Thursday, January 4, 2018

What Ecological Impact Did A Meteor Strike 800,000 Years Ago In SE Asia Have?

About a million years after Homo Erectus arrives in Southeast Asia and East Asia from Africa, and probably before or at around the same time as, the appearance of a common ancestor of Neanderthals and Denisovans, and maybe even a common ancestor of that clade and modern humans an asteroid slams into Southeast Asia causing immense short term climate effects, although not a mass extinction. There has been no bigger impact on Earth since then. Three mysteries remain.

First, where precisely was the impact crater? 

The event has been known to scientists in the field for many years, but the latest discoveries narrow the search to Southeast Asia, in someplace where erosion and the like would make the impact site less obvious than it would otherwise be.

Second, what ecological impact did it have?

There isn't much in the archaeological or fossil record to indicate that this was associated with a mass extinction event or a major ecological shift, but this record, particular in Southeast Asia, is very thin. 
A kilometer-size asteroid slammed into Earth about 800,000 years ago with so much force that it scattered debris across a 10th of our planet’s surface. Yet its impact crater remains undiscovered. Now, glassy remains believed to have come from the strike suggest the asteroid hit southeast Asia as our close ancestors walked the Earth.

“This impact event is the youngest of this size during human evolution with likely worldwide effects,” says Mario Trieloff, a geochemist at the University of Heidelberg in Germany not involved in the research. Large impacts can disrupt Earth’s climate by spewing dirt and soot high into the atmosphere, where it can block sunlight for months or even years. . . .

They’re puzzled why a crater that’s both presumably large and geologically young—meaning it hasn’t been exposed to much erosion due to rain and wind—hasn’t been found. The crater, if discovered, could also shed light on how the impact affected life nearby. “Our not-too-distant ancestors witnessed this impact,” Cavosie says. “They might have been dragging their knuckles, but an event like the formation of a 50- to 100-kilometer-diameter impact is sure to have gotten their attention.”
Third, is it plausible that this impact created conditions that spurred the evolution of Neanderthals, Denisovans and maybe even modern humans as well, by placing greater demands for intelligence and adaptability on the hominins in existence at the time?

While this particular data point is hardly conclusive and really no more than a conjecture, collectively, the evidence points pretty strongly towards key moments of punctuated change driven by climate and extraterrestrial events in what is known as the Court Jester Hypothesis.

From Science Magazine.
Australasian tektites are enigmatic drops of siliceous impact melt found in an ~8000 × ~13,000 km strewn field over Southeast Asia and Australia, including sites in both the Indian and Pacific oceans. These tektites formed only 790,000 yr ago from an impact crater estimated to be 40–100 km in diameter; yet remarkably, the young and presumably large structure remains undiscovered. 

Here we report new evidence of a rare high-pressure phase in Australasian tektites that further constrains the location of the source crater. The former presence of reidite, a high-pressure polymorph of zircon, was detected in granular zircon grains within Muong Nong–type tektites from Thailand. The zircon grains are surrounded by tektite glass and are composed of micrometer-sized neoblasts that contain inclusions of ZrO2. Each grain consists of neoblasts in three distinct crystallographic orientations as measured by electron backscatter diffraction, where all directions are orthogonal and aligned with one direction from the other two orientations. The systematic orientation relationships among zircon neoblasts are a hallmark of the high-pressure polymorphic transformation to reidite and subsequent reversion to zircon. The preserved microstructures and dissociation of zircon to ZrO2 and SiO2 require a pressure >30 GPa and a temperature >1673°C, which represent the most extreme conditions thus far reported for Australasian Muong Nong–type tektites. The data presented here place further constraints on the distribution of high-pressure phases in Australasian tektites, including coesite and now reidite, to an area centered over Southeast Asia, which appears to be the most likely location of the source crater.
Aaron J. Cavosie, et al. "New clues from Earth's most elusive impact crater: Evidence of reidite in Australasian tektites from Thailand" Geology (December 20, 2017).

18 comments:

DDeden said...

