Gigantopithecus

The largest ape to have ever existed was the Gigantopithecus blacki. Its name combines the Greek words that mean precisely that: gigantos = giant and pithekos = ape.

To be more precise, it was the largest hominoid, a superfamily (Hominoidea) that comprises three families; the: Hylobatidae (gibbons), Pongidae (orangutans), and our closest relatives, the Hominidae (gorillas, bonobos, chimpanzees, and humans); as well as our extinct ancestors, the erectus, Neanderthals, Denisovans, etc.).

Gigantopithecus lived in Asia, and was closely related to the Pongo group (which includes the orangutan), it was a gigantic variety of orangutan. It was definitely Asian, as it descended from a line of Asian apes that included the 12 million year old Sivapitheucs and the 6.5 million year old Indopithecus, both from India.

The image above depicts a band of Gigantopithecus being watched by hominins (Source).

Gigantopithecus lived in the subtropical forests of Central China, close to what is now Chongqing on the Yangtze River, and fromt there southwards into to Vietnam and as far as Java, in Indonesia. It thrived between 2 million and 300,000 years ago. Like gorillas and orangutans, it munched fruit, leaves, and juicy stems, and maybe, tubers and roots.

It was discovered by a German paleontologist Ralph von Koenigswald (1902-1982), whose sharp eye noted a large primate tooth being sold as "dragon bones" in a traditional Chinese medicine shop in Hong Kong, in 1935. He named it after Canadian anthropologist Davidson Black (1884-1934), who had passed recently. Black had identified the remains of Homo erectus in Beijing, China, naming it Sinanthropus Pekinensis (China Man of Beijing).

Gigantopithecus lived up to its name, it was very big, probably weighing 200 to 300 kg (440 to 660 lbs). It was tall, measuring 2.7 to 3.7 m (9 to 12 feet). Twice the size of a modern gorilla.

Extinction

It was well adapted to its environment, yet, vanished suddenly around 300 kya. Orangutans managed to survive in the same habitat, which makes us ask why did the Gigantopithecus become extinct.

Zhang et al., 2024 attribute its demise to environmental changes that took place between 215 and 295 kya. Climate swings altered the vegetation coverage of that region, which switched from a blend of forests and grasslands to an open forest. Gigantopithecus didn't manage to adapt, and died out. Orangutans did, and survived until now.

Tool maker?

Han et al., 2024 reported the discovery of gigantopithecus teeth associated with teeth of "an undetermined hominid" between 1 and 1.5 million years ago at the Jianshi Longgudong site in China.

These hominid teeth were studied by different scholars over the course of the past 50 years, and have been attributed to a wide variety of hominids: Australopiths, Australopithecus robustuss, early Homo, Homo erectus, and even the Meganthropus. This suggests an overlap of archaic hominids with the Gigantopithecus. Could these hominids have hunted the Gigantopithecus and caused its extinction?

There is another site in China, Longgupo Cave, where Gigantopithecus co-existed with an archaic hominin believed to be either Homo erectus, or to "have the affinities with African Homo habilis and Homo ergaster (Huang et al., 1995). Since 2009, this specimen has been considered to belong to a “mystery ape” instead of Homo (Ciochon, 2009)."

This is really interesting, hearing about typically African hominids like Australopiths and Homo habilis, whose remains have not been found (yet) in Asia.

Others, however, believe it is an Asian variety of ape, like Wu, 2000.

Surprisingly, a primitive paleolithic stone tool "culture" that has been unearthed at the Longgupo site. Over 1,000 stone artifacts have been discovered there, dated between 2.5 and 1.8 million years old. These are old dates, and would more or less overlap with the most ancient remains found to date in Asia (mostly attributed to Homo erectus, and the H. georgicus from the Dmanisi site in Georgia), and even older than those as 2.5 million years corresponds to a very early date, for which no fossils have yet been discovered outside of Africa.

Wei et al., 2014 wrote that they are of an "evident human agency such as bipolar hammer, cores, flakes, choppers, points, scrapers, proto-cleavers, drilling tools, proto-picks and proto-hand-axes... Who the creators of Longgupo culture were is still a mystery. Three types of highly-evolved primate fossils have been unearthed from Longgupo Site. They are represented by a mandibular fragment with p4-m1, an upper incisor, and 14 isolated teeth of Gigantopithecus blacki respectively. All these three types could be the possible creators of Longgupo culture. On the other hand, we cannot exclude a possibility that an ancient human still unknown but similar to Homo habilis could be revealed with the forthcoming excavations." The image above is from Wei, 2014 and shows these remarkable stone tools.

Again, a paper suggesting the presencce of Homo habilis in Asia! Even more surprising is the suggestion that these stone tools could have been made by a non-hominin ape, the Gigantopithecus. This would be a unique situation as these tools are more sophisticated than the stone tools used by monkeys.

Han, et al., 2017, in an article, review the discussion on who made the tools as an ongoing controversy, and add that "the evidence of Gigantopithecus teeth and stone artifacts on the site is still interesting, as it could provide the first indication of non-hominin tool-using apes in East Asia..."

There is a third site showing an overlap of hominids and Gigantopithecus. And, once again the Chinese authors of the paper mention Australopiths! Wei et al., 2005 also report Gigantopithecus teeth in a cave at Mohui, in Guangxi, Southern China. They were found with teeth that have a strong resemblance to Australopith teeth, but "as there is no evidence supporting the existence of Aus-tralopithecus outside Africa to date, it is difficult to attribute [it] to this genus", instead, and despite the fact that they are larger than Chinese erectus teeth, they ".temporarily assign these teeth to Homo erectus." The stone tools at the site are crude, and date back to between 1.6 and 0.8 million years.

Closing Comments

There have been suggestions (see Stringer) of an ancient, first migration of prehuman hominins out of Africa (or originating in Eurasia) or one close to Australopithecines and Homo habilis that could have been the hominid mentioned in all of these Chinese-authored papers.

Regarding Gigantopithecus, I seriously doubt it managed to survive until the present, and although some publications have proposed it as an explanation for the North American bigfoot, I don't think it could have handled the cold, icy conditions of Siberia and Beringia. Others have proposed the Gigantopithecus as the answer for the myserious Yeti. This may be based on very ancient oral traditions, but it seems unlikely.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

Chimp-Homo split in Eurasia?

Earlier this year, in my March 2nd post, I quoted Mansfield and Vaneechoutte, 2024 who put forward a new hypothesis about the split between Pan (chimpancees), Gorilla, and Homo. Instead of taking place in Africa, they argue that the split happened in Eurasia.

Since one of my recent posts dealt with the Chimpanzee-Human (Homo) spilt, assuming the orthodox view that it took place inside Africa, in today's post we will revisit the possibility of an Eurasian origin for the Homo genus.

Mansfield and Vaneechoutte's paper

In their article, Mansfield and Vaneechoutte elaborate on the lack of fossils inside Africa of a common ancestor for chimps, gorillas, and humans.

Focusing on the very early presence of apes in the Anatolia and the Balkans at 10 to 6 million years ago, they suggest that the closure of Gibraltar that led to the dissecation of the Mediterranean Sea (Messenian Salinity Event), and the very arid period that followed that event, forced the "separate branches of European hominids to migrate out of the Mediterranean region." This migration led the ancestors of gorillas and chimpanzees-bonobos across the dry seabed of the Mediterranean, from Greece, into Africa.

The authors believe that the ancestors of Gorilla and Pan entered Africa from Eurasia in two separate migratory events, and a third lineage, the one leading to Homo, and eventually to us, humans, moved in another direction into the Arabian Peninsula. There, these future Homo survived the hyperarid period that had forced them out of Europe.

Tectonic rifting led to thhe reopening of Gibraltar, and the vast Zanclean Megaflood that took place 5.3 million years ago modified the geography and cut-off potential routes of entry into Africa (like Sinai), by refilling the Mediterranean basin up, in just two years, and flooding the Sinai region and the Red Sea. Isolating the ancestors of Homo in a humid refuge in Arabia, isolated from all other apes.

The Pan lineage, of the chimpanzees and bonobos went deep into Africa and there, it split, with a branch evolving into the Australopithecines and the Paranthropus. These small-brained, small, primitive hominins are more adapted to a life in the trees than in the open savannas.

