CHLCA candidate: Often considered one of the earliest potential hominins, Sahelanthropus tchadensis, best known from the “Toumai” skull found in Chad, exhibits features that suggest bipedalism but remains debated due to limited fossil evidence. With two human anatomical traits, small canine teeth, and a spinal cord hole in the cranium further forward (on the underside of the cranium), it is possible that they are the fist of our ancestors to walk upright. If not, they likely had an intermediate stride.

Survival: From about 7 to 6 MYA in Central Africa (a densely wooded rain forest at the time)
Size: 4′ to 4’6″ (a little taller than modern chimpanzees)
Brain Size: around 320 to 380 cm³ (speculative)
Brain to Body EQ: Unknown, but like similar to chimpanzees at 2.2 to 2.5 (humans=7.4 to 7.8)

Perhaps the first species below represents Sahelanthropus tchadensis:

CHLCA candidate: This genus includes Ardipithecus ramidus (like “Ardi”) and possibly earlier species like Ardipithecus kadabba. Ardipithecus shows a mix of bipedal traits and adaptations for climbing, reflecting a transitional form in human evolution.

The dawn of collective learning can be traced back the oldest known stone tools, discovered at Lomekwi 3 in Kenya. The creation of these tools required more than just individual innovation; it involved the rudimentary form of collective learning, where knowledge of toolmaking was shared within groups. This early transmission of skills not only enhanced survival and adaptation but also marked the beginning of cultural accumulation—a fundamental characteristic that would define human societies.

Collective learning is the 6th threshold in Big History. While they place it at about 200,000 years ago, I recrafted it as Trasendental Intelligence and moved it back to 475,000 years. Collective learning, likely started with cultural transmission and the making of tools is a good example. If you agree, then collective learning moves back to at least 3.3 million years ago.

The earliest known stone tools date back to at least 2.6 million years ago. These basic stone tools were made and used by early humans–hominids. Did they also use wood tools? Sure, or at least very likely, but we have yet to find any preserved back as far as stone tools which hold up to the test of time much better than wood. 

The stone tools include hammerstones, stone cores, and sharp stone flakes. By about 1.76 million years ago, early humans began to make Acheulean handaxes and other large cutting tools.

The earliest containers were likely simple natural resources that early hominins stumbled upon and adapted for use. Starting possibly with Homo habilis around 2.0 million years ago, these early humans may have utilized large leaves, shells, or naturally hollowed-out pieces of wood as rudimentary containers. This usage marks an innovative step in early human technology, reflecting an understanding of natural resources for practical purposes.

As hominins evolved, particularly with the advent of Homo erectus, more sophisticated uses of materials likely developed. Homo erectus, known for their tool-making abilities, might have used animal hides to gather and carry items, gradually fashioning them into simple bags or slings. This represents a significant advancement in carrying technology, allowing for the transport of goods over greater distances and supporting more complex foraging strategies.

Before these developments, even earlier hominins may have employed static storage methods, such as piling resources like rocks or wood in designated locations, such as inside caves or on natural ledges. These caches would have served as communal collection points that group members could contribute to and draw from, reflecting early forms of community resource management.

Additionally, the use of vines or strong plant fibers to tie items together suggests the beginning of material manipulation for transport purposes, predating the knowledge of weaving but laying the groundwork for future technological innovations in container making.

The origins of tent-like structures in human history remain shrouded in mystery, primarily due to the perishable materials involved and the lack of direct archaeological evidence. However, as Homo erectus appeared and spread into varied climates, their enhanced tool-making skills and control of fire likely necessitated and enabled the construction of more complex shelters. This period marks a significant point where early humans may have started to build the first tent-like structures using branches, leaves, and plant fibers to create semi-permanent shelters. The move into cooler environments would have increased the need for such innovations.

Before this timeframe, it’s possible Homo habilis created simple shelters. The emergence of Homo habilis and their use of simple stone tools opens a window of possibility. They might have used vines or branches to create rudimentary windbreaks or lean-tos for temporary protection from the elements.

As Homo erectus roamed the expansive savannas, a significant evolutionary shift occurred in human ancestors: the reduction of body hair. This adaptation likely enhanced sweat-based cooling systems, crucial for surviving and thriving under the scorching sun during long hunts and foraging activities. While this change marked a general trend towards the hairiness levels observed in modern humans, variations persisted among individuals, reflecting a natural diversity similar to the range seen today. Some members of this early Homo population may have retained slightly more body hair, potentially offering better insulation in cooler climates or during seasonal changes.

