Thursday, February 14, 2019

Caribbean Population Genetics

None of the conclusions in an analysis of the modern Caribbean population genetics are a great surprise (which is to be expected for the legacy of historically attested processes). But, the details are interesting. The conclusion reached about the localized origins of indigenous American genetic ancestry in modern Caribbean populations confirms prior studies assessing these pre-Columbian processes as well.
[T]he most likely source of the indigenous ancestry in Caribbean islanders is a Native South American component shared among inland Amazonian tribes, Central America, and the Yucatan peninsula, suggesting extensive gene flow across the Caribbean in pre-Columbian times. 
We find evidence of two pulses of African migration. The first pulse—which today is reflected by shorter, older ancestry tracts—consists of a genetic component more similar to coastal West African regions involved in early stages of the trans-Atlantic slave trade. The second pulse—reflected by longer, younger tracts—is more similar to present-day West-Central African populations, supporting historical records of later transatlantic deportation. . . . 
[W]e also identify a Latino-specific European component that has significantly diverged from its parental Iberian source populations, presumably as a result of small European founder population size. 
From the abstract of this new PLOS paper.

Tuesday, February 12, 2019

Where Did Vedic Culture Come From?

This is a fascinating hypothesis that doesn't seem immediately implausible, although without downloading it onto a Kindle (at about 10% of the cost of the hard cover edition) and reading it, I'm not in a good position to evaluate how solid its arguments are and how well they are supported by the evidence. If anyone has access to a more in depth review or journal articles by the same author on this topic, I'd love to see them.

UPDATE of February 14-15, 2019

Razib mentions the book and recommends it (with a grain of salt) here. A longer discussion of the book can be found here. The longer discussion contains this statement which makes me quite skeptical of the discussion:
The primary difficulty of discussing the ancient history of India lies in the necessity of first demolishing several well-established inaccuracies, such as the Aryan Invasion Theory, for instance. Spun by white men and broadcast by colonial historians, this old wives’ tale is still taught in schools and colleges, with half of any written work – measured in terms of paper, ink and effort - being expended on it. We shall not entertain it.
Shifting geography

Either Kochhar or the author of the discussion (it isn't entirely clear to whom this analysis should be credited based upon the way the piece is written), makes a textual case that two different parts of the epic, the Ramayana and the Mahabharata involve two different places, contrary to conventional wisdom: the Mahabharata near the modern Ganges River of India is described in the later epic texts, and the Ramayana somewhere else that was the location which the earlier Rig Vedic texts describe.


Kochhar argues that ephedra is the "soma" of the Rig Vedas (a popular, but not unanimous view see also here; some scholars argue that it is another plant, while others argue that it was a mixture of ephedra and another plant) that points to a central Asian place of composition because that is where that plant, which does not grow in India, is found. Instead, it is found  found in Afghanistan, Iran, the northern Himalayas, and the Hindu Kush.


This little tidbit of evidence is intriguing (emphasis added):
There are 49 cosmic hymns in the Rig and the Yajur Vedas whose meanings have not been explained. But one particular hymn from Vedanga Jyotish informs us that the longest day of the year, or summer solstice, comprised 18 periods of daylight and 12 of night. Day and night are of equal length on the Equator; in the higher latitudes, summer days are longer than nights. 
The latitude at which the proportion of daylight and darkness is 3:2 is 34 degrees North. It is worth noting that the cities to be found around this latitude today are Herat and Kabul in Afghanistan. In other words, the place and time of the composition of the Vedanga Jyotish is the same as that of Vedic Afghanistan and Iran. This second piece of evidence offered by Rajesh Kochhar further strengthens the perception of the location and time of the Rig Veda.

Based upon textual information and geography Kochhar identifies the Sarayu river of the epics with:
the 650-km river known as the Hari-Rud in Afghanistan, whose source is in the Hindu Kush mountains. It flows past the city of Herat and then for 100 km along the Iran-Afghanistan border before disappearing in the Karakom desert of Central Asia.
Kochhar identifies another major river of the epics, the Sarasvati river, with a different river than the Ghaggar-Hakra River in India proper that it is often claimed to be:
In the Avesta we find the Saraswati as the Harahaiti – the similarity in sound is noticeable – which enters Iran along the combined basin of the river Arghandar on the Afghan-Iran border and the river Helmand. According to Kochhar, it is this Helmand that is the Vedic Saraswati river.