Homo, evolved, and produced the bigger, stronger, long-legged, brainier Homo erectus. This paper suggests that after the water levels dropped, coastal corridors and routes opened up, and these were used by erectus to walk westwards, into Africa, and east, crossing Eurasia from China and Indonesia, while the northern route through the Levant led to the Caucasus (Dmanisi) and Europe.

This theory was again put forward in a paper by Verhaegen, Munro, Bonne, Mansfield, & Vaneechoutte, 2026 (A hypothesis of ape and human evolution based on comparative biology and plate tectonics. Academia Biology, 4(2). https://doi.org/10.20935/AcadBiol8310) which is worth reading as it explains in detail the species, and gives a very good timeline for all these eventss.

Earlier, Böhme, 2017 had proposed an Eurasian origin of the Homo group and a Eurasian split between the ancestors of chimps and humans: suggesting that "the Pan-Homo split predated the Messinian and that the chimpanzee–human last common ancestor thrived in the Mediterranean region... major Miocene hominid radiations occurred outside Africa and endorse the hypothesis that the hominin clade arose in the Eastern Mediterranean."

However, these ideas are dismissed by mainstream scholars. I believe that the reason for this is that an African origin of Homo is crucial to the Out Of Africa theory.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

The human hand and Homo genus

In my previous post I discussed the similarity between chimpanzees amd bonobos, who our closest living relatives, and how different they seem to be in comparison to us, despite a relatively recent (6 million year old) split from our Last Common Ancestor (LCA).

While preparing that post I came across an old paper written by Tocheri, Orr, Jacofsky, and Marzke in 2008 (The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo. J Anat. 2008 Apr;212(4):544-62. doi: 10.1111/j.1469-7580.2008.00865.x. PMID: 18380869; PMCID: PMC2409097). That paper compares the morphology of the hands of Pan, humans, and our older Homo ancestors (Neanderthals, H. erectus), as well as those of other hominins (H. floresiensis and Autralopiths).

The paper is interesting, and the authors reached some revealing conclusions about hand shape and the possible effects of the development of Acheulean stone tool usage and the shape of human (and Homo) hands.

The authors found a clear division in the hand-shapes of pre-Acheulean and Acheulean hominins. On one side are Australopiths, Paranthropus, other early Homo, and the Homo floresiensis, who share primitive features with the LCA. On the other, are the Neanderthals, Homo erectus, Homo antecessor, and modern humans, whose hands developed "Derived changes" over the past 2.5 million years (Ma) and probably even later (1.5 Ma). These dates coincide with the dates when Acheulean stone knapping technology developed.

This suggests, to Tocheri et al., that the shape of the modern human hand evolved to adapt to stone manipulation.

The authors wonder if "the complete suite of derived characteristics present in the hands of modern humans and Neandertals originated earlier with H. erectus sensu lato or possibly with another closely related hominin species" and affirm that "the evidence reviewed in this paper suggests that currently only three species of the genus Homo (H. sapiens, H. neanderthalensis, and H. antecessor) display derived hand morphology that is noticeably absent elsewhere in the hominin lineage, including H. floresiensis... this evidence suggests that these features... may have originated sometime between approximately 1.8 and 0.8 Ma, a temporal span that encompasses the origin and initial spread of Acheulian technology (∼1.5–0.2 Ma). This does not imply that the derived features of the radial wrist are necessary to make or use Acheulian tools, only that the current evidence suggests that these features probably originated within a temporal and behavioral context characterized by Acheulian technology."

Despite their cautious comments, there seems to be a distinct line separating Australopiths and Paranthropus, and even the minute Homo floresiensis of Indonesia, from later, more developed Homo humans like Homo erectus, H. antecessor, Neanderthals, and us. I am positive that when Denisovan hands are discovered, they too will be part of this second group.

Primitive, older / earlier hominins, which are not Homo, don't share the Homo shape hand with us.

The H. floresiensis, which is a Homo, has been included in the "primitive" group. The Flores Island Hobbit has been considered by some authors (see Argue, 2017) to be "a long-surviving relict of an early (>1.75 Ma) hominin lineage and a hitherto unknown migration out of Africa, and not a recent derivative of either H. erectus or H. sapiens" Others, like Kaifu, 2015, based on dental morphology, disagree, and suggest it evolved from early Javanese H. erectus, possibly a case of insular dwarfism.

Study of Arms and Hands - by Leonardo da Vinci.

There is something distinctly unique in human hands, they have allowed us to shape the environment we live in, fashion our tools, clothes, homes, touch, write, create artistic objects. They have evolved in parallel with our brains. Other smart, bright animals (think, orcas, or dolphins) lack the physical attributes necessary to manipulate the world around them. Elephants use their trunks to interact on subtle and manipulative ways with their surroundings, but it is far less delicate than human hands.

This paper seems to find a link between human cognition and hand shape, and the development of Acheulean tools, more sophisticated than the previous cobble type stone tools of the Oldowan stone industry. Later, Neanderthals evolved their Mousterian tools, and humans would advance with other more efficient knapping techniques. But the crucial point was the creation of Acheulean tools, 2 Ma, by the erectus.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

Evolution, divergence, chimps, bonobos, and humans

I often wonder why are chimpanzees and bonobos so similar to each other, at least on their external appearance, and seem to have evolved very slowly over the past two to three million years. Modern Humans, on the other hand, compared to our 3 million year old ancestors the Australopiths and Homo habilis are very different in our abilities and appearance.

Bonobos (Pan paniscus) are a species of ape that lives in the tropical rainforests of Western Africa in the Democratic Republic of the Congo (DRC). They are, together with the chimpanzees, the closest living relatives of human beings. The chimps, (Pan troglodytes) have a wider range in both territory and environment, from tropical jungles to savannas. They live in a wide swath across central Africa, from Guinea and Liberia on the Atlantic area of West Africa, through Mali, Sierra Leone, and across th heart of Africa (Habon, Congo, DRC, Cameroon, Ruanda, and Uganda) and into East Africa (Tanzania).

Chimpanzees and bonobos share a comon ancestor. They diverged into two distinct species between 2.5 and 1.5 million years ago. But, they don't seem to be all that different (on the outside).

It seems that, unlike humans, and our ancestors, they didn't admix with each other. The Congo River seems to have been a physical barrier that kept chimps and bonobos apart (Diogo, 2017).

According to Diogo, although bonobos and chimpanzees are different, the differences between them accumulated at a much lower rate than the differences that either species have with modern humans.

We grew apart, with us mutating faster than either of the Pan species: The rate vs. humans is over 2.5 times higher for the common chimpanzee and over 1.6 times higher for the bonobo, vs. their divergences between each other.

Remarkable difference, considering that we are said to share 98.7% of their genome with us (More on this "myth" further down).

Geographic range chimpanzees and bonobos. Adapted from Fig. 1 in Prüfer, 2012

Behavior-wise, bonobos and chimps are different. See Prüfer, 2012 and Wilson, 2021. Bonobos are more intensly sexual (and creative in that field too!), female dominated and less aggressive towards other bands; they retain the playful attitude of infancy even as they age. Chimpanzees are the opposite (aggressive males, hierarchical, competitive).

However, alpha bonobo males have more offspring than lower ranking ones, and even more than chimpanzee alphas, showing that even in matriarchal societies, there can be a polygynic bias.

Chimps use tools: stones to crack nuts, and wood spears to hunt monkeys or dig for roots. Bonobos don't. Chimps can kill their kin, bonobos don't

Based on these behaviors, it seems that modern humans share traits from both ape species.

Human-Chimp & Bonobo split date

I have always believed that the 6 million year (My) date assigned to the split between humans and Pan, is too recent (see this post). A recent study by Oliveira Coelho et al., 2026 (Parting ways: Pan-Homo divergence revisited) acknowledges that over the past decades, the date has been gradually pushed back "from ~ 6 Ma to ~ 8.5 Ma over the past 56 years" This is important because it impacts on the molecular clock, often gauged using this split date (take the genetic difference between Pan and us, and divide it by the time elapsed since we split, and you have the mutation rate. A more distant split implies a lower mutation rate).

