The ‘Out of Africa’ theory is the most widely accepted theory of how modern humans (Homo sapiens) spread from Africa to eventually inhabit all the continents across the world. Plenty of readers would be surprised to learn that this happened relatively recently: while modern humans were thought to have evolved 200,000-300,000 years ago, evidence suggests they did not move beyond Africa until around 50,000 years ago (although possibly as early as 70,000 years ago).

There were earlier migrations, of other Homo species (e.g. Neanderthals and Homo erectus), and also other modern human groups, though the latter seem to have either gone extinct or returned to Africa. But it is believed that all modern non-African populations now in existence are mostly descended from the groups of Homo sapiens that left Africa around 50,000 years ago.

The strange thing about it though, as archaeologist and popularly YouTuber Stefan Milosavljevich (aka Stefan Milo) noted in a recent video, is – if dating of a number of archaeological sites across the world is accurate – those humans seem to have preferred going east a lot more than going west.

Milo pointed at two archaeological sites to illustrate his point: one in the southwest of Australia*, the other in Bulgaria:

There’s something really funny going on with ‘Out of Africa’. Let me show you on Google Maps. So, this is one of the archaeological sites I just came across in Australia, Devil’s Lair. It’s like 48,000 years ago, people started living there based on some radiocarbon dates of charcoal, I believe…it’s certainly a human-occupied site. And then this is Bacho Cave, one of the earliest sites in Europe. Dates to around 45,000 years ago. How did modern humans leaving Africa get all the way to Devil’s Lair – some 16,500 km at least – before they made it to Bacho Kira cave, a distance of 2,138km, assuming a starting point around the Mediterranean.

How is that possible? How could modern humans expand 16,000 kilometers before they just expanded 2,000 km? Isn’t that odd? Isn’t that so strange? I’m not even saying history didn’t go down like that. But if it did, why?

It’s worth noting that Stefan Milo is no mystery monger – in fact, he’s created a number of videos taking issue with alternative archaeology theories. But this particular historical anomaly has him somewhat mystified. He does however present a few possible solutions which he found in the relevant archaeological literature:

1. The Neanderthal presence in Europe around this time “in some way blocked the expansion of modern humans for a few thousand years.” That is, the land was already inhabited, and possibly hostile to new migrants moving in.
2. Maybe ‘Out of Africa’ isn’t right, and the original population of modern humans was actually in the Middle East or more towards India.
3. Modern humans weren’t so keen on heading into the cold of Europe, and instead “they just wanted to hug the nice warm coastline until they got all the way to Australia”.

Milo isn’t convinced with any of those explanations though, bringing up reasons for questioning them. But he does bring up a really interesting point about what the voyage to Australia says about these early humans:

Regardless of where they got to first, one thing that is super interesting is the speed at which human populations expanded in this time. There was something going on culturally, I think, where they just developed this expansion mindset. I really believe that because all the genetic evidence suggests we’re dealing with small populations of humans here, right? Communities of maybe 200 people.So, there was certainly lots of space for them all to live….it’s so hard for us to imagine a world so empty of humans.

And yet, they just kept expanding. That’s what all the evidence suggests. All the genetic evidence suggests that modern people outside of Africa descend from one migration that happened at a specific time. And we really seem to fill the world up very very quickly. I don’t mean to suggest that it didn’t happen this way. This is the the way that all the evidence suggest it happened. But it’s just strange, isn’t it? It’s just strange to expand 16,500 km, including an ocean crossing, before 2,000 kilometers over basically land the whole way.

 Many people in the comments below the video on YouTube shared their own theories about this mystery, but one of the most favourited of those was the simple suggestion “I’d like to think the first humans wanted to see where the sun kept rising, so they kept going east”. So simple but elegant, and putting themselves in the mind of the early human, rather than imposing our modern day and academic ideas as we often so wont to do.

(* The ‘Out of Africa’ video grew out of a larger one Stefan Milo did on “The humans that roamed Australia 50,000 years ago” – it’s super-interesting, so check it out also below.)