The source of the Helmand is in the Koh-i-Baba mountain range. Flowing for 1,300 miles through the heart of Afghanistan, the Vedic Saraswati joins the Vedic Drijadbati or Arghandar. The Avesta identifies this wide river as the Hetumanta (or, in varations, as Setumanta). In Iran the Saraswati is named the Harahaiti, which flows into the inland lake Hamun-e-Sabari in the Saistan area of northern Iran. 
Wikipedia further elaborates Kochhar's position on this issue which is actually a bit more complex than the discussion I linked to suggested (emphasis added):
Rajesh Kocchar, after a detailed analysis of the Vedic texts and geological environments of the rivers, concludes that there are two Sarasvati rivers mentioned in the Rigveda. The early Rigvedic Sarasvati, which he calls Naditama Sarasvati, is described in suktas 2.41, 7.36 etc. of the family books of the Rigveda, and drains into a samudra. The description of the Naditama Sarasvati in the Rigveda matches the physical features of the Helmand Riverin Afghanistan, more precisely its tributary the Harut River, whose older name was Haraxvatī in Avestan. 
The later Rigvedic Sarasvati, which he calls Vinasana Sarasvati, is described in the Rigvedic Nadistuti sukta (10.75), which was composed centuries later, after an eastward migration of the bearers of the Rigvedic culture to the western Gangetic plain some 600 km to the east. The Sarasvati by this time had become a mythical "disappeared" river, and the name was transferred to the Ghaggar which disappeared in the desert. The later Rigvedic Sarasvati is only in the post-Rig Vedic Brahmanas said to disappear in the sands. According to Kocchar the Ganga and Yamuna were small streams in the vicinity of the Harut River. When the Vedic people moved east into Punjab, they named the new rivers they encountered after the old rivers they knew from Helmand, and the Vinasana Sarasvati may correspond with the Ghaggar-Hakra river. 

In The Vedic People, well-known astro-physicist Rajesh Kochhar provides answers to some quintessential questions of ancient Indian history. Drawing upon and synthesizing data from a wide variety of fields — linguistics and literature, natural history, archaeology, history of technology, geomorphology and astronomy — Kochhar presents a bold hypotheses by which he seeks to resolve several paradoxes that have plagued the professional historian and archaeologist alike. . . .
This book argues that a major part of the Rgveda was composed in south Afghanistan (after c.1700 BC) before the Rgvedic people entered the Punjab plain and well before they moved east of the Ganga River. The author asserts that during their migrations the Indo-Aryans not only carried with them their rituals and hymns but also place and river names which they selectively reused.
Via Amazon (Hat tip Razib Khan's Twitter feed).

The Dispersion Of Megalithic Culture

Everything old in anthropology is new again, and 1970s anthropology is again discredited, in favor of the grand and epic conjectures of the 1800s and early 1900s. 

Megalithic grave culture did spread rapidly by maritime routes as older archaeologists reasoned. But, the phenomena originated in Northwest France, not the Near East. And, this spread reflects seafaring technologies in pre-Bell Beaker Neolithic peoples that were far more sophisticated than has been generally recognized until now.

The geography also shows a strong geographic overlap with maritime Bell Beaker expansion that started about two thousand years after the megalithic culture's expansion. This suggests that perhaps the Bell Beaker phenomena may be best understood as a fusion of steppe culture with a foundation established in the megalithic era. In this context, the Bell Beaker re-appropriation of sites like Stonehenge for their own use seems like something deeper than a mere random act of monumental recycling.