Skin Color Variety: Each time a species of our genus Homo ancestors spread to new environments, the melanin mechanisms that all primates have kick in. The following is an imagined image of our ancestors in the various environments they spread into by 1.2 mya.

Genus Homo: Rapid brain growth in our human ancestors started about 800,000 BCE. Now, by rapid brain growth we mean about 600,000 years! Larger complex brains helped early humans to survive. They interacted with each other and their surroundings in new and different ways.

Around 700,000 years ago, the development of a human-like hyoid bone suggests early hominins may have begun transitioning from simple vocalizations to more structured speech.

This period marks a critical evolutionary point for Homo heidelbergensis, whose anatomical adaptations for speech, coupled with advanced tool use and complex social structures, indicate possible use of rudimentary language. Earlier hominins like Homo erectus also showed signs of vocal communication, but whether this included structured language remains uncertain. This era highlights the beginnings of speech, setting the stage for the sophisticated linguistic capabilities of later hominins. 

NSLCA Candidate: Homo heidelbergensis, an important figure in human evolution, represents a notable advancement over its predecessor, Homo erectus and Homo antecessor. Emerging around 640,000 years ago, they exhibited a larger brain capacity, averaging about 1,100 to 1,400 cubic centimeters, which facilitated more complex thought processes and behaviors. This increase in brain size is correlated with evidence of more sophisticated tool use, particularly the development of the Levallois technique, which allowed the production of diverse and specialized tools. Unlike Homo erectus, who primarily used simple stone flakes, Homo heidelbergensis crafted tools that were pre-planned and could be retouched and reused. Physically, they were more robust than Homo erectus, with a sturdier skeletal structure that supported a larger musculature, likely an adaptation to the colder climates encountered as they spread across Europe. Furthermore, Homo heidelbergensis is credited with the earliest potential evidence of constructed shelters and the systematic use of fire, suggesting a significant leap in technological and social practices, including possibly the earliest forms of communal living and hunting strategies. These traits mark Homo heidelbergensis as a crucial intermediary between earlier hominins and later species such as Neanderthals and modern humans.

• Brain Size: 1,100 to 1,400 cc (humans=avg=1,350; 1,200 to 1,500 cc)
• Brain to Body EQ: 4.5 to 5.5 (humans=7.4 to 7.8)
• Evolved in Africa about 770,000 YA, spread to Europe by 500,000 YA.
• Spread through Africa, Europe, and Asia. Last known: Africa until about 200,000 YA. 

Transcendental Intelligence (TI) likely emerged around this time in species like Homo antecessor and Homo heidelbergensis. Species such as these mark a compelling case for the early development of TI: the ability to store information outside the mind and across generations. This would likely take the form of stories, art, or something like a symbolic marking of an area used as a warning to stay away.

Analysis: Although direct evidence of art or jewelry from this era remains elusive, the sophisticated crafting techniques observed in later Neanderthal and Denisovan artifacts, suggest advanced cognitive abilities capable of TI including symbolic thought and advanced tool making. Denisovans are thought to have split from Neanderthals in Europe about 450,000 years ago, and Homo sapiens branched off in Africa about 315,000 years ago. The speculation that TI developed during this time is grounded in the understanding that the cognitive prerequisites for such advancements—complex problem-solving, abstract thinking, and perhaps rudimentary forms of symbolic communication—were likely present.

Big History Thresholds: 1=Big Bang | 2=Stars&Galaxies | 3=Chemicals | 4=Solar System | 5=First Life | 6=TI | 7=Agrarian | 8=Science

Collective Learning: The 6th threshold in Big History is Collective Learning, what I’ve dubbed Transcendenal Intelligence, the storing of information outside our minds. While Big History has this step set about 200,000 years ago as Homo sapiens emerged, I’ve moved it back to Homo heidelbergensis before Neanderthals and us branched off. After the publication of Big History, neanderthal art was discovered, indicating symbolic thought which might imply TI abilities. It’s important to note that very early collective learning likely emerged in Homo habilis or earlier. 

True symbolic thought emerges before 430,000 BCE: The discovery in 2018 of Neanderthal art dating back to 68,000 years ago, proved symbolic thought in Neanderthals. It also indicates strongly that symbolic thought evolved in or before our common ancestor about 430,000 years ago. This must be true unless either they evolved it separately in an example of convergent evolution or we’re wrong about the art, meaning we’re wrong about our idea that humans were not in Spain until after that art. (see my Occam’s Razor article.) 

