Primates and our hominin ancestors lived in groups, and their survival was entirely dependent on their creativity and social savvy. Evolutionary pressures pushed members of the genus Homo (0) to develop these capabilities much further over time. (1)
It Took a Tribe
We saw earlier that primates nurture their young, with members of the group typically pitching in to help mom raise junior. Over time Homo took this core trait much further, out of sheer necessity.
Human infants took much longer to develop than their primate cousins and required more adult attention to learn how to navigate the complexities of social life in a human group. A mother taking this on by herself would be a significant burden. By sharing this responsibility among multiple caregivers - relatives, older siblings, and other group members - the costs and risks of raising an infant were distributed, increasing the chance of survival for both the mother and the child. The support of multiple caregivers also enabled the mothers to contribute more fully to the group. It did take a tribe to raise a human.
This collaborative approach to childcare is one of humanity's secret weapons. By having the support needed to produce offspring with woefully underdeveloped brains and bodies, humans enabled an improved ability to learn, more complexity in brain development, and increased potential for innovation and creativity. It's as if we opted for a product that required extensive post-purchase upgrades, but with the trade-off of a significantly more advanced final version.
Nurturing the young isn't a uniquely human trait - it's a foundational mammalian characteristic which Homo deepened and developed further. This nurturing instinct gave rise to deeply held values such as love, kindness, patience, and forgiveness. While we might be tempted to view these as the polished products of advanced civilization, they are, in fact, ancient programming, deeply embedded in mammalian parental relationships long before humans made their debut on the evolutionary stage.
So, the next time you're cooing over a baby or marveling at human kindness, remember: you're witnessing the continuation of a tradition older than humanity itself. We didn't invent love and nurturing - we simply turned it into an elaborate group project.
So Long Alpha Males!
As we've seen, primate groups typically operate under a strict hierarchical system, with a dominant alpha (usually male) at the helm. However, human foraging groups evolved to become much less hierarchical over time, and downright egalitarians when compared to primates. (2)
A first development came in full force with Homo Erectus, some 2 million years ago. These hominins had shoulders optimized for high-speed throwing, allowing them to hurl stones further, more precisely, and with greater force than their primate relatives. As noted by Peter Turchin, (3) while Primates can throw branches around, they don't use projectiles as lethal weapons in combat. Our closest relatives, chimpanzees, are terrible throwers. They are extremely strong and excel in close-quarters combat - they would likely make minced meat of a single human in hand-to-hand combat. They are however very vulnerable to projectiles.
Humans emerged as uniquely good throwers. This newfound ability not only helped with protection from large predators but also likely played a role in resisting bullying behavior from dominant group members. After all, it's quite risky to challenge a powerful alpha in close combat, but a group armed with stones could ambush a troublemaker with limited risk to themselves. In a twist of evolutionary irony, projectile weapons likely helped make our ancestors more equal. Who knew that the path to egalitarianism was paved with well-aimed rocks?
Of course, homicide was an extreme solution. Our ancestors had other, less drastic options at their disposal: outperforming the bully in coordinating scavenging or hunting, ignoring or ridiculing them, or forming alliances to tip the scales. In this new social order, skill mattered more than physical brawn - be it in toolmaking, leading hunts, or acting for the benefit of the group. And as we've seen, social and political skills became the most prized of all. It seems our ancestors realized that brains could indeed triumph over brawn, given the right circumstances.
Anthropologists such as Richard Wrangham argue that over thousands of years, we in effect self-domesticated, by selecting for less aggressive behavior within the group. (4) If they are right, this means that we are tamer than our ancestors - a notion that might raise eyebrows given the current state of global conflicts. Achieving status and earning recognition while doing right by the group or community is no easy undertaking - be it for primates as we saw earlier, and even more so for humans with more complex social dynamics. In essence, our journey from hierarchical primates to more egalitarian beings was less about eliminating alpha behavior entirely and more about redefining what 'alpha' means in a human context. We traded raw strength for social acumen, and in doing so, laid the groundwork for the complex societies we navigate today.
