The Del Mar skull was discovered by Malcom J. Rogers when he excavated two sites on the coast of California near San Diego.
The skull appeared at the second site named SDM-W4, in 1929. It was located (see map) between Del Mar and Solana Beach at the base of a cliff on the Northwestern side of the San Dieguito River.
He found a skull and ribs there (source), of course at that time there was no way to date the remains.
It seems that Bada was the first to try, using his amino acid racemization technique, and obtained 47,000 years (see my previous post on this technique and the "Sunnyvale girl" skull).
The skull looks like that of a regular paleoindian, and why shouldn't it? If it is 47 ky old, it should look modern. Below are some images of the Del Mar skull:
C14 date for this skull is 6,800 plus minus 100 years, which Bada didn't accept assuming that the sample could have been contaminated with carbonates.
Gerow who does not accept Bada's date, wrote (Amino Acid dating and early and early man in the New World, a rebuttal, 1981, Bert A. Gerow, page 9):
"Interestingly, the reconstructed Del Mar skull (SDM-16704) from southern
California, dated at 41,000-48,000 years by aspartic acid racemization (Bada 1975,
Table 7) corresponds closely to Gifford's Santa Catalina type (with) the following characteristics: lowest
cranial index, lowest height/length index, lowest gnathic index, longest cranium,
and broadest nose. These distinctive features are shared with the Del Mar
skeleton.
...
An anthropometric comparison of the Sunnyvale female with a comparable series from a late local prehistoric site indicates a single physical type
contrasting with other regional types proposed by Gifford for California. The Del
Mar male belongs to another physical type, although both are fully modern and
Mongoloid with respect to dentition. The idea that two distinct physical types
entered California or developed here fifty to seventy thousand years ago and remained genetically isolated and morphologically unchanged during that period is
totally unacceptable in the light of present knowledge of population movements in
prehistoric California."
So based on the shape of the bones, which are different he cannot accept that Sunnyvale woman and Del Mar man lived in California 70 and 47,000 years ago, but he can accept that they were contemporary paleoindians (?) Weird argument.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2019 by Austin Whittall ©
It´s evident that Del Mar skull looks surprisingly “not that old” for a 47 Ka H. sapiens… but this appreciation, inevitably, would only be based in “Old World Standards”…and the truth is that we are ignorant about how certain traits of H. sapiens could have evolved in America ( and even more about the timings involved in!!...)
ReplyDeleteSo, I agree with you in that It would be reckless to rule out that someone so similar to “one of us” could have lived here, even if he arrived before the immigrations at terminal Pleistocene. Indeed, we simply know almost nothing at this respect, and additionally we cannot extrapolate as if all the evolution of traits occurred in Europe´s sequence; …First H. sapiens - Cromagnon – Modern human…, because there would be the risk of being biased.
Apart from this, an age of 47 ka or so, appears to me as perfectly feasible for AMH presence in America, whatever has been their provenance.
My only complaint relies on the dating method. Amino acid racemization (AAR) results are very dependent on the history of temperature of the geological burial. In order to yield valid dates, needs to be coupled with additional paleoenvironmental data …or eventually, be validated by C14, or other method.
Its limitations for direct dating are so considerable that today is very seldom used for this....In fact, it is used in a “reverse way”, that is to say;…given an environment where reliable and valid ages were obtained by means of other methods, the dissenting results that AAR will yield about it, compared with them and properly elaborated, can often bring valuable information about variations of temperature on it.
If the question is which dating is the more valid one, I would say that AAR´s age is absolutely questionable, because of the method itself. On the other hand, C14 is one of the most reliable methods up to 45 Ka…but requires that the sample is relatively clean from more recent carbon (something very difficult to know in this case), because the usual pretreatment that precedes the dating procedure, is not able to completely eliminate some remainder impurities.
At this respect, in Buenos Aires, Argentina, and more precisely within what is known as the “Lujan Formation”, composed of geological depositional sequences filling the valleys of most rivers in the Pampean region…there are Terminal Pleistocene layers, spanning from 16 to 12,5 Ka in age, that are particularly susceptible to receive contamination from immediately upper levels, called “Black Mats”, dark layers with very rich organic content, presumably related to Younger Dryas´s local manifestations…So, this problem is also well known here.
Given the apparent lack of geological context, unless other dating methods are utilized,…perhaps Th/U on some encrusted carbonate, if the skull has any ??, (as this method usually works fine for this, giving at least a minimum age), or eventually Th/U on bone ( more restrictive)… the antiquity of Del Mar skull will remain as another mystery.
Best regards
The best possible 2020 for you and yours!!!
Marcelo
Thank you Marcelo. Yes AAR is unreliable, C14 depends on several variables and the geological context of this skull is yet unknown. So it will remain a mystery for the time being. Happy 2020 for you too!!
Deletehttps://www.nature.com/articles/s41598-019-56929-3
ReplyDeletePublished Jan 2020
This new article discusses the heterogeneity of early Cuban, Puerto Rican and Floridian skull morphological differences.
They relate it to "diverse groups" living separately and isolated.
The Lucayn specimen has a low forehead and very archaic looking eyebrow ridges and cheekbones.
It relates to what is discussed here.
The skull looks very archaic to me. Heavy slope to forehead. Flat between the eyes, so very little bridge to the nose, like some Asian. Some prognathism. Large strong jaw. Looks closest to African, but not African. Modern Africans rarely have such heavy slope to the forehead.
ReplyDelete