See Beyond the Brain: Reassessing Neanderthal Intelligence, for more information. Humans and Neanderthals had a common ancestor about 430,000 BCE (current estimates range from 430,000 to 450,000 BCE). Humans did not evolve from Neanderthals, but both are the current evolution of a common ancestor: Homo Heidelbergensis. After the split, Homo Sapiens and Neanderthals interbred up to and as recently as 29,000 BCE. Through DNA testing we can identify DNA that came from interbreeding with Neanderthals. They built shelters, wore clothes, used tools, and spoke. Neanderthal DNA in modern humans is the highest in East Asians, intermediate in Europeans, and lower in Southeast Asians.

• Class: Mammal; Genus: Homo; Diet: Omninivore
• Brain Size: 1,200 to 1,700 cm³ (humans=avg=1,350; 1,200 to 1,500 cm³)
• Brain to Body EQ: 4.5 to 5.5, but maybe 6.2, or even 7.9? (humans=7.4 to 7.8)
• Evolved in Europe, spread to Africa and the Middle East.
• Last known: 29,000 BCE in the mountains of Polar Ural, northeastern part of Komi, Russian Federation.

Speculative branch of humans. Maybe a long lost hybrid: In the evolving tapestry of human history, the emergence of Homo naledi represents a captivating mystery that challenges traditional narratives of linear progression. Positioned within the intricate web of human evolution, Homo naledi could exemplify a complex branch woven from ancient threads. Imagine a scenario where a group descended from late Australopithecus interbred with Homo erectus, resulting in a unique hybrid species. This hybrid lineage, embodying a blend of primitive and advanced traits, might have thrived alongside other hominins, contributing to a rich mosaic of human diversity. The existence of Homo naledi, with its distinct blend of characteristics, suggests that our evolutionary past may not be a simple tree with neatly diverging branches, but rather a dense network of interconnected lineages, intermingling and evolving in response to the dynamic landscapes of ancient Africa. Such a perspective invites us to reconsider the complexity of human ancestry, highlighting the possibility of multiple, overlapping narratives of evolution driven by hybridization and adaptation.

Imagined image: Homa naledi. Left is circa 250,000 BCE. Right is circa 335,000 BCE. The later Homo naledi individual as appearing more human-like is somewhat speculative but can be supported by the evidence of their anatomical features and behaviors.

Survival: From about 335,000 BCE to 236,000 BCE in Eastern and Southern Africa (in woodlands and grasslands)
Size: 3’4″ to 4’5″ (a bit taller than modern chimpanzees)
Brain Size: around 510 to 600 cm³
Brain to Body EQ: 3.3 to 3.8 (humans=7.4 to 7.8)

Neanderthals and denisovans in the genus Homo had a common ancestor about 370,000 BCE (current estimates range from 250,000 to 500,000 BCE). Though neanderthals, denisovans, and sapiens share a common ancestor, they didn’t evolve directly from each other. That common ancestor from which all three evolved from was likely a later Homo heidelbergensis. Although some research suggest Denisovans branched from an early neanderthal. If Denisovans branched from an earlier Homo heidelbergensis, it suggests modern cognitive abilities like symbolic thought may have emerged much earlier than previously believed, which aligns with discoveries of early art currently under investigation. Some suggest denisovans branched from Homo erectus, if that’s true but I don’t think it is, that pushes the evolution of our modern brains back to about 1 million years ago. Either way, it’s clear our current anthropomorphic bias has painted a cloudy picture. It’s much more likely that many of these species were roaming around with similar cognitive abilities. Occam’s Razor suggests that’s more likely than all these species evolving “intelligence” in such a short time. 

Long after the three species were on Earth, they interbred from time to time. Through DNA testing we can identify DNA that came from interbreeding with both. The highest percent of denisovan DNA in modern humans is in Melanesian population ranges; it ranges from 4 to 6 percent, lower in other Southeast Asian and Pacific Islander populations, and nearly undetectable elsewhere in the world.

Denisovans became extinct about 40,000 BCE, the last surviving in Siberia. They built shelters, wore clothes, used tools, and spoke. Late Homo heidelbergensis, neanderthals, denisovans, and sapiens all likely looked very similar: a combination of the wide variety seen in modern humans.