New Homo Species: More Brainy, More Social
Homo Erectus appears and starts to spread around Africa some 1.8 M years ago. Erectus represents an important transition in human evolution, as it had a larger brain (in the 750 cc to 900 cc range) and was the first hominin with fully modern bipedalism. Erectus was the first hominin to use fire on a regular basis; its developed more sophisticated stone tools and expanded its diet. This enabled it to expand its range beyond Africa into Asia, and to adapt to new environments. Such broad expansion across planet earth was quite a feat. Homo Erectus had to have developed ways to navigate the seas, build ocean-going vessels and acquire sailing skills. Erectus populations in Asia gave rise to a distinctive group of small-bodied hominins on the island of Flores (Indonesia), which were given the name Homo Floresiensis. A group of Erectus likely became isolated on the island of Flores about 1M years ago. The evolutionary pressure of isolation and limited resources resulted in smaller bodies, consistent with the "island effect" observed across many animal species including our own.
There is evidence of a dramatic increase in brain size about 300,000 years ago (*). Brains require significant energy (about 10x more energy compared to other organs) and the advent of control of fire some 400,000 years ago likely played a key factor, as cooking provided a boost in available energy from food and may have released prior constraints on brain size. As Robin Dunbar points out, cooking also has social benefits. The process of eating releases endorphins - cooking and eating together helps people bond with each other and enhances social cohesion. Social eating was to become a pretty universal human practice across all cultures.
From what we can ascertain, Neanderthals appeared about 300,000 years ago. They had a stocky build, were able to successfully cope with ice age conditions, and were skilled hunters of big game. They lived throughout Europe and parts of Asia. Evidence from fossil sites in the Levant seems to show that they made use of heavy spears tipped with sharpened stones, likely used to thrust and ambush at close quarters. Over time their brain grew to be similar in size to modern humans (1,320 cc vs. 1,370 cc in fossils of modern humans) - though with an elongated shape with less space for frontal lobes.
Anatomically modern humans, or Homo Sapiens, appeared about 200,000 years ago. This new species was more gracile, and benefited from a dramatic increase in brain size, comparable to that of Neanderthals. Sapiens brains had bigger frontal lobes and seemed to have developed stronger and more complex social dynamics, as well as an increase in group size. Based on the fossil record it seems that by 100,000 years ago Sapiens had replaced all other forms of hominins in Africa.
The (Real) Great Leap Forward
Starting about 70,000 years ago, there was a significant shift in the behavior and cognitive abilities of Homo. This period witnessed an explosion of creativity and innovation, as evidenced by the emergence of various new artifacts, tools, and artistic expressions. The cause for this "Great Leap Forward" (not to be confused with Mao's disastrous campaign of the same name in the late 1950s/ early 1960s, which resulted in one of the largest famines in human history) is still an ongoing debate and further research. It is most likely that a combination of factors was at play - expansion of Homo's diet providing additional energy, neurological developments and an increase in brain size, population expansion leading to the increased exchange of ideas, tools, and cultural practices, and significant improvements in communication skills (we will elaborate on the importance of that latter point in a next post). Advances in tool-making technologies, such as blade and composite tools, may also have played a role by enabling more complex problem-solving and the exploitation of new resources.
One of the most remarkable aspects of the leap forward was the emergence of artistic expressions, such as paintings, carvings, and sculptures. The oldest known cave art is more than 50,000 years old. (5) Some of the paintings are breathtakingly beautiful, such as the one from Alta Mira shown above, estimated to be 34,000 years old.
Major advances in toolmaking included blade tools (thin, sharper and more efficient flakes), composite tools (combining different materials such as stone, bone, and wood to create more specialized and effective tools), the use of bones, antlers, and ivory (which could be shaped into more specialized forms such as needles), and fishing tools.
Out of Africa - Sapiens Colonizes the World
By about 150,000 years ago there were at least four distinct species of Homo spread out across the planet, each with different morphologies. Homo Erectus was still around, mostly in Asia. The Neanderthals were firmly established in Europe; Homo Floresiensis was found in Indonesia. And then there was Homo Sapiens, roaming the African savannah.
