Rosa Rubicondior: Refuting Creationism - Why Modern Humans Took So Long To sucessfully Leave Africa.

Sunday, 29 June 2025

Refuting Creationism - Why Modern Humans Took So Long To sucessfully Leave Africa.

Humans learned to thrive in a variety of African environments before their successful expansion into Eurasia roughly 50,000 years ago.

Before Dispersing out of Africa, Humans Learned to Thrive in Diverse Habitats

Despite what creationist dogma requires its adherents to believe, anatomically modern humans (Homo sapiens) were present in Africa for a considerable time before following their archaic ancestors, H. erectus and possibly H. heidelbergensis, out of Africa and into, primarily, South Asia. One find, reported in 2017, suggested that H. sapiens were in Morocco, North Africa, as early as 315,000 years ago. Yet they don’t appear to have made a successful migration out of Africa until about 50,000 years ago.

The question is: what took us so long?

Aside from the need for favourable climatic conditions — providing habitable routes with sufficient food and water for hunter-gatherers — new research suggests that the delay may also have been due to a simple lack of the necessary skills and experience to quickly adapt to unfamiliar environments. It may have taken that long for humans to spread widely enough across Africa to acquire those crucial adaptive skills. Once we had them, there was little to stop us from using them beyond Africa.

Of course, they would not have been migrating in the sense of deliberately moving into new territory, which would imply a detailed knowledge of geography, but were simply spreading naturally into suitable adjacent areas as their population grew.

This new research was conducted by a consortium of scientists led by Professor Eleanor Scerri of the Max Planck Institute of Geoanthropology in Germany, and Professor Andrea Manica of the University of Cambridge, UK. By analysing a dataset of archaeological sites and environmental records spanning the last 120,000 years in Africa, the team determined that humans began expanding into a wider range of habitats within Africa around 70,000 years ago. Although there had been earlier windows of favourable climate for migration into Eurasia, these attempts appear to have failed. Between 70,000 and 50,000 years ago, however—despite more challenging conditions—the migration that ultimately succeeded took place. All non-African people today are descended from that event.

The consortium has recently published their findings open access in Nature. Their work is also explained in a Max Planck Institute of Geoanthropology news item.

What information is there on earlier human migrations, including that of archaic hominids? There is substantial evidence that both Homo sapiens and earlier hominins attempted migrations out of Africa long before the successful dispersal ~50,000 years ago. Here's an overview of what we know so far about these earlier migrations, including those of archaic hominins:

Archaic Hominin Migrations (pre-Homo sapiens)

Homo erectus (~1.9 million years ago onward)

H. erectus was the first hominin known to leave Africa.
Fossil evidence places them in:

Dmanisi, Georgia: ~1.8 million years ago.

Java, Indonesia: by ~1.5 million years ago.

China (Zhoukoudian and other sites): later Pleistocene, ~800,000 years ago.

This species was remarkably successful and long-lived, surviving in Southeast Asia until possibly as late as 100,000 years ago.

Homo heidelbergensis (~600,000 – 200,000 years ago)

Likely gave rise to both Neanderthals in Europe and Homo sapiens in Africa.
Fossils found in:

Europe (e.g., Sima de los Huesos, Spain).
Africa (e.g., Kabwe, Zambia).

Thought to have migrated between Africa and Eurasia during interglacial periods.

Homo naledi, Homo floresiensis, Homo luzonensis

H. naledi was likely endemic to South Africa (~335,000–236,000 years ago) and not involved in migrations.
H. floresiensis and H. luzonensis (found in Indonesia and the Philippines respectively) suggest that early hominins reached remote islands, possibly via primitive seafaring, by at least 700,000 years ago in the case of Flores.

Early Homo sapiens Migrations (before 50,000 years ago)

Misliya Cave, Israel (~180,000 years ago)

Fossils of early H. sapiens in the Levant.
Shows that modern humans attempted to leave Africa earlier than previously thought.

Skhul and Qafzeh, Israel (~120,000 – 90,000 years ago)

Anatomically modern human remains associated with Middle Palaeolithic tools.
These early migrants likely failed to establish lasting populations—possibly displaced by Neanderthals or affected by environmental changes.

Al Wusta, Saudi Arabia (~85,000 years ago)

Fossil finger bone of H. sapiens and associated tools.
Suggests humans were reaching the interior of Arabia during wetter climatic phases.

Southeast Asia and China (~80,000–45,000 years ago?)

There are claims of H. sapiens remains and artefacts from southern China and Southeast Asia predating the 50,000-year threshold, but these are often disputed or difficult to verify.
One example: Fossils from Tam Pa Ling, Laos (~46,000–63,000 years ago), may represent early migrants.

Genetic Evidence of Early Migrations

Introgression from Neanderthals (~1–2% in all non-African genomes) and Denisovans (especially in Melanesians and some East Asians) indicates that H. sapiens interacted with these archaic populations outside Africa.
These genetic signals suggest multiple waves of migration and contact, some of which didn’t result in sustained populations but left genetic traces.