That is a puzzle. Which way did it go? One of the deep trenches? Actually I think it broke up in the atmosphere and "powderized", so no big impact crater.
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OT: island dwarfing doubted in Palau http://around.uoregon.edu/content/uo-archaeologists-cast-doubt-controversial-hobbit-theory

Is there ANY Homo populations which clearly indicate dwarfing due to island effect or jungle effect or geographical isolation? I would say, not to my knowledge, not one anywhere ever. Homo being omnivorous would be much less affected by such a mechanism than strict carnivores or herbivores. Pygmies simply never grew taller since they've stayed in the tropical rainforest floor niche. Florensis and earlier hominid there also was the normal ancestral size, they didn't shrink, they just maintained. In my opinion.

andrew said...

I disagree with your conclusion with regard to Asian Negrito populations, and I am fairly sure that there are one or two less notable cases.

andrew said...

Also, there has to be an impact crater because part of the evidence involves materials kicked up out of the Earth upon impact.

DDeden said...

H Florensis 60 or 74ka? /Mata Menge ~ 700ka or ASF impact era?

https://curnoe.com/2016/06/10/the-hobbit-took-our-breath-away-now-its-the-new-normal/
(Writer of post works at Niah Cave, Borneo)

A paper published today in the journal Nature by a joint Australian, Indonesia and Japanese team led by Gerrit van den Bergh of the University of Wollongong provides new evidence the Hobbit may have lived on Flores much earlier than suggested by Liang Bua.

Excavations at the site of Mata Menge in the So’a Basin have provided an abundance of animal fossils and stone tools. And, following today’s announcement, a jaw bone and teeth that look suspiciously like the Hobbit as well.

The fossils are a bit scrappy, but they certainly hold enough clues to give us a sense that they are: 1) a human relative; 2) probably related to Homo erectus; and 3) could even be the ancestors of Homo floresiensis.

Even more exciting, the fossils are at least 700 thousand years old; so they’re in the right place at the right time and have the right physical traits to connect the dots to the Hobbit.

terryt said...

"Actually I think it broke up in the atmosphere and 'powderized', so no big impact crater".

Unlikely to be the case. 'new evidence of a rare high-pressure phase in Australasian tektites that further constrains the location of the source crater'. Therefore it must have hit land. Perhaps in the region between Borneo and Vietnam that may have been dry land at the time. I have no clue as to the sea level at the time.

"Is there ANY Homo populations which clearly indicate dwarfing due to island effect or jungle effect or geographical isolation? I would say, not to my knowledge, not one anywhere ever".

The Flores population is almost certainly a product of island dwarfing. Especially when we remember that it was also home to dwarf elephants.

"Homo being omnivorous would be much less affected by such a mechanism than strict carnivores or herbivores".

It is the availability of food within a restricted area that is probably the driving force for island dwarfing. You need a population of reasonable numbers to sustain a population. In constricted regions that can only be achieved by limiting the size of individuals.

"Florensis and earlier hominid there also was the normal ancestral size, they didn't shrink, they just maintained".

Unlikely as Homo erectus of apparently normal size is found all round the East for a long time before humans reached Flores.

DDeden said...

(Sorry, my ref. to the hobbit/Mata Menge was from 2016, I'd thought it was an update.)

I accept a 'large crater'. I'm from Missouri(sort of), show me. Otherwise, you've got a belief and a plausible explanation for the tektite composition but which might have happened in some other way (small chunks plus powder, rather than a single boulder-like impact).
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TT: The Flores population is almost certainly a product of island dwarfing. Especially when we remember that it was also home to dwarf elephants.

DD: The older 800ka Mata Menge fossils are SMALLER than 60ka LB1, so the Hobbits were ENLARGING, not dwarfing. The Congo has small Homo sapiens & small elephants (20 toed {primitive} vs. 18 toed {derived} savanna elephant), neither 'dwarfed' (->shorter limbs, same torso size, like dachshund), they maintained their ancestral form and approximate size that matches their econiche. (All big animals had smaller ancestors, all long-necked giraffes had short-necked giraffe ancestors eg. Okapi)

wiki: "A medium- to large-sized stegodont, S. florensis, with a body weight of about 850 kg (1,870 lb), appeared about 850,000 years ago"

In the past, stegodonts were believed to be the ancestors of the true elephants and mammoths,

https://web.archive.org/web/20120716232849/http://web.ncf.ca/bz050/HomePage.gne.html

How many toes did the Flores Stegodont have? 20? 16?
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TT: It is the availability of food within a restricted area that is probably the driving force for island dwarfing.

