Ancient DNA II

choi

(3) Dog's DNA as proxy of human migration from East Siberia into Alaska (proxy, because no human bones, and hence DNA, was discovered more ancient than this dog bone; dog has depended on humans to live -- besides, this dog ate seafood).
(a) Andrew Curry, Remains of Oldest American Dog Bolster Idea That First Humans Arrived Along the Coast. Science magazine, Feb 24, 2021 (online only, not published in hard copy)
https://www.sciencemag.org/news/ ... arrived-along-coast

Quote:

(i) "Researchers once thought humans initially entered the Americas about 12,000 years ago. That's when thick glaciers that covered much of North America began to melt. This opened a corridor, which allowed people to trek from Siberia across now-submerged land in the Bering Sea, and then into North America on the hunt for mammoth and other big game.  But over the past decade, archaeologists have shown people might have begun to move into North America much earlier. To get around the glaciers, they would have island hopped by boat and walked along shorelines exposed by low sea levels."

(ii) "The pup's genome revealed it was closely related to the first known dogs, which researchers think were domesticated in Siberia about 23,000 years ago. Based on the number of genetic differences between the Alaskan dog and its Siberian ancestors, the team estimates the two populations split 16,700 years ago, plus or minus a few thousand years.  That's a clue that dogs—and their humans—left Siberia and entered the Americas thousands of years before North America's glaciers melted.

My comment:
(i) A month inot my PhD program (in biology) in University of Illinois at Chicago, department chair told us that beware whether the conclusion of a scientific report is justified by data it presented.

I read this review, and was stumped by the last sentence of quotation (b), for lack of correlation between data and conclusion. I read the scientific report myself, and find the problem is not with the review, but lies in report (which makes the same conclusion as the review with data in support). Then I re-read the last sentence of quotation (b). Then I realize what the researchers of this report are trying to say: a dog that split from its East Siberia ancestor ~16,000 years ago arrived at Alaska 10,200 years ago.
(ii) So what? It does not say when humans FIRST arrived at Alaska; it only says humans had arrived at that cave by 10,200 years. It does not support or refute how humans came into Alaska (inland or seashore), either.

(b) da Silva Coelho A et al (University at Buffalo), An Early Dog from southeast Alaska Supports a Coastal Route for the First Dog Migration into the Americas. Royal Society B: Biological Sciences, _ _  (online publication Feb 24, 2021).
https://royalsocietypublishing.o ... 1098/rspb.2020.3103

Quote:

"Abstract[:] * * * Here, we present a complete mitochondrial genome of a dog from southeast Alaska, dated to 10 150 ± 260 cal BP [before present]. * * * Our analyses demonstrate that the ancient dog belongs to the PCD lineage, which diverged from Siberian dogs around 16,700 years ago.

"1. Introduction[:] * * * While genetic evidence suggests that the first Native Americans split from East Asian ancestors as early as 23 000 years ago [(footnotes) 3–6], and evidence from archaeological artefacts indicates a presence of human populations south of the continental ice sheets at possibly more than 16 000 years ago [7], the earliest human remains in North America date to only around 12 600 years ago [8]. * * * However, as with humans, archaeological evidence for dogs lags behind DNA-based dates, at no earlier than 15 000–12 500 years ago in the Old World [10]. * * * So far, the oldest confirmed domestic dog remains in North America, excavated from dog burials at the Koster and Stilwell II archaeological sites in Illinois, date to between 10 190 and 9630 calibrated years before present (cal BP) [13]—more than 2000 years younger than the oldest confirmed human remains. A recent genetic study demonstrated that these early pre-European contact dogs (PCDs) were not domesticated from North American wolves, having instead diverged from an ancestor shared with an approximately 9000-year-old dog population that inhabited Zhokhov Island in Eastern Siberia [11,14]. * * * During the LGM [Last Glacial Maximum], the Laurentide Ice Sheet and the Cordilleran Ice Sheet covered much of North America, making the area inhospitable or even impassible to humans and most other fauna and flora [5]. For many decades, it was accepted that early humans migrated through an ice-free corridor in between the two ice sheets that opened once deglaciation initiated [15–17]. Although this corridor may have opened as early as approximately 15 000 years ago [16], it was likely not biological viable until approximately 13 000 years ago [17–19]. Another hypothesis is that the retreat of the Cordilleran Ice Sheet along the Northwest Pacific coast (NPC), combined with ocean levels lower than today, provided an earlier, ice-free coastal corridor for early humans and other biota [20,21]. * * * Whether dogs colonized North America with the earliest humans or only later, they spread broadly around the continent. Archaeological evidence shows that dogs were present at different mid-continental sites approximately 10 000 years ago [13], spanning from Newfoundland to Alabama and California by 4000 years ago, and into South America by 1000 years ago [9,11,23].