Why Earlier Migrations Failed

Climate instability: Many of these attempts occurred during interglacials followed by harsh glacial periods.
Competition with other hominins: Such as Neanderthals in Europe and Denisovans in Asia.
Small population sizes: Likely made early H. sapiens groups vulnerable to extinction due to disease, starvation, or genetic bottlenecks.

Before Dispersing out of Africa, Humans Learned to Thrive in Diverse Habitats
Before the ‘Out of Africa’ migration that led humans into Eurasia and beyond, new research shows that humans expanded their niche to include African forests and deserts. The authors argue that human populations learning to adapt to new and challenging habitats was key to the long-term success of this dispersal.
Today, all non-Africans are known to have descended from a small group of people that ventured into Eurasia after around 50 thousand years ago. However, fossil evidence shows that there were numerous failed dispersals before this time that left no detectable traces in living people.

In a paper published in Nature this week, new evidence for the first time explains why those earlier migrations didn’t succeed. A consortium of scientists led by Prof. Eleanor Scerri of the Max Planck Institute of Geoanthropology in Germany, and Prof. Andrea Manica of the University of Cambridge has found that before expanding into Eurasia 50 thousand years ago, humans began to exploit different habitat types in Africa in ways not seen before.

We assembled a dataset of archaeological sites and environmental information covering the last 120 thousand years in Africa. We used methods developed in ecology to understand changes in human environmental niches, the habitats humans can use and thrive in, during this time.

Dr Emily Hallett, co-first author
Department of Anthropology
Loyola University Chicago, Chicago, IL, USA.

Our results showed that the human niche began to expand significantly from 70 thousand years ago, and that this expansion was driven by humans increasing their use of diverse habitat types, from forests to arid deserts.

Dr Michela Leonardi, co-lead-author
Department of Zoology, University of Cambridge, Cambridge, UK.

This is a key result. Previous dispersals seem to have happened during particularly favourable windows of increased rainfall in the Saharo-Arabian desert belt, thus creating ‘green corridors’ for people to move into Eurasia. However, around 70,000-50,000 years ago, the easiest route out of Africa would have been more challenging than during previous periods, and yet this expansion was sizeable and ultimately successful.

Professor Manica, co-first author.
Department of Zoology
University of Cambridge, Cambridge, UK.

Many explanations for the uniquely successful dispersal out of Africa have been made, from technological innovations to immunities granted by admixture with Eurasian hominins. However, no technological innovations have been apparent, and previous admixture events do not appear to have saved older human dispersals out of Africa.

Here the researchers show that humans greatly increased the breadth of habitats they were able to exploit within Africa before the expansion out of the continent. This increase in the human niche may have been a result of a positive feedback of greater contact and cultural exchange, allowing larger ranges and the breakdown of geographic barriers.

Unlike previous humans dispersing out of Africa, those human groups moving into Eurasia after ~60-50 thousand years ago were equipped with a distinctive ecological flexibility as a result of coping with climatically challenging habitats. This likely provided a key mechanism for the adaptive success of our species beyond their African homeland.

Prof. Eleanor M. L. Scerri, co-first author
Human Palaeosystems Group
Max Planck Institute of Geoanthropology, Jena, Germany.

Publication:
Hallett, E.Y., Leonardi, M., Cerasoni, J.N. et al.
Major expansion in the human niche preceded out of Africa dispersal. Nature (2025). https://doi.org/10.1038/s41586-025-09154-0.

Abstract
All contemporary Eurasians trace most of their ancestry to a small population that dispersed out of Africa about 50,000 years ago (ka)^{1,2,3,4,5,6,7,8,9}. By contrast, fossil evidence attests to earlier migrations out of Africa^{10,11,12,13,14,15}. These lines of evidence can only be reconciled if early dispersals made little to no genetic contribution to the later, major wave. A key question therefore concerns what factors facilitated the successful later dispersal that led to long-term settlement beyond Africa. Here we show that a notable expansion in human niche breadth within Africa precedes this later dispersal. We assembled a pan-African database of chronometrically dated archaeological sites and used species distribution models (SDMs) to quantify changes in the bioclimatic niche over the past 120,000 years. We found that the human niche began to expand substantially from 70 ka and that this expansion was driven by humans increasing their use of diverse habitat types, from forests to arid deserts. Thus, humans dispersing out of Africa after 50 ka were equipped with a distinctive ecological flexibility among hominins as they encountered climatically challenging habitats, providing a key mechanism for their adaptive success.

Main
Genetic evidence, including patterns of interbreeding with Eurasian hominins, indicates that all contemporary human populations outside Africa derive most of their ancestry from a worldwide expansion that began approximately 50 ka (refs. ^{1,2,3,4,5,6,7,8,9}). However, the fossil record shows that earlier dispersals also occurred^{10,11,12,13,14,15,16}. These dispersals out of Africa probably took place during repeated humid episodes within the Saharo-Arabian arid belt, most notably during the Last Interglacial, approximately 125 ka (refs. ^10,17). An important question, therefore, concerns why these earlier dispersals were not successful enough to contribute any detectable genetic ancestry of non-African populations today, with early Homo sapiens failing to establish long-term viable populations in areas beyond Africa.

