commissioned to create a foldout image titled “The Road to Homo sapiens.” The assignment was ambitious: the illustration had to present fifteen figures—apes and hominins—paired with brief explanatory text and a timeline indicating when each species lived.

The original March of Progress – full version | From Early Man, Wikimedia

To make this possible, he designed a foldout illustration that, when fully opened, spans four and a half pages, but can be folded down into a two-page spread showing only six figures.


The original March of Progress – two-page (folded) version | From Early Man, Wikimedia

The Making of The “March of Progress”

This spread – far simpler than the complete foldout – immediately captured many people’s imaginations. In the adaptations that followed, the timeline vanished, the scholarly explanations were dropped, and only the graphic template remained. It soon acquired a new, promise-laden name: the “March of Progress.”

The name was well chosen, because once those elements were omitted, that is precisely the message conveyed by the image’s graphic design and visual rhetoric: a procession advancing from a primitive past through steady, continuous improvement toward the most advanced model—Homo sapiens. The graphic elements make this plain. Most prominent is the upward slope, which draws the eye along an imaginary line beginning at the rear foot of the leftmost ape-like figure, rising along its bent back to its head, and then to the increasingly higher heads of the five subsequent figures. This visual path suggests growth and development, reinforced by the contrast between the rising line and a second, flat horizontal line connecting the figures’ feet.

The figures’ posture is equally rich in meaning. First, this is indeed a march: they walk in sequence, one after another, all in profile facing right, their legs angled to suggest motion. The entire procession moves from left to right. Above the waistline, however, the pattern shifts and becomes far less uniform. Upper bodies vary from one figure to the next, growing progressively more upright. We tend to interpret this as an improvement, since in our culture an upright posture signifies strength and determination. A similar progression appears in the gradual disappearance of body hair from stage to stage, and in the increasing use of tools and weapons.

Taken together, these elements tell a story of continuous, consistent development—from primitive to advanced, from wild to civilised. Through simplification and abstraction, an illustration rich in content, originally intended to convey some of the complexity of human evolution, became a highly effective and intuitive template—one that tells, without words, a story of development and progress.

A March – With a Catch

From the very beginning, this interpretation drew sharp criticism from many scientists, who argued that it offers a biased and misleading picture of evolution in general – and of human evolution in particular. Even the book’s author, Francis Clark Howell, admitted that although the illustrator had not intended this, the image took on a life of its own and escaped their control. “The graphic overwhelmed the text. It was so powerful and emotional,” he said.

At the heart of the criticism is the illustration’s linear structure. It portrays evolution as a steady, continuous process moving from one ancient species to the next, like a ladder climbed rung by rung. But this picture builds in several distortions: evolution is not linear but branching and complex; it has no inherent direction and no predetermined goal.

In his 1989 book Wonderful Life, paleontologist and popular-science writer Stephen Jay Gould argued that the image’s enormous success is also its downfall: “The March of Progress is the canonical representation of evolution—the one picture immediately grasped and viscerally understood by all… The straitjacket of linear advance goes beyond iconography to the definition of evolution: the word itself becomes a synonym for progress.”

 – Stephen Jay Gould exposes the flaws of the March of Progress

Darwin himself described evolution as a branching tree. What begins as a single species may split into several—for example, when populations become geographically separated and each undergoes natural selection that adapts it to a different environment. Some of these species will branch further, giving rise to new species; others will fail in the struggle for existence, and the branch they represent will end in extinction. Building on this idea, the German naturalist Ernst Haeckel produced one of the first detailed depictions of a human evolutionary tree – the “Pedigree of Man” (Stammbaum des Menschen) – published in the 1870s, which would later be developed into the branching “tree of life” framework central to modern phylogenetics. 


Haeckel’s “Pedigree of Man”. Like the “March of Progress,” it depicts evolution as culminating in Homo sapiens. | Illustration: Wikimedia, public domain

In the “March of Progress,” Zallinger’s original illustration arranged all fifteen species along a single straight line—very different from a branching tree. The accompanying text tried to compensate for this.  Proconsul, for example, was presented as a stage in chimpanzee evolution rather than human evolution; Oreopithecus was described as a creature once thought to be a human ancestor but now understood to be a side branch of the family tree. Only at the fifth figure in the row—Ramapithecus—does the text note that it was considered the earliest direct ancestor in the human lineage. Even that claim, however, is misleading: if one speaks of a “direct lineage” at all, it extends far deeper into the past—ultimately back to life’s earliest single-celled organisms.

When the timeline is included, another phenomenon emerges that contradicts the illustration: many early human species lived side by side. This was not a relay race in which each species hands the baton to its successor and then disappears. An ancestral species can persist for many generations alongside multiple descendant lineages. Moreover, we now know that in prehistory different human species sometimes shared the same geography—living in the same places at the same time, influencing one another, trading, and even interbreeding. Indeed, genetic studies over the past decade have shown that many modern humans carry Neanderthal DNA, clear evidence of interbreeding between Homo sapiens and Neanderthal populations.

Another distortion is the illustration’s portrayal of evolution as a process of constant improvement. From stage to stage, early humans appear more upright, more capable, more cultured, more intelligent. One might argue that changes of this kind did occur in the lineage that led to Homo sapiens, but we read them as “progress” only because they lead, ultimately, to us. Evolution as a whole has no direction: it is a shifting pattern of variation within populations, in which traits spread or disappear through natural selection, as environments favor individuals better adapted to local conditions. When conditions change, traits that were once advantageous can become liabilities—and may vanish altogether.

It follows that, contrary to what the illustration suggests, humans are not the pinnacle of evolution but merely one species among many. From an evolutionary standpoint, human intelligence does not make us superior to a monk parakeet, the American cockroach, or the bacterium Escherichia coli. All are, at present, thriving, highly adapted to their environments and remarkably resilient.

“Human beings represent just one leaf [on the evolutionary tree],” explains biologist and anthropologist Alexander Werth in a critique of the “March of Progress”. “Our long-gone extinct ancestors correspond to fallen leaves. Each leaf is a unique species. Each has traveled the same distance from the tree’s base—or, put another way, from life’s bacterial origins to the present.”

Finally, we should not overlook cultural bias. The illustration and its many offshoots have often been accused of promoting prejudice and stereotype. Most obviously, it erases half the human population by depicting a lineage composed entirely of males. In many adaptations, a subtler racial bias is also evident: skin tones of early humans grow progressively lighter as the figures approach Homo sapiens, visually reinforcing the notion of darker-skinned people as “primitive” and lighter-skinned people as agents of culture and progress.


 Even when a female “march of progress” is shown, the “advanced” figures are light-skinned and the “primitive” ones are dark-skinned. | David Gifford / Science Photo Library

And Yet, On It Marches

Whatever scientists may argue, the March of Progress template has taken on a life of its own. It appears on movie posters and old rock-album covers, and it is commercialised in advertisements for consumer products. Photographers restage it through their lenses; scientific institutions and science and popular-science websites reproduce it constantly; comedians parody it; satirists deploy it as a vehicle for criticism. Some versions reverse its direction to suggest decline. Others add a stage beyond humans – a robot, artificial intelligence, a cat – or replace humans (or place them “below” the endpoint, in the image’s implied hierarchy) with a corporate lawyer, the average television viewer, and so on. In this way, the March of Progress marches on into new realms of imagination and creativity—and even its critics must admit that no scientific theory has ever enjoyed better public relations. 


The March of Progress template has taken on a life of its own. A version featuring a robot at the front. | David Gifford / Science Photo Library

Translated with the assistance of ChatGPT. Edited, revised, and reviewed by the editorial staff of the Davidson Institute of Science Education.