When Homo sapiens first emerged, their population in Africa was likely just a few hundred thousand, while the total hominin population, including other species like Neanderthals and Homo heidelbergensis, may have ranged from 1.1 to 2.1 million. During this period, Homo sapiens were primarily found in Africa, while other hominins occupied broader ranges across Eurasia, with Neanderthals and Denisovans adapting to their environments with sophisticated tool-use and social structures. The early hominin distribution and interaction remain unclear, and this narrative, while speculative, helps us imagine the ancient world, highlighting the need for caution in interpreting these ancient population dynamics. Check out A New Look at Ancient Hominin Numbers: A Speculative Journey for more information.

Found in central India, these cupules (circular hollows on rock surfaces) are among the earliest known forms of rock art.

Discovered in 2013 and first dated in 2017, Homo naledi and humans coexisted in South and East Africa from our emergence around 315,000 years ago until their extinction about 236,000 years ago. It is possible that we share a common ancestor with them, but research is pending. Homo naledi lived in South Africa from 335,000 to 236,000 years ago, and our earliest evidence for Homo sapiens put us originating in East Africa.

Imagined Image: A speculative scene of several Homo naledi individuals around a natural fire source, set in an ancient South African landscape. This visualization highlights the social and survival aspects of early hominin life.

Survival: From about 335,000 to 236,000 years ago in South Africa.
Size: 4’9″ to 5’3″
Brain Size: around 465 to 600 cm³
Brain to Body EQ: 3.3 to 3.8 (humans=7.4 to 7.8)

All humans today share a single grandma, circa 175,000 BCE. We know this because all humans alive today share our ancestor’s haplogroup L genes — from our X chromosome. She was one of many thousands of women living in eastern Africa. Many maternal lines survived for many generations but ultimately over time all the other female lineages died out.

In the lush landscapes of northeastern China, the discovery of the Homo longi skull has opened new chapters in our understanding of human evolution. This skull, dating back to approximately 146,000 years ago, represents a pivotal moment in prehistory. Homo longi, also nicknamed “Dragon Man,” showcases a unique blend of archaic and modern traits—marked by a large, broad face and pronounced brow ridges. This solitary but exceptionally well-preserved fossil suggests that Homo longi could have emerged as a distinct species much earlier, potentially around 200,000 to 300,000 years ago. The timing and features of Homo longi indicate it might represent an earlier migration out of Africa, preceding or running concurrent with other known migrations. The implications extend further, hinting at a possible influence from Homo antecessor, which may have shaped the evolutionary path of humans more profoundly than previously recognized. The Homo longi fossil, while singular, provides a critical piece of the puzzle in tracing the intricate web of human ancestry and migration across continents.

The “out of Africa” migration took place in many waves of which two are widely recognized: 130,000 to 100,000 BCE, and the Southern Dispersal around 70,000 to 50,000 BCE. Through genetic DNA testing we know that none of the genetic differences prior to circa 70,000 BCE exist in today’s humans.

Denisovan: This bracelet dates from 70,000 to 40,000 BCE. It was discovered inside the Denisova Cave beside ancient human remains. The Denisova Cave is a cave located in Siberia, Russia. Other cave finds include woolly mammoth and woolly rhino bones. Scientists say there is evidence that the bracelet’s maker used a drill. This is the earliest known example of advanced drilling in the world.

Head of the museum Irina Salnikova said: ‘The skills of its creator were perfect. Initially we thought that it was made by Neanderthals or modern humans, but it turned out that the master was Denisovan.” This has led to speculation that these earliest humans, Denisovans, were more technologically advanced than previously thought. If true, it might be that the Denisovans were more skilled than Homo sapiens and Neanderthals of the time.

Like Neanderthal DNA, Denisovan DNA exists in modern humans. Non-African East Asians and Europeans have about 2% Neanderthal DNA. Modern Melanesians derived about 5% of their DNA from Denisovans.

Discovered in 2019, Homo luzonensis inhabited the Luzon area north of Manila in the Philippines from at least about 67,000 to about 50,000 years ago. While current evidence suggests that Homo luzonensis may have become extinct before the documented arrival of Homo sapiens around 35,000 to 40,000 years ago, the exact timing of their extinction remains uncertain.

Lineage: Similar to Homo floresiensis, the luzonensis people are not likely descendants of Homo heidelbergensis. It is more plausible that they descended from an earlier ancient human, possibly from the Dmanisi population, an early Asian Homo erectus lineage, or potentially even directly from Homo habilis. However, any direct link to Homo habilis is speculative, but particularly interesting given the small brain size and stature of the luzonensis people.