However, fossils are not there! There is a gap in the fossil record spanning the period ~7 to 9 My ago.

Let's see what future research finds.

Similarity between Humans and Pan

A study by Yoo et al., 2024 (Complete sequencing of ape genomes) is quite clear that we are not 99% similar to them (highlight is mine): "The oft-quoted statistic of ~99% sequence identity between chimpanzee and human holds for most of the genome when considering single-nucleotide variants (SNVs) (Fig. 2b). However, comparisons of T2T genomes suggest a much more nuanced estimate. Examining the distribution of 1 Mbp aligned windows shows that the tail of that distribution is much longer with 12.5–27.3% of the genome failing to align or inconsistent with a simple 1-to-1 alignment, especially within centromeres, telomeres, acrocentric regions, and SDs." Structure and content don't seem to line up in the comparison leaving only a 87.5 to 72.7% similarity.

This is quite a spread, from 99% down to 72.7% is a big difference.

Interestingly, regarding the X to A ratio (mentioned in my previous post), Yoo et al., reported an extremely low value: "for the human–chimpanzee–bonobo ancestor (Ne=76,700, X-to-A ratio of 0.42)."

Are we descended from a common ancestor of chimps and bonobos? Or not at all?

We should bear in mind that when we compare humans with the Pan, we are looking at contemporary species, alive now. But we may be far more different from the last common ancestor (LCA) of both humans and chimpanzees-bonobos (Wilson). This LCA could be radically different from Pan and Homo.

The LCA also had a more Pan-like appearance than human. Sekhavati et al., 2025 analyzed the shape of human, hominin, and Pan feet, and found that it "supports the hypothesis of a Pan-like last common ancestor of humans and chimpanzees." Furthermore, the first purported ancestors of our human lineage "the Paranthropus and the Australopithecus africanus + Australopithecus sediba clades evolved arboreal characteristics, suggesting adaptations for arboreality." This is relevant as they are probably not our ancestors after all (more below).

In fact, the earliest human ancestors after the split, members of the Homo group, are probably misclassified as such; I am refering to the Homo habilis. Fortin, 2025 argues that they were added to the Homo group because Leakey argued that even though they had minute brains (only 600 cm³) they walked on two feet and made stone tools. Now, some scholars are having second thoughts. Habilis seems to be more similar to Australopiths than to Homo (see my post: Was Homo habilis a member of our Homo genus?) Even Homo rudolfensis should probably be removed from the Homo group.

In this regard Vaneechoutte et al., 2024 (see my post about his paper: Australopithecines are not our ancestors at all (says study)) wrote: "Instead of considering [Australopith] graciles as ancestral to Pan and robusts as ancestral to Gorilla, as suggested by Kleindienst et al., Verhaegen considered the eastern African australopithecines, such as A. afarensis (incl. Lucy) as well as P. boisei to be ancestral or closer to the genus Gorilla, and the South-African australopithecines, A. africanus (incl. the Taung child) and P. robustus, ancestral or closer to the genus Pan." Vaneechoutee argues that an Ardipithecus-like ancestor evolved into Australopiths, and these evolved into A. africanus and Paranthropus robustus, leading to Pan, and the A. afarensis and P. boisei leading to Gorilla. Humans did not split from Pan, instead they did so from the Adripithecus via an "unknown missing link" adding that "Australopithecines Are Possibly Not Hominins Because Our Ancestors May Not Have Been Present in Africa in between 4 and 3 Ma."

It is possible that Eurasian apes evolved into our ancestor, Homo erectus in Western Eurasia, and that these are the base of the homo lineage.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

X / A Ratio an anomaly between Africans and Europeans-Asians

I am always on the lookout for anomalies between human populations, especially Africans and non-Africans, because they are usually explained away by the classic Out Of Africa reasons of "lower genetic diversity", "bottlenecks", and "founder effects". Natural selection and Neanderthal admixture are also used as explanations.

But, sometimes these unusual situations point at flaws in existing theories, such as mutation rates which vary between population, and over time, or influenced by genetic diversity, non-neutral evolution, etc.

In today's post we will look into the X//A ratio.

What is the X/A Ratio?

Human beings have two sex-defining chromosomes, one is called "X", the other, "Y". Women carry two X chromosomes (they receive one from each parent). So each woman has an XX pair of sex defining chromosomes.

Men on the other hand carry the male defining chromosome Y (received from their biological father), plus an X (received from their mother). Each man, therefore carries a pair of XY chromosomes.

The remaining autosomal chromosomes add up to 22 pairs of chromosomes, a total of 44 chromosomes.

The uneven distribution of X chromosomes in each sex has some interesting consequences.

Since there is roughly one woman for every man, the 44 non-sexual chromosomes are equally distributed and represented in either sex. 44 in men, 44 in women. On average, they spend 50% of their time inside women and 50% inside men, subjected to the chance presence of random mutations, or the action of natural selection.

But, when it comes to the four sexual chromosomes, three of them are "X" and only one is "Y". Women carry two out of the three "X" chromosomes, men carry only one of them.

So X chromosomes spend more time inside women than men. This means that they could be subjected to sexually oriented processes that could modify them with a different intensity, duration and, effects, in each sex.

The expected value of X/A Ratio

In a population with N individuals, half women (N/2) and the other half men (N/2), we can calculate how many X chromosomes ther are in the population. Since women carry 2, and men carry 1, the formula is the following (X in women plus X in men):

2 x (N/2) + 1 x (N/2) = 3 x (N/2) = 1.5 N

Each individual in the population is a diploid, because he, or she, carries two copies of each autosome, having received one from each parent. So for the N individuals, there are 2 copies of each autosome, resulting in 2N autosomes in the population. These are spread 50:50 between men and women.

Now we can calculate the ratio of X chromosomes (X) to autosomes (A) in the population (X/A) can be calculated as:

X/A = 1.5N/2N = 3/4 = 0.75

The "real" value of the X/A ratio

However, when the value is measured in the field, it is not 0.75. There are higher values among Africans, and lower ones in American Latinos, Europeans, and Asians.

Let's look into the X/A ratio in different populations

Among Bonobos (Pan paniscus), our closest living relative (along with the common chimpanzee —Pan troglodytes), the X/A ratio is 0.85 (see Suplemmentary Material, p 114 in Prüfer, 2012

That same study found the X/A ratio for African Yorubas as 0.8, and for a European as 0.68 (p. 120). That is a big deviation from the expected value of 0.75.

Another study by Arbiza, 2014 found similar values; They can be seen in the chart below. The authors point out that they sampled different subpopulations and confirmed the skew in the value: "three populations from the African (AFR) continental group: all three estimates were in the range 0.76–0.77... It was 0.64–0.65 for all five populations of European (EUR) ancestry and 0.60–0.62 for the three East Asian (ASN) populations."

The authors measured but then discarded the American Latino "AMR" group, where variability was even higher, ranging from 0.71 for Puerto Rican (PUR) populations to 0.64 for Mexican Americans (MXL). The reason is that these are admixed people with African (slave trade), European (migration) and Amerindian genes, and there was a sexual bias in the introgressing groups.

This is reasonable, there were many more European males than females who came to the Americas during the first centuries after its discovery. So these men displaced local native males and married/mated with Native women. There were also more men than women in the African slave trade —roughly 1.7:1 ratio (Source). Both factors, plus the "Great Dying" that wiped out up to 90% of the Amerindians between 1492 and 1550, completely distorted the original X to A ratio in the Americas. What we see now is the outcome of admixture, extinction, and migration.

Below is a slightly modified figure 1 in Arbiza, 2014, I added the 0.75 line as a marker.

Explaining the difference. Why is the X:A ratio lower in Eurasians?

The large variation from the theoretical 0.75 ratio has led scholars to propose possible causes. Let's check them out.

To lower the X:A ratio, there are two options: increase A or reduce X. An increase in autosomal pool or a reduction in the X chromosome pool.

Polygyny

Amster et al., 2019 propose that Polygyny is an important factor. The authors attribute the high X:A ratio among Yoruba (YRI) to "substantial polygyny (i.e., that a minority of males sired offspring with multiple females)... our results suggest a few conclusions. The first is that ancestral human populations were highly polygynous, as explaining the polymorphism ratios in YRI would be difficult otherwise. Second, they indicate that non-African populations likely experienced a substantial reduction in polygyny" In other words, one man and one woman pairings.

