[lkrubner]

My dad used to make this argument: of all the millions of footprints that humans made, after arriving in North America, what is the likelihood that we found the very first of those footprints?

The point is, whatever evidence we find, it's unreasonable to think that evidence we've found is the first evidence that existed, so we have to assume the real arrival was a bit before that. When we had evidence of humans arriving 17,000 years ago, it was reasonable to assume humans really arrived 21,000 years ago. When we have evidence of people arriving 23,000 years ago, you have to assume people really arrived 25,000 years ago.

There may come a point, centuries from now, when our evidence feels comprehensive, at which point the error estimate can shrink. But modern archeology is barely 100 years old and most subject areas are still under-studied, so error estimates need to remain large, for now, especially for the prehistoric era. (Obviously error estimates are much smaller for the historic era, where we have a relative abundance of evidence.)

[AlotOfReading]

This is actually how archeologists estimate their ranges for human habitation in an area, just with math instead of guesses. This paper isn't about that (try timing papers like [1] instead), it's about the actual radioisotope boundary dates for an actual site.

Part of the problem these LGM dates keep running into is that it's not obvious how people got here in the first place. After about 48kya, the ice free corridors close up and the ice sheets encompass most of the coastal islands as well until about 22kya when humans can get to Alaska again and 18kya when humans can easily get down the coastal routes. What would have been possible in the middle is very much still in the ??? grey area.

[1] https://doi.org/10.1038/s41586-020-2491-6

[irrational]

I assume they built boats. It isn't exactly surprising after 20k years that we can't find any proof of these boats, but how else would then have come across? Fly?

[AlotOfReading]

We know that humans had boats by that point due to their presence in Australia and the current dominance of the coastal migration hypothesis. The problem is that our current understanding of the climate is that the coast was too ice-locked by glaciers for coastal foraging. If there's something this old, either they were doing some very impressive and unexpectedly long distance nautical journeys, or there are gaps in the details of our paleoclimate models.

It's not that either is impossible or even improbable, it's just that it forces us to revisit everything again to try and work out the routes if these (and other similarly early dates that have been proposed in the last couple years) hold up under review.

[irrational]

Coastal foraging? Why can't they just fish? There are lots of fish in those northern reaches today, I assume there would have been even more back then. And fish doesn't necessarily have to be cooked, so no requirement to stop to make fires.

[AlotOfReading]

Note that the phrase "coastal foraging" typically implies fishing and the exploitation of other littoral/marine resources.

Anyway, the current understanding of the paleoclimate is that entire region between approximately Valdez and Vancouver Island was entirely covered by glaciers out to the edge of continental shelf until ~18kya. Lesnek et al has some good diagrams [1]. Living exclusively off deep-sea marine resources in an iceberge minefield without fire for over a thousand miles in one of the coldest, most dangerous oceans in the world without landing suggests an unprecedented level of both nautical technology and experience. Where did that come from? We have no good answers right now.

[1] https://doi.org/10.1126/sciadv.aar5040

[lugged]

A doco I watched a while back suggested they could have used seal blubber and oil lamps as a source of heat to melt ice for water.

The boat would be hauled onto the ice and turned upside down to form a shelter in remote spots.

Fishing and hunting for seals would have provided the food as they went.

[irrational]

What is the reasoning for thinking they came from the top? You’ve said they had already reached Australia via boat. Couldn’t they have reached some other part of the Americas by boat, maybe South America via Africa or Easter island?

[tzs]

One point in favor of a water route is you can carry a lot more stuff that way. Most of the migrations into the Americas were before animals other than perhaps dogs were domesticated and before the wheel was invented.

So anything you wanted to bring with you on a land route had to be carried by humans, dogs, or pulled on sleds by humans or dogs.

On a water route you could tow another boat or raft behind full of your stuff. (Rope was invented long before any migration to the Americas).

[ajross]

> I assume they built boats

There was a land bridge due to lower sea levels during the last glaciation. HOW people from Asia populated the Americas is not really the question.

[irrational]

But now they are saying that people were here before the land bridge was usable or existed, right? So, maybe they came some way other than the land bridge. Or, earlier peoples came via some other route (hence the current footprints) and then a later migration came via the land bridge.

[PaulDavisThe1st]

Actually, that absolutely is the question.

[satronaut]

tbh they were probably way more advanced than we give, or want to give, them credit for

[tejtm]

And possibly more raw intelligence as we have mainly been selecting for "smarter than grass" since beginning this experiment in agriculture 10k - 20k years ago.