There are two competing hypotheses for the origin of megaliths in Europe. The conventional view from the late 19th and early 20th centuries was of a single-source diffusion of megaliths in Europe from the Near East through the Mediterranean and along the Atlantic coast. Following early radiocarbon dating in the 1970s, an alternative hypothesis arose of regional independent developments in Europe. This model has dominated megalith research until today. We applied a Bayesian statistical approach to 2,410 currently available radiocarbon results from megalithic, partly premegalithic, and contemporaneous nonmegalithic contexts in Europe to resolve this long-standing debate. The radiocarbon results suggest that megalithic graves emerged within a brief time interval of 200 y to 300 y in the second half of the fifth millennium calibrated years BC in northwest France, the Mediterranean, and the Atlantic coast of Iberia. We found decisive support for the spread of megaliths along the sea route in three main phases. Thus, a maritime diffusion model is the most likely explanation of their expansion.
B. Schulz Paulsson, "Radiocarbon dates and Bayesian modeling support maritime diffusion model for megaliths in Europe" PNAS published ahead of print (February 11, 2019).

From the body text:
The radiocarbon results suggest that megalithic graves emerged within a time interval of 200 y to 300 y in the second half of the fifth millennium cal BC in northwest France, the Mediterranean, and the Atlantic coast of the Iberian Peninsula. Northwest France is, so far, the only megalithic region in Europe which exhibits a premegalithic monumental sequence and transitional structures to the megaliths, suggesting northern France as the region of origin for the megalithic phenomenon. For the remaining regions with an early megalithic proliferation in the fifth millennium cal BC (such as Catalonia, southern France, Corsica, Sardinia, and probably the western Iberian Peninsula and Italian mainland), megaliths are found occurring in small clusters. These are exceptional grave forms for this period in their respective regions, at a time when subterranean cists, pit burials and hypogea (dug-out subterranean burial chambers) were still the most common burial rites. A fresh expansion occurred during the first half of the fourth millennium cal BC when thousands of passage graves were built along the Atlantic coast of the Iberian Peninsula, Ireland, England, Scotland, and France. Their distribution emphasizes the maritime linkage of these societies and a diffusion of the passage grave tradition along the seaway. The passage graves mark a radical change of burial rites, along with other economic and social changes in Europe. In the second half of the fourth millennium cal BC, the passage grave tradition finally reaches Scandinavia and the Funnel Beaker areas. Again, there is evidence for the spread of megalithic architecture along the seaway. The first known passage graves in Scandinavia were built on the western coasts of the Swedish Islands Oland and Gotland, which are both situated in the Baltic. 
We have thus been able to demonstrate that the earliest megaliths originated in northwest France and spread along the sea routes of the Mediterranean and Atlantic coasts in three successive principal phases. Their expansion coincided with other social and economic changes of Neolithic and Copper Age societies beyond the scope of this article. The older generation of archaeologists were correct concerning a maritime diffusion of the megalithic concept. They were wrong regarding the region of origin and the direction of the megalithic diffusion. The megalithic movements must have been powerful to spread with such rapidity at the different phases, and the maritime skills, knowledge, and technology of these societies must have been much more developed than hitherto presumed. This prompts a radical reassessment of the megalithic horizons and invites the opening of a new scientific debate regarding the maritime mobility and organization of Neolithic societies, the nature of these interactions through time, and the rise of seafaring.

Margins of Error

While this is offered up as a joke, it would actually be very good practice in many cases (from here).

Monday, February 11, 2019

More Evidence Re No Dark Matter Galaxies And A New High Dark Matter Compact Elliptical Galaxy Anomaly

The authors of the paper claiming that NGC1052-DF2 and NGC1052-DF4 have little or no dark matter phenomena make a strong case that a potential flaw in their analysis is without merit.
It has been suggested that the dark matter-deficient galaxies NGC1052-DF2 and NGC1052-DF4 might not be members of the NGC1052 group but in the foreground at ∼13 Mpc, and satellites of the bright spiral galaxy NGC1042. We previously showed that the CMDs of the galaxies are inconsistent with this hypothesis, and derived distances of 19-20 Mpc from their surface brightness fluctuation signals. Here we note that NGC1042 is almost certainly a member of the NGC1052 group as well, based on its radial velocity, the HI distribution in the NGC1052/NGC1042 system, and the Tully-Fisher relation.
Pieter van Dokkum, Shany Danieli, Aaron Romanowsky, Roberto Abraham, Charlie Conroy, "The distance to NGC1042 in the context of its proposed association with the dark matter-deficient galaxies NGC1052-DF2 and NGC1052-DF4" (February 5, 2019) (To appear in RNAAS).