Veeramah, 2014 agrees with this effect for polygyny (higher female-to-male breeding ratio, in other words a few men monopolize many women and breed with them). This alters the 50:50 ratio assumed further up impacting on the X:A ratio.

But there is no need to imagine a single, possessive male with a collection of wives (harem). We can imagine a scenario in monogamous societies that mimic the effects of social polygyny (societies where men have many wives) such as men remarrying after death of spouse, and having therefore more than one wife, and possibly children with both, that more men than women don't marry and that some men are more successful reproductively and have many more children than a very fertile woman (Labuda, 2010).

Polygyny increases X:A ration but reduces genetic diversity

Interestingly, polygyny reduces the genetic diversity of a population if maintained over time: a few males add their autosomes to the future generations, while most males are excluded. This reduces the contribution and diversity of the male gene pool to subsequent generations.

A society with more women reproducing than men, will maintain a high diversity in the X chromosomes, because these have a 2/3 female source. However, the impact on diversity will be noticed more on autosomal chromosomes because these are supplied on a 50:50 basis by each sex.

If African societies with a high X:A ratio are more polygynic, and this reduces autosomal genetic diversity, why are they said to be the most genetically diverse human population? There is something wrong somewhere.

Hammer et al., 2008 indeed suggest that due to polygyny, fewer unique male genes find their way into the next generation, reducing diversity.

So, can African diversity be caused by other factors, and these overcompensate the loss caused by polygyny? Admixture with superarchaic hominins is one explanation, very isolated populations admixing occasionally in a highly substructured population across Africa is another option. Perhaps, even the ratio of men to women who admixed impacted on the outcome, leading to a highly diverse population with a higher X:A ratio.

Differing mutation rates

Since autosomes and X chromosomes spend their time inside men and women, they are probably subjected to sex-specific factors that alter their random mutation rates. With X chromosomes prevalent (2/3) in women vs. men (1/3), a factor impacting on female mutation rates would have a greater impact on X chromosomes and skew the ratio. The opposite is also true, if mutation rates in males is different to that in females, half of the autosomes (shared 50:50 by each sex) would undergo more (or less) mutations, impacting on the X:A ratio.

Amster et al., 2019 mention this cause, calling it Differential mutation rates. If male-to-female mutation rates are higher, the X/A ratio would be lower. This would mean that Eurasian males have higher mutation rates than Eurasian women, or that African men have lower mutation rates than African women.

Men reproduced at an older age

Amster et al., 2019 also propose that an Increase in male-biased generation times could lead to a distorted X:A ratio. This means that men were reproducing at an older age than women, and that the age gap was growing as time passed. This effect, they suggest, took place around the time of the OOA migration.

Migration (OOA)

Arbiza et al, 2014 suggest that Male dominated Migrations can influence the X to A ratio. During the Out of Africa event there were few women and many men. This impacted on the mix of X and A chromosomes.

But, why did it impact on the initial OOA population (which would have a lower X:A ratio) and not again, as the ancestors of Europeans split from the ancestors of Asians? Wouldn't these new migrations lead to successive drops in X:A ratios? They should, but, as you can see, East Asian and North European X:A ratios are similar!

The migratory theory was first put forward by Keinan and Reich 2010 who proposed that at the OOA event, those who moved out of Africa were relatively homogeneous on a genetic level, having "relatively little genetic variability." The migrant population dispersed into the Levant and more men survived than women (or there were more men in the group than women). This would be reflected in the initial non-African population as a "pronounced reduction of chromosome X effective population size relative to the autosomes". This would reduce X:A (lower X vs. similar A).

They add a twist, suggesting that the "daughters in the founder population of non-Africans b[ore] offspring with new immigrant males more often than the converse" implying successive waves of African males migrating into the original band that left Afica. For this to happen, it had to take place within the first generation after OOA, in a spot close to Africa: "Under the hypothesis of primarily male migration, the founding population of non-Africans must have been localized to a constrained geography long enough to have received the migrants.If the population quickly dispersed throughout Eurasia, we would not see the same pattern in North Europeans and East Asians." So the added wave of Africans explains the similar values of X:A for Europeans and Asians. It took place before they split.

So, Keinan and Reich patch up this anomaly (East Asians and North Europeans, despite migrating have similar X:A ratios, while the OOA group suffered a great reduction just when they left Africa). In my layman opinion the problem is in the OOA theory. Adding Ptolemaic layers to a theory to adapt it to reality does not make sense.

In the words of Keinan and Reich: "The model involves a history in which after the founder population of non-Africans lost much of its genetic diversity, subsequent mostly male gene flow from an African source brought new diversity into the population."

Polyandry

Another option is that the Out of Africa women did not all reproduce with the same success. If very few women had most of the babies in a population where most men participated in the mating, A would be greater, and X would be smaller, leading to a lower X to A ratio. Reich and Keinan consider this "implausible". But, why should we disregard alternate pair bonding societies? A polyandric society, where several men share one wife would fit this description. There are such societies in the modern world, in India, China, Tibet, and the Amazon (Source), it is rare, but not as rare as commonly thought.

Starkweather and Hames, 2012 suggest that "polyandry likely existed during early human history and should be examined from an evolutionary perspective. Our analysis reveals that it may be a predictable response to a high operational sex ratio favoring males and may also be a response to high rates of male mortality and, possibly, male absenteeism."

It makes sense, when there are more men than women, to share wives (the sex ratio favoring males part), and also when they are gone for long periods of time, or die of more frequently, that other men are available to share the load of family responsibilities as well as the marital ones and parenting.

Introgression in Eurasia

Admixture with archaics impacts on the genetic makeup of their offspring. In Eurasia, humans admixed with Neanderthals. This event affected non-Africans. Could it have an impact on the X to A ratio?

Arbiza, 2014 report that the Neanderthal-human matings resulted in a greater effect on the autosomes than on the X chromosome, and that taking this into account led to " new estimates were ∼1% higher across all comparisons, showing that Neandertal introgression can lead to a modest underestimation of relative X/A diversity."

We know that Neanderthal males mated with human females, there was a sexual bias promoting this type of interbreeding. This was also shown by Chevy et al., 2023 who noted in their modelling that "Using simulation studies, we find that when the archaics are mostly male, modern humans end up with less archaic DNA on chromosome X than their autosomes, compared to when there is a female-bias or no sex-bias. Therefore, male sex-bias could be contributing to the difference in the amount of archaic DNA on chromosome X versus the autosomes."

But, the inverse situation could also take place, with male humans partnering with female archaics or super archaics, leading to a higher presence of human DNA in the autosomes of the offspring, and fewer human variants in the X chromosomes.

Closing comments

Sexual partner ratios, introgression, polygyny, polyandry, generation times for both sexes, different mutation rates in men and women, and migration have acted in different directions upon Africans and non-Africans. Efforts to explain the X to A ratio in the framework of an out of Africa migration requires a complex migration pattern with newly arriving men mating with the daughters of the first wave before this population split and spread into East Asia and Europe.

Using an astronomical analogy, perhaps it is time to rethink the Ptolemaic OOA theory and come up with a revolutionary Copernican one.

P.S. Spring in Buenos Aires

Spring has just begun in the Southern Hemisphere, spanning September 22 and 23, 2026 (though we always use the 21st to commemorate its arrival). Now we can expect an earlier sunrise, longer evenings, sunny days, budding trees, flowering shrubs and plants. Warmer, but with cold spells of Antarctic wind interspersed with occasional bursts of hot Amazonian air.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

OOA Routes: Bab-el-Mandeb (Post 5)

The last of the corridors that could have been used by hominins and modern humans to exit Africa (or to enter that continent from Wester Eurasia), located on the southern tip of the Red Sea at a strait known as Bab-el-Mandeb.

