Guide to Patagonia's Monsters & Mysterious beings

I have written a book on this intriguing subject which has just been published.
In this blog I will post excerpts and other interesting texts on this fascinating subject.

Austin Whittall

Thursday, November 7, 2019

Hookworms and the peopling of America - revisited

A paper on hookworms mtDNA published earlier this year (Monteiro K J L, Mitochondrial DNA reveals species composition and phylogenetic relationships of hookworms in northeastern Brazil, Infect Genet Evol. 2019 Mar;68:105-112. doi: 10.1016/j.meegid.2018.11.018. Epub 2018 Nov 30) provides more information on the subject of hookworms and the peopling of America (which has been the subject of two previous posts in our blog).

The paper found "... two strongly-supported clades, including Group A, corresponding to Necator americanus, and Groups B and C, corresponding to Necator sp. Group A was divided into three main clusters: A1 grouped with Asian sequences, A2 grouped with African sequences, and A3 had only Asian sequences. Group B was closely related to Necator sp., showing a sequence similarity of 98%–99% with African samples circulating zoonotically among humans and non-human primates".

The following image shows both clades:

N. americanus mtDNA tree. From Monteiro et Al.

The interesting part is the relationship between the Groups:

  • A1 Group (shown in pink above) is, according to the authors "Grouped with Asian sequences", the samples from Asia are marked with green rhombus.
  • A2 Group (shown in pale blue) "Grouped with African sequences", displays a recent Togo sample (brown square) among an older set of sequences.
  • A3 Group (shown in pale green) has indeed "only Asian sequences".

The authors calculated that the split between the two clades (one encompassing groups A1, A2 and A3, the other with groups B and C) took place in the middle Pleistocene (that means that it happened between 781,000 and 126,000 years ago).

They also found that "The most recent common ancestor among N. americanus groups was dated to the late Pleistocene." which places it between 126,000 and 12,000 years ago.

Unfortunately I cannot read the full paper, but it seems that the sample from Togo (Africa) is far younger than the other American ones. The point that has to be explained is how did these subtropical and tropical parasites reach America from Asia and avoided the freezing cold Beringian route?

Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2019 by Austin Whittall © 

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