Once lush Sahara was home to a surprisingly unique group of humans
sciencealert.com

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142 points

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gmays

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8 days ago

33 comments

antognini ・ 7 days ago

There are around 10,000 megalith structures in the Sahara, most of which were constructed between 3000 and 2000 BC, when desertification was well underway. A large number of these were discovered within the last 20 years using Google Earth. The megaliths come in a wide variety of shapes (there are around 40 categories), but the more sophisticated megaliths have a keyhole shape [1].

Like the better known megaliths in Europe they tend to have astronomical alignments and have been used as funerary monuments. Most of the megaliths point east and have male skeletons, but the few megaliths with female skeletons are oriented towards the west.

(Shameless plug, but for anyone interested in learning more about this sort of thing I have a podcast about the history of astronomy and one of the episodes is about the astronomy of Saharan and Sub-Saharan Africa [3].)

[1]: https://www.researchgate.net/figure/Two-keyhole-structures-i...

[2]: https://songofurania.com/episode/029

  • easytiger ・ 6 days ago

    I'll have to listen to the podcast later but what's the predicate for the determination of their age?

    • antognini ・ 6 days ago

      It has been a while since I looked at the papers but I believe it's carbon dating of the human remains buried at the megaliths.

gaiagraphia ・ 6 days ago

Fascinating looking at the valleys across the Sahara, and imagining rivers once running through them.

There's some fascinating fuel for imagination when you focus on the Sahara, and some very surprising features and remnants of life hanging on. The best example is Siwa, which is an utterly magical place to visit, and feels like a real edge of civiliation.

Climate change is always spoken about with negativity in the mainstream narrative. However, I always wondered whether more heat = more evaporation = more rain = more life; bringing regions like the Sahara (and periphery regions like the Sahel) back to life .

Makes you wonder whether - in an alternate timeline - if a Mongol messenger hadn't been backstabbed, Baghdad hadn't been sacked, and the Islamic world went on to become today's centre of science, finance, development, etc, wohether our current perception of climate change would be seen as a global positive and catalyst for life?

  • kjkjadksj ・ 6 days ago

    The issue with climate change is that we have invested a lot of time and money farming our crops where they are, not in the sahel. So as places such as farming regions in western India fall further into desertification this leads to food insecurity rather than a shifting of labor around what is most suitable to farm given climate change. Some life will in fact “win” given climate change increasing temperatures and metabolism but this won’t be human life. It will be microbial or insect life that will probably go on to plague us with a greater abundance.

begueradj ・ 7 days ago

A large part of the human history remains unknown because the Sahara is very difficult to explore and study. Who knows, maybe entire city states are hidden here and there within endless quantities of sand.

  • user070223 ・ 6 days ago

    Indeed, one great path to finding those lost civilizations is to follow river vallies, Atlas pro[0] says there is no consensus on past rivers/bodies of water as evident by different maps of the region, but one can follow (underwater) river sediment which were deposited to the sea. During oil search such area was found in Cap Timiris, Mauritiania. Satelite radar image of the area from 2015 did reveal those rivers beds, Tamanrasset River seems to be the biggest, with a big drainage basin. Trees and shrubs indeed grow there.

    [0] https://www.youtube.com/watch?v=r-dZj1ZdRtY

  • ls612 ・ 6 days ago

    I would think satellite observations would have thoroughly mapped the immediate subsurface by now regardless of it being hard to explore conventionally.

    • kjkjadksj ・ 6 days ago

      Subsurface? No. Sahara is too vast and research is expensive. They can barely get funding to do that sort of work where they already know there is a Mayan temple under their feet.

  • pjmlp ・ 7 days ago

    Most likely enough stuff for some adventure movies, the kind of wearing hats or summer shorts heroes. :)

  • chairmansteve ・ 6 days ago

    And... sea levels were a lot lower 20,000 years ago.

csdvrx ・ 7 days ago

If you find that interesting, read about the African Humid Period: https://en.wikipedia.org/wiki/African_humid_period

The present day situation is fascinating: https://en.wikipedia.org/wiki/African_humid_period#Present-d... : there is an ongoing "greening" which seems caused by global warming and CO2 increases!