Researchers have proposed a range of explanations for the late dispersal of modern humans from Africa. Studies have considered that abrupt climate change in Africa¹⁸ and large shifts in human cognition, technology and subsistence permitted the development of new ‘niche-broadening’ innovations, such as the distinctly human ability to communicate symbolically or develop projectile weaponry^{19,20,21,22,23}. However, complex weaponry has now been shown to have notable time depth in Africa^24,25 and recurrent markers of symbolic behaviour are present at least during Marine Isotope Stage 5 (MIS 5, 130–71 ka) in both Africa^{26,27,28,29,30} and Southwest Asia^29,30. By around 60 ka, the Middle Stone Age/Middle Palaeolithic archaeological record of Northeast Africa and neighbouring regions of Southwest Asia had become rather generic^31,32, with no particularly notable, regionally specific shared characteristics. More broadly, the African archaeological record features complex, nonlinear trajectories of cultural change^33,34. These often include long periods of stasis punctuated by relatively brief pulses of innovation in different African regions^{35,36,37,38,39,40,41} thousands of years before the advent of Eurasian founder populations^10,42. Large, cumulative changes in the archaeological record also post-date the 60–50-ka time frame¹⁰, suggesting that the success of modern human founding populations in Eurasia did not rest on a particular widespread technological innovation or sudden increased cognitive capacity⁴³. More recent studies have focused on a variety of interrelated explanations rooted in demography. In particular, the apparent geographic expansion of Middle Stone Age archaeological sites in Africa 125–50 ka has been considered to reflect a possible growth in population coupled with an expansion inside Africa of an ancestry similar to the major expansion wave1,^44,45,46. This population expansion is also thought to include greater population density⁴⁷ and increases in connectivity through long-distance social networks⁴⁸, all of which may have acted as ‘push’ factors. Building on quantitative studies of niche changes associated with hominin species⁴⁹, and with particular Middle Stone Age lithic industries²², the spatial patterning of sites has also been used to suggest a uniquely human adaptation to a ‘generalist–specialist’ niche⁵⁰. However, none of these hypotheses have been quantitatively assessed on a continental scale and few have been examined in terms of the predictions of suitable theoretical models, risking a proliferation of post-hoc explanations^51,52. Because human expansion within and out of Africa can be linked to expansions in niche breadth under an ideal free distribution⁵³ model, we explored successful out of Africa in terms of expansions of the human niche. As population densities increase, human settlement in more challenging environments becomes profitable. Under such conditions, in which the critical population mass required for successful out of Africa movements is reached and the ecological resilience of humans increases, expansions can occur^54,55.

Here we specifically test whether the niche of Pleistocene H. sapiens expanded or contracted within Africa before major dispersals out of the continent. We define niche as the ensemble of bioclimatic factors determining where the species can survive and reproduce⁵⁶. To answer this question, we build on previous studies^{22,57,58,59,60} and use a SDM approach61 to measure changes in the breadth of the Pleistocene human niche within Africa. Our results, tested against two different sets of palaeoenvironmental simulations^62,63,64, formally demonstrate that human niche expansion precedes and coincides with successful later dispersal out of Africa.

Hallett, E.Y., Leonardi, M., Cerasoni, J.N. et al.
Major expansion in the human niche preceded out of Africa dispersal.
Nature (2025). https://doi.org/10.1038/s41586-025-09154-0.

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

This new research further undermines the young-Earth creationist narrative by reinforcing the vast and complex timeline of human evolution—one that stretches back hundreds of thousands of years, well beyond the literalist biblical chronology that claims Earth and humanity were created within the last 6,000 to 10,000 years. The study highlights that Homo sapiens existed across a wide and ecologically varied African landscape for tens of thousands of years before successfully migrating out of Africa around 50,000 years ago. Not only does this show a timescale incompatible with the Genesis account, but it also presents a slow, gradual process of behavioural and ecological adaptation wholly at odds with the idea of a single, sudden creation event.

The findings also challenge the notion of a single founding pair — such as Adam and Eve — from whom all modern humans supposedly descend. The genetic, archaeological, and environmental data collectively point to a diverse, structured population of early humans who evolved and adapted over time in different regions of Africa before their eventual dispersal. There is no evidence of a genetic bottleneck consistent with a global flood or a recent single-couple origin. Instead, the data strongly support deep population structure and long-term continuity of human lineages, which is precisely what evolutionary theory predicts and what biblical literalism fails to accommodate.

Moreover, the notion that early humans lacked the skills to survive outside Africa until they had developed sufficient ecological experience makes sense only in a framework where cognitive and cultural abilities evolve incrementally over time. This too runs counter to the biblical view of humans as created fully formed and capable from the outset. In essence, this research underscores the evolutionary model of humans as adaptive, gradually changing organisms, not as the unchanging product of divine fiat. For creationists, this represents yet another evidential blow — a demonstration, grounded in rigorous, multidisciplinary science, that the true story of humanity is far older, far more complex, and far richer than any literal reading of Genesis could possibly allow.

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