"2. Material and methods
(a) Lawyer's Cave and specimen description
The PP-00128 specimen (University of Alaska Museum Earth Sciences Collection, Fairbanks, catalogue number UAMES 52 399) was discovered in Lawyer's Cave, also called Phalanges Phreatic Tube by cavers, referring to the cave's shape and the toe bones of a bear found inside. The cave, which has two entrances and consists of an approximately 20 m long, non-branching crawlway from end to end, is located along Blake Channel on the southeast Alaskan mainland east of Wrangell Island in the Alexander Archipelago (figure 1). Lawyer's Cave is rich in other postglacial remains beyond the PP-00128 specimen, including bones of various mammals, birds and fish, as well as human remains and artefacts that were discovered during two excavations in 1998 and 2003 [30,31]. * * * The PP-00128 bone remains are a piece of the dome-like head of a femur with a diameter of about 1 cm (figure 1). Initially, the bone fragment was identified as of uncertain mammalian origin but suspected to be from a bear (Ursus). However, as part of a larger genetic survey of remains from this cave (C Lindqvist 2020, unpublished data), PP-00128 was identified as Canis lupus.

"4. Discussion[:] * * * Even though the oldest human remains and archaeological evidence [5,6,8] are older than any evidence for dogs in the New World, current genetic-based estimates for the initial human migration into the Americas south of the ice sheets [3,4] coincides with the timing reported here for the split of the PCD clade [somewhat similar to 'branch'] from Eastern Siberian dogs, approximately 16,700 years BP * * *

Note:
(i) Check Zhokhov Island, which is far, far away from Bering Sea. The en.wikipedia.org has a map that does not give a reader an idea the distance from Bering Sea.
(ii) Last Glacial Maximum
https://en.wikipedia.org/wiki/Last_Glacial_Maximum
(iii) For the corridor between the Laurentide Ice Sheet and the Cordilleran Ice Sheet, see
Lesneck AJ et al, Deglaciation of the Pacific Coastal Corridor Directly Preceded the Human Colonization of the Americas. Science Advances, 4: _ (online publication May 4, 2018)
https://advances.sciencemag.org/content/4/5/eaar5040.full
(map)
(iv) "Whether dogs colonized North America with the earliest humans or only later, they spread broadly around the continent. Archaeological evidence shows that dogs were present at different mid-continental sites approximately 10 000 years ago [13], spanning from Newfoundland to Alabama and California by 4000 years ago, and into South America by 1000 years ago [9,11,23]."

These dogs are PCD (prehistoric), not modern dogs (which are bigger; a part of this report says so).
(v) Wrangell Island
https://en.wikipedia.org/wiki/Wrangell_Island
(map)
(vi) Lawyer's Cabe was named by local residents, so name origin is unclear to me.
(vii) "coincides with the timing reported here for the split of the PCD clade [somewhat similar to 'branch'] from Eastern Siberian dogs, approximately 16,700 years BP"

It might well be that this dog (languishing in East Siberia) had been like Moses out of Egypt and went round and round in deserts for forty years before reaching promised land.