Post 1: Where was the Out of Africa Corridor?
Post 2: OOA Routes: Gibraltar
Post 3: OOA Routes: Strait of Sicily
Post 4: OOA Routes: Sinai
Post 5: OOA Routes: Bab-el-Mandeb

Bab-el-Mandeb, the southern route across the Red Sea

These straits formed when the continental crust rifted 30 to 25 million years ago, breaking up Africa from Arabia (in Asia) and creating a gap that was flooded, creating the Red Sea.

The southwestern tip of Arabia, located in Yemen (a conflictive and war-torn region nowadays) is located on the eastern side of the strait, while Eritrea and Djibouti are located on the Horn of Africa side of the strait. Southeast, in the Indian Ocean, is the Gulf of Aden.

Close to the Asian coast is Perim Island (just 2.5 km - 1.6 mi. away), then there is a main channel 21 km - 13 mi wide.

To the south, there is a small group of islands, Sawabi Islands, the "Seven brothers", very close to the African coast. From high ground, you can see across the Strait.

Map of Bab-el-Mandeb Strait. Copyright © 2026 by Austin Whittall

For those who support the Out Of Africa theory, this is an ideal corridor, located close the the main fossil sites of Tanzania, Kenya, and Ethiopia, along the Rift Valley. Humans didn't have to go far to reach the sea and cross it into Asia, to colonize it.

The Crossing

Unlike the dry route through Sinai, this one requires crossing deep water. Rafts, or watercraft were necessary, like they would have been needed to cross Gibraltar or the Tunisian-Sicilian straits.

Flemming, 2003 discusses the corridors out of Africa, and points out that the contemporary continental shelf located 20 to 30 m (60-90 ft.) below modern sea levels does not cross the strait. It would have required a sea crossing to bridge the 5 km wide gap (3.1 miles) caused by the deep cut linking the Indian Ocean and the Red Sea during Glacial Maximum periods. This was a gash with a depth of around 140 to 170 m (460-560 ft.)

López, et al., 2016 discussing the Out of Africa event mention this option as the "Southern Route" across the Red Sea, offering some arguments in favor of its use. Similar arguments are used in another paper by Oppenheimer, 2012, who suggests that, of all the potential routes leading out of Africa, this one was the most favorable for modern humans. The reason is based on genetics.

Oppenheimer points out that mtDNA haplogroup L3, expanded out of Africa around 60 to 70,000 years ago, branching into haplogroups M and N shortly after. These two are found in Eastern and Southern Asia (a region which has the highest amount of variant M and N lineages in the whole world). The Levant and Europe have N variants that are younger than those found in East and South Asia, they also have less diversity. This suggests that humans carrying L3 crossed Bab-el-Mandeb and first moved across southern Arabia (Yemen, Oman), the Persian Gulf, and dispersed east into Southern and Eastern Asia, diverging into M and N on the way. Only later did the N haplogroup head into Western Eurasia.

Further evidence is archaeological, which indicates an early peopling of the Philippines and Papua-Australia earlier than the peopling of Europe.

There is evidence of Homo erectus tools at the Saffaqah site in Saudi Arabia, some 350 km (200 mi) west of Riyadh (see Google map), the site is roughly equidistant from Bab-el-Mandeb and Sinai, so erectus, if originating in Africa, could have used either, or both. Or maybe originated in Asia, and used neither.

Saffaqah Acheulean tools are not that old. They were dated to around 200,000 years ago. They are well described by Shipton, 2018, and correspond to a very humid period in the now extremely arid Saudi deserts. At that time several rivers (Wadi) flowed into both Red Sea and Persian Gulf, creating migration routes and providing water (and prey living along them) for hominins.

An earlier, but northern site is the one located at Ti’s al Ghadah in Saudi Arabia, 300,000 to 500,000 years old. Stone tools and bones with cut marks were found at this site, which at that time was set in a more humid savannah-grassland environment (Roberts, 2018). The authors point out that "The identification of Afrotropical, Saharo-Arabian and Palaearctic fauna in association with hominin presence also highlights the possibility of middle, and perhaps also early, Pleistocene hominin migrations into the Arabian Peninsula from Africa and Eurasia" indicating that Arabia was a two-way corridor, blending pot of Africa and Asia.

Groucutt et al., 2018 describe the oldest modern human fossils outside of the Levant and Africa. They were found at Al Wusta, Saudi Arabia, (approx. location in Google Maps) and are 95,000 to 85,000 years old (older than the generally accepted date for the OOA event). Again, this is closer to Sinai than to Bab-el-Mandeb. The authors point out that "Al Wusta shows that early dispersals were more spatially and temporally extensive than previously thought. Early H. sapiens dispersals out of Africa were not limited to winter rainfall-fed Levantine Mediterranean woodlands immediately adjacent to Africa, but extended deep into the semi-arid grasslands of Arabia, facilitated by periods of enhanced monsoonal rainfall" Indeed, the Arabian Peninsula played a role in the hominin exchange between Eurasia and Africa.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025by Austin Whittall © 

OOA Routes: Sinai (Post 4)

This is the third post in my series on the possible routes taken by hominins in their Out Of Africa (OOA), or into Africa in back migrations over the course of the past 2 million years.

Post 1: Where was the Out of Africa Corridor?
Post 2: OOA Routes: Gibraltar
Post 3: OOA Routes: Strait of Sicily
Post 4: OOA Routes: Sinai
Post 5: OOA Routes: Bab-el-Mandeb

Sinai, the northern route across the Red Sea

Africa is really a vast peninsula of Eurasia, linked by a narrow strip of land that runs between the northern tip of the Gulf of Suez and the Mediterranean Sea. This stretch of desert is roughly 120 km long (76 miles). Since 1869, the Suez Canal runs across this isthmus.

On the eastern side of the isthmus lies in Asia, and is known as Sinai Peninsula, with an area of 62,000 km² (24,000 sq.mi.), jutting into the Red Sea, which surrounds it with two narrow and long gulfs, the Gulf of Suez to the west, and the Gulf of Aqaba to the east. The land connection with the rest of Asia runs along the Egyptian border with Israel.

This area marked by the confluence of different tectonic plates that are splitting the crust of the earth. The rift started to form around 28 million years ago and is still widening by 0.25 to 0.5 mm (1/100 to 1/50 inch) per year. The eastern side is also being uplifted. (Fernández-Blanco, 2025).

Africa lies to the west of the isthums. This region is part of Egypt, and the fan shaped Nile Delta (named for the Greek letter "d" = δ) is adjacent to the Asian-African border.

The delta is a fertile, humid haven in the middle of a vast arid region. The River Nile, flows into the Mediterranean here along two main branches (Rosetta and Damietta), at one time the delta had several addutuibak brabcges and they fanned out further west and east than the present delta. However, the tectonic movement of the Sinai Plate uplifted the eastern edge, causing the easternmost river channel, the Pelusiac River, to silt up, and dry out around 2800 years ago (Stanley, 2008). You can see the site of the former city of Pelusium in Google maps located 21 km, 13 mi. east of the Suez Canal (See Sneh, 1973).

This corridor is the only dry, solid ground, route out of Africa. It did not require crossing any seas, navigating or island-hopping. It was used by animals moving to and fro the Levant. The only complication is that the Sinai is an arid, rugged territory with no permanent rivers or lakes. Rainfall is scarce (120 to 200 mm - 5 to 8 inches per year). This lack of water and desertic conditions are an obstacle. But, it wasn't always like it is now.

The Green & Wet periods

I will follow Breeze, 2016 who has identified several humid periods over the past 250 thousand years that could have favored the migration of human beings across this parched territory and allowed them to cross from the Nile delta to the valley of the Jordan River, and from there, into Western Eurasia. These periods are the following:

• MIS 7. 243 to 191 ka (thousand years) ago. A humid period in NE Africa, Arabia, and the Middle East. The Nile carried plenty of water. Which "raises the possibility of dispersals out of Africa."
• MIS 6. 191 to 130 ka. Continued humidity and from 180 to 170 ka, wet climate in NE Africa and the Levant. Sea levels were lower, allowing for alternate, shorter routes that are now submerged. From 178 to 152 ka, the areas of Jerusalem Dead Sea, all the way to the north of Levant were humid and much wetter, and cooler than nowadays.
• MIS 5e and transition from MIS 6 to 5e (137 to 114 ka). There was a well watered route along the current Nefud desert along the Tabuk Corridor (from Levant, across Arabia towards the Persian Gulf).
• MIS 5a (85-71 ka). A revived damp Tabuk-Nafhyd corridor, a greater flow on the Nile and a slightly humid Sahara.