DD: Homo has an extraordinarily general diet, arboreal-submarine-benthic-subterrestrial nugivorous-frugivorous-omnivorous etc. Flores had giant rats, Congo has giant hogs, both omnivorous. Stegodonts were vegetarian/frugivorous/herbivorous.

TT: Unlikely as Homo erectus of apparently normal size is found all round the East for a long time before humans reached Flores.

DD: Hf seems to not be H erectus, but H habilis. H erectus being larger seems to have lived in more open environments.

andrew said...

@terryt The theory that hobbits are dwarf H. Erectus isn't very well supported because the hobbit traits are not sufficient derived. H. Habilis is much closer in anatomy. But, there is no denying that H. Erectus and hobbits would have been present in SE Asia contemporaneously.

Island dwarfing is certainly a thing, and there is no reason that it can't apply to hominins like every other megafauna species. Whether hobbits were a product of island dwarfing is a question with an inconclusive answer, as is the question of how they got to Flores. There is no solid evidence of any hominin crossing a body of water as impressive as the Wallace line (which hasn't been passable by a land bridge at any point in hominin evolution) until you get to Upper Paleolithic era modern humans. Hanging on for dear life to flotsam and getting lucky, or riding on the back of megafauna able to swim across it, or even being carried by a very large bird, seem like the most plausible options, although the fact that you'd need a sufficient breeding population limits some of those options. At any rate, I suspect that this was a one way trip made by accident or fleeing what would otherwise be certain death (perhaps there was a lot of flotsam and a need to flee in the wake of the ET impact around the time that the first archaeological record appears in Flores).

Ryan said...

"About a million years after Homo Erectus arrives in Southeast Asia and East Asia from Africa, and probably before or at around the same time as, the appearance of a common ancestor of Neanderthals and Denisovans, and maybe even a common ancestor of that clade and modern humans an asteroid slams into Southeast Asia causing immense short term climate effects, although not a mass extinction."

I doubt it substantially altered the selective pressure, but I would think it is very plausible that such an impact created the demographic space for a new human subspecies like the Denisovans to come in and colonize the area. Much as Toba may have done for us.

DDeden said...

African habilis(rainforest) & erectus(woodland) -> SEAsia 1ma
~ 800ka Impact tsunami -> Flores

African Pygmies(rainforest) &
Talls (woodland) -> SEAsia 80ka
~ 74ka Toba tsunami -> Wallacea

2004 tsunami debris -> a woman was found in a floating coconut palm in mid-ocean after a week. Fronds can be woven to make nest/shade, coconut water & flesh can be consumed, spears & snares made to catch fish & seabirds.

I actually think domeshields/coracles were the first watercraft used to cross Wallacea, and only later in Papua were the first longboats made of sago palm rinds, then bark canoes, then dugout log canoes.

Ryan said...

I don't think relying on a several hundred metre tall megatsunami to explain a rafting event is a very good idea. Aside from the dubious survivability of such an event, it just seems that regular tropical cyclones and earthquakes could just as easily set you adrift on a course to Flores, and they're much more frequent.

If our cousins in SE Asia were using primitive rafts even I don't think it would be that unlikely for them to occasionally get swept out to sea and sometimes wind up on other islands.

DDeden said...

What is the oldest evidence for "primitive rafts"? 7ka pitched reed raft? Rafts float IN water, boats (coracles) float ON water.
My point was the nice fit of the dated impact & supervolcano to the dated migrations. Do you have evidence of cyclones or earthquakes at those times?

Ryan said...

@DDeden - "What is the oldest evidence for "primitive rafts"? 7ka pitched reed raft? Rafts float IN water, boats (coracles) float ON water." There's no evidence of earlier coracles either. This is a part of the world though where evidence of these sorts of technologies would decay and not leave much trace unfortunately.

"My point was the nice fit of the dated impact & supervolcano to the dated migrations. Do you have evidence of cyclones or earthquakes at those times?"

First of all cyclones and earthquakes happen on a frequency of decades, so yes, every single century certainly had those. That's a rather silly question. They're part of nature.

I think you missed my point though - which was suggesting these events as having opened a ecological niche rather than they themselves being a means of transport.

DDeden said...

"every single century certainly had (cyclones & earthquakes)." Since the aforementioned migrations correlate to the impact & supervolcano dates, rather than with recurring frequency, I suggest that that should be considered significant, not "silly". Both events would have pushed migrants southward, away from danger, rather than landward (which would be the rational response to recurrent periodic cyclones & earthquakes). The principles of Parsimony & Continuity allow the determination that coracles preceded any other manufactured watercraft, but can't prove they were used on those oceanic migrations.

Ryan said...

DDeden - You're missing my point. I'm not doubting your timing, just your proposed method.

And what's a raft other than a collection of sticks or reeds. It's a lot harder to build a coracle than it is to cling to a stick.

New world monkeys managed to get there by "rafting" after all.

DDeden said...

Your point being?

All mother rainforest great apes construct woven bowl nests for their infants & selves, with leaves inserted inside for comfort.
All mother rainforest AMHs Pygmies traditionally construct woven dome huts for their infants & selves, with leaves inserted outside for waterproofness & comfort.
An inverted dome hut is a coracle, originally the dome hut was without doorway and was used as a portable dome shield (domicile). Elements of this is recalled in ancient oral history (Herakles crossing the sea in a 'cup', Greek tales of soldiers crossing rivers on their shields, etc.).

Ancestors of NW Cavies & NW monkeys crossed from Africa about 23ma, it is most likely that they were the size of tiny squirrel monkeys or bushbabies (size: human fetus) and crossed within a floating tree-hollow (not clinging to branches) while in a state of estivation (spending a hot or dry period in a prolonged state of torpor or dormancy). Are you suggesting that is how Homo crossed the open sea? Any evidence of that?

DDeden said...

Tupaia vs Island Rule: https://archaeologynewsnetwork.blogspot.com/2018/01/study-shows-treeshrews-break.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+TheArchaeologyNewsNetwork+(The+Archaeology+News+Network)&m=1#Qf2zQWSEMKdV5jsp.97

DDeden said...

Did 73.9ka Toba Supervolcano push some AMHs south to Wallacea and mtDNA L3 back to Africa? Did the 790ka Cosmic Impact push H habilis south to Flores and H er. back to Africa?
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(pre print) 2018

Carriers of mitochondrial DNA macrohaplogroup L3 basic lineages migrated back to Africa from Asia around 70,000 years ago.

Vicente M Cabrera, Julia Patricia Marrero Rodriguez, Khaled K Abu-Amero, Jose M Larruga
https://doi.org/10.1101/233502

Abstract

Background: After three decades of mtDNA studies on human evolution the only incontrovertible main result is the African origin of all extant modern humans. In addition, a southern coastal route has been relentlessly imposed to explain the Eurasian colonization of these African pioneers. Based on the age of macrohaplogroup L3, from which all maternal Eurasian and the majority of African lineages originated, that out-of-Africa event has been dated around 60-70 kya. On the opposite side, we have proposed a northern route through Central Asia across the Levant for that expansion. Consistent with the fossil record, we have dated it around 125 kya. To help bridge differences between the molecular and fossil record ages, in this article we assess the possibility that mtDNA macrohaplogroup L3 matured in Eurasia and returned to Africa as basic L3 lineages around 70 kya...

DDeden said...

Also note that the most recent geomagnetic flip co-occurred at 800ka~780ka with: Austl. Strewn Field Impact, deposition of bones & stone tools of H antecessor in (Gran dolina cave layer TD6) Spain (cannibalism may be due to aerosols blocking sunlight cf Tambora volcanic winter 1815 year w/o summer); and plausibly H georgicus at Dmanisi (riverbed dated 1.77ma but deposits near loose fossils dated at 800ka. The Ceprano (Italy) skull ~800ka most closely resembles Java man, unlike European & African skulls, possibly indicating a western migration.

Dwarfing, senso stricto, is found in Neandertals and less so in Eskimos, Tibetans & Incas, due to effects of sustained cold climate: limbs shorten, trunk thickens, brain enlarges slightly