Parasites and early contacts with America

In 2014, I posted about hookworm and how they could be linked to the peopling of America. Today I came across an article published 37 years ago, that discusses the presence of intestinal parasites in Pre-Contact Amerindians and its implications.

The article is: A. Araújo, Ferreira L. Confalonieri U., and Chame M. (1988). Hookworms and the peopling of America, Saúde Pública 4 (2), June 1988 https://doi.org/10.1590/S0102-311X1988000200006.

The fact that these parasites require warm climates for their life cycles makes it difficult for them to have crossed the Beringian land bridge into America during Glacial times with the freezing weather that prevailed at that time. This raises the question of how did they reach America?

The first explanations were that they came via Europe after the 1492 discovery of America, or from Africa with the slave trade into America, or, from Asia and Oceania with trade during the post-discovery period. However, when these parasites were found in ancient Pre-Columbian remains, so, these explanations had to be rejected.

Below, I quote the 1988 article's most substantial part on the ancient remains and their implications.

"But the discovery of the infection at 7230 ± 80 years in Brazil (Ferreira et al., 1987) is a new fact and two possibilities can be raised. First the transpacific contacts dates from before 7230 years BP (Before Present) and the paleoparasitological data indicates that archaeological research in the Pacific coast of South America may reveal more remote relations with Asiatic population than is known today. Second, if transatlantic migrations were responsible for the hookworm infection in South America, the neolithic people coming from Europe or North Africa introduced the parasite.
It is also to be noted that paleoparasitological data show that navigation technology had been known to man for more than 7230 years.
It is interesting to note that together with hookworm infection two other prehistoric helminth infections, found in human coprolites in America, support these hypothesis: Trichuris trichiura (Pizzi and Schenone, 1954; Ferreira et al., 1980; 1983; Reinhard et al., 1987), and Strongyloides stercoralis (Hall, 1972; Fry, 1980; Reinhard, 1985)."

7,000 years BP is well before Stonhenge or the Egyptian pyramids were bult. This is the Stone age. Did these people have watercraft and the knowhow to navigate them across the Pacific or the Atlantic Oceans? (see my post on the The North Atlantic Route into America).

Stone Age Navigators

Could the parasites have reached the New World during a warmer period in Beringia?

This does not seem feasible because the sea level only remained low enough to form a land bridge during the peak of an Ice Age (Glacial Maximums), and that means freezing temperatures in this polar region.

---

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

On Puma parasites and human presence in South America

A paper by Romina S. Petrigh et al, Ancient parasitic DNA reveals Toxascaris leonina presence in Final Pleistocene of South America, (Parasitology, 2019. DOI: 10.1017/S0031182019000787) reported the discovery of a parasitic roundworm in a coprolite (fossilized feces) from a puma (Felis concolor) in Northern Argentina's Puna region. The fossil stool was dated at 16,573–17,002 calibrated years BP.

The finding is indeed remarkable because "Ancient mitochondrial DNA analysis confirmed the zoological origin of the coprolite as Puma concolor and that of parasite eggs as Toxascaris leonina. This is the oldest molecular parasite record worldwide".

Mental constraints

The age is a key factor here because, based on it, the authors dismiss that the parasite that infected the puma was transmitted by domesticated dogs (or cats) as other authors postulate; the paper states this several times:

"This allowed confirming the presence of T. leonina in prehistoric times, presumably even before that of humans in the region...Therefore, the common interpretation that the presence of T. leonina in modern American wild carnivores is a consequence of their contact with domestic dogs or cats (Okulewicz et al., 2012) should no longer be assumed as the only possible explanation".

The date is supposedly older than the currently accepted arrival date of humans in the region hence no domestic dogs could have transmitted the parasite to pumas ("The first human explorers who ventured into the area ca. 11 000 years ago")

So, the authors cannot avoid the current time frame for human presence in America. But, what if there were humans here 100,000 years ago, would that have affected the puma parasites? They wouldn't of had dogs with them -domestication date of dogs is much earlier anyway. The point is that human presence is irrelevant to their finding.

I mention this because scientists cannot escape from their mental straitjackets and thes authors mention the 11 Ky date as important-it isn't. But, let's go back to the paper:

A natural origin is suggested, and I fully agree with it: "Canids and felids are infected by ingesting rodents and paratenic hosts and also directly by contact with feces with eggs containing infective larvae. "

Regarding its identity as a Toxascaris leonina the paper indicates that "The BLASTN analysis showed an identity range of 96–93% between cox1 fragment of T. leonina European and Asia isolates from different hosts (canids including dog, wolf and European fox, and felids including Eurasian lynx and South China tiger). Pairwise analysis among available T. leonina sequences showed a wide range of identity percentages, from 98 to 93%. A maximum of 1% intra-specific divergence within Iranian isolates has been reported (Mikaeili et al., 2015). Thus, this 4% divergence with ancient T. leonina could be attributed to different temporal and geographic origins."

So American T. leonina are distinct from Asian ones due to "different temporal and geographic origins", which makes sense, after all the puma belongs to a lineage that originated 6.7 Mya. Nowadays it consists of three species: puma, and on a contiguous branch the American jaguarundi (Herpailurus yagouaroundi)). The third species is the cheetah (Acinonyx jubatus) which 100,000 years ago migrated across Beringia into Eurasia and finally into Africa (this is a real "Out of America and Into Africa" event).

Puma surely got the roundworm from some non-human agent (I mean that domesticated dogs had no role in it), yet the authors had to point it out: "At a regional level, these aDNA studies have also allowed confirming the presence of pumas in the southern Puna at the end of the Pleistocene. This has significant implications for the natural history of the region, as well as for inferring the ecological context immediately previous – as far as is known so far – to the first human explorers who ventured into the area ca. 11 000 years ago".