This brief summary shows that there were plenty of windows between 243 to 71 ka for humans to cross the Sinai and surrounding deserts. This also ocurred many times since our homo ancestors appeared.

The different geography of those days also involved exposed continental shelves along the Mediterranean, a Nile River that flowed further east (Pelusic Branch or similar paleo-branches). Higher rainfall would have formed, along the coastal areas, rivers and streams running into the sea. Breeze notes that this route was used by the hippopotamus "to disperse from Africa to the Levant at the end of the last glacial."

Over the past ten thousand years, as the Egyptian and other cultures appeared in the region, the Sinai ecosystem was altered by human activity. Trees were felled, plant coverage was lost, the topsoil washed away, this led to fewer plants, less rain, and a vicious circle of desertification.

Neanderthals and Erectus in the Levant

Before modern humans, what is now Israel was the home of Homo erectus, and Neanderthals. Goren-Inbar, 2000 summarizes this as follows: There is evidence of Early Pleistocene populations 1.4 million years ago at ‘Ubeidiya with typical Acheulean erectus tools. A more recent site is Evron Quarry (1 million years).

More recently, and with another cultural setting is the Gesher Benot Ya’aqov (or GBY) site (780 ka) which the authors link to "yet another human movement out of Africa." Interestingly the stone tools from this site are not found in similar aged sites across Eurasia, only later did they appear across the continent.

Fire has been recorded at this site too 790 kya (Goren-Inbar, 2004). But who lit them is not known "The producers of the Acheulian material culture have frequently been assumed to be Homo erectus or Homo ergaster; at GBY they may just as well have been archaic Homo sapiens." This closing comment is relevant, because our species, H. sapiens is said to have appared 300 kya. If they are humans, this date is further back than accepted, even older than the split of Neanderthals and Denisovans, and that of humans and the ancestors of Neanderthals and Denisovans.

Homo ergaster is a "sister" species, a variety of African erectus.

The facts are that there are 1.8 million-year-old tools and fossils in Asia of erectus origin (see Yunxian, China), very ancient fossils at Dmanisi, Georgia and even older tools, at Zarqa in Jordania (2.4 My), and Masol, India (2.6 My) probably made by an earlier homo species. This suggests that the movement of hominins out of, and into Africa is ancient, and also, that the obvious route from Africa to Jordania and the Caucasus is through Sinai.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

Archaic Admixture in Africans (23%)

A research paper published by Fan et al., in Cell, in 2023 reported their findings regarding genetic diversity in Africa, as well as suggesting archaic introgression of very divergent ancestors into all humans, in Africa, and also a recent introgression into some specific populations.

This is the paper: Fan S,. Whole-genome sequencing reveals a complex African population demographic history and signatures of local adaptation. Cell. 2023 Mar 2;186(5):923-939.e14. doi: 10.1016/j.cell.2023.01.042. PMID: 36868214; PMCID: PMC10568978.

Introgression

There are two populations that stand out in their analysis. One is the Tikari, from the Tropical jungles of Cameroon in Western Africa, the other are the Herero, from Botswana, the same region where the Ju|’hoansi and !Xoo, San or Khoisan people, come from. The authors note that they have up to 23% of a divergent archaic genetic content, that is olver than the split of all modern humans (highlight is mine):

"The relationship of the Tikari and Herero with other populations is complex. They could be modeled as having 23% ancestry related to an archaic population that diverged prior to the divergence of all modern human populations (possibly reflecting introgression from an archaic population into modern populations) and 77% ancestry from a population related to the Nilo-Saharan-speaking Mursi. A similar pattern was observed in the ADMIXTURE analyses at K = 7 to 11 but with much lower inferred Nilo-Saharan-related ancestries in the Tikari and Herero (Figure S2). The TreeMix analyses showed evidence of gene flow between the Mursi and the ancestors of the Tikari and Herero starting at 5 migration events (Figure S3F). The results indicating archaic introgression in a population ancestral to the Bantu-speaking lineage are consistent with previous studies based on ancient African samples which suggested that the West African Niger-Congo-speaking populations carry lineages ancestral to all modern human lineages. However, time-resolved demographic history models inferred using alternate methods (described below) suggest that the ancestors of San and RHG may have been the first to split from other modern human lineages."

The gene flow from Mursi, an East African group from Ethiopia into West Africa is remarkable. Notice how the quote ends with a comment stating "yes, they may have archaic introgression, but, other methods show that the San are part of the oldest human lineage.

This ancient group, the archaics, split from us 1 to 3 million years ago. But, the authors also suggest an alternate explanation: structured populations. Isolated groups of humans exchanging alleles every now and then would produce the same effect as a ghost introgression:

"Across all pairs of populations, we inferred that all modern humans descend from deeply structured populations and that they derive approximately 5–15% of their ancestry from a lineage that may have diverged as long ago as 1–3 Mya (Figure 4C), consistent with previous findings suggesting archaic introgression in some African populations.However, such a model is also consistent with the population ancestral to modern humans being deeply structured."

They paint a complex scenario with "multiple episodes of gene flow between modern human lineages and possibly with other hominid lineages"

Below is a tree showing the splits and archaic introgressions (San on the right, non-Africans, left. Africans in between).

D: Summarization of the results of demographic analyses. Blue bars show inferred gene flow among modern human populations. OOA: out of Africa populations. Ghost: inferred introgression from a ghost population. We observe evidence of introgression from a deeply diverged population into the ancestor of all modern human populations. In addition, the Bantu-speaking and RHG populations show some ancestry that is very old, possibly reflecting subsequent introgression with a deeply diverged population.. Fan et al., 2023

Pale Skin, shared by San and Europeans

As discussed in a previous post, San and non-Africans share a variant linked to pale skin pigmentation. This paper reports that "rs1800404, a synonymous variant in exon 10, associates with skin pigmentation and eye color variation across multiple ethnicities. The light-pigmentation associated allele rs1800404-T, which is a splicing QTL of OCA252,58, is most frequent in the San (83%) compared to all other populations in the present study and gnomAD except for the Finnish population (frequency of 84%)." The supplementary material table S4 shows the frequencies in different populations as follows: Starting with African populations, and ending with the gnomAD ge nome database that gives general values for AFR (Africans), AMR are Latino-Admixed American. ASJ: Ashkenazi Jews. EAS: East Asian. FIN: Finns. NFE: non-Finnish Europeans, and OTH: unclassified, residual groups.

Amhara 37%
RHG 10%
Dizi 10%
Fulani 23%
Hadza ~0%
Herero ~0%
Ju|'hoansi 83%
Mursi 7%
Chabu 0%
Sandawe 23%
Tikari 0%
!Xoo 83%
gnomAD_genome_AFR 21%
gnomAD_genome_AMR 56%
gnomAD_genome_ASJ 71%
gnomAD_genome_EAS 39%
gnomAD_genome_FIN 83%
gnomAD_genome_NFE 80%
gnomAD_genome_OTH 73%

This seems a strange trait, absent in all of Africa (where dark pigmentation prevails, but present in San and all non-Africans. Note that ALL non-Africans have higher values than Africans except the San Koisan people. The Amhara of Ethiopia, have according to the paper "experienced strong non-African admixture (e.g., Amhara from Ethiopia)"

The paper goes on to descibe another allele, PDPK1, studying different SNPs along it, and noting that it regulates skin pigmentation (reducing the growth of skin-coloring cells called melanocytes, in mice). At one of the SNPs, rs77665059, the ancestral variant "C" (cytosine) is found at higher frequencies among the San people (67 to 83%) vs. other African groups (3%) and non-Africans (14%). "Individuals with the C allele have lighter skin pigmentation compared to individuals with the A allele in the San." Unfortunately, there is no data table to show its frequency in different populations. But from online databases, I prepared the following table (Source and Source)

Population       C (derived allele)
  Group              frequency  
Total Global    1.81%
European        0.75%
Azkhenazi Jews      1.03%
African          9.63%
African Others   10.5%
African American       9.6%
Asian          0%
East Asian          0%
Other Asian          0%
South Asian        0%
Latin American 1   3.3%
Latin American 2    1.21%
Other          1,88%

This is clearly a San, and African trait. Possibly originating from the ancestral archaic hominins. I would suggest that the high prevalence among some Latin Americans is due to the slave trade, that incorporated African genes into admixed Amerindian populations.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

OOA Routes: Sicily Strait (Post 3)

This is the third post in my series on the routes that could have been used by ancestral hominins like Homo erectus and also by Homo sapiens to migrate out of Africa (OOA). In today's post we will look into the Strait of Sicily.

