[Drammach]

But how could modern humans have reached Australia, hundreds of nautical miles from the nearest landmass? On this question, Macaulay is more vague.
"The crossing at the other end, to Australia, is much more mysterious. That was a substantial sea crossing," he said. "But there's evidence for gene flow between Africa and Arabia post-60,000 years [ago], as well. So there were other sea crossings going on."

Was there a substantial sea crossing??
What about ice ??

Nine or Ten Years of frozen ice over the Australian straits probably wouldn't even show up in a geological record..
But it would be ample time for humans to simply walk to Australia..

Ice age sea levels combined with periodically frozen southern oceans would provide the means and opportunity to migrate to Australia..
Likewise, ice fishers accidentally marooned on ice floes could have found themselves brought to the continent by ocean currents..

[blam]

This is currently my favorite, it is based on the DNA studies of Professor Stephen Oppenheimer...he shows the effect of the Toba volcano 75,000 years ago too.

Journey Of Mankind

[blam]

"Was there a substantial sea crossing??"

Yes, but much shorter than today.

"What about ice ??

No ice. The equator runs right through Indonesia and just north of New Guinea (Sundaland). An ideal place for humans to thrive during the Ice Age.

The equator runs through South America too and I suspect we have some big ancient suprises waiting down there.

[muawiyah]

Problem is a concept called "the neololithic toolkit" or "the paleolithic toolkit" ~ which refers to the technology available to stoneage, or newstoneage people in different locations or at different times.

When it comes to Australia and Tasmania, it's easy to show that the Tasmanians had a depleted "kit" and would have had a hard time withstanding a good winter. Alternatively, since they'd traveled the farthest, they had the "original kit" and it was not satisfactory for cold weather life.

10 years of serious Winter at the Equator might have made it possible for someone to walk on the ice all the way to Australia, but he'd frozen to death on the way due to the fact he didn't have good clothing or boots.

[muawiyah]

Oh, yeah, that “winter” at the Equator would have left some evidence that it’d happened. For one, the Equator would have nothing but winter-hardy plants!