The following paper is also a notable observation of an outlier galaxy that seems to be contrary to MOND and the Radial Acceleration Relation (and every other modified gravity theory that reproduces the RAR) and is also an extreme outlier with respect to the less ironclad expectations of ΛCDM theory (in the vicinity of five sigma discovery significance). 

Generally speaking, elliptical galaxies have apparent low dark matter to total mass ratios. Because it is such an extraordinary and singular outlier a first instinct is to look for possible methodological flaws. But, if there aren't any, it is an extremely significant development (far more so than the claimed bullet cluster issues for modified gravity theories). The possibility that "a hydrostatic equilibrium analysis of the luminous and relaxed X-ray plasma emission" is misleading in this case, perhaps because the system in not in equilibrium, or because the luminous and X-ray plasma emissions are atypical for reasons related to the mix of stars in the galaxy for some reason come immediately to mind as possible explanations. Another possibility is that the new and archival observations have some inconsistency that hasn't been properly considered.

The Extremely High Dark Matter Halo Concentration of the Relic Compact Elliptical Galaxy Mrk 1216
Compact elliptical galaxies (CEGs) are candidates for local analogs of the high-redshift "red nuggets" thought to represent the progenitors of today's early-type galaxies (ETGs). To address whether the structure of the dark matter (DM) halo in a CEG also reflects the extremely quiescent and isolated evolution of its stars, we use a new 122 ks Chandra observation together with a shallow 13 ks archival observation of the CEG Mrk 1216 to perform a hydrostatic equilibrium analysis of the luminous and relaxed X-ray plasma emission extending out to a radius 0.85r2500. We examine several DM model profiles and in every case obtain a halo concentration (c200) that is a large positive outlier in the theoretical ΛCDM c200M200 relation; i.e., ranging from 3.4σ6.3σabove the median ΛCDM relation in terms of the intrinsic scatter. The high value of c200 we measure implies an unusually early formation time that firmly establishes the relic nature of the DM halo in Mrk 1216. The highly concentrated DM halo leads to a higher DM fraction and smaller total mass slope at 1Recompared to nearby normal ETGs. In addition, the highly concentrated total mass profile of Mrk 1216 cannot be described by MOND without adding DM, and it deviates substantially from the Radial Acceleration Relation. Mrk 1216 contains 80% of the cosmic baryon fraction within r200. The radial profile of the ratio of cooling time to free-fall time varies within a narrow range (tc/tff1419) over a large central region (r10 kpc) suggesting "precipitation-regulated AGN feedback" for a multiphase plasma, though presently there is little evidence for cool gas in Mrk 1216. The properties of Mrk 1216 are remarkably similar to those of the nearby fossil group NGC 6482.
Comments:28 pages, 12 figures, submitted to The Astrophysical Journal
This image is from that paper:

Footnote: For future reference I'm noting the paper below, primarily as a reference which the mass ranges of low, intermediate and high mass satellite galaxies.

Quenching low-mass satellite galaxies: evidence for a threshold ICM density

We compile a sample of SDSS galaxy clusters with high-quality Chandra X-ray data to directly study the influence of the dense intra-cluster medium (ICM) on the quenching of satellite galaxies. We study the quenched fractions of satellite galaxies as a function of ICM density for low- (109M1010M), intermediate- (1010M1010.5M), and high-mass (M1010.5M) satellite galaxies with >3000 satellite galaxies across 24 low-redshift (z<0.1) clusters. For low-mass galaxies we find evidence for a broken powerlaw trend between satellite quenched fraction and local ICM density. The quenched fraction increases modestly at ICM densities below a threshold before increasing sharply beyond this threshold toward the cluster center. We show that this increase in quenched fraction at high ICM density is well matched by a simple, analytic model of ram pressure stripping. These results are consistent with a picture where low-mass cluster galaxies experience an initial, slow-quenching mode driven by steady gas depletion, followed by rapid quenching associated with ram pressure of cold-gas stripping near (one quarter of the virial radius, on average) the cluster center.
Comments:17 pages plus appendix, 10 figures, accepted to ApJ