Post 1: Where was the Out of Africa Corridor?
Post 2: OOA Routes: Gibraltar
Post 3: OOA Routes: Strait of Sicily
Post 4: OOA Routes: Sinai
Post 5: OOA Routes: Bab-el-Mandeb

Strait of Sicily

Nowadays this corridor is dismissed and not even mentioned as an option for human migration out of, or into Africa (see Oppenheimer, 2012).

The strait separating Tunisia in Africa, from the island of Sicily, Italy, Europe, is a viable route for migration across the Mediterranean Sea from North Africa into the insular region of Italy, and then, crossing the strait of Messina (~3km - 2 mi) from Northern Sicily, accessing the tip of the Italian "boot" on mainland Europe.

The crossing, now used by illegal migrants into the European Union, is some 145 km wide (90 mi.) Too wide to see Sicily from Africa. However, there are some Italian islands in the strait: Pantelleria 77 km - 48 mi. from Africa and 104 km - 65 mi. from Sicily. It is 135 km (84 mi.) from Tunez to Lampedusa, another 44 km (27 mi.) to Linosa, and 122 km - 75 mi. to Malta and Gozo, from there to Sicily it is 85 km - 52 mi.

This is a wide strait, and would require navigation skills to cross it, with current sea levels. However, sea levels were far lower during the Ice Ages of the past 2 million years, and now submerged continental shelf areas were dry land at that time.

A 100 meter drop (330 feet) in the water level of the Mediterranean would have exposed banks that are now submerged, like the Adventure Bank, or Adventure Plateau, on the southern coast of Sicily, that spans 80,000 km² or 30,090 sq. mi. On this bank is shallow area known as Pantelleria Vecchia (Old Pantelleria) which can be seen in th following map, adapted from Galili, 1981. It shows the coast exposed if sea levels dropped 100 meters (black line).

A submerged 12-meter (36 foot) long megalithic monolith ( an obelisk-like stone slab) was discovered on the seabed at Pantelleria Vecchia, it weighs 15 tons, and now lies under 40 meters (120 feet) of water. This shows that neolithic people lived here when it was emerged land. Lodolo and Ben-Avraham, 2023 note that "seawater inundated the inner lands at 9350 ± 200 year B.P., the upper limit which can be reasonably taken for the site abandonment. This discovery provides evidence for a significant Mesolithic human activity in the Sicilian Channel region."

We know (see Scerri, 2025) that late stone age people crossed from Sicily to Malta some 8,500 years ago in simple boats. But, it could have been accessed on foot, as the continental shelf linking Malta to Sicily was dry land during the Last Glacial Maximum (25 kya). Neanderthal teeth were discovered in the Għar Dalam Cave, in Malta by Despott, and reported by Keith, 1918 (more on Keith further down). However, mainstream scholars say they are more recent, and belong to modern humans. The controversy lives on (read more.

Why cross the sea here?

From the coast of Tunisia, you can spot the volcanic summits of Pantelleria on clear days (see this image), which could have enticed ancient explorers to go there. From Pantelleria it is a short crossing to the then emerged Adventure Bank (36 km - 20 mi.)

Opinions against this corridor

Villa, 2001 summarizes the points against this corridor without completely disregarding it, as follows: "In view of the endemic faunas of the Lower and early Middle Pleistocene, the uncertain context of Lower Paleolithica artifacts, the absence of verifed reports of Mousterian industries in Sicily (Mussi, 1992, p. 288), the absence of human remains before the Upper Paleolithic, and the tectonic history of the island and adjacent areas, we must conclude that Sicily is unlikely to have been an important connecting point between Africa and Italy until the Upper Paleolithic." (highlighting is mine).

The French school of archaeologists was more favorable to this corridor. Henriette Alimen (1900-1996) propsed that Acheulean Africans reached Europe through Gibraltar and the Tunisia-Sicily Strait (Alimen, MH (1975). Les "isthmes" hispano-marocain et siculo-tunisien aux temps acheuléens. L'Anthropologie, 79 (3), pp. 399-436.

Rolland, 1992 is also cautious about "The Siculo- Tunisian landbridge" he regards the pebble tools and the matching Pebble-Culture in the Maghreb as unconfirmed, and notes that Italy's mainland was a narrow and complex geography that was subjected to great changes during the Ice Ages. Furthermore, the Mediterranean and the Alps tended to isolate it. The most likely route for entry into Italy, according to Rolland, was from the east, via the Adriatic and Ionian seas' shelves, as attested by Early Paleolithic sites in that region.

Nevertheless, there is evidence of Acheulean tools, 700,000 years old, from Notarchirico in Southern Italy, see Moncel, 2020, (highlight is mine): "the location of Notarchirico in southern Italy suggests two possible paleogeography-dependent routes: (1) following the northern coasts of the Mediterranean Sea from the Levant during low sea levels in glacial phases, or (2) crossing the Sicily channel between Tunisia and Sicily, also during glacial periods with low sea levels.Given the evidence of probable hominin occupation of insular land masses in the Mediterranean during the Lower Paleolithic (Crete, Gavdos, and Naxos), along withrecent discoveries of evidence of settlement on Indonesian and Philippine Islands east of the Wallace line in Southeast Asia as early as 700 ka, the Sicilian route deserves consideration, in spite of the absence of solid evidence of a land bridge."

The following map, from Depraetere, 2025 shows the region as it stood arond 20,000 years ago, with the emerged land, and modern shores (on the lower right side in color, are the shelve regions currently submerged):

Grimaldi Cave, and the Khoisan in Europe!

Keith, mentioned further up, regarding the Maltese Neanderthal teeth, believed that primitive Africans, related to the Bushmen (now known as Khoisan or San) reached Europe via Gibraltar or Sicily, and settled there, while Neanderthals and more modern-looking Cromagnons (anatomically modern humans) were native to Europe. The Grimaldi people were an example of the African branch. They discovered in 1901 by the Prince of Monaco in Mentone, Italy, (see Google map) at the lowest level of the Grimaldi Cave, were "of a race which was neither that of Neanderthal nor that of Cro-Magnon. The skeletons... present traits which have been interpreted as Negroid in character. It will be remembered that the Cro-Magnon race, with its Aurignacian culture, is supposed to have entered Europe from Asia by way of northern Africa and the old land-bridges across to Italy. Now in recent years there are coming to light all over Africa remains of a type of art, consisting mainly of engravings and paintings of animals, which in many ways recall the remarkable cave art of the Upper Paleolithic in Europe. In South Africa works of this character are attributed in part to those dwarfish, yellow-skinned, woolly-haired little hunters, the Bushmen, themselves undoubtedly a very ancient race, now nearly extinct. Moreover, cer- tain of the physical peculiarities of the latter people are shown clearly in the figures of very stout nude women, carved from ivory or soft stone, which have been found here and there in the Upper Paleolithic of Europe. These facts, taken in conjunction with the Negroid traits ascribed to the two Grimaldi skeletons just mentioned, seem to hint at some African influence on Aurignacian art. Any more definite conclusion than this, however, we should hardly be justified in drawing as yet." (see p. 78 in Bishop, 1930)

The Grimaldi man and woman, are from the Late Paleolithic and lived 22,000 to 26,0000 years ago. They were modern humans. It is interesting that these ancient modern humans in Southern Europe were assumed to be Bushmen, we know that Europeans share the same pale skin pigmentation that Europeans have (see post).