But, as I said further up, humans could have been here in America for one million years and this would have no impact whatsoever on the fact that this team of scientists found ancient roundworm in fossil puma poo.

---

Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2014 by Austin Whittall © 

Hookworms and the peopling of America -more data

Today's post continues my previous post on hookworms and the peopling of America.

One of the issues was if it was possible for these parasites to make it into America across the cold Beringian region during the lifespan of an adult hookworm since it seemed improbable that they could fulfill their early life phase in the area's frozen soil. An option could be a warmer period which allowed the eggs to hatch and larvae appear in time to re-infest the migrating humans but, which was not warm enought to melt the ice caps and flood the Beringian landbridge. It seems that this is could be the case:

Warm but not too warm

A paper by Rabassa and Ponce [1] looks into the very cold Heinrich (H) periods and warmer Dansgaard-Oeschger (D-O) climatic events that took place during MIS 3 (Marine Isotope Stage 3), a "relatively warm climatic period" between 60-50 and 30 ky ago (cal. ka BP).

During this period the "mean annual temperatures were ca. 5 - 8°C higher than those active at the Last Glacial Maximum (LGM)". The LGM took place some 25 kya. and marks the point of maximum ice coverage (and also the lowest temperatures).

What is surprising is that even though the climate was much warmer, the ice sheets did not melt completely, so sea level remained "low enough to allow the persistence of the Beringia land bridge between Siberia and North America, without any interruptions throughout the entire MIS 3.". [1]

These peculiar conditions lead the authors to conclude that:

"... thus both the hinterland path from Beringia southwards and the coastal route would have been open and enjoying moderate climate ecosystems, and thus available for humans. In this case, it is now possible to suggest possible moments for human penetration in North America, perhaps between ca. 50 to 28 cal. ka B.P...[1]

In other words we have a period during which the Beringian land bridge was high and dry and warm enough to allow humans to cross it 60 - 30 kya. Which also opens the possibility for a Neanderthal migration into America or a very early migration of modern humans. Furthermore, since the mechanisms that originted the H and D-O events are not unique, it also may mean that similar conditions could have existed during other even earlier interstadial stages, which could have been used by Neanderthals or even H. erectus to cross into America under warmer conditions.

Could these warmer temperatures have allowed the survival of hookworm eggs in the soil? Maybe. This would do away with the need for hypothetical transoceanic migrations that purportedly brought the worm to America before the oldest dated worm sample from this continent (7.2 kya).

On Hookworms and their diversity

A recent paper by Hasegawa H, Modry D, Kitagawa M, Shutt KA, Todd A, et al. (2014) [2] looked into different genetic markers of hookworms in Africa, both among humans and Great Apes and came up with some interesting information but fail to recognize it, because of the "old" references they used:

Below they mention the "ITS" or Internal transcribed spacer of nuclear ribosomal DNA:

"The ITS sequences of type I ( = N. americanus) were much closer to those reported in samples from human in Guatemala than those in samples from humans in China or Malaysia." [2]

This is very interesting: How come American and African samples are closer to each other than to the Asian ones which are located midway between them?

The authors don't find this relevant and play it down stating that:

"This close relationship is not unexpected, as N. americanus in the Americas might have been introduced from Africa by human migration in the early modern ages." [14]
[...]
[14] Looss A (1911) The anatomy and life history of Agchylostoma duodenale Dub. A monograph. Part II: The development in the free state. Rec Sch Med 4: 159–613." [2]

But, as I reported in my previous post, N. americanus was found in +7,200 year old fossil human excrement discovered in Brazil, long before any "early modern ages" exchange between Africa and America (i.e. slave trade). The authors did not consider this paper and quote a rather old one from 1911!

Of course, it is quite probable that the Guatemalan sample came from an African hookworm, that colonized the New World after the XV century, spreading across the continent and displacing the ancestral forms such as the Brazilian one.

The paper also found "the first molecular evidence that N. americanus parasitizes wild western lowland gorillas, but at a much lower prevalence than we reported in humans." [2]. This is a clear indication of an African origin of this variety of hookworm. We would not expect a human parasite to plague gorillas, rather, it should be the opposite.

The paper also reports that "Although humans are often regarded as the only natural host of N. americanus, other primates, including gorillas, chimpanzees, several Old and New World monkeys and other mammals, such as pangolins, have also been reported as hosts of this nematode" [2]. If this is the case, then the hookworm could have entered America via a small mammal millions of years ago during a very warm period. This would make any conjectures about human migrations pointless.

Nevertheless, the similarity between American and African lineages means that the split is much more recent.

Closing Comments

I believe that more data is needed, a comparison of the genome of Asian, African, American (contemporary and archaic) hookworms in humans and other mammals to settle the issue.

But even if the hookworms don't provide evidence for an early peopling of America, the fact that the Beringian land bridge may have existed during older periods and be warmer than the latest bridge (the one H. sapiens is supposed to have used to enter America), is encouraging and may ultimately support the theory of an initial peoping by Neanderthals (or even H. erectus).

Sources

[1] Raassa J., and Ponce, J. (2013)., The Heinrich and Dansgaard-Oeschger Climatic events during Marine Isotopic Stage 3: Searching for Appropriate Times for Human colonization of the Americas. Quaternary International, 2013 vol. 299 p. 94.
[2] Hasegawa H, Modrý D, Kitagawa M, Shutt KA, Todd A, et al. (2014). Humans and Great Apes Cohabiting the Forest Ecosystem in Central African Republic Harbour the Same Hookworms. PLoS Negl Trop Dis 8(3): e2715. doi:10.1371/journal.pntd.0002715

---

Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2014 by Austin Whittall ©