Imagined Image: A small group of Homo luzonensis in a dense tropical forest on Luzon. This visualization emphasizes their survival strategies and interactions within their lush habitat.

Survival: From about 50,000 to 67,000 years ago (possibly earlier) in Luzon area, near Manilla, Philippines.
Size: 3′ 3″ to 3′ 7″ (same size or smaller than Homo floresiensis)
Brain Size: Estimated around 400 cm³ (about the same size as Homo floresiensis).
Brain to Body Encephalization Quotient (EQ): Ongoing research but likely about the same as Homo floresiensis, about 3.2.

Through minor DNA changes, we know which early humans have descendants alive today. This successful “out of Africa” migration, the Southern Dispersal, took place around 70,000 to 50,000 BCE. Our ancestors proceeded to colonize all the continents and larger islands, arriving in…

• Eurasia circa 60,000 BCE
• Australia circa 65,000 BCE
• South America circa 30,000 BCE
• North America circa 28,000 BCE (31,000 to 29,000 BCE)
• Hawaii, Easter Island, Madagascar, and New Zealand circa 300 to 1280 CE

Dark Skin Diversification: Africa’s intense UV radiation continues to select for darker skin, which protects against UV-related damage and helps in managing folate levels. The mention of some populations developing even darker skin tones could be linked to local environmental adaptations within the continent.

Homo erectus and humans last coexisted in Javanese in Asia around 50,000 years ago.

Imagined image above: A late-stage Homo erectus individual in Java, Indonesia, focused on crafting a tool from volcanic rock near a simple fire, set within the lush tropical rainforest. This visualization aims to capture the essence and appearance of Homo erectus during this late stage of their existence.

The feature of the epicanthic fold, particularly prevalent among East Asian populations descended from Haplogroup A, is an adaptation to cold, windy, and bright environments encountered as humans migrated northward from Africa. This phenotype likely developed to protect the eyes from frostbite and snow blindness, showcasing how genetic diversity within human lineages adapted to specific environmental challenges.

Homo neanderthalensis: Neanderthals and humans coexisted in Europe and Asia until around 40,000 years ago. While their exact cause of extinction remains debated, competition with modern humans and climate change are thought to be contributing factors.

Imagined image: Left is a neanderthal, right a human. Just as human looks vary widely, Neanderthals did too. This is perhaps one way neanderthals might have looked. The likely looked a bit more human than this too, but this gives you a good idea of the differences.

Current understanding suggests that the diverse skin colors among modern humans, ranging from dark brown to fair, evolved multiple times both within Africa and as Homo sapiens migrated out of Africa. This variation is driven by natural adaptation to varying levels of UV radiation exposure in different populations, a process that typically unfolds over thousands of years.

Modern humans predominantly descend from a successful migration wave out of Africa that occurred around 50,000 years ago. Although there were earlier migratory events, this later exodus has been well-documented and significantly shaped our genetic makeup. Evidence suggests that these migrants interbred with earlier waves of sapiens as well as other hominin groups they encountered, notably including Neanderthals and Denisovans.

Skin color adaptation occurred in each migratory wave of Homo sapiens, as well as through interactions with other hominins. The process that most significantly affected modern skin colors began during these migrations and continued over a span of 20 to 30 thousand years. Cross-breeding among various waves of populations, which contributed to the diversity in skin pigmentation, was almost certainly a factor. Lighter skin tones primarily evolved in areas with reduced sunlight, especially after the Last Glacial Maximum, to facilitate vitamin D synthesis under conditions of lower UV radiation.

Note: The adaptation of skin color is intricately linked to the migration patterns of ancient humans. As populations spread from Africa into Europe, the Mediterranean, the Middle East, and Asia, their skin color adapted to local environmental conditions. Robust genetic evidence, particularly concerning alleles such as those in the SLC24A5 and SLC45A2 genes, supports these adaptations. This evolutionary trajectory underscores the complex interplay between genetics, diet, and environment in shaping one of the most visible aspects of human diversity.

As dairy farming became prevalent, particularly in Europe and some African communities, natural selection favored individuals who could digest lactose into adulthood. This genetic adaptation, known as lactase persistence, is a direct result of human cultural practices (dairying) and has had significant dietary implications.