[satronaut]

I've heard that humans are evolving to become more dumb. The idea is that it's easier for an idiot to survive and procreate than it was in the past

[kwonkicker]

Technically true but wrong. If your oldest Facebook post is from 2015, how likely is it that you've been using the internet before 2005?! Archeologists are very smart people in their own right, some are much smarter than we are. They do consider everything that we think they haven't. Let's give some benefit of the doubt to our fellow researchers.

[haroldp]

I first joined facebook in 2009, but have been on the internet since 1991.

You might counter that facebook only started in 2004, and didn't get much traction until 2006. But I was invited before that and simply didn't care to join, preferring to occupy other parts of the `net.

Likewise, Clovis artifacts all date from after the peak of the last ice age, when glaciers were melting, land routes were opening, and sea levels were rising to obliterate any coastal artifacts from any previous waves of migration.

Clovis-first has been debunked for decades. This is just another - particularly solid - nail in that theory's coffin. It is worth asking why it has persisted so doggedly. I don't think it is because archeologists aren't very smart people.

[mistrial9]

you were using what network protocol stack in 1991 ? Banyan "vines" or token-ring ?

[nobody9999]

I was running a full TCP/IP stack (ka9q[0]) across over single-mode fiber via a 10MB/Sec ethernet interface on my IBM PC/XT clone in 1990.

I also used some higher-level stuff like telnet, FTP (sites mostly found via anonymous FTP lists), nntp, smtp, gopher, archie and veronica.

[0] https://en.wikipedia.org/wiki/KA9Q

[mistrial9]

sure, but I was a network engineer at the time and your TCP/IP was very, very niche.. you know very well that there was no "Internet" in 1990

[haroldp]

WTF is this? I was at university and I assure you we were connected to the internet. I got a login and an email address from the physics department in `91 because I was working on a project on their network. I used Elm for email, which had been out since the 80s. I was happy to upgrade to Pine (Pine is not elm) in 1992 and actually kept using Pine until like 1999. By `92 pretty much everyone else at my university was using the internet. I could dial up from home via modem, and check my email. NCSA Mosaic came out in `93.

[nobody9999]

>ure, but I was a network engineer at the time and your TCP/IP was very, very niche.. you know very well that there was no "Internet" in 1990

There was no consumer Internet in 1990.

However, TCP/IP was in use across a broad range of academic institutions and corporations, and it was possible for pretty much anyone to buy access to TCP/IP-based inter-networks.

Which, if you were a network engineer (and not for Novell or DEC) at the time, you would know.

[Kostchei]

direct dial to BBS, at least that was the "internet" for me at that stage. The disparate nodes of bulletin boards wasn't what I would call an internet. And it was very cliquish.

[neffy]

Some background on this, there is a long standing back to the late 20th century - and to those of us outside the field darkly funny - controversy within this particular scientific community on when the first humans arrived, which can be broadly googled by searches for "Clovis man controversy".

Sure archeologists are very smart people, and like all other very smart people, can still be caught on the wrong side of history as new evidence piles up against existing theories.

[User23]

> If your oldest Facebook post is from 2015, how likely is it that you've been using the internet before 2005?!

Who knows. It could be that person has been using the Internet for a very long time and is thus a late adopter of Facebook due to preferring to do things the old way. It could also be a person who started using the Internet in 2015. GP's point that we really can't conclude anything beyond a lower bound isn't falsified by your example

[SantalBlush]

>They do consider everything that we think they haven't.

This can be said of almost any observation made about a particular field of research. Outsiders aren't familiar enough with the current state of research and they often assume experts haven't considered some rather obvious things.

That's not to say that outsiders shouldn't participate in the discussion, but they should acknowledge that there is a good chance their ideas have already been considered.

[SECProto]

> If your oldest Facebook post is from 2015, how likely is it that you've been using the internet before 2005?!

My Facebook account dates back to 2015, but I have been using the internet since the mid 90s. (As far as I'm aware, there's no evidence of the previous account I had from 2006-2010ish)

> Let's give some benefit of the doubt to our fellow researchers.

Agree here

[njacobs5074]

Facebook usage isn’t a good metric. My first post was in 2008 but had been using the internet since the early 1980s.

There were these early internet tribes called researchers ;)

[lenzm]

This is similar to the German Tank Problem - given you have found N numbered tanks, how many total tanks are there?

https://en.wikipedia.org/wiki/German_tank_problem

[tpmx]

Variation: given you found N numbered C64s, how many were really sold?

https://www.pagetable.com/?p=547

[Stevvo]

Clovis first persisted for almost the entirety of that 100 years despite large and ever growing amounts evidence to the contrary.

There is no need for "error estimates to remain large". The field just needs to acknowledge the actual numbers the evidence gives, instead of ignoring things when the show up because they are older than expected and don't fit with the existing narrative.