
Saharan 'carpet of tools' is earliest known human-made landscape - curtis
http://www.sciencedaily.com/releases/2015/03/150311160254.htm
======
curtis
The summary:

> A new intensive survey of the Messak Settafet escarpment, a massive outcrop
> of sandstone in the middle of the Saharan desert, has shown that stone tools
> occur "ubiquitously" across the entire landscape: averaging 75 artefacts per
> square meter, or 75 million per square kilometer.

I'm having trouble wrapping my head around these numbers. But if you figure a
population density of maybe 1 hominin per every 10 square kilometers times
hundreds of stone tools per hominin per year times 1 million years, maybe the
numbers work out. I'm kind of wondering if they're counting discarded flakes
from stone tool production and not just the stone tools themselves.

~~~
1timeUse
That is correct: in the field _every_ object that was created by homo sapiens
sapiens is counted as a separate artifact. So each flake / discard is also
counted - when flint knapping, there will be many such artifacts per finished
edge.

A more interesting question to ask:

Why?

 _But around 10,500 years ago, a sudden burst of monsoon rains over the vast
desert transformed the region into habitable land._

 _This opened the door for humans to move into the area, as evidenced by the
researcher 's 500 new radiocarbon dates of human and animal remains from more
than 150 excavation sites._

 _" The climate change at [10,500 years ago] which turned most of the [3.8
million square mile] large Sahara into a savannah-type environment happened
within a few hundred years only, certainly within less than 500 years," said
study team member Stefan Kroepelin of the University of Cologne in Germany._

[http://www.livescience.com/4180-sahara-desert-lush-
populated...](http://www.livescience.com/4180-sahara-desert-lush-
populated.html) 2006

 _The findings of this study are that the sedimentological and geochemical
properties of the lake sediments confirm that the Sahara has been drying
slowly from six thousand years ago to reach the present day conditions around
1,100 years ago,” said lead author Pierre Francus, professor at the National
Institute of Scientific Research in Quebec, Canada..._

 _Climate scientist Gavin Schmidt, of NASA’s Goddard Institute for Space
Studies, explained that around 8,000 years ago, the Earth’s orbit was slightly
different to how it is today. The tilt changed from around 24.1 degrees to the
present-day 23.5 degrees._

[http://www.astrobio.net/news-exclusive/how-earths-orbital-
sh...](http://www.astrobio.net/news-exclusive/how-earths-orbital-shift-shaped-
the-sahara/)

So, about 11k years ago the Sahara suddenly burst into life, and about 8k
years ago axial tilt changes started the process of removing this burst.

The Sahara is also linked to fertility rises in rainforests in South America.

~~~
walterbell
Thanks, this was interesting:

 _" The changes in the Earth’s orbital tilt and precession (or the wobbling
motion) occur because of gravitational forces emanating from other bodies in
the solar system. To understand exactly what happens, picture a spinning top
when it is slightly disturbed. Just like a top, the Earth too wobbles slightly
about its rotational axis. This tilt changes between roughly 22 and 25 degrees
about every 41,000 years, while the precession varies on about a 26,000-year
period. These cycles have been determined by astronomers and validated by
geologists studying ocean sediment records. _"

Are there any recommended references on this 26,000 year cycle?

~~~
NathanKP
Here is a pretty decent documentary about it:
[https://www.youtube.com/watch?v=2OVAkMrdeKI](https://www.youtube.com/watch?v=2OVAkMrdeKI)

~~~
walterbell
Thanks!

------
allannienhuis
[http://www.cam.ac.uk/research/news/saharan-carpet-of-
tools-i...](http://www.cam.ac.uk/research/news/saharan-carpet-of-tools-is-the-
earliest-known-man-made-landscape) The source I believe.

------
ridgeguy
I've gotten used to the frequent feeling of "everything you know is wrong" \-
or at least, more complicated - as more fields of investigation become
computation-friendly and hop on the Moore's Law Express.

But once in awhile, something like this comes along and leaves me with skin
abrasions on my dragging lower jaw.

I'm gobsmacked by the idea that I could stand in the middle of this escarpment
and that the ground everywhere, as far as I could see, would be littered with
a million years' work of my near ancestors and cousins.

Wow.