Starting 150,000 years ago Sapiens began to expand across the globe - by 100,000 years ago Sapiens had moved across Central and East Asia, and parts of Europe. By 50,000 years ago they reached Australia and the islands of Southeast Asia. By 25,000 years ago they crossed the frozen Bering Strait into the Americas and expanded South. The expansion was to have a dramatic impact on the planet ecosystem, causing mass extinction of all types of large animals - leading Yuval Harari to state that Sapiens has "the dubious distinction of being the deadliest species in the annals of biology". Most important given our focus on human history, the Sapiens migration resulted in the disappearance of all other Homo species by about 18,000 years ago. What happened?
The Great Whodunit - the Neanderthals Vanish
We will focus on what happened to the Neanderthals, which had survived very successfully for more than 250,000 years and had brains of size comparable to that of Sapiens. In the first recorded encounter between Neanderthals and Sapiens some 100,000 years ago in the Levant, Sapiens retreated - we are not sure why that is, but it seemed to confirm Neanderthals as a successful species that could stand their ground. However, the second Sapiens migration into Europe some 45,000 years ago had a dramatically different outcome. In what would be an ominous portend, Sapiens moved into Europe and the Levant from the steppes of Asia, like so many powerful invaders that followed in history - and within 20,000 years the Neanderthals went extinct.
There have been many attempts at explaining what happened, with very different interpretations. There may be an element of truth to most of the theories advanced by scientists, as in all likelihood the Neanderthals were caught in an unfortunate combination of circumstances. The advancing ice sheet pushed the Neanderthals further South and disturbed their hunting patterns, likely causing a reduction in population and the isolation of clusters of groups. Contact with Sapiens might have exposed them to pathogens for which they had little or no immunity (a factor that led to the collapse of many indigenous populations in more recent history).
We now also know that cultural factors were at play. As stated earlier, Neanderthals had brains of similar size to Sapiens, though with smaller frontal lobes. Per our prior discussion of the "social brain", the size of the neocortex and especially the frontal lobes are crucial in determining the size of a species' social groups. Sapiens had increased social cognitive skills and could maintain social groups that were a third larger than those of the Neanderthals. Sapiens could seek refuge with extended networks and would have been able to draw on larger numbers of individuals, with greater social cohesion. Sapiens also traded over much longer distances - Robin Dunbar notes that "70% of the raw materials of tools found at Neanderthal sites had travelled less than 25km, whereas 60% of those from Sapiens sites had travelled more than 25 km, and some had travelled as much as 200 km". The fossil evidence indicates Sapiens developed more sophisticated tools, including needles and boring tools (Neanderthals likely participated in "the great leap forward" but their progress paled in comparison with that of Sapiens). The combination of all these factors would have tipped the balance in favor of Sapiens in any competition for resources or potential conflicts. Language likely also played a key role, as we will see in the next postings.
Neanderthals went extinct but left a permanent genetic imprint - recent DNA analysis has shown that 2 to 4 % of modern European DNA is shared with the Neanderthals, evidence of some degree of interbreeding between the two species.
Next: Sapiens The Chatty Ape
(0) As a reminder, Homo refers to members of the genus Homo - which include Homo Sapiens, Homo Erectus, Homo Neanderthalensis (Neanderthals)
(1) I borrowed heavily from 4 sources for this article: "Spark of Creativity" book by Agustin Fuentes, "Human Evolution" book by Robin Dunbar, "The Ultra-Social Animal" research paper by Tomasello in "The European Journal of Psychology", 2014, and "The Infinite Staircase" book by Geoffrey Moore.
(2) Note that this is a broad generalization, as there was bound to be a wide variety in group cultures. See "Hierarchy in the Forest: The Evolution of Egalitarian Behavior" book by anthropologist Christopher Boehm
(3) "Ultrasociety: How 10,000 Years of War Made Humans the Greatest Cooperators on Earth" book by Peter Turchin
(4) "The Goodness Paradox: The Strange Relationship between Virtue and Violence in Human Evolution" by Richard Wrangham
(5) Oldest known Neanderthal engravings unearthed in French cave | Natural History Museum (nhm.ac.uk)