However, a 2003 study estimated only 45% of the Sahara could be covered by vegetation, and a 2022 study found that it may not be sufficient to start another AHP: it just "lowers the threshold for orbital changes to induce Sahara greening"

singularity2001 ・ 7 days ago

One of the few cases were indigenous were not replaced by neolithic newcomers but simply adopted their technology

User23 ・ 7 days ago

I believe current evidence is that the Berber peoples have been in North Africa at least 12,000 years.

inetknght ・ 7 days ago

So this is only loosely related to the posted article, but I found the "great green wall" project from the U.N. to be super interesting. It makes me wonder if the same concepts can (and should?) be applied to other deserts, such as the American midwest.

https://www.youtube.com/watch?v=4xls7K_xFBQ

  • teruakohatu ・ 7 days ago

    According to Wikipedia the wall was reported to be 15% complete in 2019, but found to be actually just 4% complete in 2020, then reportedly 18% in 2022 and 30% last year.

    Given that is started over 15 years ago and there seems to be significant differences between what countries report and what was actually done when the UN commissioned a report in 2020, it’s anyone guess what progress has actually been made.

    In my opinion it’s probably around 10% or low teens now and would be lucky to double that by the end of the project in 2030.

    The project will probably report a much higher number when it actually finishes.

    Hopefully it will be funded to continue. It’s probably one of the most important global events environmental projects of the 21st century.

    https://en.m.wikipedia.org/wiki/Great_Green_Wall_(Africa)

    • CobaltFire ・ 7 days ago

      If you dive into the report that states the 4% number it’s measuring something entirely different than the other numbers, and agrees with the 18% in 2022 number.

      Specifically the higher percentages are in reported land reclamation out of the 100Ha goal, which was at 17.8Ha in the 2020 report. The 4% is a composite of all targets for the 2030 goals, of which the GGB is only one metric.

      Be careful in taking these types of articles at face value.

  • BurningFrog ・ 7 days ago

    Big bold projects by African dictators to leapfrog the economy has a truly atrocious track record. UN involvement makes it even worse.

    That said, if it will work long term in some of the countries, that would be great news.

    I'm glad that it's still possible to destroy an ecosystem in order to replace it with something better. That would never fly in the US. We also have no need to produce more food, and our deserts are mostly beloved natural wonders.

    • inetknght ・ 7 days ago

      > Big bold projects by African dictators to leapfrog the economy has a truly atrocious track record.

      Perhaps, yes. But the Sahara is expanding and reducing the livable area of land in those countries. That can only add to economic strife. On the other hand, building a green wall reduces or eliminates the expansion of the desert and also increases the amount of food available to those countries. I believe that would help reduce the strife between those countries. Yes there's risk of abuse but I think everyone wants to be self-sufficient and anything towards that is laudable.

      > UN involvement makes it even worse.

      Can you explain that further? The U.N. is terrible at directly preventing conflict (just look at Ukraine) but I think it has a decent track record of helping countries build their infrastructure.

      > I'm glad that it's still possible to destroy an ecosystem

      What? You think building green savannahs is destroying an ecosystem?

      > That would never fly in the US.

      I don't know about never but I do think it'd certainly be difficult.

      > We also have no need to produce more food

      I disagree. I think we have no appetite to produce more food right now, but the way we're currently growing food is rather asinine.

      > and our deserts are mostly beloved natural wonders.

      Mostly, yes. But I think there's plenty of deserts that aren't quite natural wonders.

      • Xorakios ・ 6 days ago

        The Sahara has generally been contracting for the last few decades as the "greener" Sahel band expands north due to higher average rainfall (individual years vary, and the effect is stronger in the west than the east).

        A Google search will likely list articles citing the 2018 study from UofMaryland that showed approximately a 10% increase in the Sahara's area from 1902-2012, ignoring the portions of that study that said that breaking down by decade showed a reversal in the 1980's. https://journals.ametsoc.org/view/journals/clim/31/9/jcli-d-...

        Google maps timeview has a fun animation if you search for Sahara Desert. https://earthengine.google.com/timelapse/

      • rayiner ・ 7 days ago
        ・ 4 more

        > Can you explain that further? The U.N. is terrible at directly preventing conflict (just look at Ukraine) but I think it has a decent track record of helping countries build their infrastructure

        Some UN agencies are very effective, particularly the ones that are basically run by Americans, such as the World Bank. The more third world countries participate in any given agency, the more of a tire fire it is.

        • MomsAVoxell ・ 7 days ago
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          Could you be more imperialist?

          Let’s see some examples of well-run UN agencies ‘staffed by Americans’. I guarantee you they are a cesspool of corruption and bigotry.

          • rayiner ・ 6 days ago

            Incorrect. Source: am a third worlder, my dad was exiled from the third world for being too conscientious and punctual and spent his career working with UN agencies.

    • graemep ・ 6 days ago

      > Big bold projects by African dictators to leapfrog the economy has a truly atrocious track record.

      This is a multinational project with clear benefits.

      It is very different from flashy projects like airports no one uses.