Some like Clyde Winters support interactions between Khoisan and Europe (see his comment on a formal paper) suggesting that the " southern African Khoisan (SAK) population... SAK people were the Grimaldi and Cro-Magnon people of Western Eurasia... By 70 kya Khoisan people probably spread hg N into West Africa... Sometime before 40kya there was probably a second migration event from Cameroon and possibly the Senegambian region into Northwest Africa on into Iberia." Hinting at a Gibraltar Crossing. Note that Winters is African-Centric and also supports an early migration of Africans, who peopled America.

Comments

I rate this corridor as unlikely, even though it is feasible. Perhaps future findings in Sicily will shed more light on the matter.

My next post (#4 in the series) will cover the Sinai, Northern Red Sea Route.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall © 

OOA Routes: Gibraltar (Post 2)

This is the second post in my series on the possible routes used by hominins (from Homo erectus to modern humans) for their out of Africa (OOA) migration, and, why not, for potential "Into" Africa migrations. Today's post covers the Gibraltar Strait.

Post 1: Where was the Out of Africa Corridor?
Post 2: OOA Routes: Gibraltar
Post 3: OOA Routes: Strait of Sicily
Post 4: OOA Routes: Sinai
Post 5: OOA Routes: Bab-el-Mandeb

Gibraltar

The Strait of Gibraltar is a narrow strait set between the southern tip of Spain and Gibraltar on the northern, European side, and Ceuta and Morocco on the southern, African side.

It is roughly 25 km long (16 mi.) and 14 km wide (almost 9 miles) and serves as a waterway linking the Atlantic Ocean on the west with the Mediterranean Sea on the east. It is quite deep, ranging from 300 to 900 meters (980 to 2,950 ft.)

Two tectonic plates meet here, the African and the European plates, and the movement of both plates led to the closure of an older strait that preceded Gibrlatar, the Betian Strait 5.96 Million years ago, sealing the Mediterranean off, cutting the inflow of water from the Atlantic Ocean. Evaporation over the next 600,000 years led to the drying out of the Mediterranean, with deserts and salt flats covering its barren former seabed (Messinian salinity crisis). Later, rifting along the plates' edges led to the formation of the current strait, and the catastrophic flooding that followed, refilled the Mediterranean basin (Zanclean Flood).

The strait is a continuous body of water, the coast of Europe can be seen from Morocco, and vice versa. Possibly enticing hominins to set out and cross it.

Tne idea was first suggested by Paul Pallary (1869-1942) in 1909, when he proposed that a type of stone industry was shared on both sides of the strait some 25,000 years ago, he called it "Iberomaurusian". This was taken up by Obermaier (1924) who applied it to a "Capsio Tardenoisian" culture, the former in Africa, the latter in Europe. In his work, Obermaier wrote: "Old Stone Age. First invasion — from Africa. The primitive Chellean and Acheulean industries in stone spread from Egypt over northern Africa and through Spain into western Europe. At a later cultural stage, the Mousterian, which constitutes a further evolution of the two earlier cultures (its beginning estimated at 40,000 B.C.), fossil remains of men of the Neanderthal Race are found in Spain, France, Belgium, Germany, Jugo-Slavia, and Czecho-Slovakia. The Heidelberg Race, remains of which are found in Germany, is probably ancestral to this race and may have been contemporaneous with the Pre-Chellean culture ; no trace of it has yet been found in Spain."

Spanish historian and archaeologist Luis Pericot Garcí in the 1940s and 1950s incorporated the notion to his Aterian (north Africa) and Soultrean (Europe) common culture he "organized a crossing of the Strait of Gibraltar by raft—a crossing that proved more difficult than anticipated and could not be completed. He even believed that connections might have existed between Africa and Spain as early as the Lower Paleolithic, a theory potentially supported by the presence of numerous cleavers and other Acheulean artifacts of African character in the Iberian Peninsula."

Finally, Henriette Alimen (1900-1996) explored the potential crossings from Acheulean Africa to Europe via Gibraltar and the Tunisia-Sicily strait.

Modern scholars do not agree with any of these theories.

Stepping stones for an easy crossing

The image above (Fig 2. in Gibert Beotas, 2003) displays the current coasts of Africa and Spain at Gibraltar, and how it would look with a lower sea level after it droped 150 meters (492 ft.) Islands appear on the western side of the Strait. Gibert Beotas calculates that the distance is reduced to half, from 14 km to 5 plus 2 km, island hopping.

Straus, 2001 noted that a lower sea level would make some of the seabed appear on the surface: "several small islands would appear within the Strait in the sector between Paloma Point and Tangiers whenever sea fell further than 100 m below its present level, making for several short water crossings, none greater than ca. 5 km if this (western) route were to have been taken. The distances would have been even shorter under full glacial conditions, with sea-level regression of 120-130 m"

Regarding the crossing, Flemming, 2003 points out that "To the west of the narrowest part of the Strait a group of substantial shoals become large islands at glacial low sea level, and these were visible vegetated land masses, completely changing the appearance of the Strait from either shore. The length of the Strait itself was increased, and the archipelago provided a stepping stone and safety net to anyone seeking to cross."

Straus cites (see the article here too) who suggested that Lower Pleistocene hominids like Homo ergaster could have crossed at Gibraltar around 1.8 to 1.6 Million years ago when it was only 6.5 km wide during the Aullen marine transgression.

Straus concludes that it is unlikely that early Homo crossed the strait put it is "somewhat plausible" but any later contact is discarded during the Middle Pleistocene. Only, during the Upper Pleistocene did modern humans cross the strait, navigating across it.

Proof

Gibert Beotas aruges that ancient stone tools discovered in Orce, South Eastern Spain (Andalusia), knapped using Oldowan techniques, and dated to 1.4 Million years ago, are possibly the work of hominins who used the Gibraltar crossing, instead of taking the longer route across the Levant, Anatolia, the Balkans and eastern Europe, central Europe and then into Iberia.

There is evidence of animals crossing the straits since Miocene times, a two-way exchange between Europe and Africa. Humans could have done the same. Another fact to bear in mind is that hominins did cross open stretches of sea to reach Luzon in the Philippines, and Flores in Indonesia.

Arribas and Palmqvist, 1999 (see the article here too) argue that "crossing large rivers and mountainous chains, with adaptations to different vegetation zones and to broader ranges of temperature and rainfall, and a simultaneous colonization of Europe through Gibraltar, perhaps Sicily, and the Eastern Mediterranean helps to explain the presence in several north circummediterranean sites of Spain (Orce), Italy (Pirro Nord), Greece (Apollonia)and Georgia (Dmanisi) of certain African species of large mammals which have not been found, at present, in Central Europe during Lower Pleistocene times, such as M. whitei, whose dispersal seems to have been limited up to the 40°N parallel"

They included the following map in their research paper:

Animals like wild boars found in North Africa and Spain share a common genetic origin. Soria-Boix, 2017 wrote that "Contacts across the Strait of Gibraltar in the Pleistocene have been studied in different research papers, which have demonstrated that this apparent barrier has been permeable to human and fauna movements in both directions. Our study, based on the genetic analysis of wild boar (Sus scrofa), suggests that there has been contact between Africa and Europe through the Strait of Gibraltar in the Late Pleistocene (at least in the last 90,000 years), as shown by the partial analysis of mitochondrial DNA. Cytochrome b and the control region from North African wild boar indicate a close relationship with European wild boar, and even some specimens belong to a common haplotype in Europe. The analyses suggest the transformation of the wild boar phylogeography in North Africa by the emergence of a natural communication route in times when sea levels fell due to climatic changes, and possibly through human action, since contacts coincide with both the Last Glacial period and the increasing human dispersion via the strait."

Last July I posted about The common ancestor of Denisovans, Neanderthals and Humans, citing a paper by Hublin, 2026 who mentioned that "The Spanish and Moroccan fossils share several features in their teeth and mandibles. Both groups display a combination of archaic and derived features reminiscent of later hominins... These similarities revive the question of possible exchanges across the Strait of Gibraltar during the EP."

Comments

The crossing is feasible, short, and was done by animals over the course of the past few million years. There are fossils in Spain and Morocco that suggest an exchange between Africa and Europe (possibly both ways). This could be one of the corridors used by hominins to people the world either from Eurasia into Africa, or the other way round.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall ©