What Killed the Great Beasts of North America?

sciencehabit writes "Until about 11,000 years ago, mammoths, giant beavers, and other massive mammals roamed North America. Many researchers have blamed their demise on incoming Paleoindians, the first Americans, who allegedly hunted them to extinction. But a new study points to climate and environmental changes instead. The findings could have implications for conservation strategies, including controversial proposals for 'rewilding' lions and elephants into North America."

Re:It's the orbit, stupid

[emagery]

Oh, the orbit matters... but the orbit is EXTREMELY predictable even its wobble and orientation. It might, perhaps tip the scale during the (likely ongoing) pleistocene (Where 90% of our time is spent in ice age with 10% warm snaps that should have already ended by now, contrary to spiking upwards instead) but ebbs on a timeline that should have had the pleistocene happening essentially since beginning of observable time (which it has not.) So, it's a factor, but not a decisive one. Continental arrangements and landmasses propensity for temperature extremity vs. oceanic propensity for temperature moderation and long-distance transport matter far more (even than tilt, given measuring the southern hemisphere vs. northern.) And yet, in spite of the fact that the continents and oceanic currents are still in the same messy tangle they have been for the entirety of the multi-million year pleistocene, these beasts didn't go extinct during an of the previous warm-snaps... just the one we arrived in... and now that we should be quickly descending into ice age, instead we're headed the other way. This article is of interest, but it is not argument against anthropogenic extinctions or climate change.

If so, TFS is wrong

[SirGarlon]

Seems likely that this is the article. If so, I've only read the abstract so far, but TFS seems to misrepresent the authors' conclusion.

TFS claims:

the first Americans, who allegedly hunted them to extinction. But a new study points to climate and environmental changes instead.

whereas the abstract says:

Chronological data,Sporormiella abundance, genetics, and paleoclimatic data suggest megafauna populations declined prior to human colonization and people were only briefly contemporaneous with megafauna. Local Paleoindians may have only delivered the coup de grace to small scattered and isolated populations of megafauna.

In other words, the authors are not saying humans were not involved in the extinctions. They are saying human predation cannot be the *sole* cause.

Re:It's the orbit, stupid

[CreatureComfort]

How about you actually study some real Paleoclimatology [wattsupwiththat.com] instead of pulling neo-liberal statements out of your ass?

The truth is, the earth, as a whole, is currently at about the lowest average temperature [imageshack.us] that can be inferred from the all sources of ancient data. Normally, we should be about 2-3 C higher, globally, given the historical record.

"Global Warming" is just a return to trend and should be expected whether humans are walking around or not.